報告題目：Mechanicalcuesaffects Ca2+signalingin stem cells

報 告  人✅：王英曉 Associate professor   Department of Bioengineering, University of California, San Diego

EON体育4訪問特聘教授

報告時間：7月8日 13:00

報告地點🤦🏽👨‍🦳：閔行校區生物藥學樓2-116

聯 系  人：張萍 This e-mail address is being protected from spambots. You need JavaScript enabled to view it.

個人簡歷

王英曉🥹，博士🙇🏽‍♂️🏄🏻，現任美國加州大學聖地亞哥分校生物工程系副教授👱🏼‍♀️，EON体育4訪問特聘教授。師從中國科EON4外籍院士、美國國家科EON4、國家工程院、國家醫學科EON4👨‍👧‍👦😵、國家藝術與科學EON4院士ShuChien（錢煦）教授和諾貝爾獎獲得者Roger Y. Tsien（錢永健）教授。從事力學生物學、生物技術、蛋白質工程和細胞分子力學生物學研究17年🖕🏽，在整合生物學前沿技術、新型分子傳感器和熒光共振能量轉移（FRET）技術發展和應用方面有很高的造詣💆🏼，是一位年青有為的科學家👮🏼‍♀️。他在Nature👶🏽、Nature Communications和PNAS等國際著名期刊發表論文50余篇🦷🫠，僅2008年在Ann Rev Biomed Eng發表的第1作者綜述論文迄今已累計下載9353次✉️，在國際學術會議和學術機構作邀請報告100余次👁，獲美國NSF早期職業獎、NIH K02獨立科學家獎🧙🏼‍♂️🫃🏽、Grainger獎和Xerox獎等。

Abstract

Mechanical forces play crucial roles in regulating cellular functions, such as cell spreading, traction forces, and stem cell differentiation. However, it is not clear how they influence early cell signaling events such as calcium in living stem cells. Using highly-sensitive Ca2+ biosensors based on fluorescence resonance energy transfer (FRET), we investigated the molecular mechanism by which mechanical forces affect calcium signaling in human mesenchymal stem cells (HMSCs). Spontaneous Ca2+ oscillations were observed inside the cytoplasm and the endoplasmic reticulum (ER) using the FRET biosensors targeted at subcellular locations in cells plated on rigid dishes. Lowering the substrate stiffness to 1 kPa significantly inhibited both the magnitudes and frequencies of the cytoplasmic Ca2+ oscillation in comparison to stiffer or rigid substrate. This Ca2+ oscillation was shown to be dependent on ROCK, a downstream effector molecule of RhoA, but independent of actin filaments, microtubules, myosin light chain kinase, or myosin activity. Lysophosphatidic acid, which activates RhoA, also inhibited the frequency of the Ca2+ oscillation. Consistently, either a constitutive active mutant of RhoA (RhoA-V14) or a dominant negative mutant of RhoA (RhoA-N19) inhibited the Ca2+ oscillation. Further experiments revealed that HMSCs cultured on gels with low elastic moduli displayed low RhoA activities. Therefore, our results demonstrate that RhoA and its downstream molecule ROCK may mediate the substrate rigidity-regulated Ca2+ oscillation, which determines the physiological functions of HMSCs. We further investigated the molecular and biophysical mechanisms by which mechanical force regulates Ca2+ signaling at subcellular level in HMSCs, integrating optical laser tweezers and Ca2+ FRET biosensor. Laser-tweezer-traction on a fibronectin-coated bead at the plasma membrane induces intracellular Ca2+ oscillations caused by Ca2+ release from endoplasmic reticulum (ER) in the absence of extracellular Ca2+. Ca2+ oscillations produced by ER Ca2+ release upon mechanical force are mediated not only by the mechanical support of cytoskeleton and actomyosin contractility, but also by mechanosensitive Ca2+ channels on the plasma membrane, specifically TRPM7. As the ER Ca2+ release is inhibited, the mechanical force can induce intracellular Ca2+ increase via mechanosensitive Ca2+ channels in the presence of extracellular Ca2+, which is mediated by the cytoskeletal structure but not actomyosin contractility. Taken together, our results indicate that active actomyosin contractility is essential for the force transmission into the deep intracellular organelles, ER but dispensable for the mechanical regulation of plasma membrane channels. Therefore, our results clearly suggest a crucial role of mechanical force in regulating calcium signaling in live stem cells with a well-coordinated molecular hierarchy.