The Role of Extrusion in Controlling Epithelial Homeostasis

项目总结/摘要 上皮细胞一起工作，形成一个保护层，为所有的器官，他们包围，但他们周转通过 细胞死亡和分裂的速度在体内是最高的。保持功能屏障，防止 为了防止实体瘤的产生，死亡的细胞数量必须与分裂的细胞数量相匹配。我们发现， 张力控制这两个过程：当细胞太稀疏时，拉伸迅速激活细胞分裂，然而， 当细胞太多时，拥挤激活细胞挤出和死亡。令人惊讶的是，我们发现 单一牵张激活通道Piezo 1控制牵张诱导细胞分裂和拥挤诱导细胞 挤出在仅仅一个小时的拉伸内，Piezo 1激活了处于G2期的上皮细胞群， 积累细胞周期蛋白B并进入有丝分裂。相反，在拥挤过程中，Piezo 1激活细胞产生和 释放一种脂质，鞘氨醇1-磷酸（S1 P），它结合邻近的G蛋白偶联受体， 细胞，S1 P2，它激活Rho介导的肌动球蛋白收缩，将细胞从顶部挤出， 保持严密的屏障。当凋亡信号激活垂死细胞的挤出时，通常，Piezo 1感测 拥挤以激活活细胞的挤出，所述活细胞随后由于失巢凋亡或由于存活信号的丧失而死亡。 在这个提议中，我们研究了Piezo 1如何激活细胞分裂或挤压和死亡，这取决于细胞的类型。 它所感受到的力量。Piezo 1定位于稀疏上皮细胞中的核膜、ER和质膜 最有可能分裂的区域，然后在拥挤的老年细胞中积累成大的细胞质斑块， 可能会挤出。因此，我们提出Piezo 1可以在需要产生更多细胞的地方感知拉伸 和感觉拥挤在需要通过其定位消除细胞的地方。在我们的资助更新中，我们 研究稀疏与拥挤细胞中Piezo 1水平和定位是否控制Ca+2激活差异 靶点分别驱动细胞分裂或挤出。在这里，我们调查：1）Piezo 1如何促进 上皮细胞拥挤区域的挤压？2)钙激活S1 P的形成还是抑制 粘附（或其他）复合物？3)Piezo 1如何触发稀疏上皮区域的细胞分裂？ 我们相信这些问题的答案将使我们更好地了解细胞分裂和死亡 由上皮细胞控制。我们还希望我们的发现对癌症和其他疾病有更广泛的影响。 基于上皮的疾病，因为我们发现不同的疾病似乎劫持了挤出的每个方面， 我们目前已经确认的信号。因此，揭示控制细胞死亡的基本途径， 部门将给我们一个独特的优势是发现新的方法来治疗疾病所造成的， 监管不当

Project Summary/Abstract Epithelial cells work together to form a protective layer for all the organs they encase yet they turnover through cell death and division at some of the highest rates in the body. To maintain a functional barrier and prevent solid tumors from arising, the numbers of cells that die must match those that divide. We found that mechanical tensions control both processes: when cells are too sparse, stretch rapidly activates cell division, whereas, when cells are too abundant, crowding activates cell extrusion and death. Astonishingly, we identified that a single stretch-activated channel, Piezo1, controls both stretch-induced cell division and crowding-induced cell extrusion. Within only one hour of stretch, Piezo1 activates a population of epithelial cells poised in G2 to accumulate cyclin B and enter mitosis. Conversely, during crowding, Piezo1 activates cells to produce and emit a lipid, Sphingosine 1-Phosphate (S1P), which binds a G-Protein Coupled Receptor in the neighboring cells, S1P2, which activates Rho-mediated actomyosin contraction to squeeze the cell out apically, while maintaining a tight barrier. While apoptotic signaling activates extrusion of dying cells, normally, Piezo1 senses crowding to activate extrusion of live cells that later die by anoikis, or apoptosis due to loss of survival signaling. In this proposal, we investigate how Piezo1 activates cells to divide or extrude and die, depending on the type of force it senses. Piezo1 localizes to the nuclear envelope, ER, and plasma membrane in sparser epithelial regions most likely to divide, and then accumulates into large cytoplasmic plaques in crowded, older cells most likely to extrude. Thus, we propose that Piezo1 can sense stretch in places that need to generate more cells and sense crowding in places that need to eliminate cells through its localization. In our grant renewal, we investigate if Piezo1 levels and localization in sparse versus crowded cells control Ca+2 activation of differential targets to drive cell division or extrusion, respectively. Here we investigate: 1) How does Piezo1 promote extrusion in crowded regions of epithelia? 2) Does calcium activate S1P formation or inactivate adhesion (or other) complexes? 3) How does Piezo1 trigger cell division in sparser epithelial regions? We believe the answers to these questions will give us a better understanding of how cell division and death are governed in epithelia. We also expect our findings to have much broader implications in cancer and other epithelial-based diseases, since we have found that different diseases appear to hijack every facet of extrusion signaling we have identified so far. Thus, uncovering the fundamental pathways that control cell death and division will give us a unique edge is discovering new approaches to treat diseases resulting from their misregulation.