Translational Control by elF2 Kinase during ER Stress

描述（由申请人提供）：细胞应激，如内质网中错误折叠蛋白质的积累（ER应激）、营养剥夺、UV照射和氧化损伤诱导旨在减轻细胞损伤的基因表达程序。应激基因表达的一个重要贡献者是磷酸化真核起始因子-2（eIF2）的蛋白激酶家族。eIF2的磷酸化降低了这种翻译因子的活性，导致调节一般蛋白质合成和诱导mRNA的翻译，这对应激修复很重要。该提议集中于eIF2激酶PEK（PERK，EIF2AK3），其在响应ER应激时被激活。eIF2的PEK磷酸化通过激活多种转录因子（包括ATF4和NF-κ B）来增强细胞对ER应激的反应，所述转录因子指导参与应激修复或凋亡的基因的表达。异常的ER应激反应与一系列人类疾病相关，包括糖尿病、骨和肝脏疾病以及循环和神经病理学。该建议涉及调节应激相关基因表达的机制，以响应ER应激，及其在疾病中的作用。我们提出了四个具体目标。目的1研究内质网应激时PEK对基因特异性翻译的调控。我们将确定是否翻译重新启动或替代翻译机制是重要的PEK反应途径中的调节蛋白的合成。目的2研究eIF2磷酸化在NF-κ B活性调节中的作用。我们将描述PEK在ER应激过程中激活NF-κ B的分子机制，并将其与替代NF-κ B调节过程进行比较。目的3探讨eIF2磷酸化在抗肿瘤药物细胞保护中的作用。在这个目标中，我们将探索eIF2激酶和p53应激通路之间的联系，并确定eIF2磷酸化是否有助于对抗癌药物的耐药性。目标4。确定在人群中发现的PEK突变的功能后果。我们将使用哺乳动物培养细胞来表征来自WRS患者或多态性的PEK错义变化的功能后果。总之，解决这些目标将增加我们对细胞适应环境压力的过程及其对人类疾病的影响的理解。

DESCRIPTION (provided by applicant): Cellular stresses such as accumulation of misfolded protein in the endoplasmic reticulum (ER stress), nutrient deprivation, UV irradiation, and oxidative damage induce a program of gene expression designed to alleviate cellular injury. An important contributor to stress gene expression is a family of protein kinases that phosphorylate eukaryotic initiation factor -2 (eIF2). Phosphorylation of eIF2 reduces the activity of this translation factor, leading to regulation of general protein synthesis and induced translation of mRNAs important for stress remediation. This proposal focuses on the eIF2 kinase, PEK (PERK, EIF2AK3), that is activated in response ER stress. PEK phosphorylation of eIF2 enhances cell viability in response to ER stress via activation of multiple transcription factors, including ATF4 and NF-KB, that direct expression of genes involved in stress remediation or apoptosis. An aberrant ER stress response is associated with a range of human diseases, including diabetes, bone and liver disorders, and circulatory and neurological pathologies. This proposal addresses the mechanisms regulating the program of stress-related gene expression in response to ER stress, and its role in disease. We propose four specific aims. Aim 1 Characterize PEK control of gene-specific translation in response to ER stress. We will determine whether translation reinitiation or alternative translation mechanisms are important for synthesis of regulatory proteins in the PEK response pathway. Aim 2 Characterize the role of eIF2 phosphorylation in the regulation of NF-KB activity. We will characterize the molecular mechanisms by which PEK activates NF-KB during ER stress and compare it to alternative NF-KB regulatory processes. Aim 3 Determine the role of eIF2 phosphorylation in cytoprotection against anti-cancer drugs. In this aim, we will explore the link between the eIF2 kinase and p53 stress pathways, and determine whether eIF2 phosphorylation contributes to resistance to anti-cancer drugs. Aim 4. Determine the functional consequences of PEK mutations identified in the human population. We will characterize the functional consequence of PEK missense changes derived from WRS patients or polymorphisms using mammalian cultured cells. Together, addressing these aims will increase our understanding of the process of cellular adaptation to environmental stresses and its impact in human disease.