Combinatorial control of signal-induced Exon repression by hnRNP l and PSF
Combinatorial control of signal-induced Exon repression by hnRNP l and PSF
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DOI：
10.1128/mcb.00419-07
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发表时间：
2007-10-01
影响因子：
5.3
通讯作者：
Lynch, Kristen W.
中科院分区：
文献类型：
--
作者：
Melton, Alexis A.;Jackson, Jason;Lynch, Kristen W.
细胞可以通过选择性剪接来调节其蛋白质库以响应细胞外刺激;然而，控制这一过程的机制知之甚少。CD 45基因响应于T细胞活化而经历选择性剪接以调节T细胞功能。CD 45外显子4中的ESS 1剪接沉默子通过hnRNP L的活性在静息T细胞中赋予基础外显子跳跃，并通过先前未知的机制在T细胞中赋予活化诱导的外显子跳跃。在这里，我们已经开发了一种体外剪接试验，概括的信号诱导的选择性剪接的CD 45和证明，细胞刺激导致两个变化的ESS 1结合的剪接调控复合物。激活诱导的翻译后修饰hnRNP L与蛋白质的抑制活性适度增加相关。更重要的是，剪接因子PSF以激活依赖的方式被募集到ESS 1复合物中，并占信号调节ESS 1活性的大部分。hnRNP L和PSF与ESS 1复合物的关联在很大程度上是相互独立的，但这些蛋白质一起解释了在体外和体内观察到的CD 45剪接中的总信号调节变化。这种对剪接的组合效应允许精确调节信号诱导的选择性剪接。
Cells can regulate their protein repertoire in response to extracellular stimuli via alternative splicing; however, the mechanisms controlling this process are poorly understood. The CD45 gene undergoes alternative splicing in response to T-cell activation to regulate T-cell function. The ESS1 splicing silencer in CD45 exon 4 confers basal exon skipping in resting T cells through the activity of hnRNP L and confers activation-induced exon skipping in T cells via previously unknown mechanisms. Here we have developed an in vitro splicing assay that recapitulates the signal-induced alternative splicing of CD45 and demonstrate that cellular stimulation leads to two changes to the ESS1-bound splicing regulatory complex. Activation-induced posttranslational modification of hnRNP L correlates with a modest increase in the protein's repressive activity. More importantly, the splicing factor PSF is recruited to the ESS1 complex in an activation-dependent manner and accounts for the majority of the signal-regulated ESS1 activity. The associations of hnRNP L and PSF with the ESS1 complex are largely independent of each other, but together these proteins account for the total signal-regulated change in CD45 splicing observed in vitro and in vivo. Such a combinatorial effect on splicing allows for precise regulation of signal-induced alternative splicing.