The role of adipokines in bone homeostasis

Abstract

Growing evidence has shown that adipose tissue accumulation is associated with bone metabolism. Arguably, adipokines, secretory proteins of adipose tissue, are involved in bone homeostasis including development and remodeling. The classical adipokine leptin regulates bone formation negatively and bone resorption positively via central nervous system. Leptin also stimulates directly osteoblastogenesis and inhibits osteoclastogenesis through stimulation of osteoprotegerin and inhibition of receptor activator for nuclear factor IoB ligand (RANKL) expression in osteoblasts. Another major adipokine, adiponectin, and its receptor are expressed in osteoblasts. Adiponectin stimulates the proliferation, differentiation, and mineralization of osteoblastic cells, and indirectly stimulates osteoclast differentiation via enhancement of RANKL and inhibition of osteoprotegerin expression in osteoblasts, whereas directly inhibits osteoclast activity and bone resorption. Altogether, adipose tissue via adipokines plays a crucial role in the maintenance of bone homeostasis. These findings are reviewed herein. Adipobiology 2011; 3: 39-50.