Direct interaction of the spinal muscular atrophy disease protein SMN with the small nucleolar RNA-associated protein fibrillarin
Direct interaction of the spinal muscular atrophy disease protein SMN with the small nucleolar RNA-associated protein fibrillarin
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DOI：
10.1074/jbc.m106161200
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发表时间：
2001-10-19
影响因子：
4.8
通讯作者：
Terns, MP
中科院分区：
文献类型：
--
作者：
Jones, KW;Gorzynski, K;Terns, MP
存活运动神经元（SMN）基因的破坏导致脊髓运动神经元的选择性丧失，从而导致致命的人类神经退行性疾病脊髓性肌萎缩症（SMA）。SMN已被证明在剪接体小核核糖核蛋白（snRNP）的生物发生和前mrna剪接中起作用。我们已经证明SMN也与纤原蛋白相互作用，纤原蛋白是一种高度保守的核仁蛋白，与所有Box C/D小核仁rna相关，并在rRNA的加工和修饰中起作用。纤维蛋白和SMN在HeLa细胞提取物中共同免疫沉淀，表明这两种蛋白在体内以复合物的形式存在。此外，体外结合研究表明，SMN和纤维蛋白之间的相互作用是直接的和盐稳定的。我们发现纤维蛋白的富含甘氨酸/精氨酸的结构域对于SMN的结合是必要和充分的，而SMN的外显子3编码的区域，包括Tudor结构域，介导了纤维蛋白的结合。都铎结构域错义突变，包括在SMA患者中发现的突变，损害了SMN和纤维蛋白（以及常见的snRNP蛋白SmB）之间的相互作用。我们的研究结果表明SMN在小核仁RNP生物发生中的作用（类似于其作为snRNP组装因子的已知作用），并揭示了小核仁RNP生物发生与SMA之间的潜在联系。
Disruption of the survival motor neuron (SMN) gene leads to selective loss of spinal motor neurons, resulting in the fatal human neurodegenerative disorder spinal muscular atrophy (SMA). SMN has been shown to function in spliceosomal small nuclear ribonucleoprotein (snRNP) biogenesis and pre-mRNA splicing. We have demonstrated that SMN also interacts with fibrillarin, a highly conserved nucleolar protein that is associated with all Box C/D small nucleolar RNAs and functions in processing and modification of rRNA. Fibrillarin and SMN co-immunoprecipitate from HeLa cell extracts indicating that the proteins exist as a complex in vivo. Furthermore, in vitro binding studies indicate that the interaction between SMN and fibrillarin is direct and salt-stable. We show that the glycine/arginine-rich domain of fibrillarin is necessary and sufficient for SMN binding and that the region of SMN encoded by exon 3, including the Tudor domain, mediates the binding of fibrillarin. Tudor domain missense mutations, including one found in an SMA patient, impair the interaction between SMN and fibrillarin (as well as the common snRNP protein SmB). Our results suggest a function for SMN in small nucleolar RNP biogenesis (akin to its known role as an snRNP assembly factor) and reveal a potential link between small nucleolar RNP biogenesis and SMA.