Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UNIPROT:P10636 (tau protein)
5,110 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

DYRK1A, dual-specificity tyrosine-regulated kinase 1A, maps to human chromosome 21 within the Down syndrome (DS) critical region. Dyrk1 phosphorylates the human microtubule-associated protein tau at Thr212 in vitro, a residue that is phosphorylated in fetal tau and hyper-phosphorylated in Alzheimer disease (AD) and tauopathies, including Pick disease (PiD). Furthermore, phosphorylation of Thr212 primes tau for phosphorylation by glycogen synthase kinase 3 (GSK-3). The present study examines Dyrk1A in the cerebral cortex of sporadic AD, adult DS with associated AD, and PiD. Increased Dyrk1A immunoreactivity has been found in the cytoplasm and nuclei of scattered neurons of the neocortex, entorhinal cortex, and hippocampus in AD, DS, and PiD. Dyrk1A is found in sarkosyl-insoluble fractions which are enriched in phosphorylated tau in AD brains, thus suggesting a possible association of Dyrk1A with neurofibrillary tangle pathology. Yet, no clear relationship has been observed between tau phosphorylation at Thr212, and GSK-3 and Dyrk1A expression in diseased brains. Transgenic mice bearing a triple tau mutation (G272V, P301L, and R406W) and expressing hyper-phosphoyrylated tau in neurons of the entorhinal cortex, hippocampus, and cerebral neocortex show increased expression of Dyrk1A in individual neurons in the same regions. However, transgenic mice over-expressing Dyrk1A do not show increased phosphorylation of tau at Thr212, thus suggesting that Dyrk1A over-expression does not trigger per se hyper-phosphorylation of tau at Thr212 in vivo. The present observations indicate modifications in the expression of constitutive Dyrk1A in the cytoplasm and nuclei of neurons in various neurodegenerative diseases associated with tau phosphorylation.
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PMID:Constitutive Dyrk1A is abnormally expressed in Alzheimer disease, Down syndrome, Pick disease, and related transgenic models. 1624 44

In Alzheimer disease (AD), the microtubule-associated protein tau is found hyperphosphorylated in paired helical filaments. Among many phosphorylated sites in tau, Ser-262 is the major site for abnormal phosphorylation of tau in AD brain. The kinase known to phosphorylate this particular site is MARK2, whose activation mechanism is yet to be studied. Our first finding that treatment of cells with LiCl, a selective inhibitor of another major tau kinase, glycogen synthase kinase-3beta (GSK-3beta), inhibits phosphorylation of Ser-262 of tau led us to investigate the possible involvement of GSK-3beta in MARK2 activation. In vitro kinase reaction revealed that recombinant GSK-3beta indeed phosphorylates MARK2, whereas it failed to phosphorylate Ser-262 of tau. Our further findings led us to conclude that GSK-3beta phosphorylates MARK2 on Ser-212, one of the two reported phosphorylation sites (Thr-208 and Ser-212) found in the activation loop of MARK2. Down-regulation of either GSK-3beta or MARK2 by small interfering RNAs suppressed the level of phosphorylation on Ser-262. These results, respectively, indicated that GSK-3beta is responsible for phosphorylating Ser-262 of tau through phosphorylation and activation of MARK2 and that the phosphorylation of tau at this particular site is predominantly mediated by a GSK-3beta-MARK2 pathway. These findings are of interest in the context of the pathogenesis of AD.
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PMID:GSK-3beta directly phosphorylates and activates MARK2/PAR-1. 1625 59

Tungstate treatment increases the phosphorylation of glycogen synthase kinase-3beta (GSK3beta) at serine 9, which triggers its inactivation both in cultured neural cells and in vivo. GSK3 phosphorylation is dependent on the activation of extracellular signal-regulated kinases 1/2 (ERK1/2) induced by tungstate. As a consequence of GSK3 inactivation, the phosphorylation of several GSK3-dependent sites of the microtubule-associated protein tau decreases. Tungstate reduces tau phosphorylation only in primed sequences, namely, those prephosphorylated by other kinases before GSK3beta modification, which are serines 198, 199, or 202 and threonine 231. The phosphorylation at these sites is involved in reduction of the interaction of tau with microtubules that occurs in Alzheimer's disease.
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PMID:Sodium tungstate decreases the phosphorylation of tau through GSK3 inactivation. 1639

Aberrant phosphorylated tau is the major component of the neurofibrillary tangles in Alzheimer's disease (AD) brains. Glycogen synthase kinase-3beta (GSK-3beta) phosphorylates tau protein, and increased GSK-3beta expression has been associated with neurofibrillary tangles. Saitohin (STH) is a recently identified protein that shares tissue expression pattern with tau, and previous evidence in the Spanish population indicated that a polymorphism at codon 7 (Q7R) of the STH gene was associated with late-onset AD. Since both GSK-3beta and STH are related to tau, we examined the association between a polymorphism in the promoter region (-50) of the GSK-3beta gene and AD, either through an independent effect or through interaction with the STH (Q7R) polymorphism, in a well-defined group of 333 sporadic AD patients and 307 control subjects from Spain. The current study reveals that GSK-3beta (-50) TT genotype is associated with an increased risk (OR 1.99, p = 0.003) for late-onset (after the age of 72 years) AD. Our results indicate that both the GSK-3beta (-50) and STH (Q7R) polymorphisms increase the risk of late-onset (subjects >72 years) AD, although they appear to be independent and thus not to interact synergistically.
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PMID:Association between glycogen synthase kinase-3beta genetic polymorphism and late-onset Alzheimer's disease. 1642 84

Glycogen synthase kinase-3 (GSK-3) is a multifunctional serine/threonine kinase that is usually inactivated by serine phosphorylation in response to extracellular cues. However, GSK-3 can also be activated by tyrosine phosphorylation, but little is known about the upstream signaling events and tyrosine kinase(s) involved. Here we describe a G protein signaling pathway leading to GSK-3 activation during lysophosphatidic acid (LPA)-induced neurite retraction. Using neuronal cells expressing the LPA(1) receptor, we show that LPA(1) mediates tyrosine phosphorylation and activation of GSK-3 with subsequent phosphorylation of the microtubule-associated protein tau via the G(i)-linked PIP(2) hydrolysis-Ca(2+) mobilization pathway. LPA concomitantly activates the Ca(2+)-dependent tyrosine kinase Pyk2, which is detected in a complex with GSK-3beta. Inactivation or knockdown of Pyk2 inhibits LPA-induced (but not basal) tyrosine phosphorylation of GSK-3 and partially inhibits LPA-induced neurite retraction, similar to what is observed following GSK-3 inhibition. Thus, Pyk2 mediates LPA(1)-induced activation of GSK-3 and subsequent phosphorylation of microtubule-associated proteins. Pyk2-mediated GSK-3 activation is initiated by PIP(2) hydrolysis and may serve to destabilize microtubules during actomyosin-driven neurite retraction.
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PMID:GSK-3 is activated by the tyrosine kinase Pyk2 during LPA1-mediated neurite retraction. 1645 34

The two classical pathological hallmarks of Alzheimer's disease are deposits of aggregated beta-amyloid (Abeta) peptide and neurofibrillary tangles composed of hyperphosphorylated tau protein. In addition to Abeta pathology, an invariant trait of Alzheimer's disease, disruption of tau processing is a necessary event in the neurotoxic cascade which eventually leads to neuronal death and subsequent dementia. Tau is a neuronal, microtubule-bound protein which becomes hyperphosphorylated as a result of an imbalance of the kinase and phosphatase activities which normally tightly regulate its phosphorylation. In addition to this pathogenic hyperphosphorylation, tau dissociates from microtubules and self-aggregates to form insoluble oligomers which progress to the macroscopic tangles evident in post mortem Alzheimer's disease tissue. Subsequent toxicity may ensue either as a direct toxic effect of free tau oligomers or as a result of altered microtubule-dependent processes. In order to intervene pharmacologically in this disease process, much effort has been expended in order to identify and inhibit the kinases responsible for pathogenic hyperphosphorylation and many candidate kinases have been investigated including glycogen synthase kinase (GSK-3), cyclin-dependant kinase-5 (Cdk-5), MAPK family members (extracellular signal-regulated kinases 1 and 2 [Erk-1 and 2], MEK [MAP kinase kinase], c-Jun NH(2)-terminal kinases (JNKs) and p38), casein kinase, calcium calmodulin-dependant kinase II (CaMK-II), microtubule affinity regulating kinase (MARK), protein kinase A (PKA/cAMP-dependant protein kinase) and others. Focus has also fallen upon the role of the phosphatases responsible for dephosphorylation of tau. This review will describe the tau-related etiology of Alzheimer's disease and other tauopathies as well as the therapeutic strategies to inhibit the hyperphosphorylation of tau.
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PMID:Tau therapeutic strategies for the treatment of Alzheimer's disease. 1671 93

During aging basal forebrain cholinergic neurons (BFCNs) degenerate, and we hypothesize this to be the result of a degeneration of the cytoskeleton. As a corollary, retrograde transport of the complex of nerve growth factor (NGF) and its activated receptor phospho-TrkA (P-TrkA) is impaired. Using immunocytochemistry, we here compare young and aged rat brains in their subcellular localization of NGF and P-TrkA in relation to the compartmentalization of phosphorylation-dependent tau protein isoforms. Despite lower P-TrkA immunoreactivity in cortex and hippocampus of aged rats, NGF immunoreactivity was not altered in these areas, but was significantly lower in aged basal forebrain. In young animals, expression of tau isoforms and glycogen synthase kinase-3beta (GSK-3beta) was restricted to neuritic structures in cortex, hippocampus, and basal forebrain. In contrast, tau and GSK-3beta labeling was confined to cell bodies in aged rats. Since a somatic localization of phospho-tau is indicative of cytoskeletal breakdown, we suggest this to be the mechanism the breakdown of trophic support in aging BFCNs.
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PMID:Compartmental protein expression of Tau, GSK-3beta and TrkA in cholinergic neurons of aged rats. 1673 40

The hallmarks of Alzheimer's disease include extracellular plaques primarily consisting of amyloid-beta peptide and intracellular neurofibrillary tangles composed of highly phosphorylated tau protein. We report that exposure of organotypic hippocampal cultures to synthetic amyloid-beta peptide(25-35) (50 microM, 96 h) causes neurodegeneration concomitant with a significant increase in tau phosphorylation at the Ser epitope (+60%). Furthermore, the level of active glycogen synthase kinase-3beta (GSK-3beta [pTyr]) was increased (+55%) after amyloid-beta peptide(25-35) exposure. These findings support the role of amyloid-beta peptide as a mediator of tau phosphorylation and demonstrate the usefulness of organotypic cultures for investigating the link between amyloid-beta peptide-induced neurotoxicity and tau phosphorylation. Our results also confirm that amyloid-beta peptide induces activation of glycogen synthase kinase-3beta.
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PMID:Increased tau phosphorylation at the Ser396 epitope after amyloid beta-exposure in organotypic cultures. 1673 86

It has been pointed out that hyperphosphorylation of microtubule-associated protein tau caused by stress might participate in the early stages of Alzheimer's disease pathogenesis. In the present study, we investigated the effects of cold water stress (CWS) on tau phosphorylation in the mouse hippocampus and the effects of GSK-3beta inhibitor, LiCl, on CWS-induced changes in tau phosphorylation levels by immunoblot analyses. CWS exposure caused an increase in tau phosphorylation at the Tau-1 (Ser199/202), AT8 (Ser202/Thr205) and Ser396 sites. CWS-induced changes in tau phosphorylation at the Ser199/202 and Ser396, but not at Ser202/Thr205, were significantly attenuated by LiCl pretreatment. Total tau levels also showed a decided tendency to increase after CWS, which tendency was also countered by LiCl. Finally, we showed that CWS increased the active form of GSK-3beta that was phosphorylated at Tyr216. These results suggest that a CWS-induced increase in phosphorylated tau in the hippocampus is mediated, at least partly, by the activation of GSK-3beta.
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PMID:Lithium inhibits stress-induced changes in tau phosphorylation in the mouse hippocampus. 1685 14

Glycogen synthase kinase-3 (GSK-3) has been proposed as the main kinase able to aberrantly phosphorylate tau in Alzheimer's disease (AD) and related tauopathies, raising the possibility of designing novel therapeutic interventions for AD based on GSK-3 inhibition. Lithium, a widely used drug for affective disorders, inhibits GSK-3 at therapeutically relevant concentrations. Therefore, it was of great interest to test the possible protective effects of lithium in an AD animal model based on GSK-3 overexpression. We had previously generated a double transgenic model, overexpressing GSK-3beta in a conditional manner, using the Tet-off system and tau protein carrying a triple FTDP-17 (frontotemporal dementia and parkinsonism linked to chromosome 17) mutation. This transgenic line shows tau hyperphosphorylation in hippocampal neurones accompanied by neurofibrillary tangles (NFTs). We used this transgenic model to address two issues: first, whether chronic lithium treatment is able to prevent the formation of aberrant tau aggregates that result from the overexpression of FTDP-17 tau and GSK-3beta; second, whether lithium is able to change back already formed NFTs in aged animals. Our data suggest that progression of the tauopathy can be prevented by administration of lithium when the first signs of neuropathology appear. Furthermore, it is still possible to partially reverse tau pathology in advanced stages of the disease, although NFT-like structures cannot be changed. The same results were obtained after shut-down of GSK-3beta overexpression, supporting the possibility that GSK-3 inhibition is not sufficient to reverse NFT-like aggregates.
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PMID:Chronic lithium administration to FTDP-17 tau and GSK-3beta overexpressing mice prevents tau hyperphosphorylation and neurofibrillary tangle formation, but pre-formed neurofibrillary tangles do not revert. 1705 63


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