Phosphoiylation -dependent regulation of alternative splicing

剪接位点使用的调控为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重要作用。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、渗透休克和UVC照射，通过合成、磷酸化和富含丝氨酸/精氨酸（SR）蛋白的定位改变而改变。SR蛋白是pre-mRNA组成剪接所需的重要因子家族，在调节选择性剪接中发挥重要作用。它们在真核生物中高度保守，其特征是在氨基端有一个或两个rna识别基序（RRMs），在羧基端有一个RS结构域。SR蛋白的磷酸化状态似乎影响其一般剪接和选择性剪接的活性。更多的激酶包括srpk家族激酶（SRPK1和SRPK2）， Clk/Sty家族激酶，由四个成员组成（Clkl/Sty和Clk2-4）， DNA拓扑异构酶I， p34cdc2激酶和hPRP4。将纯化的SRPK1添加到渗透细胞中，或转染细胞中SRPK1, 2或CIk家族成员之一的过表达导致核斑点的明显解体。激酶抑制剂DRB（5,6-二氯-1-β- d -核糖-呋喃基苯并咪唑）先前被证明可以抑制酪蛋白激酶II，抑制Clk2并诱导SR蛋白的重新分配。最近，通过对化学文库的广泛筛选，发现了Clkl/Sty和Clk4的特异性抑制剂，并将其命名为TG003。TG003抑制了clk1 / sty依赖性核斑点的剪接和拆卸。此外，给药TG003可以挽救Xen opus中Clk/Sty活性过高引起的胚胎缺陷。由于选择性剪接的重要性已经被越来越多的人类疾病归因于剪接错误事件所说明，TGOO3将适用于治疗性的操作。活化的Clk/Sty诱导异常剪接。考虑到SR蛋白激酶抑制剂的治疗应用，病毒的预防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中，8个受体位点在竞争中产生vif、vpu、vpr、nef、env、tat和rev mrna，这些剪接位点的使用受SR蛋白和hnRNPs的调节。此外，Akusjarvi小组报道了从晚期腺病毒感染细胞中纯化的SR蛋白通过病毒诱导的去磷酸化作为剪接增强蛋白或剪接抑制蛋白而失活。我们实验室正在研究SR蛋白激酶抑制剂的抗病毒作用。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