Phosphoiylation -dependent regulation of alternative splicing

剪接位点利用的调节为控制基因表达和蛋白质组多样性的产生提供了一种通用的机制，在许多生物过程中起着至关重要的作用。剪接位点的选择可以通过多种细胞外刺激，包括生长因子、细胞因子、激素、去极化、渗透压休克和UVC照射，通过合成、磷酸化和富含丝氨酸/丝氨酸（SR）蛋白的定位变化来改变。SR蛋白是前体mRNA组成性剪接所必需的一个家族，在调节选择性剪接中起重要作用。SR蛋白在真核生物中高度保守，氨基端具有1 ~ 2个RNA识别基序（RRM），羧基端具有1个RS结构域，其磷酸化状态影响其一般活性和选择性剪接活性。迄今为止，已经报道了几种激酶磷酸化SR蛋白， ...更多信息 包括SRPK-家族激酶（SRPK 1和SRPK 2），Clk/Sty家族激酶，其由四个成员组成激酶抑制剂DRB可抑制细胞核斑点的形成，例如，细胞核斑点（Clkl/Sty和Clk 2 -4）、DNA拓扑异构酶I、p34 cdc 2激酶和hPRP 4，向透化细胞中添加纯化的SRPK 1，或在转染细胞中过表达SRPK 1、2或Clk家族成员之一，导致细胞核斑点的明显解体。（5，6-dichloro-1-β-D-ribo-furanosylbenzimidazole），其先前显示抑制酪蛋白激酶II，抑制Clk 2并诱导SR蛋白的再分布。最近，通过对化学文库的广泛筛选，发现了Clkl/Sty和Clk 4的特异性抑制剂，并将其命名为TG 003。TG 003抑制Clk 1/Sty依赖的核斑点的剪接和分解。此外，TG 003的施用挽救了由Xen opus中过量Clk/Sty活性诱导的胚胎缺陷。由于选择性剪接的重要性已被越来越多的人类疾病归因于错误剪接事件，TGOO 3将适用于治疗操纵由激活的Clk/Sty诱导的异常剪接。考虑到SR蛋白激酶抑制剂的治疗应用，预防病毒是有希望的领域之一，因为剪接是病毒增殖的关键步骤。在HIV的情况下，8个受体位点用于竞争产生vif、vpu、vpr、nef、env、达特和rev mRNA，并且这些剪接位点的使用受SR蛋白和hnRNP的调节。此外，Akusjarvi小组报道，从晚期腺病毒感染的细胞中纯化的SR蛋白通过病毒诱导的去磷酸化而作为剪接增强子或剪接阻遏蛋白失活。SR蛋白激酶抑制剂的抗病毒作用目前正在我们实验室进行研究。少

The regulation of splice site usage provides a versatile mechanism for controlling gene expression and for the generation of proteome diversity, playing an essential role in many biological processes. The selection of splice site can be altered by numerous extracellular stimuli, including growth factors, cytokines, hormones, depolarization, osmotic shock, and UVC irradiation, through synthesis, phosphorylation, and a change in localization of serine/arginine-rich (SR) proteins. SR proteins are a family of essential factors required for constitutive splicing of pre-mRNA and play an important role in modulating alternative splicing. They are highly conserved in eukaryotes and are characterized by having one or two RNA-recognition motifs (RRMs) at the amino terminus and an RS domain at the carboxy terminus.Phosphorylation state of SR proteins appears to influence their activities in general and alternative splicing. To date, several kinases have been reported to phosphorylate SR proteins, … More including SRPK-familykinases (SRPK1 and SRPK2), Clk/Sty family kinases, which consisted of four members (Clkl/Sty and Clk2-4), DNA topoisomerase I, p34cdc2 kinase and hPRP4, Addition of purified SRPK1 to permeabilized cells, or overexpression of SRPK1, 2 or one of CIk family members in transfected cells result in an apparent disassembly of the nuclear speckles.The kinase inhibitor DRB (5,6-dichloro-1-β-D-ribo-furanosylbenzimidazole), which was previously shown to inhibit casein kinase II, inhibited Clk2 and induced the redistribution of SR proteins. Recently, through extensive screening of a chemical library, a specific inhibitor of Clkl/Sty and Clk4 was found and named as TG003. Clk 1/Sty-dependent splicing and disassembly of nuclear speckles were suppressed by TG003. Moreover, administration of TG003 rescued the embryonic defects induced by excessive Clk/Sty activity in Xen opus. As the importance of alternative splicing has been illustrated by the increasing number of human diseases attributed to missplicing events, TGOO3 will be applicable for the therapeutic manipulation of.abnormal splicing induced by activated Clk/Sty.Considering the therapeutic application of inhibitors of SR protein kinases, prevention of virus is one of hopeful fields, because splicing is a crucial step for virus multiplication. In the case of HIV, 8 acceptor sites are used in competition to produce the vif, vpu, vpr, nef, env, tat and rev mRNAs, and the usage of these splicing sites are regulated by SR proteins and hnRNPs. In addition, Akusjarvi group reported that SR proteins purified from late adenovirus-infected cells are inactivated as splicing enhancer or splicing repressor proteins by virus-induced dephosphorylation. The anti-virus effects of inhibitors of SR protein kinases are now under investigation in our laboratory. Less