The survival of motor neurons protein determines the capacity for snRNP assembly: Biochemical deficiency in spinal muscular atrophy
The survival of motor neurons protein determines the capacity for snRNP assembly: Biochemical deficiency in spinal muscular atrophy
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DOI：
10.1128/mcb.25.13.5543-5551.2005
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发表时间：
2005-07-01
影响因子：
5.3
通讯作者：
Dreyfuss, G
中科院分区：
文献类型：
--
作者：
Wan, LL;Battle, DJ;Dreyfuss, G
运动神经元存活 (SMN) 蛋白水平的降低会导致运动神经元退行性疾病脊髓性肌萎缩，其严重程度与 SMN 降低的程度相关。 SMN 与 Gemins 2 至 7 一起形成一个复合物，在小核核糖核蛋白颗粒 (snRNP) 的组装中发挥作用。从细胞提取物中完全耗尽 SMN 复合物会消除 snRNP 组装，即 snRNA 上七聚 Sm 核心的形成。然而，脊髓性肌萎缩症患者中 SMN 蛋白水平的降低（如果有的话）对细胞产生 snRNP 的能力有何影响尚不清楚。为了解决这个问题，我们开发了一种灵敏且定量的 snRNP 组装检测方法，即严格依赖于 SMN 复合物的高盐和抗肝素稳定 Sm 核心的形成。我们发现 Sm 核心组装的程度与细胞提取物中 SMN 蛋白的量成正比。与此一致的是，脉冲标记实验表明低 SMN 细胞中 snRNP 生物发生率显着降低。此外，脊髓性肌萎缩症患者的细胞提取物的 snRNP 组装能力较低，这与 SMN 量的减少直接相关。因此，SMN 决定了 snRNP 生物发生的能力，我们的研究结果为脊髓性肌萎缩症患者细胞中生化活性的可测量缺陷提供了证据。
Reduction of the survival of motor neurons (SMN) protein levels causes the motor neuron degenerative disease spinal muscular atrophy, the severity of which correlates with the extent of reduction in SMN. SMN, together with Gemins 2 to 7, forms a complex that functions in the assembly of small nuclear ribonucleoprotein particles (snRNPs). Complete depletion of the SMN complex from cell extracts abolishes snRNP assembly, the formation of heptameric Sm cores on snRNAs. However, what effect, if any, reduction of SMN protein levels, as occurs in spinal muscular atrophy patients, has on the capacity of cells to produce snRNPs is not known. To address this, we developed a sensitive and quantitative assay for snRNP assembly, the formation of high-salt- and heparin-resistant stable Sm cores, that is strictly dependent on the SMN complex. We show that the extent of Sm core assembly is directly proportional to the amount of SMN protein in cell extracts. Consistent with this, pulse-labeling experiments demonstrate a significant reduction in the rate of snRNP biogenesis in low-SMN cells. Furthermore, extracts of cells from spinal muscular atrophy patients have a lower capacity for snRNP assembly that corresponds directly to the reduced amount of SMN. Thus, SMN determines the capacity for snRNP biogenesis, and our findings provide evidence for a measurable deficiency in a biochemical activity in cells from patients with spinal muscular atrophy.