摘要
Molecular mechanisms transducing physical forces in the bone microenvironment to regulate bone mass are poorly understood.Here,we used mouse genetics,mechanical loading,and pharmacological approaches to test the possibility that polycystin-1 and Wwtr1 have interdependent mechanosensing functions in osteoblasts.We created and compared the skeletal phenotypes of control Pkd1^(flox/)+;Wwtr1^(flox/)+,Pkd1^(Oc-cKO),Wwtr1^(Oc-cKO),and Pkd1/Wwtr1^(Oc-cKO)mice to investigate genetic interactions.Consistent with an interaction between polycystins and Wwtr1 in bone in vivo,Pkd1/Wwtr1^(Oc-cKO)mice exhibited greater reductions of BMD and periosteal MAR than either Wwtr1Oc-cKOor Pkd1^(Oc-cKO)mice.Micro-CT 3D image analysis indicated that the reduction in bone mass was due to greater loss in both trabecular bone volume and cortical bone thickness in Pkd1/Wwtr1Oc-cKO mice compared to either Pkd1Oc-cKOor Wwtr1^(Oc-cKO)mice.Pkd1/Wwtr1^(Oc-cKO)mice also displayed additive reductions in mechanosensing and osteogenic gene expression profiles in bone compared to Pkd1Oc-cKOor Wwtr1^(Oc-cKO)mice.Moreover,we found that Pkd1/Wwtr1^(Oc-cKO)mice exhibited impaired responses to tibia mechanical loading in vivo and attenuation of loadinduced mechanosensing gene expression compared to control mice.Finally,control mice treated with a small molecule mechanomimetic,MS2 that activates the polycystin complex resulted in marked increases in femoral BMD and periosteal MAR compared to vehicle control.In contrast,Pkd1/Wwtr1^(Oc-cKO)mice were resistant to the anabolic effects of MS2.These findings suggest that PC1 and Wwtr1 form an anabolic mechanotransduction signaling complex that mediates mechanical loading responses and serves as a potential novel therapeutic target for treating osteoporosis.
基金
supported by National Institutes of Health(NIH),National Institute of Arthritis and Musculoskeletal and Skin Diseases(Grant RO1-AR071930)
National Institute of Diabetes and Digestive and Kidney Diseases(Grant RO1 DK121132)
supported by the Office of Science of the U.S.Department of Energy under Contract No.DE-AC05-00OR22725。