Matrix Rigidity‐Dependent Regulation of Ca²⁺ at Plasma Membrane Microdomains by FAK Visualized by Fluorescence Resonance Energy Transfer

Abstract

The dynamic regulation of signal transduction at plasma membrane microdomains remains poorly understood due to limitations in current experimental approaches. Genetically encoded biosensors based on fluorescent resonance energy transfer (FRET) can provide high spatiotemporal resolution for imaging cell signaling networks. Here, distinctive regulation of focal adhesion kinase (FAK) and Ca 2+ signals are visualized at different membrane microdomains by FRET using membrane‐targeting biosensors. It is shown that rigidity‐dependent FAK and Ca 2+ signals in human mesenchymal stem cells (hMSCs) are selectively activated at detergent‐resistant membrane (DRM or rafts) microdomains during the cell–matrix adhesion process, with minimal activities at non‐DRM domains. The rigidity‐dependent Ca 2+ signal at the DRM microdomains is downregulated by either FAK inhibition or lipid raft disruption, suggesting that FAK and lipid raft integrity mediate the in situ Ca 2+ activation. It is further revealed that transient receptor potential subfamily M7 (TRPM7) participates in the mobilization of Ca 2+ signals within DRM regions. Thus, the findings provide insights into the underlying mechanisms that regulate Ca 2+ and FAK signals in hMSCs under different mechanical microenvironments.

Towards an integrative understanding of cancer mechanobiology: calcium, YAP, and microRNA under biophysical forces

“…Increasing evidence demonstrates that the mechanical microenvironment mediates Ca 2+ signaling in non-cancer cells (Fig. 3A), such as human mesenchymal stem cells (HMSCs), 146,147 fibroblasts, 148 neutrophils, 149 myofibroblasts, 150 macrophages, 151 and human neuronal progenitor cells. 152 HMSCs cultured on rigid dishes (Young's modulus: E B 3 GPa) have been observed to generate spontaneous [Ca 2+ ] cyt oscillations.…”

“…83 In HMSCs, prolonged stretch triggers intracellular Ca 2+ oscillations. 156 This Ca 2+ response is dependent on calcium 147 integrin/FAK/ actin mechanotransduction, 146,149 mechanosensitive ion channels, 146,[149][150][151] and mechanosensitive-GPR68-triggered Gq-PLC-IP 3 R pathway. 152 Soft substrates enhance calcium oscillations in mouse fibroblasts in an F-actin-dependent manner.…”

“…3.3.2 Mechanosensitive ion channels and cytoskeletal proteins. In Section 3.2, we summarized how (1) mechanosensitive ion channels, such as Piezo1, [83][84][85]88 TRPM7, 136,146,158 and TRPV4, 130,150,151 and (2) GPCRs, such as GPR68 86,152 and H 1 R, 159 can sense mechanical stimuli and trigger Ca 2+ signaling. Reciprocally, Ca 2+ signaling induced by mechanosensitive ion channels affects cytoskeleton remodeling.…”

“…Fig.3Biophysical cues regulate calcium signaling. (A) Stiff substrates enhance intracellular calcium signaling via RhoA/ROCK pathway,147 integrin/FAK/ actin mechanotransduction,146,149 mechanosensitive ion channels,146,[149][150][151] and mechanosensitive-GPR68-triggered Gq-PLC-IP 3 R pathway 152. Soft substrates enhance calcium oscillations in mouse fibroblasts in an F-actin-dependent manner 148.…”

Insights and perspectives on calcium channel functions in the cockpit of cancerous space invaders

“…TRPM7 is locally associated with FAK and the integrin/FA complex and controls normal and pathological migration through the regulation of Ca 2+ -sensitive calpain activity and actomyosin contractility [49,120,[123][124][125]. TRPM7-mediated increases in intracellular Ca 2+ levels enhance cell spreading and cell matrix adhesion independently of TRPM7 kinase activity.…”