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)

Proximal spinal muscular atrophy (SMA) is a common motor neuron disorder caused by mutation of the telomeric survival of motor neuron gene SMN1. The centromeric survival of motor neuron SMN2 gene is retained in all SMA patients but does not produce sufficient SMN protein to prevent the development of clinical symptoms. The SMN1 and SMN2 genes differ functionally by a single nucleotide change. This change affects the efficiency with which exon 7 is incorporated into the mRNA transcript. Thus, SMN2 produces less full-length mRNA and protein than SMN1. We have screened a library of compounds in order to identify ones that can alter the splicing pattern of the SMN2 gene. Here, we report that the compound aclarubicin increases the retention of exon 7 into the SMN2 transcript. We show that aclarubicin effectively induces incorporation of exon 7 into SMN2 transcripts from the endogenous gene in type I SMA fibroblasts as well as into transcripts from a SMN2 minigene in the motor neuron cell line NSC34. In type I fibroblasts, treatment resulted in an increase in SMN protein and gems to normal levels. Our results suggest that alteration of splicing pattern represents a new approach to modification of gene expression in disease treatment and demonstrate the feasibility of high throughput screens to detect compounds that affect the splicing pattern of a gene.
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PMID:Aclarubicin treatment restores SMN levels to cells derived from type I spinal muscular atrophy patients. 1173 49

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 majority of patients with hereditary proximal spinal muscular atrophy (SMA) have a homozygous deletion of the survival motor neuron gene (SMN1). The number of SMN2 gene copies modifies the phenotype, which ranges from a lethal infantile disorder to an adult-onset disease causing mild impairment and disability. The SMN protein plays a role in an apparently essential cell metabolism process, the splicing of pre-mRNA in the spliceosomes. Why SMN1 deletions are only clinically expressed in motor neuron cells and not in other cell types is still unknown. DNA analysis, prenatal diagnosis and carrier testing as means of diagnosing SMA are all routinely available in the Netherlands and are currently performed at the DNA laboratory of the University of Groningen.
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PMID:[From gene to disease; 'survival' motor neuron protein and hereditary proximal spinal muscle atrophy]. 1179 27

Proximal spinal muscular atrophy (SMA) is caused by the homozygous loss of survival motor neuron (SMN1). SMN2, a nearly identical copy gene, is present in all SMA patients; however this gene cannot provide protection from disease due to the aberrant splicing of a critical exon. SMN1-derived transcripts are exclusively full-length, whereas SMN2-derived transcripts predominantly lack SMN exon 7. A single non-polymorphic nucleotide difference (C in SMN1; T in SMN2) is responsible for the alternative splicing patterns. We have previously shown that transient expression of an SR-like splicing factor, hTra2 beta 1, stimulates inclusion of exon 7 in SMN2-derived mini-gene transcripts through an interaction with the AG-rich exonic splice enhancer within exon 7. We now demonstrate that a second splicing factor, SRp30c, can stimulate SMN exon 7-inclusion and that this activity required the same AG-rich enhancer as hTra2 beta 1. SRp30c did not directly associate with SMN exon 7; rather its association with the exonic enhancer was mediated by a direct interaction with hTra2 beta 1. In the absence of the hTra2 beta 1 binding site, SRp30c failed to complex with SMN exon 7. Taken together, these results identify SRp30c as a modulator of SMN exon 7-inclusion and provide insight into the molecular regulation of this critical exon.
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PMID:SRp30c-dependent stimulation of survival motor neuron (SMN) exon 7 inclusion is facilitated by a direct interaction with hTra2 beta 1. 1187 52

Autosomal recessive spinal muscular atrophy (SMA) is a disease resulting from mutations in the telomeric survival motor neuron gene ( SMN1). In our sample of 150 Spanish SMA families, 87% of patients had homozygous deletions of SMN1. To identify patients who retained a single SMN1 copy, SMN dosage analysis was performed by a fluorescent quantitative PCR assay. In five out of 19 patients tested we detected one SMN1 copy. An extensive SMN gene analysis in these patients led to identification of four intragenic mutations, including two novel ones: a frameshift mutation in exon 6 (773insC) and a splice site mutation in intron 6 (c.867+2T-->G). Two previously described mutations were also found: a deletion in exon 3 (430del4), identified in several Spanish patients, and a frequently occurring mutation in exon 6 (813ins/dup11), reported in several populations. Although the spectrum of intragenic mutations is small, only 27 reported up to now, identification of three mutations found exclusively in the Spanish population indicates that the occurrence of different intragenic mutations depends on the ethnic origin of SMA patients. In the remaining patient, who had a single SMN1 copy and three SMN2 copies, we found that the SMN1 allele was non-functional; the patient did not show any SMN1 transcript. Sequencing of the SMN promoter regions revealed various differences between promoters of the patient's four SMN genes, in particular a change in the length of a polyA run removing a putative YY1 binding site, which may affect the expression of SMN genes.
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PMID:Genetic study of SMA patients without homozygous SMN1 deletions: identification of compound heterozygotes and characterisation of novel intragenic SMN1 mutations. 1193 38

Spinal muscular atrophy results from the loss of functional survival motor neuron (SMN1) alleles. Two nearly identical copies of SMN exist and differ only by a single non-polymorphic C to T transition in exon 7. This transition leads to alteration of exon 7 splicing; that is, SMN1 produces a full-length transcript, whereas SMN2 expresses a low level of full-length transcript and predominantly an isoform lacking exon 7. The truncated transcript of SMN encodes a less stable protein with reduced self-oligomerization activity that fails to compensate for the loss of SMN1. In this paper, we identified a cis-acting element (element 1), which is composed of 45 bp in intron 6 responsible for the regulation of SMN exon 7 splicing. Mutations in element 1 or treatment with antisense oligonucleotides directed toward element 1 caused an increase in exon 7 inclusion. An approximately 33-kDa protein was demonstrated to associate with a pre-mRNA sequence containing both element 1 and the C to T transition in SMN exon 7 but not with the sequence containing mutated element 1, suggesting that the binding of the approximately 33-kDa protein plays crucial roles in the skipping of SMN exon 7 containing the C to T transition.
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PMID:Identification of a cis-acting element for the regulation of SMN exon 7 splicing. 1195 96

Spinal muscular atrophy (SMA) is caused by the loss of functional survival motor neuron 1 (SMN1) protein. This ubiquitously expressed protein is a component of a novel complex immunodetected in both the cytoplasm and the nucleus, which is associated with complexes involved in mRNA splicing, ribosome biogenesis and transcription. Here, we study a mutant protein corresponding to the N-terminal half of the protein that is encoded by the SMA frameshift mutation SMN 472del5. We show by confocal microscopy that the resulting mutant protein exhibits various distribution patterns in different transiently transfected COS cells. The mutant distributes into the nucleoplasm and/or the nucleolus, whereas the normal SMN protein accumulates at discrete nucleocytoplasmic dot-like structures previously named gems/Cajal bodies. The cell population with the nucleolar distribution is enriched upon treatment with mimosine, a synchronizing drug in late G(1) phase. Co-immunoprecipitation studies carried out on nuclear extracts reveal that both the endogenous SMN and mutant proteins are associated with complexes containing two major non-ribosomal nucleolar proteins, namely nucleolin and protein B23, and that the association is mediated, by among other things, RNA moieties. Both the association of the SMN protein with nucleolin-containing complexes and the nucleolin/B23 complex are disrupted in fibroblasts derived from a type I SMA patient harboring a homozygous SMN1 gene deletion. These findings suggest that altered assembly and/or stability of ribonucleoprotein complexes may contribute to the pathophysiological processes in SMA.
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PMID:A novel association of the SMN protein with two major non-ribosomal nucleolar proteins and its implication in spinal muscular atrophy. 1197 61

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

Spinal muscular atrophies (SMA) are characterized by degeneration of lower motor neurons associated with muscle paralysis and atrophy. Childhood SMA is a frequent recessive autosomal disorder and represents one of the most common genetic causes of death in childhood. Mutations of the SMN1 gene are responsible for SMA. The knowledge of the genetic basis of SMA, a better understanding of SMN function, and the recent generation of SMA mouse models represent major advances in the field of SMA. These are starting points towards understanding the pathophysiology of SMA and developing therapeutic strategies for this devastating neurodegenerative disease, for which no curative treatment is known so far.
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PMID:Spinal muscular atrophy: recent advances and future prospects. 1211 44

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


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