Mechano-sensitive control of intestinal stem cell divisions in Drosophila.

描述（由申请人提供）：肠上皮的更新需要祖细胞分裂和分化细胞损失之间的平衡。维持分裂-损失平衡对消化系统健康至关重要，而它的破坏是许多肠道疾病的特征。分裂-损失平衡涉及上皮内的反馈信号；然而，这些信号的分子性质在很大程度上是未知的。我们的长期目标是了解肠道细胞在体内产生时空动态的过程。为了支持这一目标，本提案的目的是研究协调干细胞分裂与上皮细胞对新细胞需求的机械敏感机制。这些研究将利用成年果蝇肠道的可追溯性，其简单的干细胞谱系和先进的遗传工具使精确的机制研究成为可能。我们之前已经证明果蝇肠道对增加的饮食负荷表现出干细胞驱动的可逆生长反应（O'Brien等人，cell 2011）。我们实验室的初步证据表明，干细胞分裂率与肠道膨胀程度之间存在相关性。这种相关性让人想起上皮细胞培养中的密度敏感增殖，这是一种由粘附受体E-cadherin和转录因子YAP的机械转导控制的集体细胞行为。在这里，我们将检验当肠细胞稀疏时类似的机械敏感信号刺激肠干细胞分裂的假设。具体而言，我们将(1)确定肠膨胀过程中E-cadherin和YAP在生态位和非生态位细胞中的机械敏感性；(2)阐明E-cadherin和YAP在密度敏感分裂控制中的生态位和非生态位作用。这些目标的实现可能会确定连接肠细胞密度和干细胞分裂的机械敏感途径，为肠道更新的稳态控制提供基本的见解。我们提出的工作意义重大，因为了解细胞损失和生成如何协调可能会产生未来的治疗策略，以增强肠道修复和再生。我们的方法是创新的，因为它在密度敏感增殖和体内平衡组织更新之间建立了新的概念联系，并且因为它利用了新兴实验系统的独特属性。最后，这些研究的数据将为肠道更新和重塑的详细的r01水平的机械生物学研究提供基础。

DESCRIPTION (provided by applicant): Renewal of the intestinal epithelium requires a balance between progenitor cell divisions and differentiated cell loss. Maintaining division-loss balance is essential for digestive health, while its disruption characterizes numerous intestinal pathologies. Division-loss balance involves feedback signals that act within the epithelium; however, the molecular nature of these signals is largely unknown. Our long-range goal is to understand the processes that give rise to the spatiotemporal dynamics of intestinal cells in vivo. Supporting this goal, the objective of this proposal is to investigate mechano-sensitive mechanisms that coordinate stem cell divisions with the epithelium's need for new cells. These studies will exploit the tractability of the adult Drosophila intestine, whose simple stem cell lineage and advanced genetic tools enable precise mechanistic investigation. We have previously shown that the Drosophila intestine exhibits a stem cell driven, reversible growth response to increased dietary load (O'Brien et al., Cell 2011). Preliminary evidence from our lab suggests a correlation between stem cell division rate and the degree of intestinal distention. This correlation is reminiscent of density-sensitive proliferation in epithelial culture, a collectve cell behavior controlled by mechanotransduction through the adhesion receptor E-cadherin and the transcription factor YAP. Here, we will examine the hypothesis that analogous mechano-sensitive signals stimulate intestinal stem cell divisions when enterocytes are sparse. Specifically, we will (1) determine the mechano-sensitivity of E-cadherin and YAP in niche and non-niche cells during intestinal distention, and (2) elucidate the niche- and non-niche roles of E-cadherin and YAP in density-sensitive division control. Accomplishment of these aims may identify a mechano-sensitive pathway that links enterocyte density to stem cell divisions, providing basic insight into homeostatic control of intestinal renewal. Our proposed work is significant because knowledge of how cell loss and production are coordinated may engender future therapeutic strategies to enhance intestinal repair and regeneration. Our approach is innovative because it draws a novel conceptual link between density-sensitive proliferation and homeostatic tissue renewal, and because it exploits the unique attributes of an emerging experimental system. Finally, data from these studies will provide the foundation for a detailed, R01-level investigation of the mechanobiology of intestinal renewal and remodeling.