Zyxin蛋白與肌動蛋白結構調控非等向性YAP力學傳遞

Abstract

人體中的細胞會因為組織結構與功能需求而持續受到具有非等向的變形，例如肌腱細胞和肌肉細胞，通常受限於其細胞外基質結構，並沿著主要受力方向平行排列。然而目前大多數體外實驗模型尚無法真實重現體內所經歷之非等向性的力學環境。本研究透過結合微製程技術限制細胞形狀與單軸向拉伸系統，建立精確的幾何與受力控制條件，並驗證外部受力方向為決定細胞骨架重組與下游訊號傳遞的重要開關。我們證實幹細胞內細胞骨架排列方式與機械負載的方向一致時，可促進活化的YAP蛋白移至細胞核;但當拉伸方向垂直於細胞骨架排列方向時，則未觀察到相同現象。進一步分析細胞骨架在細胞受到機械負載的早期階段的反應顯示，平行拉伸會在60秒內誘導肌動蛋白絲結構重組，包含結構斷裂與隨後修復，此過程受到focal adhesion protein zyxin所調控。此外，由zyxin所調控的肌動蛋白絲結構重組之修復反應受到focal adhesion kinase (FAK)所調控，而此反應進一步活化YAP訊號。有鑑於上述分子在機械刺激過程中所調控的反應具有關鍵作用，本研究結果顯示zyxin、YAP在非等向性機械訊號傳導中扮演重要角色外，且可作為細胞適應性反應(cellular adaptive responses)及維持組織體內平衡(tissue homeostasis)提供新的觀點。內容已於2022年發表在Acta Biomater期刊

Cells in the human body are continuously subjected to anisotropic mechanical deformation arising from tissue architecture and functional demands. For example, tenocytes and muscle cells are constrained by their extracellular matrix and typically align parallel to their principal loading direction. However, most in vitro experimental models fail to recapitulate the anisotropic geometric and mechanical environment experienced in vivo. In this study, we integrated cell pattering with a controllable uniaxial stretching system to establish precise control of cell geometry and force direction. We demonstrate that when cytoskeletal is oriented parallel to the direction of mechanical loading, YAP translocate into the nucleus. In contrast, no comparable nuclear translocation is observed when the stretch is applied perpendicular to cytoskeletal alignment. Further analysis of early cytoskeletal response to mechanical loading revealed that parallel stretching induces actin filament remodeling within 60 seconds, characterized by filament disruption followed by repair. This process is mediated by the focal adhesion protein zyxin. Moreover, zyxin-dependent actin repair is regulated by focal adhesion kinase (FAK), and this signaling cascade subsequently promotes YAP activation. Given the critical roles of these mechanism in anisotropic mechanotransduction, our finding indicates that zyxin and YAP serve as key regulators in anisotropic mechanical signaling. These results provide new insights into cellular adaptive responses and contribute to our understanding of tissue homeostasis under directional mechanical stimulation and was published in Acta Biomater in 2022