The product of the Survival of Motor Neuron (SMN) gene is a human telomerase-associated protein
The product of the Survival of Motor Neuron (SMN) gene is a human telomerase-associated protein
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DOI：
10.1091/mbc.e02-04-0216
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发表时间：
2002-09-01
影响因子：
3.3
通讯作者：
Autexier, C
中科院分区：
文献类型：
--
作者：
Bachand, F;Boisvert, FM;Autexier, C
端粒酶是一种核糖核蛋白（RNP）复合物，其最低限度地由蛋白质催化亚基（端粒酶逆转录酶（TERT））和RNA组分（端粒酶RNA）组成。运动神经元存活基因（SMN）编码参与某些RNP生物发生的蛋白质。在这里，我们报告，SMN是一种端粒酶相关蛋白。使用体外结合试验和免疫沉淀实验，我们证明了SMN和端粒酶RNP在体外和人类细胞之间的关联。从人293细胞中特异性免疫纯化SMN共纯化端粒酶活性，表明SMN与功能性端粒酶全酶的子集相关。我们的研究结果还表明，人端粒酶RNA和人（h）端粒酶不与Sm蛋白，相反，酿酒酵母端粒酶。免疫荧光分析表明，hTERT不特异性共定位与野生型SMN的宝石或卡哈尔体。然而，一个显性负突变的SMN（SMNDeltaN27）以前的特点是引发细胞重组的小核RNP引起的积累，在特定的SMNDeltaN27诱导的细胞体的hTERT。此外，在兔网织红细胞裂解物中SMNDeltaN27和hTERT的共表达降低了体外人端粒酶重建的效率。我们的研究结果建立SMN作为一种新的端粒酶相关蛋白，很可能在人类端粒酶生物合成的功能。
Telomerase is a ribonucleoprotein (RNP) complex that is minimally composed of a protein catalytic subunit, the telomerase reverse transcriptase (TERT), and an RNA component, the telomerase RNA. The survival of motor neuron (SMN) gene codes for a protein involved in the biogenesis of certain RNPs. Here, we report that SMN is a telomerase-associated protein. Using in vitro binding assays and immunoprecipitation experiments, we demonstrate an association between SMN and the telomerase RNP in vitro and in human cells. The specific immunopurification of SMN from human 293 cells copurified telomerase activity, suggesting that SMN associates with a subset of the functional telomerase holoenzyme. Our results also indicate that the human telomerase RNA and the human (h) TERT are not associated with Sm proteins, in contrast to Saccharomyces ccrevisiae telomerase. Immunofluorescence analysis showed that hTERT does not specifically colocalize with wild-type SMN in gems or Cajal bodies. However, a dominant-negative mutant of SMN (SMNDeltaN27) previously characterized to elicit the cellular reorganization of small nuclear RNPs caused the accumulation of hTERT in specific SMNDeltaN27-induced cellular bodies. Furthermore, coexpression of SMNDeltaN27 and hTERT in rabbit reticulocyte lysates decreased the efficiency of human telomerase reconstitution in vitro. Our results establish SMN as a novel telomerase-associated protein that is likely to function in human telomerase biogenesis.