Translational Control by Osmotically Active Solutes

描述（由申请人提供）：细胞对营养和环境应激的反应与许多疾病的病理学有关。响应于应激的细胞命运决定的主要贡献者是：（i）细胞类型特异性因素，（ii）时间和（iii）应激强度。慢性和高强度应激条件减弱存活信号并有利于凋亡信号。本研究将探讨高渗应激过程中细胞命运决定的分子机制。高渗应激引起细胞内水的损失、细胞收缩和大分子拥挤。与疾病相关的实例是糖尿病中的高血糖症（HHS，高血糖高渗状态）、炎症部位的巨噬细胞死亡、干眼综合征中的眼表面脱水以及糖尿病视网膜病变中对感染和视网膜细胞凋亡的易感性增加。在上一个资助周期中，我们是第一个确定在高渗应激过程中促进细胞死亡的新途径的人。我们发现，一个特定的信号通路（eIF 21-P），在所有的应激反应的生存和凋亡信号的主调节器，介导的细胞质定位的核蛋白，抑制蛋白质的合成，促进细胞存活。这种细胞反应通过削弱应激细胞的存活机制将平衡转移到细胞死亡（凋亡）。细胞外信号对核蛋白亚细胞定位的调节是一个研究不足和新兴的研究领域。我们建议，以确定一些关键因素，参与开关的平衡，从生存到凋亡在高渗应激。我们将确定（i）影响高渗应激期间决定细胞命运的蛋白质编码mRNA翻译的信号通路。(ii)在高渗应激过程中参与抑制蛋白质合成的特异性信号分子（切割的tRNA）和（iii）在人类疾病模型中炎症在高渗应激诱导的细胞死亡中的作用。这些研究将增加我们对压力引起的人类疾病的理解，并产生可用于药物开发的生物标志物。 公共卫生相关性：最近认识到的病理学是炎症部位细胞外渗透压升高。增加的细胞外渗透压引起渗透胁迫，这导致细胞内水的损失、细胞收缩、大分子拥挤和死亡。诸如糖尿病性视网膜病、糖尿病中的高血糖高渗状态（HHS）、炎性部位处的巨噬细胞死亡和干眼综合征中的眼表面脱水的疾病是涉及增加的全身或局部细胞外渗透压的一些实例。本提案中的研究将为当渗透压升高至正常水平以上时决定细胞命运的分子事件带来新的见解，并将有助于开发药物以减轻健康细胞的不良凋亡。

DESCRIPTION (provided by applicant): The cellular response to nutritional and environmental stress has been associated with the pathology of many diseases. Major contributors to cell fate decisions in response to stress are: (i) cell-type specific factors, (ii) time and (iii) intensity of stress. Chronic and high intensity stress conditions attenuate survival signals and favor apoptotic signals. This proposal will explore the molecular mechanisms of cell fate decisions during hypertonic stress. Hypertonic stress causes loss of intracellular water, cell shrinkage and macromolecular crowding. Disease-related examples are hyperglycemia in diabetes (HHS, Hyperglycemic Hyperosmolar State), macrophage cell death in inflammatory sites, dehydration of the ocular surface in dry eye syndrome and increased susceptibility to infections and retinal cell apoptosis in diabetic retinopathy. During the previous grant cycle we were the first to identify a novel pathway that promotes cell death during hypertonic stress. We showed that a specific signaling pathway (eIF21-P), the master regulator of survival and apoptotic signals in all stress responses, mediates the cytoplasmic localization of a nuclear protein that represses synthesis of proteins that promote cell survival. This cellular response shifts the balance to cell death (apoptosis) by weakening the survival mechanisms of the stressed cells. Regulation of the subcellular localization of nuclear proteins by extracellular signaling is an understudied and emerging area of research. We propose to identify some of the critical factors which are involved in the switch of balance from survival to apoptosis during hypertonic stress. We will determine (i) the signaling pathways that affect translation of mRNAs coding for proteins that determine cell fate during hypertonic stress. (ii) specific signaling molecules (cleaved tRNAs) involved in inhibition of protein synthesis during hypertonic stress and (iii) the effect of inflammation in hypertonic stress-induced cell death in a model of human disease. These studies will increase our understanding of stress-induced human diseases and generate biological markers that can be used for drug development. PUBLIC HEALTH RELEVANCE: A recently recognized pathology is the increased extracellular osmolarity at sites of inflammation. Increased extracellular osmolarity causes osmotic stress, which leads to loss of intracellular water, cell shrinkage, macromolecular crowding and death. Diseases such as diabetic retinopathy, Hyperglycemic Hyperosmolar State (HHS) in diabetes, macrophage cell death at inflammatory sites, and dehydration of the ocular surface in dry eye syndrome are some examples that involve increased systemic or local extracellular osmolarity. The studies in this proposal will bring new insights into the molecular events that determine cell fate when osmolarities increase above normal and will assist in the development of drugs to attenuate undesirable apoptosis of healthy cells.