Literature: A-K ; L-Z ; subject area
Compiled by: Julian Thorpe
Online Review Paper
The Peptidyl-Prolyl Cis-Trans Isomerase Protein Pin1:
a key player in the molecular pathogenesis of Alzheimer’s disease?
Julian Robert Thorpe
School of Biological Sciences, University of Sussex, Falmer, Brighton
BN1 9QG, East Sussex, U.K.
Abstract
1. Pin1 Protein
Table 1
2. Involvement of Pin1 Protein in Alzheimer’s Disease
2.1 Molecular pathogenic events leading to plaque and
tangle formation
Figure 1
2.2 Pin1 provides a link between plaques and tangles
Figure 2
Figure 3
Figure 4
Figure 5
2.3 Tau Hyperphosphorylation in AD
2.3.1 Kinases
2.3.2 Phosphatases
2.4 Pin1 and mitotic events in AD
2.5 Pin1 depletion as a contributory factor in neuronal
apoptosis
3. Conclusions and Future Perspectives
Acknowledgments
Literature Cited
Pin1 protein is a peptidyl-prolyl cis-trans isomerase that binds to a specific motif of a phosphorylated serine or threonine preceding a proline. Its target proteins include a subset of mitotic and nuclear proteins involved in cell cycle control and transcriptional regulation, and others with roles in endocytosis, translation and control of cell size, and apoptosis. The isomerising action of Pin1 can modulate target protein conformation and mediate their dephosphorylation, so its influence at the interface of specific kinase and phosphatase activities may therefore exert a control over a range of cellular activities. Pin1 has recently been implicated in Alzheimer’s disease (AD); it has been demonstrated to bind to the amyloid protein precursor and to phosphorylated tau in tangles. In binding to the latter in the neuronal cytoplasm, nuclear Pin1 levels are depleted. This review seeks to draw together the various demonstrated and potential interactions of Pin1 protein with its upregulated target proteins in the progression of AD. An attempt is made to suggest how nuclear Pin1 depletion and mitotic activation in AD might lead to nuclear instability and apoptosis and that this depletion might be a unifying, contributory factor towards neuronal cell death in both AD and the tauopathies.
Pin1 is a member of the parvulin family within the peptidyl-prolyl cis-trans
isomerase (PPIase) group of proteins and was the first human parvulin
to be found (88). PPIases are chaperone proteins with a range of functions
that include modulating the assembly, folding, activity and transport of
essential cell proteins (49,124) at different subcellular sites, reflecting
their target protein diversity (68,121). They can additionally regulate
intracellular signalling, direct intracellular transport, influence transcription,
cell cycle progression and apoptosis by altering protein bioactivity or stability
(58,159).
Pin1 is an 18kDa protein with a C-terminal PPIase domain and an N-terminal
WW domain (88). The latter domain binds a specific motif of a phosphorylated
serine or threonine residue preceding a proline (Ser/Thr-Pro; 91,125,147)
and can catalyse the cis-trans isomerisation of such proline-containing
peptides (133). It is predominantly nuclear (88,140) and is a mitotic regulator
(87,88) whose activity is required for the DNA replication checkpoint (153).
In addition to binding to targets of the mitotic phosphoprotein monoclonal-2
antibody (MPM-2), Pin1 interacts specifically with, and regulates the activity
of, a subset of mitotic and nuclear proteins in a phosphorylation-dependent
manner (127,159). Pin1 targets not only include nuclear proteins involved
in control of the cell cycle, transcription and DNA supercoiling, but also
other non-nuclear targets with roles in apoptosis, endocytosis, translation
and control of cell size, maintenance of the cytoskeleton and neuronal function
(see Table 1). In yeast and mammalian cells, the interaction of Pin1 with
its phosphorylated mitotic targets regulates entry and progression of cells
through the cell cycle (44,88,89). Indeed, in HeLa cells, Pin1 depletion
causes mitotic arrest and apoptosis, whilst overexpression results in G2
phase arrest (88). Additionally, very recent work has revealed that Pin1
is overexpressed in breast cancer (157); it was suggested that this overexpression
promotes oncogenesis through the interaction of Pin1 with c-Jun, thereby
increasing the latter’s transcriptional activity, resulting in increased
cellular levels of cyclin D1.
| Pin1 Target Proteins | ||
| Target | Role | Ref. |
| NIMA kinase (never in mitosis, gene a) | cell-cycle kinase | 88 |
| Wee1 | cell-cycle kinase | 127 |
| Plk1 (polo-like kinase 1) | cell-cycle kinase | 25, 127 |
| Myt1 | cell-cycle kinase | 127, 152 |
| Cdc25 | cell-cycle protein phosphatase | 25, 127 |
| Cdc27 | cell cycle protein: anaphase initiation | 127 |
| Topoisomerase IIa | affects DNA supercoiling | 159 |
| RNA polymerase II | transcription initiator | 3, 100 |
| c-Jun | mediates transcriptional regulation | 157 |
| NFAT (nuclear factor of activated T cells) | transcription factor | 86 |
| Bcl-2 | suppressor of apoptosis | 110 |
| Rab4 | endocytotic protein transport regulator | 45 |
| p70/p85S6K (ribosomal protein S6 kinases) | control of cell size; translation | 159 |
| APP (amyloid protein precursor) | neuronal cell surface protein | 29 |
| tau | microtubule-associated protein | 90 |
The phosphorylation-dependent
prolyl isomerization by Pin1 has been suggested to be a novel post-translational
cell cycle regulatory mechanism which organises the phosphorylated proteins
into a defined set of mitotic structural modifications (87). Zhou and
colleagues have recently demonstrated an example of this organisational
influence of Pin1. They have shown that the PPIase activity of Pin1 introduces
kinks into the peptide chains of its targets (166) and, more specifically
(165), that the cis-trans isomerase action of Pin1 upon Cdc25C (and tau:
see Section 2.2) facilitates its dephosphorylation by the protein phosphatase
2A (PP2A). Indeed, the latter’s activity is conformation-specific for the
trans-phosphorylated Ser/Thr-Pro isomer in target proteins.
Thus, the isomerising
action of Pin1 may take place at the interface of specific kinase and
phosphatase activities. This may provide a novel mechanism regulating
the dephosphorylation of specific targets in subcellular compartments,
thereby mediating the control of a range of cellular activities. The potential
role of Pin1 in Alzheimer’s disease (AD) is discussed below.
AD is a progressive neurodegenerative disease that affects the higher order processing cortical regions of the brain, leading to a slow but progressive deterioration in cognitive ability (dementia). Recently, Pin1 protein has been shown to have an intimate involvement in the formation of the two hallmark lesions of AD, the extracellular neuritic plaques which contain dystrophic neurites and aggregates of beta-amyloid (A beta) protein (29) and the intraneuronal neurofibrillary tangles (90).
Although the majority
of research evidence appears to suggest that deposition of (extracellular)
beta-amyloid plaques precedes (intraneuronal) tangle formation in AD-affected
neocortical areas, there is still some debate about how plaques and tangles
interrelate. Many researchers hold the view that fibrillar amyloid plaques
are directly toxic to neurons and thereby initiate a cascade of events
leading to cytoskeletal disruption, tangle development, loss of synapses
and, ultimately, neuronal cell death and dementia. This is the so-called
‘beta-amyloid cascade theory’ of AD (59,126). However, others dispute this
notion of such a ‘linear’ chain of events as, for example, tangles may occur
in the absence of plaques in the class of neurodegenerative diseases known
as ‘tauopathies’ (79). Additionally, some AD studies have revealed no correlation
between these two lesions: for example, a thorough systematic study of the
olfactory bulb in AD and normal brain yielded no correlation between A beta
deposition and tangle formation (70). Furthermore, very recently, a view
has emerged that the neurotoxicity of A beta may be plaque-independent (53,102,104),
an observation which might serve to clarify this latter dispute. Such studies
indicate that AD is not always necessarily as linear and uni-directional
as the ‘cascade’ theory implies; future research on the recently-discovered
tau mutations (26) should shed important new light on our understanding of
the progression of the disease.
The following
description (and see Fig.1) is nonetheless based upon the ‘beta-amyloid
cascade’ theory of AD. As stated, although not all subscribe to this theory,
it is a useful framework on which to base a description of the various aspects
and events of the disease. AD is initiated by factors that may be genetic
or environmental in nature. The former include mutations in the amyloid
protein precursor (APP) gene on chromosome 21 and in the two presenilin
genes on chromosomes 14 (presenilin-1) and 1 (presenilin-2) which
give rise to the familial early-onset forms of the disease (23). In the
vast majority of cases, however, AD is of the sporadic, late-onset form brought
about by the so-called ‘susceptibility’ apolipoprotein E gene (allelic
variant 4 on chromosome 19; 95) or by mitochondrial mutations and polymorphisms
(108). Environmental risk factors are generally considered to be more contentious,
but may include head trauma (116) and heavy metals such as aluminium (21,40,67),
iron (115) and zinc (109).
All the above
risk factors, either directly or indirectly, give rise to effects upon the
proteolysis of the APP protein. APP is a neuronal cell surface protein,
the precise function of which is presently unknown. While it is usually rapidly
degraded in healthy neurons (76), aberrant proteolysis and/or reduced clearance
of the proteolytic products of APP occurs in AD. This latter leads to the
production of novel proteolytic products which include the A beta peptides
(51). APP proteolysis is mediated by alpha-, beta- and gamma-secretases (proteases),
on which much recent research attention has been focused (14,57,60,61,73,105,144,151),
especially in regard to the hypothesis that the gamma-secretases might
actually be the presenilins (82,154,155,158).
A build-up of
secreted A beta peptide then accumulates extracellularly and subsequent
fibrillogenesis of the peptide results in plaque formation. Oxidative stress
effects of the soluble and fibrillar A beta (117,145) elicit an inflammatory
response (17). Activated microglial cells (20,156) and the release of proinflammatory
cytokines (137) promote inflammation and invasion of the plaques by astrocytes
(2) that ‘mature’ the plaques into the ‘neuritic’ plaques symptomatic of AD
brain.
Within the neurons
(Fig. 2), the deleterious effects of oxidative stress, cytokine release
by microglia and, also perhaps, intra-neuronal effects of APP misprocessing
(10) and physically-damaging effects of adjacent neuritic plaques (31,148),
combine to produce aberrant (increased) kinase and (decreased) phosphatase
activities. The ensuing hyperphosphorylation of the microtubule (Mt)-associated
protein tau results in its dissociation from the Mt (65). The maintenance
and assembly of the latter, normally mediated by tau, is compromised so
that Mt fragmentation follows. The overall end-product of this cytoskeletal
breakdown are the cytoplasmic (perikaryal) neurofibrillary tangles, which
are ultimately composed predominantly of hyperphosphorylated tau (p-tau).
Synaptic loss and cell death follow, eventually leading to dementia.
Figure 1: Molecular Pathogenic Events of AD
A diagrammatic representation of the molecular pathogenic events associated
with AD.
The recent finding that Pin1 binds to APP (29), alongside the earlier demonstration of its binding to p-tau in the neurofibrillary tangles of AD-affected neurons (90), means that the protein provides a link between the development of the two major histopathological hallmark features of this disease, the plaques and tangles. As outlined above, aberrant proteolytic processing of APP leads to the secretion and ultimate aggregation of A beta peptides into extracellular plaques in AD brain, whilst p-tau is the major component of the tangles within the perikaryon of affected neurons.
Figure 2: Involvement of Pin1 in Neurofibrillary Tangle Formation
and Apoptosis
Diagrammatic representation of the probable biochemical
pathways and interactions associated with Pin1 involvement in tangle formation
within AD-affected neurons. Phosphorylation of tau (p-tau) leads to its
dissociation from tubulin (crossed black arrows). Cis-trans isomerisation
of p-tau by Pin1 normally mediates its dephosphorylation by (trans p-tau
specific) PP2A and thence its ability to re-associate with tubulin; however,
insufficient levels of soluble Pin1 (and down-regulation of PP2A) creates
a pool of p-tau which results in tangle formation. Redirection of Pin1 to
the neuronal cytoplasm might contribute to apoptosis through depletion of
nuclear Pin1 (e.g. through lack of binding to Cdc25 [see 2.4]; crossed black
arrows) or binding to cytoplasmic Bcl-2 (see 2.5). (Numbers in parentheses
refer to References)
In binding to the large accumulations of p-tau in tangles, Lu et al. showed that Pin1 is redirected from the nucleus to the cytoplasm of AD neurons (90; and see Fig. 2). In vitro methods revealed that Pin1 bound to the phosphorylated threonine 231 (pThr 231) of p-tau and tissue extractions of Pin1 protein showed that it becomes sequestered within tangles. Furthermore, this leads to a shortfall of available soluble Pin1 protein. Results from this author’s laboratory have confirmed the redirection, shortfall and binding to tangles of Pin1 at the transmission electron microscope level (141). Quantification of endogenous Pin1 immunolabelling (Fig. 3, white bars) corroborated that the protein is less preferentially nuclear and becomes more cytoplasmic in distribution in AD-affected neurons; it is also associated with tangles (Fig. 4A & B).
Figure 3: Endogenous Pin1 Immunolabelling and Exogenous Pin1 Binding
to Normal and AD Neurons
Immunogold labelling transmission electron microscopy
results from normal and AD (frontal lobe) neurons. Sections incubated either
in buffer alone (to reveal endogenous Pin1 levels: white bars [End]) or
in 20mg/ml recombinant Pin1 protein (to reveal endogenous plus exogenous
Pin1 binding levels: black bars [End+Exo]) before being immunolabelled with
goat anti-Pin1 antibody followed by rabbit-anti-goat 10nm gold probe. The
grey bars represent net levels of exogenous Pin1 binding (derived by subtracting
label density after buffer incubation from the label density after recombinant
Pin1 protein incubation). Nu = nucleus; Cyt = cytoplasm; Tau = tau-immunoreactive
tangles. Data = gold particles/mm2 (Data from Thorpe et al., 2001).
Figure 4: Examples of Tau-Immunoreactive Neurofibrillary Tangles
Examples of neurofibrillary tangles in AD (A and
B) and frontotemporal dementia (FTD) brain (C). AD brain immunolabelled
with a polyclonal anti-tau antibody followed by 10nm goat anti-rabbit gold
probe. B is an enlarged view of the tau-positive tangle region within the
neuron in A (marked by * ) (A and B reproduced, with permission, from Thorpe
JR, Morley SJ, Rulten SL: Utilising the Peptidyl-Prolyl Cis-Trans Isomerase
Pin1 as a Probe of its Phosphorylated Target Proteins: Examples of Binding
to Nuclear Proteins in a Human Kidney Cell Line and to Tau in Alzheimer’s
Diseased Brain. Journal of Histochemistry and Cytochemistry 49: p.104, 2001).
FTD brain immunolabelled with AT8 monoclonal anti-human paired helical filament
(PHF)-tau antibody followed by 10nm goat anti-mouse gold probe. Note complete
absence of non-specific labelling over the nucleus (Cairns NJ, Thorpe JR,
unpublished data). N = nucleus; bars = 100nm.
Increased levels
of immunolabelling (compared with endogenous Pin1 levels and with normal
brain) after exogenous Pin1 binding reflect the greater amounts of
(unbound) phosphorylated Pin1 target proteins in these neurons (especially
in the tangles; Fig. 3, black bars). Net levels of Pin1 binding derived
from these results show greatly-increased amounts of binding to AD (compared
to normal) neurons and evidences a shortfall of available Pin1 protein in
all subcellular compartments (Fig. 3, grey bars). Lu et al. suggested that
depletion of nuclear Pin1 might contribute to cell death (as in HeLa cells;
88). Significantly, they also showed that Pin1 could restore the ability
of p-tau to bind Mt and promote their assembly in vitro: a possible future
therapeutic use of Pin1 was therefore postulated (90).
On reporting
the binding of Pin1 to APP, Davies et al. (29) suggested that pathogenic
changes to APP and tau might both be triggered by a single underlying event:
pThr 231 on tau has a conformation that is similar to that of pThr 668
on APP. Additional experimental corroboration was provided by immunostaining
of AD brain tissues which showed that pThr 668 APP occurred in the lysosomal
compartment specifically of those hippocampal and cortical neurons which
were also positive for pThr 231 tau. Importantly, it was speculated that
Pin1 binding to APP might result in increased A beta production. Indeed,
NMR spectroscopy has shed new light on the interactions of the cytoplasmic
tail of APP with intracellular signalling and A beta peptide proteolytic
factors (119). The serine residue at 655 and the threonine residues at 654
and 668 are known to be phosphorylated in vivo and may be involved with
regulating these interactions. Backbone dihedral angle changes were symptomatic
of hydrogen bond formation and the biggest conformational change occurred
upon phosphorylation of Thr 668, the Pin1-binding motif (29); they concluded
that the most likely candidate kinase for this phosphorylation in vivo was
cdk5. Their results showed that the unphosphorylated T668 is in a stable
trans conformation and that its phosphorylation produced an equilibrium of
cis and trans isomers. They proposed a model whereby this could initiate
a regulatory mechanism in which cytosolic binding factors were isomer-specific.
This opens up a situation whereby the isomerase action of Pin1 could mediate
increased APP proteolysis by trans-conformation specific secretases (in
similar manner to the trans-conformation specific dephosphorylation of
tau and Cdc25C by PP2A [165; and see Section 1.]; see Fig. 5).
Figure 5: The Involvement of Pin1 in Plaque Formation
Diagrammatic representation of a proposed mechanism
whereby the cis-trans isomerisation of phosphorylated APP (at T668) by Pin1
might mediate increased A beta production through elevated proteolysis by
trans-phosphorylation conformation-specific secretases. Pin1 interactions
with phosphorylated rab4-GTP might also contribute to APP misprocessing
(see Section 2.2). (Numbers in parentheses refer to References)
Another Pin1 target protein that is upregulated in AD and might influence APP proteolytic processing is the endocytotic protein transport regulator, rab4 (22). Rab4 is phosphorylated by p34/cdc2 and regulates protein transport through the early endosomes when activated by GTP binding. As endocytotic protein transport is inhibited during mitosis, when phosphorylated rab4(-GTP) has been shown to be bound by Pin1 (45), this might well have implications with regard to the spurious mitotic activation in AD-affected neurons; see Section 2.4). The distribution of rab4 was found to be more cytosolic and these authors suggested that phosphorylation of rab4 inhibits both the recruitment of rab4 effector proteins to early endosomes and the docking of rab4-containing transport vesicles.
In AD, perturbations to the balance of kinase and phosphatase activities lead to the inappropriate hyperphosphorylation of various proteins. Hyperphosphorylated tau proteins have been shown to accumulate in neurons prior to tangle formation, suggesting that an imbalance of protein kinase and phosphatase activities is an early event in the disease progression (16). This latter would therefore also create a cytoplasmic ‘sink’ for nuclear Pin1 protein early in AD.
Cyclin-Dependent Kinase 5 (Cdk5; 94,130) is abundant in brain tissue and has been shown to associate with tau (and neurofilament and tubulin proteins; 146). With its neuron-specific activator p35, Cdk5 is required for neuritic outgrowth, cortical lamination and synaptogenesis in cultured rat brain neurons (142). In AD, p25, a neuron-specific proteolytic cleavage product of p35, accumulates in the brain and promotes activation and mislocalization of Cdk5 (111). It should be noted, however, that others have recently suggested that the conversion of p35 to p25 is a post-mortem degradation event mediated by calpain (138). Other experiments on cultured primary cortical neurons have revealed that A beta, excitotoxins, hypoxic stress and calcium influx induce p25 production; calpain (a calcium-dependent cysteine protease) was found to cleave p35 to release a product corresponding precisely to p25, while inhibition of Cdk5 or calpain reduced cell death in A beta-treated neurons (78).
The p25/Cdk5 kinase has been demonstrated to hyperphosphorylate tau (81), leading to cytoskeletal disruption and the apoptosis of primary neurons (78,94). It has subsequently been shown that phosphorylation of serine residues 396 and 404 by Cdk5 is primarily responsible for the mediation of tau's inability to polymerise tubulin (36). Cdk5 has been shown to be preferentially and consistently associated with tangles (160). Also, increases in its immunoreactivity within pre-tangle and early stage tangle-containing neurons in AD brain have been reported (113). Examination of neuronal Cdc2-like kinase (p25/Cdk5) activity in prefrontal and cerebellar cortex from AD and control subjects (77) has provided further corroboration. The ratio of p25/Cdk5 activity in prefrontal versus cerebellar cortex was higher in AD than control, a finding consistent with a role for this kinase in the pathogenesis of tangles in AD (prefrontal regions being tangle-rich and cerebellar regions almost tangle-free in AD).
Work on model systems has also pointed to a role for Cdk5 in AD tau hyperphosphorylation. The tau protein kinase II system (TPK II; involving Cdk5 and p35) has been studied in cultured rat hippocampal cells (6). This work showed that fibrillary A beta increased Cdk5 activity, while a Cdk5 inhibitor and an (Cdk5) antisense probe protected the cells from A beta-induced neurotoxic damage. This group’s later work (5) has correlated the increased Cdk5 activity with changes in both the phosphorylation patterns and intraneuronal distribution of tau protein. The effects on Cdk5 were shown to be post-translational. They therefore concluded that Cdk5 plays a major role in the molecular path leading to the neurodegenerative process. Also, a transgenic mouse model overexpressing human p25 showed a resultant hyperphosphorylation of tau (and neurofilament proteins) by Cdk5 (1). This latter was accompanied by cytoskeletal disruption.
Glycogen Synthase Kinase-3 (GSK-3; also known as tau protein kinase I [TPKI]) is a kinase with a well-known role in glycogen metabolism and activation of transcription factors that can also phosphorylate tau (66). GSK-3 beta (but not GSK-3 alpha) has been shown to be increased in pre-tangle (112) and closely-associated with the p-tau of tangle-bearing neurons (160). GSK-3 beta has been shown to be equivalent to TPKI and, with TPKII (consisting of a novel 23 kDa protein activator and CDK5), could account for most major phosphorylation sites of fetal and PHF(paired helical filament)-tau (64). GSK-3 beta (and TPKII) was associated with tangles in vivo and it was suggested to be important in the formation of neural networks in the neonatal brain. Using primary cultures of embryonic rat hippocampus, it was also demonstrated that A beta treatment induced GSK-3 beta activity, extensive phosphorylation of tau and cell death. GSK-3 beta also interacted with pyruvate dehydrogenase (PDH), thereby reducing levels of acetyl-CoA, essential for (the neurotransmitter) acetylcholine synthesis. Further corroborating in vivo evidence of GSK-3 beta’s potential role in AD has come from research on transgenic mouse models overexpressing this kinase (92,132), which evidenced tau hyperphosphorylation and associated astrocytosis, microglial activation and cell death in hippocampal neurons.
The MAP kinase pathway is one branch of the complex cellular regulatory machinery, the aberrant activation of which may contribute to the hyperphosphorylation of tau associated with AD. MAP kinases (24) are serine-threonine kinases that have a significant role in hormonal signal transduction. They are activated by MAP kinase kinase (MAP kinase/ERK kinase: MEK). MEKs are highly specific for ERK1 and 2. MEKs are themselves activated by MEK kinase. The latter and MAP kinases are highly-expressed in the brain, with ERK1 mRNA apparently enriched in astrocytes and glia. ERK2 has been found in neuronal processes, tangles and plaques (143).
The MAP kinases phosphorylate many key regulatory proteins such as other protein kinases, transcription factors (e.g. Egr1; 54), membrane enzymes and cytoskeletal proteins (including tau; 38). It has also now been demonstrated (in PC12 cells; 54) that activation of the MAP kinase pathway by nerve growth factor induces p35, the neuron-specific activator of Cdk5. This induction is mediated via the transcription factor Egr1. Significantly, MAP kinases can phosphorylate tau in up to 15 of the 17 Ser-Pro or Thr-Pro motifs of the largest human isoform and have been seen to be associated with complexes of tau (and neurofilament and tubulin proteins; 146). A secreted fragment of the amyloid protein precursor (APP) can stimulate MAP kinase in a ras-dependent manner, leading to tau phosphorylation (69). The results suggested an interaction of tau with actin in addition to microtubules. On this note, it has been suggested (164) that, in AD, amyloid fibrils may activate cell death signalling pathways involving the neurotrophins which regulate apoptosis via protein kinase cascades (inc. the MAP kinase pathway).
Another potential route for tau phosphorylation is via activation of protein kinase cascades by the 14-3-3 protein family. The latter are highly conserved and exist as seven isoforms, which regulate diverse cellular processes (42). They have been shown to be present in tangles (75), while the 14-3-3 zeta isoform is associated with tau in brain extract and profoundly stimulates cAMP-dependent protein kinase-catalysed in vitro phosphorylation on Ser(262)/Ser(356) located within the microtubule-binding region of tau (56). It was suggested that 14-3-3 (zeta) is a tau protein effector involved in abnormal tau phosphorylation.
As well as the
upregulation of the protein kinases, a concomitant downregulation of protein
phosphatases (PP) during AD progression has also been demonstrated, which
would contribute to the aberrant hyperphosphorylation of neuronal proteins.
In regard to research on human brain, a neuron-specific reduction in the
levels of both catalytic and regulatory PP2A mRNA in the hippocampus of AD
brain has been shown (150). Also, reduced activity (but not protein
levels) of PP2B (calcineurin) in AD frontal cortex has been correlated with
the presence of tangle pathology but not with (diffuse or neuritic) plaques
(83). Expression data for PP2B in prefrontal cortical AD tissue has also
revealed a great reduction compared with control brain tissue (122). Additionally,
and significantly, the PP2B inhibitory gene known as DSCR1 (“Down Syndrome
Candidate Region”; 43) is chronically overexpressed in AD compared with normal
brain; these data were reinforced by cell culture experiments, which revealed
that A beta could directly induce this increased expression (35).
Iqbal and co-workers
(11,13,47,48) have carried out a series of investigations on a rat model
system (forebrain or metabolically-active brain slices). PP2A and PP2B
were both shown to regulate the dephosphorylation of tau at Ser262, 356,
396 and 404, with PP2A alone dephosphorylating Ser198, 199, and 202. PP1
was demonstrated to indirectly upregulate tau dephosphorylation via regulating
the activities of GSK-3, Cdk5 and cdc2 kinases. Selective inhibition of
PP2A activity led to the AD-like hyperphosphorylation and accumulation of
tau (in pyramidal cortical and hippocampal neurons), while inhibition of
PP2B had no such effects. Their most recent work has implicated CaMKII activity
in the process of tau hyperphosphorylation at Ser262 and 356. CaMKII was
shown to be regulated mainly by PP2A, so that decreased activity of the latter
(and PP1) increases tau pathology via the resultant promotion of CaMKII activity
(12).
Neurons of the
adult brain are normally considered to be in a ‘terminally-differentiated’
state. However, accumulation of mitotic phosphoepitopes, via the spurious
re-expression and activation of Cdc2/cyclin B (the mitotic phase regulating
kinase), and associated cell cycle-related proteins has been shown in AD
and has attracted much research interest (8,9,19,22,32,33,46,55,62,63,103,149).
It has been described as an ‘interrupted’ mitotic process which leads to
associated cytoskeletal abnormalities (including tangle formation) and, ultimately,
apoptosis (7,34,98).
The cellular
signal transduction pathways initiating these cell-cycle events are triggered
by the various deleterious effects of AD upon the neurons (outlined in Section
2.1; Fig. 1). The upregulation of the MAP kinase phosphorylation cascade
(described in Section 2.3.1) is an obvious example, being a state, which
would normally imply activation by mitogens and signal entry into the cell
cycle. Specific examples of cell-cycle proteins that have been demonstrated
to be elevated in AD, and which are also known Pin1 targets, are Cdc25A (32)
and Plk1 (55). The Cdc25 phosphatases play a key role in cell-cycle progression
by activating the cyclin-dependent kinases, including cdc2/cyclin B. Plk1
(74) is a regulator of Cdc25. Cdc25A is associated with both neuritic plaques
and tangles and its tyrosine dephosphorylating activity is elevated (32).
Also, as this phosphatase is activated by phosphorylation by cdc2/cyclin
B, the Cdc25A exhibited increased mitotic phosphoepitope-specific antibody
(MPM-2)-reactivity, and colocalized with the MPM-2 immunoreactivity in AD
neurons. These data suggest that Cdc25A participates in mitotic activation
during neurodegeneration.
It has been shown
that Pin1 may modulate Cdc2/cyclin B, and thus cell cycle control, through
its interactions with Cdc25 and Plk1 (25). Although the mitotic activation
of Cdc25 is not fully understood, certain conclusions have been drawn by
Stukenberg and Kirschner (133) from their most recent work, including, of
particular relevance to this review, the effect of (>95%) Pin1 (immuno-)depletion.
This study demonstrated that Pin1 could produce conformational changes
in Cdc25 (as previously reported; 165), but, additionally, they showed that
it was acting catalytically. Pin1 could either activate or inhibit Cdc25
phosphatase activity, dependent upon its phosphorylation status: if phosphorylated
by Cdc2 alone (as in lag phase), Cdc25 is inhibited by Pin1, but, if phosphorylated
by both Cdc2 and Plx (as in G2/M transition), Pin1 increases the phosphatase
activity of the protein. It was this latter activation that was suggested
to be mediated by a conformational change in the Cdc25 protein, with the
experimental data indicating a cis-trans isomerization of proline residues
in the folded Cdc25 protein. Depletion of Pin1 halted the full activation
of Cdc25, with a resultant slower, less-concerted action of Cdc2. If this
scenario occurred within similarly nuclear Pin1-depleted AD-affected neurons,
then an ensuing aberrant, interrupted mitosis might follow, giving rise to
nuclear instability and ultimately to cell death (and see Fig. 2).
Other Pin1 targets
such as RNA polymerase II (15), rab4 (22) and c-Jun (129) have been similarly
shown to be upregulated in AD and, quite probably, future research will
reveal further examples. Overall, increased expressions of such proteins
would create more potential Pin1 binding motifs and an additional reason
why insufficient levels of available, soluble Pin1 protein in the neurons
(especially in the nucleus) could have a potentially damaging effect on their
ultimate fate.
2.5 Pin1 depletion as a contributory factor in neuronal apoptosis
Several lines of
evidence support a role for apoptosis in the neuronal loss observed in AD
(7,27). A recent review (164) concludes that neuronal apoptosis has a potentially
important role in neurodegenerative diseases (in addition to its involvement
in the 'sculpturing' of the developing brain) and that the precise elucidation
of such neuronal cell death might provide additional points for therapeutic
interventions.
The stimulation
of mitotic events in AD-affected neurons may well contribute to this apoptosis
(see Section 2.4; 85,98,107,164). Pin1 may have a key role in this apoptosis
for the following reasons. Depletion of Pin1 activity in HeLa cells causes
mitotic arrest and apoptosis (88). The upregulated kinase (see Section
2.3.1) and downregulated phosphatase (see section 2.3.2) activities and
associated 'spurious' mitotic events in affected neurons would create numerous
nuclear Pin1 targets. If these latter are not bound by Pin1, due to depletion
of nuclear Pin1 protein (see Section 2.2), then this would be likely to contribute
to nuclear instability and thence apoptosis. Examples of these would include
Cdc25, as detailed above (Section 2.4), and also, perhaps, c-Jun. Intracellular
A beta-activation of c-Jun N-terminal kinase (JNK) has been demonstrated
in presenilin 1-linked AD brain (129). This would result in increased levels
of phosphorylated (activated) c-Jun. The authors hypothesised that this
JNK activation might lead to neuronal death.
Another, possibly
direct, mechanism whereby Pin1 nuclear depletion and redirection to neuronal
cytoplasm in AD might invoke apoptosis is offered up by the recent suggestion
(110) that Bcl-2, a potent inhibitor of apoptosis (71,128) might be a Pin1
target protein. Bcl-2 has been shown to be located on cytosol-facing membranes
of the nucleus, endoplasmic reticulum and the mitochondria (in transgenic
mouse cell lines; 84), although others have suggested that the mitochondrial
localisation is more predominantly at the inner membrane and cristae (in
rat liver; 101). In regard to AD, Bcl-2 expression has been found to become
up-regulated in neurons containing damaged DNA but down-regulated in those
containing tangles (135). Also, treatment of neuronal cell cultures with
A beta peptide has been shown to promote the up-regulation (of both mRNA
and protein levels) of Bcl-xL, a member of the Bcl-2 family (93).
Phosphorylation
of Bcl-2 is induced at serine residues when microtubule-targeted drugs are
used to arrest tumour cells (110). This phosphorylation leads to the inactivation
of the Bcl-2 protein’s anti-apoptotic role (161). Pin1 was found to associate
with phosphorylated Bcl-2 in these M-phase-arrested cells and it was suggested
that Pin1 might have a role in modulating its conformation, and thence
its function (110). Phosphorylation of a proline-rich loop region (probably
by Cdc2) within the Bcl-2 protein creates potential Pin1-binding motifs,
and it was suggested (110) that Pin1 binding might block the conformational
changes required for Bcl-2’s normal, cytoprotective, ion-channel forming
activities (123). There is evidence that Bcl-2 is phosphorylated transiently
during mitosis (161), thereby presumably creating an ‘apoptotic opportunity’
should aberrant chromosomal segregation or cytokinesis occur.
During
neurodegeneration,
increased (neuronal ‘cdc2-like’) Cdk5 activity and elevated cytoplasmic
levels of Pin1 would create a cellular situation akin to mitosis with regard
to potential prolonged admixing of phosphorylated Bcl-2 and Pin1 protein.
In this way, redirection of Pin1 to the cytoplasm in itself (apart from
the effects of concomitant nuclear depletion; 90,141) and binding to phosphorylated
Bcl-2 could initiate a cascade of events leading ultimately to apoptosis
(and see Fig. 2).
Pin1 protein is
apparently a ‘key player’ in the pathogenesis of AD: it has been shown to
bind to both APP (29) and p-tau (90) in affected neurons and, by so doing,
is thereby intimately involved in the development of the two classical,
histopathological features of the disease, the extracellular neuritic plaques
and the intraneuronal neurofibrillary tangles. Additionally, as Pin1 protein
is a mitotic regulator, it will also, implicitly, have a role in the spurious
re-expression and activation of cell cycle proteins in AD. Finally, because
of all the above, Pin1 will have a role in neuronal apoptosis, either indirectly,
via depletion of levels of nuclear Pin1 (resulting from redirection of nuclear
Pin1 to tangle-bearing cytoplasm), or directly, via association with specific
upregulated phosphoprotein targets.
Pin1’s role in AD appears to be, potentially at least, rather
ambivalent, reflecting the promiscuous nature of its binding to a broad
range of phosphorylated target proteins: on the one hand it may contribute
to increased proteolytic production of neurotoxic A beta peptide molecules,
yet, on the other, if present in sufficient quantities, could seemingly
redress the dissociation of hyperphosphorylated tau protein from the microtubules
and thus prevent tangle formation. Both of these latter influences are mediated
by the same mechanism: the isomerase action of Pin1 upon APP and p-tau renders
them targets themselves for trans-phosphorylation conformation-specific
proteolysis (by secretases in the case of APP) or dephosphorylation
(by PP2A in the case of p-tau). In either case, the net result of the redirection
of Pin1 to these cytoplasmic target proteins is its depletion from the nucleus,
with concomitant nuclear instability which could, at the least, contribute
to eventual neuronal cell death in AD.
While there is
no doubt that death is the ultimate fate of at least a significant proportion
of AD-affected neurons, there is still much debate about the nature of
this death. There are those (30) who dispute that the involvement of apoptosis
in AD has been truly confirmed, as the more terminal phases, such as chromatin
condensation, apoptotic bodies, and blebbing, are rarely (134) seen in
AD. However, most researchers appear to agree that some sort of apoptosis
occurs, albeit, perhaps, in a different form from that occurring in normal
tissues.
What appears certain is that the spurious reactivation of cell cycle
proteins in AD-affected neurons is closely-involved with this apoptosis.
The combined deleterious effects of AD trigger cellular signal transduction
pathways that result in the inappropriate phosphorylation of a range of proteins.
The spurious re-expression and activation of cell cycle proteins also appears
to follow from the reactivation of these pathways and an ‘interrupted’ neuronal
mitosis may result (106). Very recently, evidence that AD-affected neurons
actually replicate DNA and complete most of S-phase before death has been
reported (162). Presumably, the latter occurs because the neurons lack
the full capability to divide.
There are those
who take the view that the ensuing neuronal apoptosis is similarly interrupted,
or at least proceeds very slowly. This latter has been termed ‘abortosis’
by Raina et al. (118), who have shown that while upstream caspase activation
(e.g. caspases 8 and 9) is associated with affected neurons, downstream
caspase activation is not. These authors surmise that this might represent
neuronal exit from apoptosis and is thus a survival mechanism. Other recent
research, however, has provided conflicting data. For example, decreases
in caspases 3, 8 and 9 have been reported (34), and associated increases
in ARC (apoptosis repressor with caspase recruitment domain) and RICK (Receptor-interacting
protein [RIP]-like interacting CLARP kinase) were taken as evidence of
an involvement of apoptotic protein dysregulation in AD neuropathology.
Conversely, other work (136) has shown an elevation of caspase 3 expression
in AD that correlated with both (senile) plaques and tangles, while, in
cultured cerebellar granule cells treated with A beta, the ensuant neuronal
apoptosis was associated with increases in caspases 2, 3 and 6 activities
(4).
Other work has
shown a correlation between tau phosphorylation, tangle formation and apoptosis.
For example, hippocampal tissue slices immunostained with an antibody
recognising a caspase-cleavage product of fodrin (a cytoskeletal protein)
revealed that increased levels of anti-fodrin reactivity paralleled, and
colocalised with, increases in levels of (the tangle marker antibody) PHF-1
reactivity (120). Also, in neuroblastoma SK-N-SH cells, abnormal tau
phosphorylation,
which is similar to AD, has been induced by an anticancer drug (paclitaxel).
The use of an ERK inhibitor, which also inhibited apoptosis, showed that
the tau phosphorylation resulted from sustained ERK activation and led to
apoptosis (52).
There is clearly much
that needs to be clarified with regard to the precise mechanisms involved
in regard to neuronal cell death in AD (and other neurodegenerative diseases).
Although the consensus appears to be that some form of apoptosis takes place,
the latter is but one of an apparently increasing number of programmed cell
death (PCD) mechanisms that can occur in cells and that may be triggered
concurrently. These latter have recently been reviewed (80) with the conclusion
that, specifically in regard to neurons, there appear to be extra controls
for caspase activation and that caspase-independent death pathways may be
preferentially-activated. Other recent reviews (28,96,97,98,99) have sought
to address these issues in regard to neuropathology, with the authors concluding
that a better understanding of neuronal cell death mechanisms would not only
expand the general knowledge of cell death biology but could lead to new
therapeutic approaches.
Whatever the
precise form of apoptosis that occurs in AD-affected neurons may be, an
important involvement of Pin1 protein would seem to be highly probable.
In normal dividing cells Pin1 would help to ‘orchestrate’ the mitotic phosphoproteins
and regulate entry and progression through the cell cycle (159). In AD-affected
cells, where levels of nuclear Pin1 are depleted, these events would not
be able to proceed normally. Of particular importance in this regard would
be the absence of Pin1’s normal modulating action upon CdC25 (25,127,133,165)
when the latter is phosphorylated and is targeted to the nucleus (72; and
see Section 2.4).
Back to Top
In regard to
this nuclear Pin1 depletion and the potential detrimental effects upon
neuronal cell survival, hyperphosphorylation and aggregation of tau also
occurs in the tauopathies. These latter include Down’s syndrome, Pick’s
disease, corticobasal degeneration, frontotemporal dementia and parkinsonism
linked to chromosome 17 (Fig. 4C) and progressive supranuclear palsy (18,26,41,79).
Also as in AD, spurious cell cycle events have been reported in these tauopathies
(62). There is thus every likelihood that depletion of nuclear Pin1 will
also occur in these diseases and might therefore be a unifying, contributory
factor in neuronal cell death in this class of neurodegenerative disorder.
Future studies on Pin1 protein distributions during the progression of these
diseases would clarify the validity of this hypothesis. A useful adjunct to
the latter would be the acquisition of Pin1 protein expression data for different
(affected/non-affected) brain regions in these various diseases. One study
has already revealed that the deranged expression of certain chaperone proteins
does occur in AD (163); a similar approach using Pin1 could further unveil
its potential importance in AD and the tauopathies.
This review has
sought to bring together the various demonstrated and possible involvements
of Pin1 protein in the molecular pathogenesis of AD. There is clearly much
further research suggested by, and required to build upon, that published
so far. In vitro research on Pin1 has elucidated much about the manner and
range of its potential interactions with other proteins within living cells.
Pin1 protein is abundant within cells (88) and, although preferentially nuclear,
is also found in the cytoplasm. It has also been shown to have a measurable
in vitro affinity for perhaps hundreds of mitotic phosphoproteins (127).
Thus, any hypotheses concerning putative functions of Pin1 within AD-affected
(and normal) cells must take into account this widespread cellular distribution
and the promiscuous nature of its binding to other proteins. The cellular
regulation of Pin1 effects (apart from possible differential expression
of Pin1 itself) must therefore depend upon the subcellular juxtaposition
of target and associated proteins (e.g. kinase, phosphatase, protease) and
their phosphorylation status, levels and activities. Only after acquisition
of such in vivo data could a role for Pin1 at the interface of specific kinases
and phosphatases/proteases be ascribed with any certainty. The recent emergence
of microarray technologies and the increasing availability of the relevant
phosphorylation-specific antibodies should help immensely in this regard.
This author believes
that future work on Pin1 (and other proteins of interest) in AD should utilise
the increasingly wide range of available and suitable transgenic mouse
models (1,50,102,131,132,139). However, it would seem paramount that
any results from such work should be correlated with those from AD brain
tissue and with confirmatory in vitro biochemical approaches where required.
Such research should reveal important insights into the involvement of Pin1,
and its associated target and other proteins, in lesion formation and neuronal
cell death in AD and the tauopathies. Such studies should also provide
important basic data on the cellular control of mitosis and apoptosis.
The author is indebted to a number of colleagues without whose collaboration this review would not have been possible. I would like to thank John Kay, whose established research and reputation in the field of the PPIase proteins first led me into the area of Pin1 protein research, and also Stuart Rulten, who collaborated extensively, enthusiastically and with excellent and wide-ranging expertise with myself during the course of my research on Pin1. I am also very grateful to Simon Morley for his enthusiastic support and freely-given experienced biochemical input whenever requested. Finally, I should like to acknowledge the indispensable support of Nigel Cairns who provided brain samples and neuropathological advice.
1. Ahlijanian MK, Barrezueta NX, Williams RD, Jakowski A, Kowsz KP, McCarthy S, Coskran T, Carlo A, Seymour PA, Burkhardt JE, Nelson RB, McNeish JD (2000) Hyperphosphorylated tau and neurofilament and cytoskeletal disruptions in mice overexpressing human p25, an activator of cdk5. Proc Natl Acad Sci USA 97: 2910-2915
2. Akiyama H, Barger S, Barnum S, Bradt B, Bauer J, Cole GM, Cooper NR, Eikelenboom P, Emmerling M, Fiebich BL, Finch CE, Frautschy S, Griffin WST, Hampel H, Hull M, Landreth G, Lue LF, Mrak R, Mackenzie IR, McGeer PL, O'Banion MK, Pachter J, Pasinetti G, Plata-Salaman C, Rogers J, Rydel R, Shen Y, Streit W, Strohmeyer R, Tooyoma I, Van Muiswinkel FL, Veerhuis R, Walker D, Webster S, Wegrzyniak B, Wenk G, Wyss-Coray T (2000) Inflammation and Alzheimer's disease. Neurobiol Aging 21: 383-421
3. Albert A, Lavoie S, Vincent M (1999) A hyperphosphorylated form of RNA polymerase II is the major interphase antigen of the phosphoprotein antibody MPM-2 and interacts with the peptidyl-prolyl isomerase Pin1. J Cell Sci 112: 2493-2500
4. Allen JW, Eldadah BA, Huang XL, Knoblach SM, Faden AI (2001) Multiple caspases are involved in beta-amyloid-induced neuronal apoptosis. J Neurosci Res 65: 45-53
5. Alvarez A, Munoz JP, Maccioni RB (2001) A cdk5-p35 stable complex is involved in the beta-amyloid-induced deregulation of cdk5 activity in hippocampal neurons. Exp Cell Res 264: 266-274
6. Alvarez A, Toro R, Caceres A, Maccioni RB (1999) Inhibition of tau phosphorylating protein kinase cdk5 prevents beta-amyloid-induced neuronal death. FEBS Lett 459: 421-426
7. Anderson AJ, Stoltzner S, Lai F, Su J, Nixon RA (2000) Morphological and biochemical assessment of DNA damage and apoptosis in Down syndrome and Alzheimer disease, and effect of postmortem tissue archival on TUNEL. Neurobiol Aging 21: 511-524
8. Arendt T, Holzer M, Bruckner MK (1998) Neuronal expression of cell-cycle-markers in Alzheimer's disease. Eur J Neurosci 10: 3217
9. Arendt T, Holzer M, Stobe A, Ueberham U, Gartner U, Bruckner MK (2000) Cell cycle regulatory factors in Alzheimer's disease. Brain Pathol 10: 786
10. Bayer TA, Wirths O, Majtenyi K, Hartmann T, Multhaup G, Beyreuther K, Czech C (2001) Key factors in Alzheimer's disease: beta-amyloid precursor protein processing, metabolism and intraneuronal transport. Brain Pathol 11: 1-11
11. Bennecib M, Gong CX, Grundke-Iqbal I, Iqbal K (2000a) Role of protein phosphatase-2A and-1 in the regulation of GSK-3, cdk5 and cdc2 and the phosphorylation of tau in rat forebrain. FEBS Lett 485: 87-93
12. Bennecib M, Gong CX, Grundke-Iqbal I, Iqbal K (2001) Inhibition of PP-2A upregulates CaMKII in rat forebrain and induces hyperphosphorylation of tau at Ser 262/356. FEBS Lett 490: 15-22
13. Bennecib M, Gong CX, Wegiel J, Lee MH, Grundke-Iqbal I, Iqbal, K (2000b) Inhibition of protein phosphatases and regulation of tau phosphorylation in rat brain. Alzheimers Reports 3: 295-304
14. Bennett BD, Denis P, Haniu M, Teplow DB, Kahn S, Louis JC, Citron M, Vassar R (2000) A furin-like convertase mediates propeptide cleavage of BACE, the Alzheimer's beta-secretase. J Biol Chem 275: 37712-37717
15. Bregman DB, Pestell RG, Kidd VJ (2000) Cell cycle regulation and RNA polymerase II. Frontiers In Bioscience 5: D244-D257
16. Brion JP (1998) Neurofibrillary tangles and Alzheimer's disease. Eur Neurol 40: 130-40
17. Brod SA (2000) Unregulated inflammation shortens human functional longevity. Inflamm Res 49: 561-570
18. Buee L, Bussiere T, Buee-Scherrer V, Delacourte A, Hof PR (2000) Tau protein isoforms, phosphorylation and role in neurodegenerative disorders. Brain Res Brain Res Rev 33: 95-130
19. Busser J, Geldmacher DS, Herrup K (1998) Ectopic cell cycle proteins predict the sites of neuronal cell death in Alzheimer's disease brain. J Neurosci 18: 2801-2807
20. Cagnin A, Brooks DJ, Kennedy AM, Gunn RN, Myers R, Turkheimer FE, Jones T, Banati RB (2001) In-vivo measurement of activated microglia in dementia. Lancet 358: 461-467
21. Campbell A, Hamai D, Bondy SC (2001) Differential toxicity of aluminum salts in human cell lines of neural origin: Implications for neurodegeneration. Neurotoxicology 22: 63-71
22. Cataldo AM, Peterhoff CM, Troncosco JC, Gomez-Isla T, Hyman BT, Nixon RA (2000) Endocytic pathway abnormalities precede amyloid beta deposition in sporadic Alzheimer's disease and Down syndrome - Differential effects of APOE genotype and presenilin mutations. Am J Pathol 157: 277-286
23. Chapman PF, Falinska AM, Knevett SG, Ramsay MF (2001) Genes, models and Alzheimer’s disease. Trends Genet 17: 254-261
24. Cobb MH, Hepler JE, Zhen E, Ebert D, Cheng M, Dang A, Robbins D (1995) Regulation and Structure of the MAP Kinases ERK1 and ERK2. In: Alzheimer's Disease: Lessons from Cell Biology. Kosik KS, Christen Y, Selkoe DJ (eds.), pp. 78-87, Springer-Verlag.
25. Crenshaw DG, Yang J, Means AR, Kornbluth S (1998) The mitotic peptidyl-prolyl isomerase, Pin1, interacts with Cdc25 and Plx1. EMBO J 17:1315-1327
26. Crowther RA, Goedert M (2000) Abnormal tau-containing filaments in neurodegenerative diseases. J Struct Biol 130: 271-279
27. Czech C, Tremp G, Pradier L (2000) Presenilins and Alzheimer's disease: biological functions and pathogenic mechanisms. Prog Neurobiol 60: 363-84
28. Daniel PT (2000) Dissecting the pathways to death. Leukemia 14: 2035-2044
29. Davies P, DeBernardis J, Espinoza M, Stahl, M, Vianna C (2000) APP and tau phosphorylation in Alzheimer's disease. World Alzheimer Congress 2000; abstract 956. Brain Pathol 10: 493
30. del Rio MJ, Velez-Pardo C (2001) Apoptosis in neurodegenerative diseases: Facts and controversies. Rev Neurol 32: 851-860
31. Dickson TC, King CE, McCormack GH, Vickers JC (1999) Neurochemical diversity of dystrophic neurites in the early and late stages of Alzheimer's disease. Exp Neurol 156: 100-110
32. Ding XL, Husseman J, Tomashevski A, Nochlin D, Jin LW, Vincent I (2000) The cell cycle Cdc25A tyrosine phosphatase is activated in degenerating postmitotic neurons in Alzheimer's disease. Am J Pathol 157: 1983-1990
33. Dranovsky A, Vincent I, Gregori L, Schwarzman A, Colflesh D, Enghild J, Strittmatter W, Davies P, Goldgaber D (2001) Cdc2 phosphorylation of nucleolin demarcates mitotic stages and Alzheimer's disease pathology. Neurobiol Aging 22: 517-528
34. Engidawork E, Gulesserian T, Yoo BC, Cairns N, Lubec G (2001) Alteration of Caspases and Apoptosis-Related Proteins in Brains of Patients with Alzheimer's Disease. Biochem Biophys Res Commun 281: 84-93
35. Ermak G, Morgan T, Davies KJ (2001) Chronic overexpression of the calcineurin inhibitory gene DSCR1 (Adapt78) is associated with Alzheimer's disease. J Biol Chem In Press
36. Evans DB, Rank KB, Bhattacharya K, Thomsen DR, Gurney ME, Sharma SK (2000) Tau phosphorylation at serine 396 and serine 404 by human recombinant tau protein kinase II inhibits tan's ability to promote microtubule assembly. J Biol Chem 275: 24977-24983
37. Feng Y, Hodge DR, Palmieri G, Chase DL, Longo DL, Ferris DK (1999) Association of polo-like kinase with alpha-, beta- and gamma-tubulins in a stable complex. Biochem J 339: 435-442
38. Ferrer I, Blanco R, Carmona M, Ribera R, Goutan E, Puig B, Rey MJ, Cardozo A, Vinals F, Ribalta T (2001) Phosphorylated map kinase (ERK1, ERK2) expression is associated with early tau deposition in neurones and glial cells, but not with increased nuclear DNA vulnerability and cell death, in Alzheimer disease, Pick's disease, progressive supranuclear palsy and corticobasal degeneration. Brain Pathol 11: 144-158
39. Flaherty DB, Soria JP, Tomasiewicz HG, Wood JG (2000) Phosphorylation of human tau protein by microtubule-associated kinases: GSK3 beta and cdk5 are key participants. J Neurosci Res 62: 463-472
40. Flaten TP (2001) Aluminium as a risk factor in Alzheimer's disease, with emphasis on drinking water. Brain Res Bull 55: 187-196
41. Forman MS, Lee VMY, Trojanowski JQ (2001) New insights into genetic and molecular mechanisms of brain degeneration in tauopathies. J Chem Neuroanat 20: 225-244
42. Fu HA, Subramanian RR, Masters SC (2000) 14-3-3 proteins: Structure, function, and regulation. Annu Rev Pharmacol Toxicol 40: 617-647
43. Fuentes JJ, Pritchard MA, Planas AM, Bosch A, Ferrer I, Estivill XA (1995) A New Human Gene From The Down-Syndrome Critical Region Encodes A Proline-Rich Protein Highly Expressed In Fetal Brain And Heart. Hum Mol Genet 4: 1935-1944
44. Fujimori F, Takahashi K, Uchida C, Uchida T (1999) Mice lacking Pin1 develop normally, but are defective in entering cell cycle from G(0) arrest. Biochem Biophys Res Commun 265: 658-663
45. Gerez L, Mohrmann K, van Raak M, Jongeneelen M, Zhou XZ, Lu KP, van der Sluijs P (2000) Accumulation of rab4GTP in the cytoplasm and association with the peptidyl-prolyl isomerase Pin1 during mitosis. Mol Biol Cell 11: 2201-2211
46. Giovanni A, Wirtz-Brugger F, Keramaris E, Slack R, Park DS (1999) Involvement of cell cycle elements, cyclin-dependent kinases, pRb, and E2F center dot DP, in B-amyloid-induced neuronal death. J Biol Chem 274: 19011-19016
47. Gong CX, Lidsky T, Wegiel J, Grundke-Iqbal I, Iqbal, K (2001) Metabolically active rat brain slices as a model to study the regulation of protein phosphorylation in mammalian brain. Brain Res Protocols 6: 134-140
48. Gong C-X, Lidsky T, Weigel J, Zuck L, Grundke-Iqbal I, Iqbal K (2000) Phosphorylation of microtubule-associated protein tau is regulated by protein phosphatase 2A in mammalian brain - Implications for neurofibrillary degeneration in Alzheimer's disease. J Biol Chem 275: 5535-5544
49. Gothel SF, Marahiel MA (1999) Peptidyl-prolyl cis-trans isomerases, a superfamily of ubiquitous folding catalysts. Cellular and Molecular Life Sciences 55: 423-436
50. Gotz J (2001) Tau and transgenic animal models. Brain Res Brain Res Rev 35: 266-286
51. Grote E, Bonzelius F, Herman G, Ramaswami M, van de Goor J, Green S, Kelly RB (1995) Endocytotic pathways in neurons. In: Alzheimer's Disease: Lessons from Cell Biology. Kosik KS, Christen Y, Selkoe DJ (eds.), pp. 1-14, Springer-Verlag.
52. Guise S, Braguer D, Carles G, Delacourte A, Briand C (2001) Hyperphosphorylation of tau is mediated by ERK activation during anticancer drug-induced apoptosis in neuroblastoma cells. J Neurosci Res 63: 257-267
53. Haass C, Steiner H (2001) Protofibrils, the unifying toxic molecule of neurodegenerative disorders? Nature Neurosci 4: 859-860
54. Harada T, Morooka T, Ogawa S, Nishida E (2001) ERK induces p35, a neuron-specific activator of Cdk5, through induction of Egr1. Nature Cell Biol 3: 453 - 459
55. Harris PLR, Zhu XW, Pamies C, Rottkamp CA, Ghanbari HA, McShea A, Feng Y, Ferris, DK, Smith, MA (2000) Neuronal polo-like kinase in Alzheimer disease indicates cell cycle changes. Neurobiol Aging 21: 837-841
56. Hashiguchi M, Sobue K, Paudel HK (2000) 14-3-3 zeta is an effector of tau protein phosphorylation. J Biol Chem 275: 25247-25254
57. Howlett DR, Simmons DL, Dingwall C, Christie G (2000) In search of an enzyme: the beta-secretase of Alzheimer's disease is an aspartic proteinase. Trends Neurosci 23: 565-570
58. Hunter T (1998) Prolyl isomerases and nuclear function. Cell 92: 141-143
59. Huse JT, Doms RW (2001) Closing in on the amyloid cascade: recent insights into the cell biology of Alzheimer's disease. Mol Neurobiol 22: 81-98
60. Huse JT, Pijak DS, Leslie GJ, Lee VMY, Doms RW (2000) Maturation and endosomal targeting of beta-site amyloid precursor protein-cleaving enzyme - The Alzheimer's disease beta-secretase. J Biol Chem 275: 33729-33737
61. Hussain I, Powell DJ, Howlett DR, Chapman GA, Gilmour L, Murdock PR, Tew DG, Meek TD, Chapman C, Schneider K, Ratcliffe SJ, Tattersall D, Testa TT, Southan C, Ryan DM, Simmons DL, Walsh FS, Dingwall C, Christie G (2000) ASP1 (BACE2) cleaves the amyloid precursor protein at the beta-secretase site. Mol Cell Neurosci 16: 609-619
62. Husseman JW, Nochlin D, Vincent I (2000) Mitotic activation: a convergent mechanism for a cohort of neurodegenerative diseases. Neurobiol Aging 21: 815-828
63. Illenberger S, Zheng-Fischhofer QY, Preuss U, Stamer K, Baumann K, Trinczek B, Biernat J, Godemann R, Mandelkow EM, Mandelkow E (1998) The endogenous and cell cycle-dependent phosphorylation of tau protein in living cells: Implications for Alzheimer's disease. Mol Biol Cell 9: 1495-1512
64. Imahori K, Uchida T (1997) Physiology and pathology of tau protein kinases in relation to Alzheimer's disease. J Biochem (Tokyo) 121: 179-188
65. Iqbal K, Alonso ADC, Gong C-X, Khatoon PJ-J, Wang JZ, Grundke–Iqbal I (1998) Mechanisms of neurofibrillary degeneration and the formation of neurofibrillary tangles. J Neural Transm Suppl 53:169-180
66. Ishiguro K, Takamatsu M, Tomizawa K, Omori A, Takahashi M, Arioka M, Uchida T, Imahori K (1992) Tau protein kinase-I converts normal tau protein into a68-like component of paired helical filaments. J Biol Chem 267: 10897-10901
67. Jones KR, Black MJ, Oorschot DE (1998) Do aluminium and/or glutamate induce Alzheimer PHF-like formation? An electron microscopic study. J Neurocytol 27: 59-68
68. Kay JE (1996) Structure-function relationships in the FK506-binding protein (FKBP) family of peptidylprolyl cis-trans isomerases. Biochem J 314: 361-385
69. Kosik KS, Ferreira A, Knowles R, Leclerc N, Greenberg SM (1995) Linking amyloid precursor protein processing and tau-related pathology in Alzheimer's disease. In: Alzheimer's Disease: Lessons from Cell Biology. Kosik KS, Christen Y, Selkoe DJ (eds.), pp. 230-240, Springer-Verlag.
70. Kovacs T, Cairns NJ, Lantos PL (1999) Beta-amyloid deposition and neurofibrillary tangle formation in the olfactory bulb in ageing and Alzheimer's disease. Neuropathol Appl Neurobiol 25: 481-491
71. Kroemer G (1997) The proto-oncogene Bcl-2 and its role in regulating apoptosis. Nature Med 3: 614-620
72. Kumagai A, Dunphy WG (1999) Binding of 14-3-3 proteins and nuclear export control the intracellular localization of the mitotic inducer Cdc25. Genes Dev 13: 1067-1072
73. Kumar-Singh S, De Jonghe C, Cruts M, Kleinert R, Wang R, Mercken M, De Strooper B, Vanderstichele H, Lofgren A, Vanderhoeven I, Backhovens H, Vanmechelen E, Kroisel PM, Van Broeckhoven C (2000) Nonfibrillar diffuse amyloid deposition due to a gamma(42)-secretase site mutation points to an essential role for N- truncated A beta(42) in Alzheimer's disease. Hum Mol Genet 9: 2589-2598
74. Lane HA, Nigg EA (1997) Cell-cycle control: POLO-like kinases join the outer circle. Trends Cell Biol 7: 63-68
75. Layfield R, Fergusson J, Aitken K, Lowe J, Landon NI, Mayer R J (1996) Neurofibrillary tangles of Alzheimer's disease brains contain 14-3-3 proteins. Neurosci Lett 209, 57-60
76. Ledesma MD, Da Silva JS, Crassaerts K, Delacourte A, De Strooper B, Dotti CG (2000) Brain plasmin enhances APP alpha-cleavage and A beta degradation and is reduced in Alzheimer's disease brains. EMBO Reports 1: 530-535
77. Lee KY, Clark AW, Rosales JL, Chapman K, Fung T, Johnston RN (1999) Elevated neuronal Cdc2-like kinase activity in the Alzheimer disease brain. Neurosci Res 34: 21-29
78. Lee MS, Kwon YT, Li MW, Peng JM, Friedlander RM, Tsai LH (2000) Neurotoxicity induces cleavage of p35 to p25 by calpain. Nature 405: 360-364
79. Lee VMY, Goedert M, Trojanowski JQ (2001) Neurodegenerative tauopathies. Annu Rev Neurosci 24: 1121-1159
80. Leist M, Jäättelä M (2001) Four Deaths And A Funeral: From Caspases To Alternative Mechanisms. Nature Rev Mol Cell Biol 2, 589 -598
81. Lew J, Huang QQ, QI Z, Winkfein RJ, Aebersold R, Hunt T, Wang JH (1994) A Brain-Specific Activator Of Cyclin-Dependent Kinase-5. Nature 371: 423-426
82. Li YM, Xu M, Lai MT, Huang Q, Castro JL, DiMuzio-Mower J, Harrison T, Lellis C, Nadin JL, Neduvelil JG, Register RB, Sardana MK,Shearman MS, Smith AL, Shi XP, Yin KC, Shafer JA, Gardell SJ (2000) Photoactivated gamma-secretase inhibitors directed to the active site covalently label presenilin 1. Nature 405: 689-694
83. Lian QY, Ladner CJ, Magnuson D, Lee JM (2001) Selective changes of calcineurin (protein phosphatase 2B) activity in Alzheimer's disease cerebral cortex. Exp Neurol 167: 158-165
84. Lithgow T, Vandriel R, Bertram JF, Strasser A (1994) The protein product of the oncogene bcl-2 is a component of the nuclear-envelope, the endoplasmic reticulum, and the outer mitochondrial-membrane. Cell Growth Differ 5: 411-417
85. Liu DX, Greene LA (2001) Neuronal apoptosis at the G1/S cell cycle checkpoint. Cell Tissue Res 305: 217-228
86. Liu W, Youn H-D, Zhou XZ, Lu KP, Liu JO (2001) Binding and regulation of the transcription factor NFAT by the peptidyl prolyl cis-trans isomerase Pin1. FEBS Lett 496: 105-108
87. Lu KP (2000) Phosphorylation-dependent prolyl isomerization: a novel cell cycle regulatory mechanism. Prog Cell Cycle Res 4: 83-96
88. Lu KP, Hanes SD, Hunter T (1996) A human peptidyl-prolyl isomerase essential for regulation of mitosis. Nature 380: 544-547
89. Lu KP, Hunter T (1995) Evidence for a NIMA-like mitotic pathway in vertebrate cells. Cell 81: 413-424
90. Lu P-J, Wulf G, Zhou XZ, Davies P, Lu KP (1999) The prolyl isomerase Pin1 restores the function of Alzheimer-associated phosphorylated tau protein. Nature 399: 784-788
91. Lu PJ, Zhou XZ, Shen MH, Lu KP (1999) Function of WW domains as phosphoserine- or phosphothreonine-binding modules. Science 283: 1325-1328
92. Lucas JL, Hernandez F, Gomez-Ramos P, Moran MA, Hen R, Avila J (2001) Decreased nuclear beta-catenin, tau hyperphosphorylation and neurodegeneration in GSK-3 beta conditional transgenic mice. EMBO J 20: 37-39
93. Luetjens CM, Lankiewicz S, Bui NT, Krohn AJ, Poppe M, Prehn JHM (2001) Up-regulation of Bcl-xL in response to subtoxic beta-amyloid: Role in neuronal resistance against apoptotic and oxidative injury. Neuroscience 102: 139-150
94. Maccioni RB, Otth C, Concha II, Munoz JP (2001) Minireview: The protein kinase Cdk5: structural aspects, roles in neurogenesis and involvement in Alzheimer's pathology. Eur J Biochem 268: 1518-1527
95. Mahley RW, Rall SC (2000) Apolipoprotein E: Far more than a lipid transport protein. Annu Rev Genom Hum Genetic 1: 507-537
96. Martin LJ (2001) Neuronal cell death in nervous system development, disease, and injury (Review). Int J Mol Med 7: 455-478
97. Martin S, Vallette FM (2000) Apoptosis and pathologies of the central nervous system. Neurochirurgie 46: 370-375
98. Mattson MP (2000) Apoptosis in neurodegenerative disorders. Nature Rev Mol Cell Biol 1: 120-129
99. Mattson MP, Duan W, Pedersen WA, Culmsee C (2001) Neurodegenerative disorders and ischemic brain diseases. Apoptosis 6: 69-81
100. Morris DP, Phatnani HP, Greenleaf AL (1999) Phospho-carboxyl-terminal domain binding and the role of a prolyl isomerase in pre-mRNA 3'-end formation. J Biol Chem 274: 31583-31587
101. Motoyama S, Kitamura M, Saito S, Minamiya Y, Suzuki H, Saito R, Terada K, Ogawa J, Inaba, H (1998) Bcl-2 is located predominantly in the inner membrane and crista of mitochondria in rat liver. Biochem Biophys Res Commun 249: 628-636
102. Mucke L, Masliah E, Yu GQ, Mallory M, Rockenstein EM, Tatsuno G, Hu K, Kholodenko D, Johnson-Wood K, McConlogue L (2000) High-level neuronal expression of A beta(1-42) in wild-type human amyloid protein precursor transgenic mice: Synaptotoxicity without plaque formation. J Neurosci 20: 4050-4058
103. Nagy Z (2000) Cell cycle regulatory failure in neurones: causes and consequences. Neurobiol Aging 21: 761-769
104. Nilsberth C, Westlind-Danielsson A, Eckman CB, Condron MM, Axelman K, Forsell C, Stenh C, Luthman J, Teplow DB, Younkin SG, Naslund J, Lannfelt L (2001) The 'Arctic' APP mutation (E693G) causes Alzheimer's disease by enhanced A beta protofibril formation. Nature Neurosci 4: 887-893
105. Nunan J, Small DH (2000) Regulation of APP cleavage by alpha-, beta- and gamma-secretases. FEBS Lett 483: 6-10
106. Nuydens R, de Jong M, Van Den Kieboom G, Heers C, Dispersyn G, Cornelissen F, Nuyens R, Borgers M, Geerts H (1998) Okadaic acid-induced apoptosis in neuronal cells: Evidence for an abortive mitotic attempt. J Neurochem 70: 1124-1133
107. Offen D, Elkon H, Melamed E (2000) Apoptosis as a general cell death pathway in neurodegenerative diseases. J Neural Transmission-Supplement 58: 153-166
108. Orth M, Schapira AHV (2001) Mitochondria and degenerative disorders. Am J Med Genet 106: 27-36
109. Park IH, Jung MW, Mori H, Mook-Jung I (2001) Zinc enhances synthesis of presenilin 1 in mouse primary cortical culture. Biochem Biophys Res Commun 285: 680-688
110. Pathan N, Aime-Sempe C, Kitada S, Haldar S, Reed JC (2001) Microtubule-targeting drugs induce Bcl-2 phosphorylation and association with Pin1. Neoplasia 3: 70-79
111. Patrick GN, Zukerberg L, Nikolic M, de la Monte S, Dikkes P, Tsai LH (1999) Conversion of p35 to p25 deregulates Cdk5 activity and promotes neurodegeneration. Nature 402: 615-622
112. Pei JJ, Braak E, Braak H, Grundke-Iqbal I, Iqbal K, Winblad B, Cowburn RF (1999) Distribution of active glycogen synthase kinase 3 beta (GSK-3 beta) in brains staged for Alzheimer disease neurofibrillary changes. J Neuropathol Exp Neurol 58: 1010-1019
113. Pei JJ, Grundke-Iqbal I, Iqbal K, Bogdanovic N, Winblad B, Cowburn RF (1998) Accumulation of cyclin-dependent kinase 5 (cdk5) in neurons with early stages of Alzheimer's disease neurofibrillary degeneration. Brain Res 797: 267-277
114. Pelech SL (1995) Networking With Proline-Directed Protein-Kinases Implicated In Tau Phosphorylation. Neurobiol Aging 16: 247-256
115. Pinero DJ, Connor JR (2000) Iron in the brain: An important contributor in normal and diseased states. Neuroscientist 6: 435-453
116. Plassman BL, Havlik RJ, Steffens DC, Helms MJ, Newman TN, Drosdick D, Phillips C, Gau BA, Welsh-Bohmer KA, Burke JR, Guralnik JM, Breitner JCS (2000) Documented head injury in early adulthood and risk of Alzheimer's disease and other dementias. Neurology 55: 1158-1166
117. Pratico D, Delanty N (2000) Oxidative injury in diseases of the central nervous system: Focus on Alzheimer's disease. Am J Med 109: 577-585
118. Raina AK, Hochman A, Zhu XW, Rottkamp CA, Nunomura A, Siedlak SL, Boux H, Castellani RJ, Perry G, Smith MA (2001) Abortive apoptosis in Alzheimer's disease. Acta Neuropathol (Berl) 101: 305-310
119. Ramelot TA, Nicholson LK (2001) Phosphorylation-induced Structural Changes in the Amyloid Precursor Protein Cytoplasmic Tail Detected by NMR. J Mol Biol 307: 871-884
120. Rohn TT, Head E, Su JH, Anderson AJ, Bahr BA, Cotman CW, Cribbs DH (2001) Correlation between caspase activation and neurofibrillary tangle formation in Alzheimer's disease. Am J Pathol 158: 189-198
121. Rulten SL, Thorpe JR, Kay JE (1999) Identification of eukaryotic parvulin homologues: A new subfamily of peptidylprolyl cis-trans isomerases. Biochem Biophys Res Commun 259: 557-562
122. Ryan M, Starkey M, Faull R, Emson P, Bahn S (2001) Indexing-based differential display - studies on post-mortem Alzheimer's brains. Mol Brain Res 88: 199-202
123. Schendel SL, Xie ZH, Montal MO, Matsuyama S, Montal M, Reed JC (1997) Channel formation by antiapoptotic protein Bcl-2. Proc Natl Acad Sci USA 94: 5113-5118
124. Schiene C, Fischer G (2000) Enzymes that catalyse the restructuring of proteins. Curr Opin Struct Biol 10: 40-45
125. Schutkowski M, Bernhardt A, Zhou XZ, Shen MH, Reimer U, Rahfeld JU, Lu KP, Fischer G (1998) Role of phosphorylation in determining the backbone dynamics of the serine/threonine-proline motif and Pin1 substrate recognition. Biochemistry 37: 5566-5575
126. Selkoe DJ (1999) Translating cell biology into therapeutic advances in Alzheimer’s disease. Nature 399: A23-A31 Suppl. S
127. Shen MH, Stukenberg PT, Kirschner MW, Lu KP (1998) The essential mitotic peptidyl-prolyl isomerase Pin1 binds and regulates mitosis-specific phosphoproteins. Genes Dev 12: 706-720
128. Shimizu S, Eguchi Y, Kamiike W, Itoh Y, Hasegawa J, Yamabe K, Otsuki Y, Matsuda H, Tsujimoto Y (1996) Induction of apoptosis as well as necrosis by hypoxia and predominant prevention of apoptosis by Bcl-2 and Bcl-X(L). Cancer Res 56: 2161-2166
129. Shoji M, Iwakami N, Takeuchi S, Waragai M, Suzuki M, Kanazawa I, Lippa CF, Ono S, Okazawa, H (2000) JNK activation is associated with intracellular beta-amyloid accumulation. Mol Brain Res 85: 221-233
130. Smith DS, Greer PL, Tsai LH (2001) Cdk5 on the brain. Cell Growth Differ 12: 277-283
131. Spittaels K, Van den Haute C, Van Dorpe J, Bruynseels K, Vandezande K, Laenen I, Geerts H, Mercken M, Sciot R, Van Lommel A, Loos R, Van Leuven F (1999) Prominent axonopathy in the brain and spinal cord of transgenic mice overexpressing four-repeat human tau protein. Am J Pathol 155: 2153-2165
132. Spittaels K, Van den Haute C, Van Dorpe J, Geerts H, Mercken M, Bruynseels K, Lasrado R, Vandezande K, Laenen I, Boon T, Van Lint J, Vandenheede J, Moechars D, Loos R, Van Leuven F (2000) Glycogen Synthase Kinase-3 Phosphorylates Protein Tau and Rescues the Axonopathy in the Central Nervous System of Human Four-repeat Tau Transgenic Mice. J Biol Chem 275: 41340-41349
133. Stukenberg PT, Kirschner MW (2001) Pin1 acts catalytically to promote a conformational change in Cdc25. Mol Cell 7: 1071-1083
134. Su JH, Anderson AJ, Cummings BJ, Cotman CW (1994) Immunohistochemical Evidence For Apoptosis In Alzheimers Disease. Neuroreport 5: 2529-2533
135. Su JH, Satou T, Anderson AJ, Cotman CW (1996) Up-regulation of Bcl-2 is associated with neuronal DNA damage in Alzheimer's disease. Neuroreport 7: 437-440
136. Su JH, Zhao M, Anderson AJ, Srinivasan A, Cotman CW (2001) Activated caspase-3 expression in Alzheimer's and aged control brain: correlation with Alzheimer pathology. Brain Res 898: 350-357
137. Szczepanik AM, Funes S, Petko W, Ringheim GE (2001) IL-4, IL-10 and IL-13 modulate A beta(1-42)-induced cytokine and chemokine production in primary murine microglia and a human monocyte cell line. J Neuroimmunol 113: 49-62
138. Taniguchi S, Fujita Y, Hayashi S, Kakita A, Takahashi H, Murayama S, Saido TC, Hisanaga S, Iwatsubo T, Hasegawa M (2001) Calpain-mediated degradation of p35 to p25 in postmortem human and rat brains. FEBS Lett 489: 46-50
139. Terai K, Iwai A, Kawabata S, Tasaki Y, Watanabe T, Miyata K, Yamaguchi T (2001) beta-amyloid deposits in transgenic mice expressing human beta-amyloid precursor protein have the same characteristics as those in Alzheimer's disease. Neuroscience 104: 299-310
140. Thorpe JR, Rulten SL, Kay JE (1999) The binding of a putative and a known chaperone protein revealed by immunogold labelling transmission electron microscopy: A suggested use of chaperones as probes for the distribution of their target proteins. J Histochem Cytochem 47, 1633-1640
141. Thorpe JR, Morley SJ, Rulten SL (2001) Utilising the Peptidyl-Prolyl Cis-Trans Isomerase Pin1 as a Probe of its Phosphorylated Target Proteins: Examples of Binding to Nuclear Proteins in a Human Kidney Cell Line and to Tau in Alzheimer’s Diseased Brain. J Histochem Cytochem 49: 97-108
142. Tokuoka H, Saito T, Yorifuji H, Wei F, Kishimoto T, Hisanaga S (2000) Brain-derived neurotrophic factor-induced phosphorylation of neurofilament-H subunit in primary cultures of embryo rat cortical neurons. J Cell Sci 113: 1059-68
143. Trojanowski JQ, Mawal-Dewan M, Scmidt ML, Martin J, Lee VM-Y (1993) Localisation of the mitogen activated protein kinase ERK2 in Alzheimer's Disease neurofibrillary tangles and senile plaque neurites. Brain Res 618: 333-337
144. Van Broeckhoven C, Kumar-Singh S, De Jonghe C, Cruts M, Kleinert R, Wang R, Mercken M, Vanderstichele H, Lofgren, A Vanmechelen E, Kroisel PM (2000) A missense mutation at the gamma 42 secretase site in APP points to an essential role for N- truncated A beta 42 in Alzheimer's disease. Am J Hum Genet 67: 2288
145. Varadarajan S, Yatin S, Aksenova M, Butterfield, DA (2000) Review: Alzheimer's amyloid beta-peptide-associated free radical oxidative stress and neurotoxicity. J Struct Biol 130: 184-208
146. Veeranna GJ, Shetty KT, Takahashi M, Grant P, Pant HC (2000) Cdk5 and MAPK are associated with complexes of cytoskeletal proteins in rat brain. Mol Brain Res 76: 229-36
147. Verdecia MA, Bowman ME, Lu KP, Hunter T, Noel JP (2000) Structural basis for phosphoserine-proline recognition by group IV WW domains. Nat Struct Biol 7: 639-643
148. Vickers JC, Chin D, Edwards AM, Sampson V, Harper C, Morrison J (1996) Dystrophic neurite formation associated with age-related beta amyloid deposition in the neocortex: Clues to the genesis of neurofibrillary pathology. Exp Neurol 141: 1-11
149. Vincent I, Rosado M, Davies P (1996) Mitotic mechanisms in Alzheimer's disease? J Cell Biol 132: 413-425
150. Vogelsberg-Ragaglia V, Schuck T, Trojanowski JQ, Lee, VM-Y (2001) PP2A mRNA Expression Is Quantitatively Decreased in Alzheimer's Disease Hippocampus. Exp Neurol 168: 402-412
151. Weidemann A (2000) Proteolytic processing of the Alzheimer's disease precursor protein. Eur J Neurosci 12: 320
152. Wells NJ, Watanabe N, Tokusumi T, Jiang W, Verdecia MA, Hunter T (1999) The C-terminal domain of the Cdc2 inhibitory kinase Myt1 interacts with Cdc2 complexes and is required for inhibition of G(2)/M progression. J Cell Sci 112: 3361-3371
153. Winkler KE, Swenson KI, Kornbluth S, Means AR (2000) Requirement of the prolyl isomerase Pin1 for the replication checkpoint. Science 287: 1644-1647
154. Wolfe MS, De los Angeles J, Miller DD, Xia WM, Selkoe DJ (1999a) Are presenilins intramembrane-cleaving proteases? Implications for the molecular mechanism of Alzheimer's disease. Biochemistry 38: 11223-11230
155. Wolfe MS, Xia WM, Ostaszewski BL, Diehl TS, Kimberly WT, Selkoe DJ (1999b) Two transmembrane aspartates in presenilin-1 required for presenilin endoproteolysis and gamma-secretase activity. Nature 398: 513-517
156. Wu Q, Combs C, Cannady SB, Geldmacher DS, Herrup K (2000) Beta-amyloid activated microglia induce cell cycling and cell death in cultured cortical neurons. Neurobiol Aging 21: 797-806
157. Wulf GM, Ryo A, Wulf GG, Lee SW, Niu T, Petkova V, Lu KP (2001) Pin1 is overexpressed in breast cancer and cooperates with Ras signaling in increasing the transcriptional activity of c-Jun towards cyclin D1. EMBO J 20: 3459-3472
158. Xia W (2000) Role of presenilin in gamma-secretase cleavage of amyloid precursor protein. Exp Gerontol 35: 453-460
159. Yaffe MB, Schutkowski M, Shen MH, Zhou XZ, Stukenberg PT, Rahfeld JU, Xu J, Kuang J, Kirschner MW, Fischer G, Cantley LC, Lu KP (1997) Sequence specific and phosphorylation-dependent isomerization: A potential mitotic regulatory mechanism. Science 278: 1957-1960
160. Yamaguchi H, Ishiguro K, Uchida T, Takashima A, Lemere CA, Imahori K (1996) Preferential labeling of Alzheimer neurofibrillary tangles with antisera for tau protein kinase (TPK)I glycogen synthase kinase-3 beta and cyclin-dependent kinase 5, a component of TPK II. Acta Neuropathol (Berl) 92: 232-241
161. Yamamoto K, Ichijo H, Korsmeyer SJ (1999) Bcl-2 is phosphorylated and inactivated by an ask1/jun n-terminal protein kinase pathway normally activated at G(2)/M. Mol Cell Biol 19: 8469-8478
162. Yang Y, Geldmacher DS, Herrup K (2001) DNA replication precedes neuronal cell death in Alzheimer's disease. J Neurosci 21: 2661-2668
163. Yoo BC, Kim SH, Cairns N, Fountoulakis M, Lubec, G (2001) Deranged expression of molecular chaperones in brains of patients with Alzheimer's disease. Biochem Biophys Res Commun 280: 249-258
164. Yuan JY, Yankner BA (2000) Apoptosis in the nervous system. Nature 407: 802-809
165. Zhou XZ, Kops O, Werner A, Lu PJ, Shen M, Stoller G, Kullertz G, Stark M, Fischer G, Lu KP (2000) Pin1-dependent prolyl isomerisation regulates dephosphorylation of Cdc25C and tau proteins. Mol Cell 6: 873-883
166. Zhou XZ, Lu PJ, Wulf G, Lu KP (1999) Phosphorylation-dependent prolyl isomerization: a novel signaling regulatory mechanism. Cell Mol Life Sci 56: 788-806