Direct Recruitment of ERK Cascade Components to Inducible Genes Is Regulated by Heterogeneous Nuclear Ribonucleoprotein (hnRNP) K
Direct Recruitment of ERK Cascade Components to Inducible Genes Is Regulated by Heterogeneous Nuclear Ribonucleoprotein (hnRNP) K
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DOI：
10.1074/jbc.m110.213330
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发表时间：
2011-03-18
影响因子：
4.8
通讯作者：
Bomsztyk, Karol
中科院分区：
文献类型：
--
作者：
Mikula, Michal;Bomsztyk, Karol
ERK级联的组成部分被招募到基因中，但它们在这些位点是如何调控的仍不清楚。RNA结合蛋白异质性核糖核蛋白(HnRNP)K与激酶相互作用，并与包括丝裂原诱导的早期反应基因EGR-1在内的基因一起被发现。在这里，我们使用染色质免疫沉淀来研究沿着EGR-1基因的hnRNP K和ERK级联活性的共同招募。这些测量表明ERK级联转导(Grb2、SOS、B-Raf、MEK和ERK)在EGR-1基因座上的时空结合模式类似于hnRNP K和RNA聚合酶II(Pol II)。用血清反应因子基因敲除或5，6-di-chloro-1-beta-D-ribofuranosylbenzimidazole抑制EGR-1转录改变了所有上述ERK级联成分沿该基因位点的重新募集，这反映了POL II和hnRNP K谱的变化。HnRNP K的siRNA敲除降低了EGR-1处活性MEK和ERK的水平，这种变化与延长的Pre-mRNA水平降低和剪接效率降低有关。C-myc基因座的hnRNP K依赖性和ERK级联激活模式与EGR-1不同。核糖核蛋白免疫沉淀显示hnRNP K与EGR-1相关，但与c-myc mRNAs无关。这些数据表明了一种模型，在该模型中，Pol II转录驱动的hnRNP K沿着EGR-1基因的招募将这些基因上ERK级联的激活区分开来，这些事件调节成熟mRNA的合成。
Components of the ERK cascade are recruited to genes, but it remains unknown how they are regulated at these sites. The RNA-binding protein heterogeneous nuclear ribonucleoprotein (hnRNP) K interacts with kinases and is found along genes including the mitogen-inducible early response gene EGR-1. Here, we used chromatin immunoprecipitations to study co-recruitment of hnRNP K and ERK cascade activity along the EGR-1 gene. These measurements revealed that the spatiotemporal binding patterns of ERK cascade transducers (GRB2, SOS, B-Raf, MEK, and ERK) at the EGR-1 locus resemble both hnRNP K and RNA polymerase II (Pol II). Inhibition of EGR-1 transcription with either serum-responsive factor knockdown or 5,6-di-chloro-1-beta-D-ribofuranosylbenzimidazole altered recruitment of all of the above ERK cascade components along this locus that mirrored the changes in Pol II and hnRNP K profiles. siRNA knockdown of hnRNP K decreased the levels of active MEK and ERK at the EGR-1, changes associated with decreased levels of elongating pre-mRNA and less efficient splicing. The hnRNP K dependence and pattern of ERK cascade activation at the c-MYC locus were different from at EGR-1. Ribonucleoprotein immunoprecipitations revealed that hnRNP K was associated with the EGR-1 but not c-MYC mRNAs. These data suggest a model where Pol II transcription-driven recruitment of hnRNP K along the EGR-1 locus compartmentalizes activation of the ERK cascade at these genes, events that regulate synthesis of mature mRNA.