Alpha-Catenins in Mechanochemical Signaling

描述(申请人提供)：在出生后早期，心肌细胞经历快速生长和成熟，这是正常心脏发育所必需的。与心肌细胞分化和细胞周期退出相一致的是基于N-钙粘附素的黏附连接(AJ)的建立，AJ是提供心肌细胞之间端到端连接的间盘(ID)结构的关键决定因素。AJ通过细胞内钙粘蛋白结构域通过β-和α-连环蛋白与肌动蛋白细胞骨架的动态结合稳定在ID。为了探讨机械转导在心脏发育和稳态中的作用，我们建立了一种新的动物模型(α-CAT双基因敲除(DKO))，在该模型中，细胞骨架连接蛋白αE-和αT-catenin在心脏中都被耗尽。我们发现，α-连环蛋白通常会抑制出生后心肌细胞重新进入细胞周期的能力。在α-CAT DKO心脏中，伴随着α-CAT DKO心脏增殖增加，河马途径的关键成分-核YAP显著增加。重要的是，我们发现，与对照组相比，阿尔法-CAT DKO小鼠在心肌梗死后表现出更好的心功能。我们假设�/�连接素的缺失导致细胞骨架重排和张应力的丧失，从而导致YAP移位到细胞核，在那里它激活了对心肌细胞增殖至关重要的基因。提出了以下相关目标：(1)确定调控YAP细胞活性的基于细胞骨架的信号通路。(2)明确N-钙粘蛋白/α-连环蛋白/细胞骨架相互作用与心肌细胞弹性和增殖的功能关系。可变形的N-钙粘附素涂层水凝胶将被用来确定刚性和N-钙粘附素/连环素介导的细胞骨架组织如何协同调节增殖。原子力显微镜(AFM)将被用来测量不同生理和病理条件下α-CAT DKO的细胞和组织硬度。(3)为了临床应用，我们将确定心肌梗死后操纵α-连环蛋白/YAP通路的机会窗。这项研究的长期目标是确定干扰细胞骨架蛋白α-连环素是否代表着一种潜在的治疗方法，可以加强心力衰竭患者的心脏修复。

DESCRIPTION (provided by applicant): In the early postnatal period, cardiomyocytes undergo rapid growth and maturation that is essential for normal cardiac development. Coincident with cardiomyocyte differentiation and cell cycle withdrawal is the establishment of the N-cadherin-based adherens junction (AJ), a critical determinant of intercalated disc (ID) structure that provides the end-to-end connection between cardiomyocytes. AJ are stabilized at the ID by the dynamic I has binding of the intracellular cadherin domain to the actin cytoskeleton via beta- and alpha-catenins. To explore the role of mechanotransduction in cardiac development and homeostasis, we developed a novel animal model (alpha-cat double knockout (DKO)) in which both cytoskeletal linker proteins alphaE- and alphaT-catenin were depleted in the heart. We discovered that alpha-catenin proteins normally inhibit the ability of postnatal cardiomyocytes to re-enter the cell cycle. A significant increase in nuclear Yap, a key component of the Hippo pathway, accompanied the increased proliferation in the alpha-cat DKO hearts. Importantly, we found that alpha-cat DKO mice exhibit improved cardiac function following myocardial infarction compared to their control littermates. We hypothesize that loss of �/�catenin causes cytoskeletal rearrangement and loss of tensional stress resulting in translocation of Yap to the nucleus where it activates genes critical for cardiomyocyte proliferation. The following interrelated aims are proposed: (1) To determine the cytoskeletal-based signaling pathways that regulate the cellular activity of Yap. (2) To define the functional relationship between N-cadherin/alpha- catenin/cytoskeleton interactions and myocyte elasticity and proliferation. Deformable N-cadherin- coated hydrogels will be used to determine how stiffness and N-cadherin/catenin-mediated cytoskeletal organization cooperate to regulate proliferation. Atomic force microscopy (AFM) will be used to measure cell and tissue stiffness in alpha-cat DKO under different physiological and pathological conditions. (3) In order to pursue clinical application, we will determine the window of opportunity for manipulating alpha-catenin/Yap pathway after myocardial infarction. The long term goal of this research is to determine if interfering with the cytoskeletal proteins, alpha-catenins, represents a potential therapy to enhance cardiac repair in heart failure patients.