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)

Ataxia-oculomotor apraxia (AOA1) is a neurological disorder with symptoms that overlap those of ataxia-telangiectasia, a syndrome characterized by abnormal responses to double-strand DNA breaks and genome instability. The gene mutated in AOA1, APTX, is predicted to code for a protein called aprataxin that contains domains of homology with proteins involved in DNA damage signalling and repair. We demonstrate that aprataxin is a nuclear protein, present in both the nucleoplasm and the nucleolus. Mutations in the APTX gene destabilize the aprataxin protein, and fusion constructs of enhanced green fluorescent protein and aprataxin, representing deletions of putative functional domains, generate highly unstable products. Cells from AOA1 patients are characterized by enhanced sensitivity to agents that cause single-strand breaks in DNA but there is no evidence for a gross defect in single-strand break repair. Sensitivity to hydrogen peroxide and the resulting genome instability are corrected by transfection with full-length aprataxin cDNA. We also demonstrate that aprataxin interacts with the repair proteins XRCC1, PARP-1 and p53 and that it co-localizes with XRCC1 along charged particle tracks on chromatin. These results demonstrate that aprataxin influences the cellular response to genotoxic stress very likely by its capacity to interact with a number of proteins involved in DNA repair.
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PMID:Aprataxin, a novel protein that protects against genotoxic stress. 1504 83

Aprataxin (APTX) is the causative gene product for early-onset ataxia with ocular motor apraxia and hypoalbuminemia (EAOH/AOA1). In our previous study, we found that APTX interacts with X-ray repair cross-complementing group 1 (XRCC1), a scaffold protein with an essential role in single-strand DNA break repair (SSBR). To further characterize the functions of APTX, we determined the domains of APTX and XRCC1 required for the interaction. We demonstrated that the 20 N-terminal amino acids of the FHA domain of APTX are important for its interaction with the C-terminal region (residues 492-574) of XRCC1. Moreover, we found that poly (ADP-ribose) polymerase-1 (PARP-1) is also co-immunoprecipitated with APTX. These findings suggest that APTX, together with XRCC1 and PARP-1, plays an essential role in SSBR.
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PMID:The FHA domain of aprataxin interacts with the C-terminal region of XRCC1. 1555 65

Several different autosomal recessive genetic disorders characterized by ataxia with oculomotor apraxia (AOA) have been identified with the unifying feature of defective DNA damage recognition and/or repair. We describe here the characterization of a novel form of AOA showing increased sensitivity to agents that cause single-strand breaks (SSBs) in DNA but having no gross defect in the repair of these breaks. Evidence for the presence of residual SSBs in DNA was provided by dramatically increased levels of poly (ADP-ribose)polymerase (PARP-1) auto-poly (ADP-ribosyl)ation, the detection of increased levels of reactive oxygen/nitrogen species (ROS/RNS) and oxidative damage to DNA in the patient cells. There was also evidence for oxidative damage to proteins and lipids. Although these cells were hypersensitive to DNA damaging agents, the mode of death was not by apoptosis. These cells were also resistant to TRAIL-induced death. Consistent with these observations, failure to observe a decrease in mitochondrial membrane potential, reduced cytochrome c release and defective apoptosis-inducing factor translocation to the nucleus was observed. Apoptosis resistance and PARP-1 hyperactivation were overcome by incubating the patient's cells with antioxidants. These results provide evidence for a novel form of AOA characterized by sensitivity to DNA damaging agents, oxidative stress, PARP-1 hyperactivation but resistance to apoptosis.
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PMID:A novel form of ataxia oculomotor apraxia characterized by oxidative stress and apoptosis resistance. 1734 66

Upon genotoxic stresses, cells activate IkappaB kinases (IKKs) and the transcription factor NF-kappaB to modulate apoptotic responses. The SUMO-1 ligase PIASy and the kinase ataxia talengiectasia mutated (ATM) have been implicated to SUMOylate and phosphorylate nuclear IKKgamma (NEMO) in a consecutive mode of action, which in turn results in activation of cytoplasmic IKK holocomplexes. However, the nuclear signals and scaffold structures that initiate IKKgamma recruitment and activation are unknown. Here, we show that poly(ADP-ribose)-polymerase-1 (PARP-1) is the DNA proximal regulator, which senses DNA strand breaks and, through poly(ADP-ribose) (PAR) synthesis, assembles IKKgamma, PIASy, and ATM in a dynamic manner. Signalosome formation involves direct protein-protein interactions and binding to ADP-ribose polymers through PAR binding motifs (PARBM). Activated PARP-1 and a PARBM in PIASy are required to trigger IKKgamma SUMOylation, which in turn permits IKK and NF-kappaB activation, as well as NF-kappaB-regulated resistance to apoptosis.
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PMID:A nuclear poly(ADP-ribose)-dependent signalosome confers DNA damage-induced IkappaB kinase activation. 1991 42