Trpv4 Mediates The Ca2+ Influx Required For The Interaction Between Flightless-1 And Non-Muscle Myosin, And Collagen Remodeling
JOURNAL OF CELL SCIENCE(2017)
摘要
Fibroblasts remodel extracellular matrix collagen, in part, through phagocytosis. This process requires formation of cell extensions, which in turn involves interaction of the actin-binding protein flightless-1 (FliI) with non-muscle myosin IIA (NMMIIA; heavy chain encoded by MYH9) at cell-matrix adhesion sites. As Ca2+ plays a central role in controlling actomyosin-dependent functions, we examined how Ca2+ controls the generation of cell extensions and collagen remodeling. Ratio fluorimetry demonstrated localized Ca2+ influx at the extensions of fibroblasts. Western blotting and quantitative (q) PCR showed high expression levels of the Ca(2+)permeable transient receptor potential vanilloid-4 (TRPV4) channel, which co-immunoprecipitated with beta 1 integrin and localized to adhesions. Treatment with alpha 2 beta 1-integrin-blocking antibody or the TRPV4-specific antagonist AB159908, as well as reduction of TRPV4 expression through means of siRNA, blocked Ca2+ influx. These treatments also inhibited the interaction of FliI with NMMIIA, reduced the number and length of cell extensions, and blocked collagen remodeling. Pulldown assays showed that Ca2+ depletion inhibited the interaction of purified FliI with NMMIIA filaments. Fluorescence resonance energy transfer experiments showed that FliI-NMMIIA interactions require Ca2+ influx. We conclude that Ca2+ influx through the TRPV4 channel regulates FliI-NMMIIA interaction, which in turn enables generation of the cell extensions essential for collagen remodeling.
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关键词
Ca2+, Actin, Extracellular matrix, Remodeling, Cell extensions
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