Alpha-Catenins in Mechanochemical Signaling

描述（由申请人提供）：在出生后早期，心肌细胞经历快速生长和成熟，这对正常的心脏发育至关重要。与心肌细胞分化和细胞周期退出相一致的是基于n-钙粘蛋白的粘附连接（AJ）的建立，这是嵌入盘（ID）结构的关键决定因素，该结构提供心肌细胞之间的端到端连接。通过-和-连环蛋白，细胞内钙粘蛋白结构域与肌动蛋白细胞骨架的动态I结合，AJ稳定在ID。为了探索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 -猫双敲除（DKO）），在这种模型中，细胞骨架连接蛋白α -和α -catenin在心脏中都被耗尽。我们发现-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。核Yap （Hippo通路的关键组成部分）的显著增加伴随着α猫DKO心脏的增殖增加。重要的是，我们发现与对照组相比，阿尔法猫DKO小鼠在心肌梗死后表现出改善的心脏功能。我们假设，缺失“/”catenin会导致细胞骨架重排和张力丧失，从而导致Yap易位到细胞核，在细胞核中激活心肌细胞增殖的关键基因。提出了以下相关目标：(1)确定调节Yap细胞活性的基于细胞骨架的信号通路。(2)明确N-cadherin/ α - catenin/细胞骨架相互作用与肌细胞弹性和增殖的功能关系。可变形的n-钙粘蛋白包被水凝胶将用于确定刚度和n-钙粘蛋白/连环蛋白介导的细胞骨架组织如何协同调节增殖。原子力显微镜（AFM）将用于测量不同生理和病理条件下alpha-cat DKO的细胞和组织刚度。(3)为了追求临床应用，我们将确定心肌梗死后操纵α -catenin/Yap通路的机会窗口。这项研究的长期目标是确定干扰细胞骨架蛋白（α -连环蛋白）是否代表一种潜在的治疗方法，以增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.