Cell autonomous requirement of Cx43 for osteocyte viability: consequences for endocortical resorption and periosteal bone formation

BIVI N; CONDON K; ALLEN MR; FARLOW N; PASSERI G; BRUN LR; RHEE Y; BELLIDO T; PLOTKIN LI

AMER SOC BONE & MINERAL RES

Año: 2012 vol. 27 p. 374 - 374

onnexin43 (Cx43) mediates osteocyte communication with other cells and with the extracellular milieu and regulates osteoblastic cell signaling and gene expression. We now report that mice lacking Cx43 in osteoblasts/osteocytes or only in osteocytes (Cx43Ot mice)exhibit increased osteocyte apoptosis, endocortical resorptionand periosteal bone formation, resulting in higher marrow cavityand total tissueareas measured at the femoral mid-diaphysis.Blockade of resorption reversed the increasedmarrow cavity but not total tissue area, demonstrating that endocortical resorption andperiosteal apposition are independently regulated.Anatomical mappingof apoptotic osteocytes,osteocytic protein expression, and resorption and formation,suggeststhat Cx43 controls osteoclast and osteoblast activity by regulating osteoprotegerin and sclerostinlevels, respectively, in osteocytes located in specific areas of the cortex.Whereas empty lacunae and living osteocytes lacking osteoprotegerinwere distributed