V. Joshi, C. Seavey, K. Knutson, A. Sawant, Y. M. Hamed, M. D'Ambrosio, E. Laible, V. Dokic, J. P. Sinnwell, Y. Liu, F. F. Jin, C. Thomas, G. Garramone, A. P. Mazzone, F. Bonfiglio, M. D'Amato, R. Avci, P. Du, M. Grover, P. C. Kashyap, B. R. Druliner, D. R. Linden, G. Cipriani, K. L. Marshall, Y. L. Bae, G. Farrugia, A. Beyder
Age-related gastrointestinal dysfunction is common, but the mechanisms of aging-associated smooth muscle failure remain unclear. We show that aging in mice slows whole gut and colonic transit, increases regional stiffness, and reduces smooth muscle contractility. Inducible smooth muscle cell (SMC) specific deletion of Piezo1 preserved youthful transit and force generation, whereas Piezo1 activation in young mice phenocopied aging-associated transit delay. Single cell transcriptomics, RNA velocity, stiffness-controlled cell and tissue cultures, and pharmacologic studies revealed that Piezo1 couples increased stiffness to Ca2+, calcineurin, NFAT signaling, loss of contractile gene programs, leading to age-related contractile loss and contractile to synthetic SMC remodeling and gut wall stiffening. Human intestinal SMCs supported conservation of this pathway, and PIEZO1 gain of function carriers showed a trend toward delayed colonic transit. Thus, maladaptive SMC Piezo1 mechanotransduction is a targetable mechanism of aging-associated gut dysmotility.