Alternative splicing events are a late feature of pathology in a mouse model of spinal muscular atrophy.
Alternative splicing events are a late feature of pathology in a mouse model of spinal muscular atrophy.
复制标题
DOI：
10.1371/journal.pgen.1000773
复制
发表时间：
2009-12
期刊：
影响因子：
4.5
通讯作者：
Talbot K
中科院分区：
文献类型：
--
作者：
Bäumer D;Lee S;Nicholson G;Davies JL;Parkinson NJ;Murray LM;Gillingwater TH;Ansorge O;Davies KE;Talbot K
脊髓性肌萎缩症是一种严重的运动神经元疾病，由SMN 1基因失活突变引起，导致全长功能性SMN蛋白水平降低。SMN是剪接体蛋白组装的关键介质，并且蛋白质的完全损失或急剧减少导致细胞活力的损失。然而，当SMN降低到所有其他细胞类型耐受的水平时，选择性运动神经元变性的原因目前尚不清楚。最近在SMA小鼠模型的终末期报告了广泛的剪接异常，从而提出了有效剪接的破坏是运动神经元死亡的主要机制的主张。然而，目前尚不清楚剪接异常是否存在于疾病的早期阶段，这将是一个疾病发病机制中的直接作用的要求。我们在症状前（P1）、早期症状（P7）和晚期症状（P13）3个时间点对SMN缺陷小鼠脊髓的RNA进行了外显子阵列分析。与同窝对照小鼠相比，SMA小鼠显示差异表达的外显子数量呈时间依赖性增加，P1和P7基因型之间差异极小，但在晚期症状（P13）小鼠中差异显著。基因本体分析揭示了与神经元发育以及细胞损伤相关的途径的差异。通过RT-PCR对所选靶点的验证证实了阵列结果，并与生理上存在的mRNA亚型之间的转变保持一致。我们的结论是，大多数剪接的变化发生在SMA的后期，可能代表细胞损伤的继发性影响，虽然我们不能排除显着的早期变化，在少数转录运动神经元的生存至关重要。运动神经元存活基因（SMN）突变是导致严重运动神经元疾病脊髓性肌萎缩症的原因，这是一系列发现之一，表明选择性运动神经元易受RNA及其相关核糖核蛋白复合物加工缺陷的影响。一个尚未解决的问题是，SMN在剪接体组装中的一般细胞功能的丧失（预计会导致mRNA剪接的广泛缺陷）是否直接导致运动神经元死亡。我们使用外显子特异性微阵列来评估SMA小鼠模型中脊髓中剪接改变的程度。我们的发现，绝大多数剪接的变化是一个晚期的疾病的特点，并可能代表一个转变为替代异构体表达，而不是剪接保真度的损失，提供了证据，广泛的剪接干扰不是一个主要的特点，疾病的发病机制，但在疾病的晚期细胞损伤的继发性影响。然而，我们的研究不能排除一个或几个转录的微妙早期变化的作用，这些转录对运动神经元的存活至关重要，它们以低水平表达或仅在脊髓细胞亚群中表达。
Spinal muscular atrophy is a severe motor neuron disease caused by inactivating mutations in the SMN1 gene leading to reduced levels of full-length functional SMN protein. SMN is a critical mediator of spliceosomal protein assembly, and complete loss or drastic reduction in protein leads to loss of cell viability. However, the reason for selective motor neuron degeneration when SMN is reduced to levels which are tolerated by all other cell types is not currently understood. Widespread splicing abnormalities have recently been reported at end-stage in a mouse model of SMA, leading to the proposition that disruption of efficient splicing is the primary mechanism of motor neuron death. However, it remains unclear whether splicing abnormalities are present during early stages of the disease, which would be a requirement for a direct role in disease pathogenesis. We performed exon-array analysis of RNA from SMN deficient mouse spinal cord at 3 time points, pre-symptomatic (P1), early symptomatic (P7), and late-symptomatic (P13). Compared to littermate control mice, SMA mice showed a time-dependent increase in the number of exons showing differential expression, with minimal differences between genotypes at P1 and P7, but substantial variation in late-symptomatic (P13) mice. Gene ontology analysis revealed differences in pathways associated with neuronal development as well as cellular injury. Validation of selected targets by RT–PCR confirmed the array findings and was in keeping with a shift between physiologically occurring mRNA isoforms. We conclude that the majority of splicing changes occur late in SMA and may represent a secondary effect of cell injury, though we cannot rule out significant early changes in a small number of transcripts crucial to motor neuron survival. The identification of mutations in the Survival Motor Neuron (SMN) gene as the cause of the severe motor neuron disorder spinal muscular atrophy is one of a number of discoveries implicating selective motor neuron vulnerability to defects in processing of RNA and its associated ribonucleoprotein complexes. An unresolved issue is whether loss of the general cellular function of SMN in spliceosomal assembly, which is predicted to result in widespread defects in mRNA splicing, is directly responsible for motor neuron death. We have used exon-specific microarrays to assess the degree of altered splicing in the spinal cord in a mouse model of SMA. Our finding that the vast majority of splicing changes are a late feature of the disease and may represent a shift to alternative isoform expression, rather than loss of splicing fidelity, provides evidence that widespread splicing disturbance is not a primary feature of the disease pathogenesis but a secondary effect of cell injury in a late phase of the disease. However, our study cannot rule out a role for subtle early changes in one or a few transcripts crucial to motor neuron survival expressed at low levels or in only in a sub-population of spinal cord cells.
登录
查看更多内容
DOI：
10.1002/neu.10313
发表时间：
2004-02-05
期刊：
JOURNAL OF NEUROBIOLOGY
影响因子：
--
作者：
Jablonka, S;Wiese, S;Sendtner, M
通讯作者：
Sendtner, M
影响因子：
64.5
作者：
LEFEBVRE, S;BURGLEN, L;MELKI, J
通讯作者：
MELKI, J
影响因子：
30.8
作者：
Lefebvre, S;Burlet, P;Melki, J
通讯作者：
Melki, J
影响因子：
3.5
作者：
Lorson, CL;Androphy, EJ
通讯作者：
Androphy, EJ
DOI：
10.1111/j.2517-6161.1995.tb02031.x
发表时间：
1995-01-01
影响因子：
5.8
作者：
BENJAMINI, Y;HOCHBERG, Y
通讯作者：
HOCHBERG, Y