Piezo2 senses airway stretch and mediates lung inflation-induced apnoea
NATURE
Authors: Nonomura, Keiko; Woo, Seung-Hyun; Chang, Rui B.; Gillich, Astrid; Qiu, Zhaozhu; Francisco, Allain G.; Ranade, Sanjeev S.; Liberles, Stephen D.; Patapoutian, Ardem
Abstract
Respiratory dysfunction is a notorious cause of perinatal mortality in infants and sleep apnoea in adults, but the mechanisms of respiratory control are not clearly understood. Mechanical signals transduced by airway-innervating sensory neurons control respiration; however, the physiological significance and molecular mechanisms of these signals remain obscured. Here we show that global and sensory neuron-specific ablation of the mechanically activated ion channel Piezo2 causes respiratory distress and death in newborn mice. Optogenetic activation of Piezo2(+) vagal sensory neurons causes apnoea in adult mice. Moreover, induced ablation of Piezo2 in sensory neurons of adult mice causes decreased neuronal responses to lung inflation, an impaired Hering-Breuer mechanoreflex, and increased tidal volume under normal conditions. These phenotypes are reproduced in mice lacking Piezo2 in the nodose ganglion. Our data suggest that Piezo2 is an airway stretch sensor and that Piezo2-mediated mechanotransduction within various airway-innervating sensory neurons is critical for establishing efficient respiration at birth and maintaining normal breathing in adults.
Piezo1 Inactivation in Chondrocytes Impairs Trabecular Bone Formation
JOURNAL OF BONE AND MINERAL RESEARCH
Authors: Hendrickx, Gretl; Fischer, Verena; Liedert, Astrid; von Kroge, Simon; Haffner-Luntzer, Melanie; Brylka, Laura; Pawlus, Eva; Schweizer, Michaela; Yorgan, Timur; Baranowsky, Anke; Rolvien, Tim; Neven, Mona; Schumacher, Udo; Beech, David J.; Amling, Michael; Ignatius, Anita; Schinke, Thorsten
Abstract
The skeleton is a dynamic tissue continuously adapting to mechanical stimuli. Although matrix-embedded osteocytes are considered as the key mechanoresponsive bone cells, all other skeletal cell types are principally exposed to macroenvironmental and microenvironmental mechanical influences that could potentially affect their activities. It was recently reported that Piezo1, one of the two mechanically activated ion channels of the Piezo family, functions as a mechanosensor in osteoblasts and osteocytes. Here we show that Piezo1 additionally plays a critical role in the process of endochondral bone formation. More specifically, by targeted deletion of Piezo1 or Piezo2 in either osteoblast (Runx2Cre) or osteoclast lineage cells (Lyz2Cre), we observed severe osteoporosis with numerous spontaneous fractures specifically in Piezo1(Runx2Cre) mice. This phenotype developed at an early postnatal stage and primarily affected the formation of the secondary spongiosa. The presumptive Piezo1(Runx2Cre) osteoblasts in this region displayed an unusual flattened appearance and were positive for type X collagen. Moreover, transcriptome analyses of primary osteoblasts identified an unexpected induction of chondrocyte-related genes in Piezo1(Runx2Cre) cultures. Because Runx2 is not only expressed in osteoblast progenitor cells, but also in prehypertrophic chondrocytes, these data suggested that Piezo1 functions in growth plate chondrocytes to ensure trabecular bone formation in the process of endochondral ossification. To confirm this hypothesis, we generated mice with Piezo1 deletion in chondrocytes (Col2a1Cre). These mice essentially recapitulated the phenotype of Piezo1(Runx2Cre) animals, because they displayed early-onset osteoporosis with multiple fractures, as well as impaired formation of the secondary spongiosa with abnormal osteoblast morphology. Our data identify a previously unrecognized key function of Piezo1 in endochondral ossification, which, together with its role in bone remodeling, suggests that Piezo1 represents an attractive target for the treatment of skeletal disorders. (c) 2020 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).