UNIPROT:P10636 - FACTA Search

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Query: UNIPROT:P10636 (tau protein)
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Multiple factors have been hypothesized over the last century to be causative or contributory for Parkinson's disease. Hereditary factors have recently emerged as a major focus of Parkinson's disease research. Until recently most of the research on the etiology of Parkinson's disease concentrated on environmental factors, and the possibility that genetic factors contribute significantly to the pathogenesis of Parkinson's disease has been neglected. However, it has become increasingly apparent that even in sporadic cases, the disease most likely reflects a combination of genetic susceptibility and an unknown environmental insult. Moreover, the identification of genes and proteins that may cause hereditary parkinsonism substantially contributes to our ability to understand the pathogenesis of Parkinson's disease and may help in the early identification of the disease and its treatment. The discovery of alpha-synuclein mutations in families with autosomal dominant Parkinson's disease sheds light on its role in sporadic Parkinson's disease. It seems that this protein tends to aggregate when the cellular milieu is altered [14-16]. The question as to the exact changes that cause its deposition remains open. One of the major possibilities is oxidative stress [16]. The role of these aggregates in neuronal cell death is also still unclear. Transgenic mice expressing wild-type human alpha-synuclein developed progressive accumulation of alpha-synuclein and ubiquitin-immunoreactive inclusions in neurons in the neocortex, hippocampus and the substantia nigra. These alterations were associated with loss of dopaminergic terminals and motor impairments [24]. This finding suggests that accumulation of alpha-synuclein may play a causal role in sporadic Parkinson's disease as well. The parkin protein seems to be a crucial survival factor for nigral neurons [15]. The parkin protein is related to the ubiquitin pathway, which is important in the elimination of damaged proteins. Ubiquitin-mediated degradation of proteins plays a central role in the control of numerous processes, including signal transduction, receptor and transcriptional regulations, programmed cell death, and breakdown of abnormal proteins that may interfere with normal cell functions. Further studies on the function of Parkin protein and its relation to the ubiquitin pathway could elucidate at least one of the molecular mechanisms of nigral neuronal death. A mutation in the ubiquitin carboxy-teminal hydrolase L1 gene also implies the importance of the ubiquitin pathway in Parkinson's disease. Abnormal tau protein was found to be the cause of familial frontotemporal dementia and parkinsonism. It tends to form filamentous structures, which may lead to neuronal death. Elucidation of the molecular mechanism of neuronal death in this disease may contribute to our understanding of sporadic diseases with tau accumulation, such as corticobasal degeneration, progressive supranuclear palsy, Pick's disease, Alzheimer's disease and possibly also the pathogenesis of Parkinson's disease. Other genetic loci have been identified by linkage analysis of patients with familial parkinsonism. These loci conceal other genes and proteins that may be pivotal factors in the pathogenesis of Parkinson's disease. The discovery of genetic mutations in patients with parkinsonism may offer us new insights into the understanding of the pathways leading to neuronal death and development of Parkinson's disease. It may also help in the early identification of susceptible people to this disease and possibly in developing new treatment strategies.
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PMID:Heredity in Parkinson's disease: new findings. 1143 38

The microtubule-binding protein tau has been implicated in the neurofibrillary pathology of Alzheimer's disease. Within affected cells, ubiquitinated and hyperphosphorylated tau assembles into massive filamentous polymers. Eventually these tangle-bearing neurons die. The formation of neurofibrillary tangles closely parallels the progression and anatomic distribution of neuronal loss in Alzheimer's disease, suggesting that these lesions play a role in the disease pathogenesis. Mutations in the human tau gene cause autosomal dominant neurodegenerative disorders. These and other neurodegenerative conditions are also characterized by extensive neurofibrillary pathology. The mechanisms underlying tau-mediated neurotoxicity remain unclear; however, phosphorylated tau is a strong candidate for a toxic molecule, particularly those isoforms phosphorylated by the kinases glycogen synthase kinase 3beta and Cdk5. Here we show that Alzheimer tau binds to Hsc70, and its phosphorylation is a recognition requirement for the addition of ubiquitin (Ub) by the E3 Ub ligase CHIP (carboxyl terminus of the Hsc70-interacting protein) and the E2 conjugating enzyme UbcH5B. Other E3 Ub ligases including parkin and Cbl failed to ubiquitinate phosphorylated tau. CHIP could rescue phosphorylated tau-induced cell death, and therefore the CHIP-Hsc70 complex may provide a new therapeutic target for the tauopathies.
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PMID:CHIP-Hsc70 complex ubiquitinates phosphorylated tau and enhances cell survival. 1461 56

PD (Parkinson's disease) is an aetiologically heterogeneous disorder characterized by a clinical phenotype consisting of resting tremor, rigidity and bradykinesia. Motor symptoms are associated with a progressive loss of dopaminergic neurons, with Lewy body inclusions within surviving neurons. Although heritability studies have shown evidence of familial aggregation, twin studies have provided limited support for a genetic aetiology. Nevertheless, classical linkage methods have nominated 11 regions of the genome and pathogenic mutations have been identified in several genes, including alpha-synuclein, parkin, ubiquitin C-terminal hydrolase L1, oncogene DJ-1, PTEN-induced protein kinase 1 and microtubule-associated protein tau. Most recently, heterozygous mutations in LRRK2 (leucine-rich repeat kinase 2) were found to cause late-onset, autosomal-dominant PD. Despite their consistent clinical phenotype, family members with LRRK2 mutations can have variable alpha-synuclein and tau pathologies. Lrrk2 is a member of the Roc (Ras of complex proteins) family, with Ras GTPase and MAPKKK (mitogen-activated protein kinase kinase kinase) catalytic domains. Thus its discovery highlights vesicle dynamics and secondary-messenger signalling in disease pathophysiology. To diagnose a disease accurately and effectively treat it, requires an understanding of its molecular pathogenesis. Herein, we provide an overview of the genetics of PD, how these discoveries are revolutionizing long-held beliefs and more importantly how this knowledge may be translated into patient therapy.
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PMID:Pathophysiology, pleiotrophy and paradigm shifts: genetic lessons from Parkinson's disease. 1604 50

Parkin is a ubiquitin ligase involved in the ubiquitin-proteasome system. Elevating parkin expression in cells reduces markers of oxidative stress while blocking parkin expression increases oxidative stress. In parkin gene knock down mouse and fly models, mitochondria function is deficient. Parkin is neuroprotective against a variety of toxic insults, while it remains unclear which of the above properties of parkin may mediate the protective actions. One of the models for which parkin is protective is overexpression of alpha-synuclein, a protein that self-aggregates in Parkinson disease. The microtubule-associated protein tau is another protein that self-aggregates in specific neurodegenerative diseases that also involve loss of dopamine neurons such as frontotemporal dementia with parkinsonism linked to chromosome 17, progressive supranuclear palsy and corticobasal degeneration. We recently developed a tau-induced dopaminergic degeneration model in rats using adeno-associated virus vectors. In this study, we successfully targeted either a mixed tau/parkin vector or mixed tau/control vector to the rat substantia nigra. While there was significant loss of dopamine neurons in the tau/control group relative to uninjected substantia nigra, there was no cell loss in the tau/parkin group. We found no difference in total tau levels between tau/control and tau/parkin groups. Parkin therefore protects dopamine neurons against tau as it does against alpha-synuclein, which further supports parkin as a therapeutic target for diseases involving loss of dopamine neurons.
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PMID:Parkin is protective for substantia nigra dopamine neurons in a tau gene transfer neurodegeneration model. 1655 20

Mutations, haplotypes, and polymorphisms of tau and Park-2 genes constitute risk factors for developing tauopathies. In order to analyze the possible relationship between parkin and tau we generated a double-mutant mouse deficient for Park-2 expression and overexpressing a mutant tau protein (hTauVLW). Mice develop normally, although the median survival rate is considerably reduced with respect to wild type (45%). Aggregates of phosphorylated tau in neurons and reactive gliosis are quite abundant in cortex and hippocampus of these mice. Moreover, while in young transgenic mice the hTauVLW immunostained transgene product is observed in both cell bodies and dendrites, the hTauVLW mutant protein is only detected in the neuronal cell bodies when Park-2 gene is additionally deleted. Moreover, DNA fragmentation was detected by the TUNEL method, and cerebral atrophy is also present in these regions. The levels of phosphorylated tau and Hsp70 are increased in the double-mutant mice, while CHIP expression in hippocampus is lower when the Park-2 gene is deleted. Thus, the combination of Park-2 gene deletion with hTauVLW transgene overexpression in mice produces serious neuropathological effects, which reflect the existence of some relationship between both proteins.
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PMID:Park2-null/tau transgenic mice reveal a functional relationship between parkin and tau. 1837 58

To clarify the genetic background of amyotrophic lateral sclerosis (ALS)/parkinsonism-dementia complex (PDC) of the Kii peninsula, Japan (Kii ALS/PDC), we performed extended mutation analyses of three patients with pathologically diagnosed Kii ALS/PDC. Direct sequencing analyses were performed in 19 genes, including ALS/frontotemporal lobar degeneration (FTLD)-related genes (SOD2, SOD3, ALS2/alsin, SMN1, PGRN, ANG, VEGF, VCP, VAPB, DCTN1, CHMP2B, and TARDBP or TDP-43), tauopathy-related gene (GSK3beta), and parkinsonism-related genes (alpha-synuclein, LRRK2, parkin, DJ-1, PINK1, and ATP13A2). Gene dosage analyses were conducted in screening of MAPT, alpha-synuclein, TDP-43 (or TARDBP), GSK3beta, and parkin. We found no mutation in the 19 genes. We found a homozygous nonsynonymous SNP (ALS2/alsin V368M) shared by all the three patients. Gene dosage was normal in MAPT, alpha-synuclein, TDP-43, GSK3beta, and parkin. The present findings, together with a previous negative study on MAPT and SOD1 mutation, further elucidated the lack of causative mutations in all exons, exon-intron boundaries, or some rearrangements of the reported major causative or susceptible genes related to ALS, FTLD, parkinsonism, synucleinopathy, TDP-43 proteinopathy, and tauopathy. However, the familial aggregation and lack of any environment factors suggest that Kii ALS/PDC is caused by other yet unidentified genetic factors.
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PMID:Mutation analyses in amyotrophic lateral sclerosis/parkinsonism-dementia complex of the Kii peninsula, Japan. 1875 52

Mutations in the PARK2 gene encoding parkin cause autosomal recessive juvenile parkinsonism, but have also been found in patients diagnosed with certain tauopathies. Conversely, mutations in the MAPT gene encoding tau are present in some types of parkinsonism. In order to investigate the possible relationship between these two proteins, we generated a double mutant mouse that is deficient in PARK2 and that over-expresses the hTauVLW transgene, a mutant form of the tau protein present in FTDP-17. Independent deletion of PARK2 or over-expression of the hTauVLW transgene produces mild phenotypic alterations, while a substantial increase in parkin expression is observed in hTauVLW transgenic mice. However, double mutant mice present memory and exploratory deficits, and accumulation of PHF-1 and AT8 hyperphosphorylated tau epitopes in neurons. These phenomena are coupled with reactive astrocytosis, DNA fragmentation, and variable cerebral atrophy. Here, we show that cortical and hippocampal neurons of double mutant mice develop argyrophilic Gallyas-Braak aggregates of phosphorylated tau from 3 months of age. Their number decreases in old animals. Moreover, numerous phosphorylated tau aggregates were identified with the conformation-dependent Alz-50 antibody and the S-Thioflavin staining. Ventral motor nuclei of the spinal cord also present Alz-50, AT8, and PHF1 hyperphosphorylated tau aggregates when parkin is deleted in mice over-expressing the hTauVLW transgene, begining at early ages. Thus, the combination of PARK2 gene deletion with hTauVLW over-expression in mice produces abnormal hyperphosphorylated tau aggregates, similar to those observed in the brain of patients diagnosed with certain tauopathies. In the light of these changes, these mice may help to understand the molecular processes responsible for these diseases, and they may aid the development of new therapeutic strategies to treat neurodegenerative diseases related to tau and parkin proteins.
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PMID:Hyperphosphorylated tau aggregates in the cortex and hippocampus of transgenic mice with mutant human FTDP-17 Tau and lacking the PARK2 gene. 1905 15

Parkin suppression induces accumulation of beta-amyloid in mutant tau mice. We studied the effect of parkin suppression on behaviour and brain pathology in APP(swe) mutant mice. We produced double mutant mice with human mutated APP(swe)+partial (hemizygote) or total (homozygote) deletion of Park-2 gene. We studied the development, behaviour, brain histology, and biochemistry of 12- and 16-month-old animals in 6 groups of mice, with identical genetic background: wild-type (WT), APP(swe) overexpressing (APP), hemizygote and homozygote deletion of Park-2 (PK(+/-) and PK(-/-), respectively), and double mutants (APP/PK(+/-) and APP/PK(-/-)). APP mice have reduced weight gain, decreased motor activity, and reduced number of entrances and of arm alternation in the Y-maze, abnormalities which were partially or completely normalized in APP/PK(+/-) and APP/PK(-/-) mice. The double mutants had similar number of mutant human APP transgene copies than the APP and levels of 40 and 80 kDa proteins; but both of them, APP/PK(+/-) and APP/PK(-/-) mice, had less plaques in cortex and hippocampus than the APP mice. APP mutant mice had increased apoptosis, proapoptotic Bax/Bcl2 ratios, and gliosis, but these death-promoting factors were normalized in APP/PK(+/-) and APP/PK(-/-) mice. APP mutant mice had an increased number of tau immunoreactive neuritic plaques in the cerebral cortex as well as increased levels of total and phosphorylated tau protein, and these changes were partially normalized in APP/PK(+/-) heterozygotic and homozygotic APP/PK(-/-) mice. Compensatory protein-degrading systems such as HSP70, CHIP, and macroautophagy were increased in APP/PK(+/-) and APP/PK(-/-). Furthermore, the chymotrypsin- and trypsin-like proteasome activities, decreased in APP mice in comparison with WT, were normalized in the APP/PK(-/-) mice. We proposed that partial and total suppression of parkin triggers compensatory mechanisms, such as chaperone overexpression and increased autophagy, which improved the behavioural and cellular phenotype of APP(swe) mice.
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PMID:The effects of parkin suppression on the behaviour, amyloid processing, and cell survival in APP mutant transgenic mice. 1981 12

Tauopathies are neurodegenerative diseases, sporadic or familial, mainly characterized by dementia and parkinsonism associated to atrophy of the frontotemporal cortex and the basal ganglia, with deposition of abnormal tau in brain. Hereditary tauopathies are related with mutations of the tau gene. Up to the present, these diseases have not been helped by any disease-modifying treatment, and patients die a few years after the onset of symptoms. We have developed and characterized a mouse model of tauopathy with parkinsonism, overexpressing human mutated tau protein with deletion of parkin (PK(-/-)/Tau(VLW)). At 3 months of age, these mice present abnormal dopamine-related behavior, severe dropout of dopamine neurons in the ventral midbrain, reduced dopamine levels in the striatum and abundant phosphorylated tau-positive neuritic plaques, neurofibrillary tangles, astrogliosis, and, at 12 months old, plaques of murine beta-amyloid in the hippocampus. Trehalose is a natural disaccharide that increases the removal of abnormal proteins through enhancement of autophagy. In this work, we tested if 1% trehalose in the drinking water reverts the PK(-/-)/Tau(VLW) phenotype. The treatment with trehalose of 3-month-old PK(-/-)/Tau(VLW) mice for 2.5 months reverted the dropout of dopamine neurons, which takes place in the ventral midbrain of vehicle treated PK(-/-)/Tau(VLW) and the reduced dopamine-related proteins levels in the midbrain and striatum. The number of phosphorylated tau-positive neuritic plaques and the levels of phosphorylated tau decreased, as well as astrogliosis in brain regions. The autophagy markers in the brain, the autophagic vacuoles isolated from the liver, and the electron microscopy data indicate that these effects of trehalose are mediated by autophagy. The treatment with trehalose for 4 months of 3-month-old PK(-/-)/Tau(VLW) mice maintained the amelioration of the tau pathology and astrogliosis but failed to revert DA-related pathology in the striatum. Furthermore, the 3-week treatment with trehalose of 14-month-old PK(-/-)/Tau(VLW) mice, at the limit of their life expectancy, improved the motor behavior and anxiety of these animals, and reduced their levels of phosphorylated tau and the number of murine beta-amyloid plaques. Trehalose is neuroprotective in this model of tauopathy. Since trehalose is free of toxic effects at high concentrations, this study opens the way for clinical studies of the effects of trehalose in human tauopathies.
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PMID:Trehalose ameliorates dopaminergic and tau pathology in parkin deleted/tau overexpressing mice through autophagy activation. 2054 95

In 1997 a mutation in the a-synuclein (SNCA) gene was associated with familial autosomal dominant Parkinson's disease (PD). Since then, several loci (PARK1-15) and genes have been linked to familial forms of the disease. There is now sufficient evidence that six of the so far identified genes at PARK loci (a-synuclein, leucine-rich repeat kinase 2, parkin, PTEN-induced putative kinase 1, DJ-1, and ATP13A2) cause inherited forms of typical PD or parkinsonian syndromes. Other genes at non-PARK loci (MAPT, SCA1, SCA2, spatacsin, POLG1) cause syndromes with parkinsonism as one of the symptoms. The majority of PD cases are however sporadic "idiopathic" forms, and the recent application of genome-wide screening revealed almost 20 genes that might contribute to disease risk. In addition, increasing evidence suggests that epigenetic mechanisms, such as DNA methylation, histone modifications, and small RNA-mediated mechanisms, could regulate the expression of PD-related genes.
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PMID:Genetics and epigenetics of Parkinson's disease. 2262

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