Heat Shock Factor mediates actin phosphorylation in tissue integrity and age

项目摘要/摘要 衰老涉及组织、器官和器官系统的逐渐腐烂。在这一过程的早期，防渗性或 组织的选择性通透性恶化，并导致器官功能障碍的增加。这一现象 已被称为屏障功能障碍，然而驱动组织“渗漏”和 导致器官老化的因素尚不清楚。为了探究其潜在的机制，我们检查了老化的肠道。 线虫，线虫，以确定肠道屏障的弹性如何经受住时间的考验。 我实验室的初步筛查表明，热休克转录因子HSF-1对年龄的调节与 肠道特有的肌动蛋白ACT-5的活性。虽然在少数细胞中表达， ACT-5不到蠕虫肌动蛋白总量的2%，在肠道和组织的衰老过程中起着至关重要的作用。 通过建议的五年研究期，我们旨在了解与年龄相关的HSF-1活动下降的原因 会导致组织功能障碍和动物衰老。特别是，我们将描述分子机制 HSF-1失调损害细胞结构和肠道生理的年龄进展。我们 推测与年龄相关的HSF-1活性下降损害了肠道中专门的肌动蛋白网络 上皮细胞，最终损害囊泡运输、细胞-细胞连接完整性和组织屏障 维修。我们已经确定应激激活的jun激酶kgb-1是一种受抑制的转录因子。 HSF-1的靶标，它催化ACT-5蛋白在其与肌动蛋白的结合位置上加成磷酸 微丝稳定肌钙蛋白复合体。丝氨酸残基232处磷酸化ACT-5的显著积累 影响顶端网状结构的完整性和囊泡通过它的运输。总体而言， 拟议的研究将揭示HSF-1控制下的磷酸化依赖的肌动蛋白松弛机制， 这促进了囊泡在密集、富含肌动蛋白的“路障”之间的运输，同时仍保持其结构 僵化和蜂窝结构。

Project Summary/Abstract Aging involves the gradual decay of tissues, organs and organ systems. Early in this process, impermeability or selective permeability of tissues deteriorates and gives rise to increasing organ dysfunction. This phenomenon has been termed barrier dysfunction, yet the molecular mechanisms, which drive tissue “leakiness” and contribute to organ aging are unclear. To interrogate the underlying mechanism, we examine the aging intestine of the nematode, C. elegans, to determine how resiliency of the intestinal barrier withstands the test of time. Preliminary screens from my lab have linked age regulation by the Heat Shock transcription Factor, HSF-1, with the activity of the intestine-specific actin protein, ACT-5. Although expressed in a small number of cells and comprising less than 2% of total worm actin, ACT-5 plays an essential role in intestinal and organismal aging. Through the proposed five-year research period, we aim to understand how age-related decline in HSF-1 activity contributes to tissue dysfunction and animal aging. In particular, we will characterize the molecular mechanism of age progression in which HSF-1 dysregulation impairs cellular architecture and intestinal physiology. We speculate that age-associated decline in HSF-1 activity impairs specialized actin networks in intestinal epithelium, which ultimately compromise vesicular traffic, cell-cell junctional integrity and tissue barrier maintenance. We have already identified the stress-activated JUN kinase, KGB-1, as a repressed transcriptional target of HSF-1, which catalyzes phosphate addition to the ACT-5 protein within its binding site for the actin filament stabilizing Troponin complex. Accumulation of phosphorylated ACT-5 at serine residue 232 dramatically influences the structural integrity of the apical terminal web and vesicular transport across it. Overall, the proposed research will uncover a phosphorylation-dependent actin relaxation mechanism under HSF-1 control, which facilitates vesicular transport across dense, actin-rich “roadblocks” while still maintaining their structural rigidity and cellular architecture.