SMN1(Survival Motor Neuron 1,运动神经元存活基因1)是一个关键基因,其编码的SMN蛋白对运动神经元的存活和功能至关重要。SMN蛋白的主要生物学功能是参与剪接体(spliceosome)的组装,剪接体是细胞中负责剪切pre-mRNA(前体信使RNA)以形成成熟mRNA的复合物,这一过程对基因表达调控至关重要。此外,SMN蛋白还参与小核核糖核蛋白(snRNP)的生物合成,这是剪接体的核心组成部分。SMN1基因的主要作用位点在运动神经元,特别是在脊髓中,其功能缺陷会导致运动神经元退化。SMN1基因的突变,尤其是外显子7的缺失或变异,会导致脊髓性肌萎缩症(SMA,Spinal Muscular Atrophy),这是一种严重的神经肌肉疾病,表现为肌肉无力和萎缩,严重时可危及生命。SMN1的突变通常导致SMN蛋白水平显著降低,进而影响剪接体的正常功能,导致运动神经元死亡。SMN1属于SMN基因家族,该家族还包括SMN2基因。SMN2与SMN1高度相似,但由于外显子7的剪接效率较低,其产生的功能性SMN蛋白较少,因此SMN2无法完全补偿SMN1的功能缺失。SMN基因家族的共性在于它们都编码SMN蛋白,但不同成员在表达水平和剪接效率上存在差异。当SMN1过表达时,可能对运动神经元起到保护作用,理论上可缓解SMA症状;而SMN1表达降低则直接导致SMA的发生。SMN1的表达水平还会影响其他基因的剪接效率,进而影响多个细胞过程。目前针对SMA的治疗策略之一是通过药物或基因疗法提高SMN蛋白水平,例如使用诺西那生钠(Nusinersen)来调节SMN2的剪接,以增加功能性SMN蛋白的产生。SMN1的研究不仅对理解神经退行性疾病有重要意义,也为开发相关治疗方法提供了靶点。
This gene is part of a 500 kb inverted duplication on chromosome 5q13. This duplicated region contains at least four genes and repetitive elements which make it prone to rearrangements and deletions. The repetitiveness and complexity of the sequence have also caused difficulty in determining the organization of this genomic region. The telomeric and centromeric copies of this gene are nearly identical and encode the same protein. However, mutations in this gene, the telomeric copy, are associated with spinal muscular atrophy; mutations in the centromeric copy do not lead to disease. The centromeric copy may be a modifier of disease caused by mutation in the telomeric copy. The critical sequence difference between the two genes is a single nucleotide in exon 7, which is thought to be an exon splice enhancer. Note that the nine exons of both the telomeric and centromeric copies are designated historically as exon 1, 2a, 2b, and 3-8. It is thought that gene conversion events may involve the two genes, leading to varying copy numbers of each gene. The protein encoded by this gene localizes to both the cytoplasm and the nucleus. Within the nucleus, the protein localizes to subnuclear bodies called gems which are found near coiled bodies containing high concentrations of small ribonucleoproteins (snRNPs). This protein forms heteromeric complexes with proteins such as SIP1 and GEMIN4, and also interacts with several proteins known to be involved in the biogenesis of snRNPs, such as hnRNP U protein and the small nucleolar RNA binding protein. Multiple transcript variants encoding distinct isoforms have been described. [provided by RefSeq, Jul 2014]
该基??因位于染色体5q13 500 kb的倒重复的一部分。这种重复区域包含至少四个基因和重复元件,这使得它易于重排和缺失。序列的重复性和复杂性也确定该基因组区域的组织造成的困难。该基因的端粒和着丝粒拷贝几乎是相同的,并且编码相同的蛋白质。然而,在该基因的端粒复制,突变与脊髓性肌萎缩相关联;在着丝粒拷贝的突变不会导致疾病。着丝粒副本可能引起的端粒复制突变疾病的改性剂。这两个基因之间的关键序列差异是外显子7的单核苷酸,这被认为是一个外显子剪接增强子。注意,无论是端粒和着丝粒拷贝的九个外显子历史指定为外显子1,图2a,2b和3-8。它被认为是基因转化事件可能涉及两个基因,导致改变每个基因的拷贝数。由该基因编码的蛋白质定位于细胞质和细胞核两者。在细胞核,蛋白质定位于亚核机构称为宝石这是附近发现含有高浓度的小核糖核蛋白(的snRNPs)的盘绕机构。该蛋白质的形式的异聚复合物与蛋白质如SIP1和GEMIN4,同时还与已知的能参与的snRNPs,如核糖核蛋白ù蛋白质和小核仁RNA结合蛋白的生物合成的几种蛋白质相互作用。编码不同同种型的多个转录物变体已有描述。 [由RefSeq的,2014年7月提供]
SMN1基因(以及对应的蛋白质)的细胞分布位置:
SMN1基因的本体(GO)信息:
| 名称 |
|---|
| 3013 RNA transport [PATH:hsa03013] |
| 名称 |
|---|
| Gene Expression |
| Metabolism of non-coding RNA |
| snRNP Assembly |
| 疾病名称 | 关系值 | NofPmids | NofSnps | 来源 |
| HMN (Hereditary Motor Neuropathy) Proximal Type I | 0.447600372 | 31 | 5 | BeFree_CLINVAR_MGD_ORPHANET_UNIPROT |
| Juvenile Spinal Muscular Atrophy | 0.442714419 | 15 | 9 | BeFree_CLINVAR_MGD_ORPHANET_UNIPROT |
| Muscular Atrophy, Spinal, Type II | 0.361085767 | 8 | 5 | BeFree_CLINVAR_ORPHANET_UNIPROT |
| Spinal Muscular Atrophy | 0.28892053 | 604 | 0 | BeFree_CTD_human_GAD_LHGDN |
| SPINAL MUSCULAR ATROPHY, TYPE IV | 0.24 | 0 | 0 | CLINVAR_ORPHANET |
| Spinal Muscular Atrophies of Childhood | 0.132192478 | 6 | 0 | CTD_human_GAD_LHGDN |
| Spinal muscular atrophy 4 | 0.12 | 0 | 0 | CTD_human |
| Neuromuscular Diseases | 0.01302921 | 48 | 0 | BeFree |
| Motor Neuron Disease | 0.012681823 | 38 | 0 | BeFree_GAD |
| Amyotrophic Lateral Sclerosis | 0.012344368 | 20 | 0 | BeFree_GAD_LHGDN |
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