Piezo proteins are mechanically activated ion channels,which are required for mechanosensing functions in a variety of cell types.While we and others have previously demonstrated that the expression of Piezo1 in osteo...Piezo proteins are mechanically activated ion channels,which are required for mechanosensing functions in a variety of cell types.While we and others have previously demonstrated that the expression of Piezo1 in osteoblast lineage cells is essential for boneanabolic processes,there was only suggestive evidence indicating a role of Piezo1 and/or Piezo2 in cartilage.Here we addressed the question if and how chondrocyte expression of the mechanosensitive proteins Piezo1 or Piezo2 controls physiological endochondral ossification and pathological osteoarthritis(OA)development.Mice with chondrocyte-specific inactivation of Piezo1(Piezo1^(Col2a1Cre)),but not of Piezo2,developed a near absence of trabecular bone below the chondrogenic growth plate postnatally.Moreover,all Piezo1^(Col2a1Cre) animals displayed multiple fractures of rib bones at 7 days of age,which were located close to the growth plates.While skeletal growth was only mildly affected in these mice,OA pathologies were markedly less pronounced compared to littermate controls at 60 weeks of age.Likewise,when OA was induced by anterior cruciate ligament transection,only the chondrocyte inactivation of Piezo1,not of Piezo2,resulted in attenuated articular cartilage degeneration.Importantly,osteophyte formation and maturation were also reduced in Piezo1^(Col2a1Cre) mice.We further observed increased Piezo1 protein abundance in cartilaginous zones of human osteophytes.Finally,we identified Ptgs2 and Ccn2 as potentially relevant Piezo1 downstream genes in chondrocytes.Collectively,our data do not only demonstrate that Piezo1 is a critical regulator of physiological and pathological endochondral ossification processes,but also suggest that Piezo1 antagonists may be established as a novel approach to limit osteophyte formation in OA.展开更多
The recent identification of homozygous WNT1 mutations in individuals with osteogenesis imperfecta type XV(OI-XV)has suggested that WNT1 is a key ligand promoting the differentiation and function of bone-forming osteo...The recent identification of homozygous WNT1 mutations in individuals with osteogenesis imperfecta type XV(OI-XV)has suggested that WNT1 is a key ligand promoting the differentiation and function of bone-forming osteoblasts.Although such aninfluence was supported by subsequent studies,a mouse model of OI-XV remained to be established.Therefore,we introduced a previously identified disease-causing mutation(G177C)into the murine Wnt1 gene.Homozygous Wnt1^(G177C/G177C)mice were viable and did not display defects in brain development,but the majority of 24-week-old Wnt1^(G177C/G177C)mice had skeletal fractures.This increased bone fragility was not fully explained by reduced bone mass but also by impaired bone matrix quality.Importantly,the homozygous presence of the G177C mutation did not interfere with the osteoanabolic influence of either parathyroid hormone injection or activating mutation of LRP5,the latter mimicking the effect of sclerostin neutralization.Finally,transcriptomic analyses revealed that short-term administration of WNT1 to osteogenic cells induced not only the expression of canonical WNT signaling targets but also the expression of genes encoding extracellular matrix modifiers.Taken together,our data demonstrate that regulating bone matrix quality is a primary function of WNT1.They further suggest that individuals with WNT1 mutations should profit from existing osteoanabolic therapies.展开更多
基金supported by the German Research Foundation(SCHI 504/19-1(to TS)and IG 18/22-1(to AI))the Else Kröner-Fresenius foundation under grant no.2021_EKEA.23(to TR)financial support from the Open Access Publication Fund of UKE–Universitatsklinikum Hamburg-Eppendorf and DFG–German Research Foundation.
文摘Piezo proteins are mechanically activated ion channels,which are required for mechanosensing functions in a variety of cell types.While we and others have previously demonstrated that the expression of Piezo1 in osteoblast lineage cells is essential for boneanabolic processes,there was only suggestive evidence indicating a role of Piezo1 and/or Piezo2 in cartilage.Here we addressed the question if and how chondrocyte expression of the mechanosensitive proteins Piezo1 or Piezo2 controls physiological endochondral ossification and pathological osteoarthritis(OA)development.Mice with chondrocyte-specific inactivation of Piezo1(Piezo1^(Col2a1Cre)),but not of Piezo2,developed a near absence of trabecular bone below the chondrogenic growth plate postnatally.Moreover,all Piezo1^(Col2a1Cre) animals displayed multiple fractures of rib bones at 7 days of age,which were located close to the growth plates.While skeletal growth was only mildly affected in these mice,OA pathologies were markedly less pronounced compared to littermate controls at 60 weeks of age.Likewise,when OA was induced by anterior cruciate ligament transection,only the chondrocyte inactivation of Piezo1,not of Piezo2,resulted in attenuated articular cartilage degeneration.Importantly,osteophyte formation and maturation were also reduced in Piezo1^(Col2a1Cre) mice.We further observed increased Piezo1 protein abundance in cartilaginous zones of human osteophytes.Finally,we identified Ptgs2 and Ccn2 as potentially relevant Piezo1 downstream genes in chondrocytes.Collectively,our data do not only demonstrate that Piezo1 is a critical regulator of physiological and pathological endochondral ossification processes,but also suggest that Piezo1 antagonists may be established as a novel approach to limit osteophyte formation in OA.
基金This project has received funding from the Deutsche Forschungsgemeinschaft(SCHI 504/15-1 and YO 299/1-1),the European Community's Seventh Framework Programme under grant agreement no.602300(SYBIL),and the German Federal Ministry of Education and Research(BMBF)within the project"Detection and Individualized Management of Early Onset Osteoporosis(DIMEOS)"Parts of this work were supported by the Deutsche Forschungsgemeinschaft through FOR 2722 to O.S.(SE2373/1-1)W.Z.received funding through the China Scholarship Council.
文摘The recent identification of homozygous WNT1 mutations in individuals with osteogenesis imperfecta type XV(OI-XV)has suggested that WNT1 is a key ligand promoting the differentiation and function of bone-forming osteoblasts.Although such aninfluence was supported by subsequent studies,a mouse model of OI-XV remained to be established.Therefore,we introduced a previously identified disease-causing mutation(G177C)into the murine Wnt1 gene.Homozygous Wnt1^(G177C/G177C)mice were viable and did not display defects in brain development,but the majority of 24-week-old Wnt1^(G177C/G177C)mice had skeletal fractures.This increased bone fragility was not fully explained by reduced bone mass but also by impaired bone matrix quality.Importantly,the homozygous presence of the G177C mutation did not interfere with the osteoanabolic influence of either parathyroid hormone injection or activating mutation of LRP5,the latter mimicking the effect of sclerostin neutralization.Finally,transcriptomic analyses revealed that short-term administration of WNT1 to osteogenic cells induced not only the expression of canonical WNT signaling targets but also the expression of genes encoding extracellular matrix modifiers.Taken together,our data demonstrate that regulating bone matrix quality is a primary function of WNT1.They further suggest that individuals with WNT1 mutations should profit from existing osteoanabolic therapies.
