Signal-dependent regulation of splicing via phosphorylation of Sam68
Signal-dependent regulation of splicing via phosphorylation of Sam68
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DOI：
10.1038/nature01153
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发表时间：
2002-12-12
期刊：
影响因子：
64.8
通讯作者：
König, H
中科院分区：
文献类型：
--
作者：
Matter, N;Herrlich, P;König, H
人类有机体复杂性的进化来自相对较少的基因（1，2-），大约是蠕虫或苍蝇的两倍-主要是通过从单个基因产生多种蛋白质的机制来解释的，其中最普遍的是选择性前信使RNA剪接（1，3，4）。合适的空间和时间产生的剪接变异体的要求，选择性剪接受到广泛的监管，类似于转录控制。几种细胞信号传导途径的细胞外信号的激活确实可以调节选择性剪接（5-8）。在这里，我们解决信号转导和剪接调节之间的联系。我们表明，核RNA结合蛋白Sam 68是一个新的细胞外信号调节激酶（ERK）的目标。其结合由Ras信号传导途径生理调节的可变剪接外显子的外显子剪接调节元件，即CD 44的外显子v5。Sam 68的强制表达增强了ERK介导的mRNA中v5外显子序列的包含。这种增强作用受到Sam 68中ERK磷酸化位点突变的损害，而Sam 68的ERK磷酸化在体外刺激v5外显子的剪接。最后，Ras途径诱导的内源性CD 44-v5外显子的选择性剪接通过抑制Sam 68表达而被消除。我们的数据定义Sam 68作为一个原型调节器的选择性剪接，其功能取决于蛋白质修饰响应细胞外的线索。
Evolution of human organismal complexity from a relatively small number of genes(1,2-)only approximately twice that of worm or fly-is explained mainly by mechanisms generating multiple proteins from a single gene, the most prevalent of which is alternative pre-messenger-RNA splicing(1,3,4). Appropriate spatial and temporal generation of splice variants demands that alternative splicing be subject to extensive regulation, similar to transcriptional control. Activation by extracellular cues of several cellular signalling pathways can indeed regulate alternative splicing(5-8). Here we address the link between signal transduction and splice regulation. We show that the nuclear RNA-binding protein Sam68 is a new extracellular signal-regulated kinase (ERK) target. It binds exonic splice-regulatory elements of an alternatively spliced exon that is physiologically regulated by the Ras signalling pathway, namely exon v5 of CD44. Forced expression of Sam68 enhanced ERK-mediated inclusion of the v5-exon sequence in mRNA. This enhancement was impaired by mutation of ERK-phosphorylation sites in Sam68, whereas ERK phosphorylation of Sam68 stimulated splicing of the v5 exon in vitro. Finally, Ras-pathway-induced alternative splicing of the endogenous CD44-v5 exon was abolished by suppression of Sam68 expression. Our data define Sam68 as a prototype regulator of alternative splicing whose function depends on protein modification in response to extracellular cues.