Regulation of expression of poly (A) binding protein in mammalian cells

mRNA翻译和稳定性的控制对于基因表达的调节是重要的，并且在包括正常细胞生长和癌症在内的各种细胞过程中发挥关键作用。在mRNA翻译过程中涉及到许多因素。在各种翻译起始因子中，poly（A）结合蛋白在mRNA翻译的起始中起关键作用。胞质多聚腺苷酸结合蛋白（PABP 1）结合蛋白与真核mRNA的多聚腺苷酸束结合。 PABP 1与5 '帽结合的eIF 4G和mRNA的poly（A）束同时相互作用并刺激mRNA翻译。 此外，PABP 1被认为可以保护mRNA免受降解。由于PABP 1在mRNA代谢的几乎所有方面都具有重要作用，因此在多个水平上严格控制这种重要多肽的表达是至关重要的 我们实验室发表的结果表明，多聚腺苷酸结合蛋白（PABP）的表达在mRNA翻译水平上受到调控。PABP mRNA的5 '非翻译区含有两个翻译控制顺式元件。第一个是末端寡嘧啶段（TOP），它在热休克处理后细胞恢复过程中上调PABP mRNA的翻译。第二个控制元件位于TOP的下游，富含腺嘌呤残基。 PABP在这个自动调节顺式元件处与其自身的mRNA结合并阻止翻译。此外，我们发现，PABP是通过有丝分裂原活化蛋白激酶激酶-2（MKK-2）？ERK 1/2信号通路，PABP反过来通过使同源mRNA不稳定来控制MKK-2的水平。在MKK-2 mRNA的3 'UTR处，我们已经定位了 一种62个核苷酸长的稳定性控制元件（SCE），其结合PABP并形成用于mRNA衰变的异源RNA-蛋白质复合物。我们的研究计划的目的是研究TOP和SCE元件如何在人类细胞中发挥作用的机制细节。为了实现这一目标，我们将确定与这些控制元件相互作用的蛋白质，并研究这些蛋白质如何相互作用。

Control of mRNA translation and stability is important for the regulation of gene expression, and play crucial roles in a variety of cellular processes including normal cellular growth and cancer. A large number of factors are involved in the process of mRNA translation. Amongst the various translation initiation factors the poly (A) binding protein plays a crucial role in initiation of mRNA translation. The cytoplasmic poly (A) binding protein (PABP1) binding protein binds to the poly (A) tract of eukaryotic mRNA. PABP1 interacts with the 5 ' cap bound eIF4G and the poly (A) tract of mRNA simultaneously and stimulates mRNA translation. Furthermore, PABP1 is believed to protect mRNAs from degradation. Because of the important roles of PABP1 in almost all aspects of mRNA metabolism it is crucial that expression of this important polypeptide is tightly controlled at multiple levels Published results from our own laboratory have shown that expression of the poly (A)-binding protein (PABP) is regulated at the mRNA translation level. The 5 ' untranslated region of PABP mRNA contains two translational control cis elements. The first one is a terminal oligopyrimidine tract (TOP); it up regulates PABP mRNA translation during recovery of cells from heat shock treatment. The second control element is down stream from the TOP and is rich in adenine residues. PABP binds to its own mRNA at this auto regulatory cis element and prevents translation. In addition, we showed that PABP is phosphorylated through the mitogen activated protein kinase-kinase-2 (MKK-2) ? ERK1/2 signaling pathway, and PABP in turn controls the level of MKK-2 by destabilizing the cognate mRNA. At the 3 'UTR of the MKK-2 mRNA we have located the presence of a 62-nucleotide long stability control element (SCE) that binds PABP and forms a hetromeric RNA-protein complex for mRNA decay. The objective of our research proposal is to examine the mechanistic details of how the TOP and SCE elements function in human cells. To achieve this we will identify the proteins that interact with these control elements and also examine how these proteins interact with each other.