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)

Intracellular inclusions are a unifying feature of polyglutamine (polyQ) neurodegenerative diseases, yet each polyQ disease displays a unique pattern of neuronal degeneration. This implies that the protein context of expanded polyQ plays an important role in establishing selective neurotoxicity. Here, in studies of the spinocerebellar ataxia type 3 disease protein ataxin-3, we demonstrate that the protein sequence surrounding polyQ specifies the constituents of nuclear inclusions (NI) formed by the disease protein. The nuclear proteins cAMP response element-binding protein-binding protein (CBP) and Mastermind-like-1 strongly colocalize only to NI formed by full-length ataxin-3, whereas the splicing factor SC35 colocalizes only to NI formed by a polyQ-containing, carboxyl-terminal fragment of ataxin-3. These differences in NI formation reflect specific protein interactions normally undertaken by ataxin-3, as both normal and mutant full-length ataxin-3 co-immunoprecipitate with CBP and sediment on density gradients as macromolecular complexes. Moreover, normal ataxin-3 represses cAMP response element-binding protein-mediated transcription, indicating a functional consequence of ataxin-3 interactions with CBP. Finally, we show that mutant ataxin-3 forms insoluble intranuclear complexes, or microaggregates, before NI can be detected, implying a precursor-product relationship. These results suggest that protein context-dependent recruitment of nuclear proteins to intranuclear microaggregates, and subsequently to NI, may contribute to selective neurotoxicity in polyQ diseases.
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PMID:The role of protein composition in specifying nuclear inclusion formation in polyglutamine disease. 1157 63

Ataxin-1 (Atx1), a member of the polyglutamine (polyQ) expanded protein family, is responsible for spinocerebellar ataxia type 1. Requirements for developing the disease are polyQ expansion, nuclear localization and phosphorylation of S776. Using a combination of bioinformatics, cell and structural biology approaches, we have identified a UHM ligand motif (ULM), present in proteins associated with splicing, in the C-terminus of Atx1 and shown that Atx1 interacts with and influences the function of the splicing factor U2AF65 via this motif. ULM comprises S776 of Atx1 and overlaps with a nuclear localization signal and a 14-3-3 binding motif. We demonstrate that phosphorylation of S776 provides the molecular switch which discriminates between 14-3-3 and components of the spliceosome. We also show that an S776D Atx1 mutant previously designed to mimic phosphorylation is unsuitable for this aim because of the different chemical properties of the two groups. Our results indicate that Atx1 is part of a complex network of interactions with splicing factors and suggest that development of the pathology is the consequence of a competition of aggregation with native interactions. Studies of the interactions formed by non-expanded Atx1 thus provide valuable hints for understanding both the function of the non-pathologic protein and the causes of the disease.
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PMID:Phosphorylation of S776 and 14-3-3 binding modulate ataxin-1 interaction with splicing factors. 2003 28

Mutant transcripts containing expanded CUG repeats in the untranslated region are a pathogenic factor in myotonic dystrophy type 1 (DM1). The mutant RNA sequesters the muscleblind-like 1 (MBNL1) splicing factor and causes misregulation of the alternative splicing of multiple genes that are linked to clinical symptoms of the disease. In this study, we show that either long untranslated CAG repeat RNA or short synthetic CAG repeats induce splicing aberrations typical of DM1. Alternative splicing defects are also caused by translated CAG repeats in normal cells transfected with a mutant ATXN3 gene construct and in cells derived from spinocerebellar ataxia type 3 and Huntington's disease patients. Splicing misregulation is unlikely to be caused by traces of antisense transcripts with CUG repeats, and the possible trigger of this misregulation may be sequestration of the MBNL1 protein with nuclear RNA inclusions containing expanded CAG repeat transcripts. We propose that alternative splicing misregulation by mutant CAG repeats may contribute to the pathological features of polyglutamine disorders.
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PMID:CAG repeats mimic CUG repeats in the misregulation of alternative splicing. 2179 78

Alternative splicing is a fundamental posttranscriptional mechanism for controlling gene expression, and splicing defects have been linked to various human disorders. The splicing factor FOX-2 is part of a main protein interaction hub in a network related to human inherited ataxias, however, its impact remains to be elucidated. Here, we focused on the reported interaction between FOX-2 and ataxin-1, the disease-causing protein in spinocerebellar ataxia type 1. In this line, we further evaluated this interaction by yeast-2-hybrid analyses and co-immunoprecipitation experiments in mammalian cells. Interestingly, we discovered that FOX-2 localization and splicing activity is affected in the presence of nuclear ataxin-1 inclusions. Moreover, we observed that FOX-2 directly interacts with ataxin-2, a protein modulating spinocerebellar ataxia type 1 pathogenesis. Finally, we provide evidence that splicing of pre-mRNA of ataxin-2 depends on FOX-2 activity, since reduction of FOX-2 levels led to increased skipping of exon 18 in ataxin-2 transcripts. Most striking, we observed that ataxin-1 overexpression has an effect on this splicing event as well. Thus, our results demonstrate that FOX-2 is involved in splicing of ataxin-2 transcripts and that this splicing event is altered by overexpression of ataxin-1.
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PMID:FOX-2 dependent splicing of ataxin-2 transcript is affected by ataxin-1 overexpression. 2266 29

Innervation of skeletal muscle by motor neurons occurs through the neuromuscular junction, a cholinergic synapse essential for normal muscle growth and function. Defects in nerve-muscle signaling cause a variety of neuromuscular disorders with features of ataxia, paralysis, skeletal muscle wasting, and degeneration. Here we show that the nuclear zinc finger protein ZFP106 is highly enriched in skeletal muscle and is required for postnatal maintenance of myofiber innervation by motor neurons. Genetic disruption of Zfp106 in mice results in progressive ataxia and hindlimb paralysis associated with motor neuron degeneration, severe muscle wasting, and premature death by 6 mo of age. We show that ZFP106 is an RNA-binding protein that associates with the core splicing factor RNA binding motif protein 39 (RBM39) and localizes to nuclear speckles adjacent to spliceosomes. Upon inhibition of pre-mRNA synthesis, ZFP106 translocates with other splicing factors to the nucleolus. Muscle and spinal cord of Zfp106 knockout mice displayed a gene expression signature of neuromuscular degeneration. Strikingly, altered splicing of the Nogo (Rtn4) gene locus in skeletal muscle of Zfp106 knockout mice resulted in ectopic expression of NOGO-A, the neurite outgrowth factor that inhibits nerve regeneration and destabilizes neuromuscular junctions. These findings reveal a central role for Zfp106 in the maintenance of nerve-muscle signaling, and highlight the involvement of aberrant RNA processing in neuromuscular disease pathogenesis.
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PMID:Severe muscle wasting and denervation in mice lacking the RNA-binding protein ZFP106. 2741

Tight coordination of gene expression in the developing cerebellum is crucial for establishment of neuronal circuits governing motor and cognitive function. However, transcriptional changes alone do not explain all of the switches underlying neuronal differentiation. Here we unveiled a widespread and highly dynamic splicing program that affects synaptic genes in cerebellar neurons. The motifs enriched in modulated exons implicated the splicing factor Sam68 as a regulator of this program. Sam68 controls splicing of exons with weak branchpoints by directly binding near the 3' splice site and competing with U2AF recruitment. Ablation of Sam68 disrupts splicing regulation of synaptic genes associated with neurodevelopmental diseases and impairs synaptic connections and firing of Purkinje cells, resulting in motor coordination defects, ataxia, and abnormal social behavior. These findings uncover an unexpectedly dynamic splicing regulatory network that shapes the synapse in early life and establishes motor and cognitive circuitry in the developing cerebellum.
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PMID:A Dynamic Splicing Program Ensures Proper Synaptic Connections in the Developing Cerebellum. 3249 19