SRp38基因在小鼠视网膜细胞中的表达以及对GluR-B小基因可变剪接的调控

SR蛋白在前体mRNA可变剪接调控中发挥重要作用.SRp38作为一种新近发现的具有神经及生殖组织特异性的SR蛋白,能够调控一些在神经组织中起重要作用的基因(如GluR-B,Trk-C,NCAML1等)的前体mRNA可变剪接,同时还可以在有丝分裂M期及热休克时抑制前体mRNA剪接的发生.利用Western blot以及免疫组织化学方法研究了SRp38蛋白在小鼠视网膜中的表达以及分布情况,结果显示,SRp38蛋白在视网膜中的表达具有区域特异性,在外网层、内核层、内网层以及节细胞层中均有表达,而在外核层无表达.对分离培养的小鼠视网膜细胞进行免疫双标记分析的结果表明,SRp38蛋白在视杆-双极细胞的胞体、轴突、树突中表达.通过瞬时共转染以及RT_PCR分析,发现在R28细胞中,SRp38过表达可以促进GluR-B小基囚Flip亚型的剪接.结果提示SRp38蛋白可能通过调控小鼠视网膜内前体mRNA可变剪接、进而在小鼠视网膜功能中发挥重要作用.

The Expression of SRp38 Gene in Mouse Retina and It's Regulation of Alternative Splicing of GluR-B Minigene

SR proteins play important roles in regulating alternative pre-mRNA splicing. As a newly discovered neural and reproductive tissue specific SR protein, SRp38 regulates the alternative splicing of several genes important for neural function, such as GluR-B, Trk-C and NCAML1. It also acts as a splicing inhibitor during mitosis or stress response in order to prevent wrong splicing. The expression of SRp38 in mouse retina was investigated by Western blot and immunohistochemistry (IHC) analyses. The result shows that the expression of SRp38 proteins in mouse retina is region-specific, with extensive distribution in the outer and inner plexiform layers, inner nuclear layer and ganglion cell layer, but no expression in outer nuclear layer. Double staining of isolated retina cells with anti-SRp38 and anti-Trk-C antibodies showed that SRp38 is localized in the dendrites, somata and axon terminals of rod-bipolar cells. By transient co-transmission of over-expressed SRp38 plasmid and RT-PCR analyses, the further results showed that overexpressed SRp38 could promote the splicing of the Flip isoform of GluR-B minegene in R28 cells. The result suggests that SRp38 may play important roles in the retinal function, possibly via regulating the neural-specific alternative splicing of genes as GluR-B.