Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027819 (neuroblastoma)
 27,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Spinocerebellar ataxia type 3 (SCA3), like other polyglutamine (polyQ) diseases, is characterized by the formation of intraneuronal inclusions, but the mechanism underlying their formation is poorly understood. Here, we tested the "toxic fragment hypothesis", which predicts that proteolytic production of polyQ-containing fragments from the full-length disease protein initiates the aggregation process associated with inclusion formation and cellular dysfunction. We demonstrate that the removal of the N-terminus of polyQ-expanded ataxin-3 (AT3) is required for aggregation in vitro and in vivo. Consistently, proteolytic cleavage of full-length, pathogenic AT3 initiates the formation of sodium dodecylsulfate-resistant aggregates in neuroblastoma cells. Although full-length AT3 does not readily aggregate on its own, it is susceptible to co-aggregation with polyQ-expanded AT3 fragments. Interestingly, interaction with soluble polyQ-elongated fragments causes a structural distortion of wild-type AT3 prior to the formation of stable co-aggregates. These results establish the critical role of C-terminal, proteolytic fragments of AT3 in the molecular pathomechanism of SCA3, in strong support of the toxic fragment hypothesis.
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PMID:Proteolytic cleavage of polyglutamine-expanded ataxin-3 is critical for aggregation and sequestration of non-expanded ataxin-3. 1640 71

The formation of intraneuronal inclusions is a common feature of neurodegenerative polyglutamine disorders, including Spinocerebellar ataxia type 3. The mechanism that triggers inclusion formation in these typically late onset diseases has remained elusive. However, there is increasing evidence that proteolytic fragments containing the expanded polyglutamine segment are critically required to initiate the aggregation process. We analyzed ataxin-3 proteolysis in neuroblastoma cells and in vitro and show that calcium-dependent calpain proteases generate aggregation-competent ataxin-3 fragments. Co-expression of the highly specific cellular calpain inhibitor calpastatin abrogated fragmentation and the formation of inclusions in cells expressing pathological ataxin-3. These findings suggest a critical role of calpains in the pathogenesis of Spinocerebellar ataxia type 3.
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PMID:Calpain inhibition is sufficient to suppress aggregation of polyglutamine-expanded ataxin-3. 1748 27

Spinocerebellar ataxia type 8 (SCA8) involves bidirectional expression of CUG (ATXN8OS) and CAG (ATXN8) expansion transcripts. The pathogenesis of SCA8 is complex and the spectrum of clinical presentations is broad. In the present study, we assessed the SCA8 repeat size ranges in Taiwanese Parkinson's disease, Alzheimer's disease and atypical parkinsonism and investigated the genetic variation modulating ATXN8 expression. Thirteen large SCA8 alleles and a novel ATXN8 -62 G/A promoter SNP were found. There is a significant difference in the proportion of the individuals carrying SCA8 larger alleles in atypical parkinsonism (P = 0.044) as compared to that in the control subjects. In lymphoblastoid cells carrying SCA8 large alleles, treatment of MG-132 or staurosporine significantly increases the cell death or caspase 3 activity. Although expressed at low steady-state, ATXN8 expression level is significantly higher (P = 0.012) in cells with SCA8 large alleles than that of the control cells. The ATXN8 transcriptional activity was significantly higher in the luciferase reporter construct containing the -62G allele than that containing the -62A allele in both neuroblastoma and embryonic kidney cells. Therefore, our preliminary results suggest that ATXN8 gene -62 G/A polymorphism may be functional in modulating ATXN8 expression.
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PMID:SCA8 repeat expansion: large CTA/CTG repeat alleles in neurological disorders and functional implications. 1922 59

Spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD) is a late-onset neurodegenerative disorder caused by the expansion of a polyglutamine tract within the gene product, ataxin-3. Microarray analysis revealed a dramatic differential expression of carbonic anhydrase-related protein XI (CA-RPXI/CA11) in the presence or absence of mutant ataxin-3. Therefore, we examined the expression and distribution of all three CA-RPs (CA8, 10, and 11) in human neuronal cells that stably express mutant ataxin-3. Compared with the cells containing normal ataxin-3, protein expression of CA8 and CA11 is significantly increased in human neuroblastoma cells harboring mutant ataxin-3. Semi-quantitative RT-PCR demonstrated that all three CA-RPs exhibited significantly higher transcript levels in neuronal cells expressing mutant ataxin-3. Interestingly, CA11 is distributed not only in the cytoplasm but also within the nuclei of the stably transfected mutant cells when compared with the sole cytoplasmic distribution in cells containing normal ataxin-3. In addition, results from transient transfection assays in SK-N-SH and Neuro2a (N2a) cells also confirmed the nuclear localization of CA11 in the presence of truncated ataxin-3. Most importantly, immunohistochemical staining of the MJD transgenic mouse and post-mortem MJD human brain also revealed that CA11 is highly expressed in both cytoplasm and nuclei of the brain cells. Recruitment of CA11 into nuclear inclusions containing mutant ataxin-3 revealed a possible correlation between CA11 and disease progression. Although the exact function of CA-RPs is still undefined in the central nervous system, our findings suggest that CA-RPs, especially CA11, may play specific roles in the pathogenesis of Machado-Joseph disease.
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PMID:Altered expression of carbonic anhydrase-related protein XI in neuronal cells expressing mutant ataxin-3. 2318 27

Spinocerebellar ataxia type 8 (SCA8) involves the expansion of CTG/CAG repeats from the overlapping ataxin 8 opposite strand (ATXN8OS) and ataxin 8 (ATXN8) genes located on chromosome 13q21. Although being transcribed, spliced and polyadenylated in the CTG orientation, ATXN8OS does not itself appear to be protein coding, as only small open reading frames (ORFs) were noted. In the present study we investigated the translation of a novel 102 amino acids containing-ORF in the ATXN8OS RNA. Expression of chimeric construct with an in-frame ORF-EGFP gene demonstrated that ATXN8OS RNA is translatable. Using antiserum raised against ORF, ATXN8OS ORF expression was detected in various human cells including lymphoblastoid, embryonic kidney 293, neuroblastoma IMR-32, SK-N-SH, SH-SY5Y cells and human muscle tissue. The biological role of the ATXN8OS ORF and its connection to SCA8 remains to be determined.
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PMID:Internal ribosome entry segment activity of ATXN8 opposite strand RNA. 2404 Jan 7

Spinocerebellar ataxia type 17 (SCA 17) is a polyglutamine disease caused by the expansion of CAG/CAA repeats in the TATA box-binding protein (TBP) gene. The Ginkgo biloba extract, EGb 761, contains flavonoids and terpenoids with a potential use for the treatment of neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. The neuroprotective effects of EGb 761 are obvious, but whether the EGb 761 has therapeutic effects in SCA 17 is still unclear. To manage our issues, we have generated TBP/79Q-expressing SH-SY5Y cells and SCA 17 transgenic mice with the mutant hTBP gene. In in vitro experiment, we observed that the EGb 761 treatment decreased the amount of sodium dodecyl sulfate-insoluble proteins in the TBP/79Q-expressing SH-SY5Y cells. We further found that the EGb 761 treatment could inhibit excitotoxicity and calcium influx and reduce the expression of apoptotic markers in glutamate-treated SH-SY5Y neuroblastoma cells. In in vivo experiment, we observed that the EGb 761 treatment (100 mg/kg intraperitoneal injection per day) could relieve the motor deficiencies of the SCA 17 transgenic mice. Our findings provide evidence that the EGb 761 treatment can be a remedy for SCA 17 via suppressing excitotoxicity and apoptosis in SCA 17 cell and animal models. Therefore, we suggest that EGb 761 may be a potential therapeutic agent for treating SCA 17.
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PMID:Treatment with a Ginkgo biloba extract, EGb 761, inhibits excitotoxicity in an animal model of spinocerebellar ataxia type 17. 2693 74

Spinocerebellar ataxia type 3 (SCA3), known as Machado-Joseph disease, is an autosomal dominant disease caused by an abnormal expansion of polyglutamine in ATXN3 gene, leading to neurodegeneration in SCA3 patients. Similar to other neurodegenerative diseases, the dysfunction of mitochondria is observed to cause neuronal death in SCA3 patients. Based on previous studies, proteolytic cleavage of mutant ATXN3 is found to produce truncated C-terminal fragments in SCA3 models. However, whether these truncated mutant fragments disturb mitochondrial functions and result in pathological death is still unclear. Here, we used neuroblastoma cell and transgenic mouse models to examine the effects of truncated mutant ATXN3 on mitochondria functions. In different models, we observed truncated mutant ATXN3 accelerated the formation of aggregates, which translocated into the nucleus to form intranuclear aggregates. In addition, truncated mutant ATXN3 caused more mitochondrial fission, and decreased the expression of mitochondrial fusion markers, including Mfn-1 and Mfn-2. Furthermore, truncated mutant ATXN3 decreased the mitochondrial membrane potential, increased reactive oxygen species and finally increased cell death rate. In transgenic mouse models, truncated mutant ATXN3 also led to more mitochondrial dysfunction, neurodegeneration and cell death in the cerebellums. This study supports the toxic fragment hypothesis in SCA3, and also provides evidence that truncated mutant ATXN3 is severer than full-length mutant one in vitro and in vivo.
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PMID:The Truncated C-terminal Fragment of Mutant ATXN3 Disrupts Mitochondria Dynamics in Spinocerebellar Ataxia Type 3 Models. 2867 41

Machado-Joseph disease (MJD)/Spinocerebellar ataxia type 3 (SCA3) is an inherited neurodegenerative disease that can lead to a regression of motor coordination and muscle control in the extremities. It is known that expansion of CAG repeats encodes abnormally long polyQ in mutant ataxin-3, the disease protein. It is also noted that mutant ataxin-3 interacts with 1,4,5-trisphosphate receptor type 1 (IP3R1) and induces abnormal Ca2+ release. Previously, we have shown a significant increase in the expression of carbonic anhydrase VIII (CA8) in SK-N-SH-MJD78 cells, which are human neuroblastoma cells overexpressing mutant ataxin-3 with 78 glutamine repeats. In the current study, we showed the presence of significantly increased CA8 expression in MJD mouse cerebellum in either early or late disease stage, with a gradual decrease in CA8 expression as the MJD mice naturally aged. By immunofluorescence and immunoprecipitation analysis, we also found that CA8 co-localized and interacted with mutant ataxin-3 in SK-N-SH-MJD78 cells harboring overexpressed CA8 (SK-MJD78-CA8). In addition, we found that SK-MJD78-CA8 cells, as well as cerebellar granule neurons (CGNs) of MJD transgenic (Tg) mouse with overexpressed CA8, were more resistant to reactive oxygen species (ROS) stress than the control cells. Importantly, overexpression of CA8 in SK-MJD78-CA8 cells and in MJD CGNs rescued abnormal Ca2+ release and caused an increase in cell survival. In summary, we demonstrate the protective function of CA8 in MJD disease models and speculate that the declining expression of CA8 following an initial increased expression may be related to the late onset phenomenon of MJD.
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PMID:Protective roles of carbonic anhydrase 8 in Machado-Joseph Disease. 3115 58