Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004134 (ataxia)
 15,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The role of autophagy in the degradation of aggregate-prone proteins has been well established. As a result, autophagy upregulation has become an attractive therapeutic strategy for the treatment of proteinopathies, a group of diseases caused by the accumulation of mutant misfolded proteins. We have previously shown that rapamycin attenuates the phenotype in a mouse model of Huntington disease when administered pre-symptomatically and have recently extended this to demonstrate the effectiveness of rapamycin in a transgenic mouse model of spinocerebellar ataxia type 3, a polyglutamine disorder caused by mutations in the ataxin-3 gene. Rapamycin, administered from the initial onset of disease signs, improves motor coordination and results in a decrease in the levels of soluble mutant ataxin-3 and protein aggregates in the brain.
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PMID:Broadening the therapeutic scope for rapamycin treatment. 2008 60

Several causal missense mutations in the protein kinase Cgamma (gammaPKC) gene have been found in spinocerebellar ataxia type 14 (SCA14), an autosomal dominant neurodegenerative disease. We previously showed that mutant gammaPKC found in SCA14 is susceptible to aggregation and causes apoptosis. Aggregation of misfolded proteins is generally involved in the pathogenesis of many neurodegenerative diseases. Growing evidence indicates that macroautophagy (autophagy) is important for the degradation of misfolded proteins and the prevention of neurodegenerative diseases. In the present study, we examined whether autophagy is involved in the degradation of the mutant gammaPKC that causes SCA14. Mutant gammaPKC-GFP was transiently expressed in SH-SY5Y cells by using an adenoviral tetracycline-regulated system. Subsequently, temporal changes in clearance of aggregates and degradation of gammaPKC-GFP were evaluated. Rapamycin, an autophagic inducer, accelerated clearance of aggregates and promoted degradation of mutant gammaPKC-GFP, but it did not affect degradation of wild-type gammaPKC-GFP. These effects of rapamycin were not observed in embryonic fibroblast cells from Atg5-deficient mice, which are not able to perform autophagy. Furthermore, lithium, another type of autophagic inducer, also promoted the clearance of mutant gammaPKC aggregates. These results indicate that autophagy contributes to the degradation of mutant gammaPKC, suggesting that autophagic inducers could provide therapeutic potential for SCA14.
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PMID:Mutant protein kinase C gamma that causes spinocerebellar ataxia type 14 (SCA14) is selectively degraded by autophagy. 2039 63

A balanced diet reduces the risk of life-threatening diseases such as diabetes and cancer. A reduced supply of energy at the cellular level leads to an increased concentration of AMP, which, in turn, results in LKB1-mediated activation of the AMPK kinase. The activation of the p53 tumor suppressor protein by metabolic stress has been shown to be mediated by AMPK. Increased intracellular AMP can be mimicked by 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR). We showed that AICAR activated the p53 pathway in LKB1-deficient cells. This activation was strongly attenuated by two inhibitors of the ATM kinase (caffeine and Ku-55933), which is dysfunctional in ataxia-telanagiectasia patients. In cells with ATM expression silenced by shRNA, AICAR-induced p53 phosphorylation at Ser(15) and Ser(37) was attenuated. Furthermore, p53 activation by AICAR was blocked by rapamycin, a specific inhibitor of the mTOR kinase, which is a crucial regulator of cell growth. Rapamycin did not block p53 activation by resveratrol, which, in contrast to AICAR, induced the DNA damage response, senescence-like growth inhibition, a high level of post-translational modification of p53, and weak upregulation of MDM2 (the negative regulator of p53). Thus, ATM and mTOR participate in the activation of p53 in response to a compound mimicking metabolic stress.
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PMID:The activation of the p53 pathway by the AMP mimetic AICAR is reduced by inhibitors of the ATM or mTOR kinases. 2194 51

Fragile X associated tremor/ataxia syndrome (FXTAS) is a late onset neurodegenerative disorder caused by aberrant expansion of CGG repeats in 5' UTR of FMR1 gene. The elevated mRNA confers a toxic gain-of-function thought to be the critical event of pathogenesis. Expressing rCGG90 repeats of the human FMR1 5'UTR in Drosophila is sufficient to induce neurodegeneration. Rapamycin has been demonstrated to attenuate neurotoxicity by inducing autophagy in various animal models of neurodegenerative diseases. Surprisingly, we observed rapamycin exacerbated rCGG90-induced neurodegenerative phenotypes through an autophagy-independent mechanism. CGG90 expression levels of FXTAS flies exposed to rapamycin presented no significant differences. We further demonstrated that activation of the mammalian target of rapamycin (mTOR) signaling could suppress neurodegeneration of FXTAS. These findings indicate that rapamycin will exacerbate neurodegeneration, and that enhancing autophagy is insufficient to alleviate neurotoxicity in FXTAS. Moreover, these results suggest mTOR and its downstream molecules as new therapeutic targets for FXTAS by showing significant protection against neurodegeneration.
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PMID:Activation of mTOR ameliorates fragile X premutation rCGG repeat-mediated neurodegeneration. 2362 35

Nijmegen Breakage Syndrome (NBS) is a recessive genetic disorder characterized by immunodeficiency, elevated sensitivity to ionizing radiation, chromosomal instability, microcephaly, and high predisposition to malignancies. Since the underlying molecular mechanisms of the NBS microcephaly are still obscure, thus our group previously inactivated the Nbn gene in the central nervous system (CNS) of mice by nestin-Cre targeting gene system, and generated Nbn(CNS-del) mice. Interestingly, the newborn Nbn(CNS-del) mice exhibit obvious microcephaly, which is accompanied by severe ataxia and balance deficiency. In this study presented here, we report that Nbn-deficiency induces the enhanced apoptosis of the mature oligodendrocytes at postnatal day 7, which further affects the myelination of the nerve fibers of cerebrum and corpus callosum.The distinct regulatory roles of Ataxia telangiectasia mutated (ATM) signaling and protein kinase B(Akt)/the mammalian target of Rapamycin (AKT/mTOR) signaling are responsible for the enhanced apoptosis of the Nbn-deficient oligodendrocytes. In addition, a series of transcriptional factors including histonedeacetylase (HDAC), zinc finger protein 191 (ZFP-191) and myelin sheath regulatory factor (MRF) play distinct roles in regulating the myelination of the Nbn-deficient oligodendrocytes. Based on these results, it concludes that ATM-Chk2-P53-P21 signaling pathway and the AKT/mTOR signaling pathway are both responsible for the enhanced apoptosis of the Nbn-deficient oligodendrocytes. HDAC, ZFP-191, and MRF are also involved in the pathogenesis of the hypomyelination of the Nbn-deficient oligodendrocytes.
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PMID:Nbn gene inactivation in the CNS of mouse inhibits the myelinating ability of the mature cortical oligodendrocytes. 2427 8

Friedreich's ataxia (FRDA), the most common inherited ataxia in the Caucasian population, is a multisystemic disease caused by a significant decrease in the frataxin level. To identify genes capable of modifying the severity of the symptoms of frataxin depletion, we performed a candidate genetic screen in a Drosophila RNAi-based model of FRDA. We found that genetic reduction in TOR Complex 1 (TORC1) signalling improves the impaired motor performance phenotype of FRDA model flies. Pharmacologic inhibition of TORC1 signalling by rapamycin also restored this phenotype and increased the lifespan and ATP levels. Furthermore, rapamycin reduced the altered levels of malondialdehyde + 4-hydroxyalkenals and total glutathione of the model flies. The rapamycin-mediated protection against oxidative stress is due in part to an increase in the transcription of antioxidant genes mediated by cap-n-collar (Drosophila ortholog of Nrf2). Our results suggest that autophagy is indeed necessary for the protective effect of rapamycin in hyperoxia. Rapamycin increased the survival and aconitase activity of model flies subjected to high oxidative insult, and this improvement was abolished by the autophagy inhibitor 3-methyladenine. These results point to the TORC1 pathway as a new potential therapeutic target for FRDA and as a guide to finding new promising molecules for disease treatment.
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PMID:TORC1 Inhibition by Rapamycin Promotes Antioxidant Defences in a Drosophila Model of Friedreich's Ataxia. 2615 31