Longman D, Johnstone I L, Cáceres J F
MRC Human Genetics Unit, Western General Hospital, Edinburgh EH4 2XU.
EMBO J. 2000 Apr 3;19(7):1625-37. doi: 10.1093/emboj/19.7.1625.
The SR proteins constitute a family of nuclear phosphoproteins, which are required for constitutive splicing and also influence alternative splicing regulation. Initially, it was suggested that SR proteins were functionally redundant in constitutive splicing. However, differences have been observed in alternative splicing regulation, suggesting unique functions for individual SR proteins. Homology searches of the Caenorhabditis elegans genome identified seven genes encoding putative orthologues of the human factors SF2/ASF, SRp20, SC35, SRp40, SRp75 and p54, and also several SR-related genes. To address the issue of functional redundancy, we used dsRNA interference (RNAi) to inhibit specific SR protein function during C.elegans development. RNAi with CeSF2/ASF caused late embryonic lethality, suggesting that this gene has an essential function during C.elegans development. RNAi with other SR genes resulted in no obvious phenotype, which is indicative of gene redundancy. Simultaneous interference of two or more SR proteins in certain combinations caused lethality or other developmental defects. RNAi with CeSRPK, an SR protein kinase, resulted in early embryonic lethality, suggesting an essential role for SR protein phosphorylation during development.
SR蛋白构成了一个核磷蛋白家族,它们是组成型剪接所必需的,并且也影响可变剪接调控。最初,有人提出SR蛋白在组成型剪接中功能冗余。然而,在可变剪接调控方面已观察到差异,这表明单个SR蛋白具有独特功能。对秀丽隐杆线虫基因组进行同源性搜索,鉴定出七个编码人类因子SF2/ASF、SRp20、SC35、SRp40、SRp75和p54假定直系同源物的基因,以及几个与SR相关的基因。为了解决功能冗余问题,我们在秀丽隐杆线虫发育过程中使用双链RNA干扰(RNAi)来抑制特定SR蛋白的功能。用CeSF2/ASF进行RNAi导致胚胎后期致死,这表明该基因在秀丽隐杆线虫发育过程中具有重要功能。用其他SR基因进行RNAi未产生明显表型,这表明基因冗余。以特定组合同时干扰两种或更多种SR蛋白会导致致死或其他发育缺陷。用SR蛋白激酶CeSRPK进行RNAi导致胚胎早期致死,这表明SR蛋白磷酸化在发育过程中起重要作用。