Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q16637 (SMA)
 8,107 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Autosomal recessive spinal muscular atrophy (SMA) is a common motor neuron disease caused by absence or mutation in the survival motor neuron (SMN1) gene. SNM1 and a nearly identical copy, SMN2, encode identical proteins, but SMN2 only produces a little full length protein due to alternative splicing. The level of functional SMN protein and the number of SMN2 genes correlate with the clinical phenotype ranging from severe to very mild. Here, we report on premature termination mutations in SMN1 exon 3 (425del5 and W102X) which induce skipping of the mutated exon. The novel nonsense mutation W102X was detected in two patients with a relatively mild phenotype who had only two copies of the SMN2 gene, a number that has previously been found associated with the severe form of SMA. We show that the shortened transcripts are translated into predicted in frame protein isoforms. Aminoglycoside treatment suppressed the nonsense mutation in cultured cells and abolished exon skipping. Fibroblasts from both patients show a high number of nuclear structures containing SMN protein (gems). These findings suggest that the protein isoform lacking the exon 3 encoded region contributes to the formation of the nuclear protein complex which may account for the milder clinical phenotype.
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PMID:Premature termination mutations in exon 3 of the SMN1 gene are associated with exon skipping and a relatively mild SMA phenotype. 1131 44

Spinal muscular atrophy (SMA), the most common hereditary motor neuron disease in children and young adults is caused by mutations in the telomeric survival motor neuron (SMN1) gene. The human genome, in contrast to mouse, contains a second SMN gene (SMN2) which codes for a gene product which is alternatively spliced at the C-terminus, but also gives rise to low levels of full-length SMN protein. The reason why reduced levels of the ubiquitously expressed SMN protein lead to specific motor neuron degeneration without affecting other cell types is still not understood. Using yeast two-hybrid techniques, we identified hnRNP-R and the highly related gry-rbp/hnRNP-Q as novel SMN interaction partners. These proteins have previously been identified in the context of RNA processing, in particular mRNA editing, transport and splicing. hnRNP-R and gry-rbp/hnRNP-Q interact with wild-type Smn but not with truncated or mutant Smn forms identified in SMA. Both proteins are widely expressed and developmentally regulated with expression peaking at E19 in mouse spinal cord. hnRNP-R binds RNA through its RNA recognition motif domains. Interestingly, hnRNP-R is predominantly located in axons of motor neurons and co-localizes with Smn in this cellular compartment. Thus, this finding could provide a key to understand a motor neuron-specific Smn function in SMA.
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PMID:Specific interaction of Smn, the spinal muscular atrophy determining gene product, with hnRNP-R and gry-rbp/hnRNP-Q: a role for Smn in RNA processing in motor axons? 1177 3

The etiology of amyotrophic lateral sclerosis remains unknown in the majority of cases. Homozygous SMN1 (survival motor neuron) gene deletion causes spinal muscular atrophy, and SMN2 gene deletions are possible risk factors in lower motor neuron disease. We studied SMN1 and SMN2 genes copy numbers in 167 amyotrophic lateral sclerosis patients and in 167 matched controls. We noted that 16% of amyotrophic lateral sclerosis patients had an abnormal copy number of the SMN1 gene (1 or 3 copies), compared with 4% of controls. An abnormal SMN1 gene locus may be a susceptibility factor for amyotrophic lateral sclerosis.
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PMID:Abnormal SMN1 gene copy number is a susceptibility factor for amyotrophic lateral sclerosis. 1244 45

Mutations in the telomeric copy of the SMN gene (SMN1) are responsible for almost all infantile motor neuron disease (MND). In contrast, the role of the centromeric copy of the SMN gene (SMN2) in MND remains unclear. We searched for deletions of SMN1 and SMN2 in a group of 11 patients with sporadic adult-onset lower motor neuron disease (also referred to as "progressive muscular atrophy") and found an excess of patients carrying homozygous deletions of SMN2 exon 7 (36% versus 5% in the normal population). This result suggests that SMN2 deletions could act as a susceptibility factor for sporadic lower motor neuron disease in adults.
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PMID:Homozygous exon 7 deletion of the SMN centromeric gene (SMN2): a potential susceptibility factor for adult-onset lower motor neuron disease. 1199 28

Recent research has significantly advanced our understanding of the molecular mechanisms of neurodegenerative diseases, including Alzheimer's disease (AD) and motor neuron disease. Here we emphasize the use of genetically engineered mouse models that are instrumental for understanding why AD is a neuronal disease, and for validating attractive therapeutic targets. In motor neuron diseases, Cu/Zn superoxide dismutase and survival motor neuron mouse models are useful in testing disease mechanisms and therapeutic strategies for amyotrophic lateral sclerosis (ALS) and spinal motor atrophy, respectively, but the mechanisms that account for selective motor neuron loss remain uncertain. We anticipate that, in the future, therapies based on understanding disease mechanisms will be identified and tested in mouse model systems.
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PMID:Genetically engineered mouse models of neurodegenerative diseases. 1208 93

Spinal muscular atrophy (SMA) is an inherited motor neuron disease caused by mutations in the survival motor neuron gene (SMN1). While it has been shown that the SMN protein is involved in spliceosome biogenesis and pre-mRNA splicing, there is increasing evidence indicating that SMN may also perform important functions in the nucleolus. We demonstrate here through the use of a previously characterized polyclonal anti-SMN antibody, abSMN, that the SMN protein shows a striking colocalization with the nucleolar protein, fibrillarin, in both nucleoli and Cajal bodies/gems of primary neurons. Immunoblot analysis with antifibrillarin and two different anti-SMN antibodies reveals that SMN and fibrillarin also cofractionate in the insoluble protein fraction of cultured cell lysates. Immunoprecipitation experiments using whole cell extracts of HeLa cells and cultured neurons revealed that abSMN coprecipitated small amounts of the U3 small nucleolar RNA (snoRNA) previously shown to be associated with fibrillarin in vivo. These studies raise the possibility that SMN may serve a function in rRNA maturation/ribosome synthesis similar to its role in spliceosome biogenesis.
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PMID:Survival motor neuron protein in the nucleolus of mammalian neurons. 1212 78

Proximal spinal muscular atrophy (SMA) is a common motor neuron disease caused by homozygous loss of the survival motor neuron gene (SMN1). SMN2, a nearly identical copy of the gene and present in all SMA patients, fails to provide protection from SMA, due to the disruption of an exonic splicing enhancer (ESE) by a single translationally silent nucleotide exchange, which causes alternative splicing of SMN2 exon 7. Identification of splicing factors that stimulate exon 7 inclusion and thereby produce sufficient amounts of full-length transcripts from the SMN2 gene is of great importance for therapy approaches. Here, by use of in vivo splicing assays, we identified the protein hnRNP-G and its paralogue RBM as two novel splicing factors that promote the inclusion of SMN2 exon 7. Moreover, hnRNP-G and RBM non-specifically bind RNA, but directly and specifically bind Htra2-beta1, an SR-like splicing factor which we have previously shown to stimulate inclusion of exon 7 through a direct interaction with the AG-rich ESE in SMN2 exon 7 pre-mRNA. By using deletion mutants of hnRNP-G, we show that the specific protein-protein interaction of hnRNP-G with Htra2-beta1 mediates the inclusion of SMN2 exon 7 rather than the non-specific interaction of hnRNP-G with SMN pre-mRNA. Additionally, we show for the first time that recombinant trans-acting splicing factors such as hnRNP-G and Htra2-beta1 are also effective on endogenous SMN2 transcripts and increase the endogenous SMN protein level. Finally, we suggest a model of how the exon 7 mRNA processing is regulated by the splicing factors identified so far.
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PMID:hnRNP-G promotes exon 7 inclusion of survival motor neuron (SMN) via direct interaction with Htra2-beta1. 1216 65

Spinal muscular atrophy (SMA) is a motor neuron disease caused by mutations of the survival motor neuron 1 gene (SMN1). No curative treatment is available. Mutant mice carrying homozygous deletion of Smn exon 7 directed to neurons display a degenerative process of motor neurons similar to that found in human SMA. To test whether riluzole, which exhibits neurotrophic properties, might have a protective role in SMA, mutant mice were treated with it after the onset of the degenerative process. Riluzole improved median survival and exerted a protective effect against aberrant cytoskeletal organization of motor synaptic terminals but not against loss of proximal axons. These results demonstrate that the disease course of SMA can be attenuated after the onset of neuromuscular defects and may warrant further investigation in a therapeutic trial in SMA.
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PMID:Riluzole attenuates spinal muscular atrophy disease progression in a mouse model. 1450 14

Spinal muscular atrophy (SMA) is an inherited motor neuron disease caused by mutation of the telomeric copy of the survival motor neuron gene (SMN1). Although a centromeric copy of the survival motor neuron gene (SMN2) is retained in all patients with SMA, it differs from SMN1 at a critical nucleotide such that the majority of SMN2 transcripts lack exon 7 and encode an unstable, truncated protein. Here, we show that valproic acid increases levels of exon 7-containing SMN transcript and SMN protein in type I SMA patient-derived fibroblast cell lines. Valproic acid may increase SMN levels both by activating the SMN promoter and by preventing exon 7 skipping in SMN transcripts. Valproic acid and related compounds warrant further investigation as potential treatment for SMA.
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PMID:Valproic acid increases SMN levels in spinal muscular atrophy patient cells. 1459 54

Five affected siblings were referred with a probable diagnosis of proximal adult-type spinal muscular atrophy (SMA) based on lower motor neuron signs (muscle weakness and atrophy, hypotony, hypoactive or absent reflexes, and fasciculations), normal or borderline serum creatine kinase levels, and a neurogenic pattern on electromyography, compatible with motor neuron disease, in one patient. No exon 7-8 deletion in the survival motor neuron (SMN) gene was found. Linkage analysis excluded the SMN and all known autosomal recessive limb girdle muscular dystrophy loci, with the exception of LGMD-2A. A homozygous R769Q mutation in the calpain-3 gene and absence of muscle calpain-3 protein confirmed a calpainopathy. This family suggests that the clinical spectrum of calpainopathy might be broader and that this diagnosis might be considered in patients with an atypical motor neuron disease.
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PMID:Calpainopathy: how broad is the spectrum of clinical variability? 1464 90


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