Regulation of mRNA decay and metabolism during endoplasmic reticulum stress

项目摘要 维持内质网（ER）折叠和加工蛋白质的能力 通过一系列称为未折叠蛋白质反应（UPR）的信号通路。普遍定期审议是 对于分泌细胞的发育和分化是必需的，并调节多种人类 包括糖尿病、癌症和阿尔茨海默病在内的疾病。本提案的总体目标是 了解UPR在哺乳动物细胞中的作用，重点关注其两个知之甚少的方面， 功能：调节mRNA降解和葡萄糖代谢。 哺乳动物UPR的激活导致膜蛋白的高度特异性降解， 相关的mRNA。虽然已经在小鼠中观察到了这种途径，并且在实验室中得到了很好的理解， 分子水平上，其细胞生物学功能尚不清楚。该提案旨在了解 这一mRNA降解途径的重点是其主要靶点，EST1。启动普遍定期审议和 通过RNA干扰耗尽RIP1导致溶酶体的核周积聚， 在质膜上稳定表皮生长因子受体（EFGR）。拟议 研究将使用培养的细胞来测试这些表型的机制和后果， 潜在的假设是溶酶体重新定位增加质膜蛋白质再循环， 当从ER的运输被破坏时，允许细胞维持表面蛋白活性。 本建议的第二个目标是了解普遍定期审议与 葡萄糖代谢。在UPR激活期间，细胞将其代谢转换为有氧糖酵解。这 代谢特征也是癌细胞的标志，表明UPR在癌症中的作用 新陈代谢. Hes1是一种参与分化、静止和癌症的转录抑制因子， 新的UPR靶点，下调TCA循环中的关键酶。这项提案将考验 UPR的代谢调节机制，无论是在细胞中受到破坏ER的化学物质 功能和细胞分化成成熟的胶原分泌成骨细胞。拟议 然后，实验将测试关于为什么普遍定期审议以这种方式调节新陈代谢的两个假设：（a） 氧化磷酸化的减少可以保护细胞免于过度产生活性氧 当ER氧化蛋白质折叠增加时，糖酵解的上调与ER氧化蛋白质的种类有关，以及（B）当ER氧化蛋白质折叠增加时，糖酵解的上调与ER氧化蛋白质的种类有关，以及（B）当ER氧化蛋白质折叠增加时，糖酵解的上调与ER氧化蛋白质的种类有关。 必需的是提供增加糖蛋白和膜产生的中间体。

Project summary The capacity of the endoplasmic reticulum (ER) to fold and process proteins is maintained through a collection of signaling pathways termed the Unfolded Protein Response (UPR). The UPR is essential for development and differentiation of secretory cells and modulates a variety of human diseases including diabetes, cancer, and Alzheimer’s disease. The overall goal of this proposal is to understand the effects of the UPR in mammalian cells, focusing on two poorly understood aspects of its function: the regulation of mRNA decay and glucose metabolism. Activation of the mammalian UPR leads to the highly specific degradation of membrane- associated mRNAs. While this pathway has been observed in mice and is well-understood at the molecular level, its cell biological function is not clear. This proposal aims to understand the effects of this mRNA degradation pathway by focusing on its main target, Blos1. Both activation of the UPR and depletion of Blos1 by RNA interference lead to the perinuclear accumulation of lysosomes and the stabilization of Epidermal Growth Factor Receptor (EFGR) at the plasma membrane. The proposed research will use cultured cells to test the mechanism and consequences of these phenotypes, with the underlying hypothesis that lysosome re-positioning increases plasma membrane protein recycling, allowing cells to maintain surface protein activities by when trafficking from the ER is disrupted. The second goal of this proposal is to understand the interplay between the UPR and the metabolism of glucose. During UPR activation, cells switch their metabolism to aerobic glycolysis. This metabolic signature is also a hallmark of cancer cells, suggesting a role for the UPR in cancer metabolism. Hes1, a transcriptional repressor involved in differentiation, quiescence, and cancer, is a novel UPR target that down-regulates a key enzyme in the TCA cycle. This proposal will test the mechanism of metabolic regulation by the UPR, both in cells subjected to chemicals disrupting ER function and in cells differentiating into mature, collagen-secreting osteoblasts. The proposed experiments will then test two hypotheses regarding why the UPR regulates metabolism in this way: (a) that the reduction in oxidative phosphorylation protects cells from over-production of reactive oxygen species when ER oxidative protein folding is increased, and (b) that the upregulation of glycolysis is necessary to provide intermediates for increased glycoprotein and membrane production.