Role of DLX regulatory proteins in osteogenesis and chondrogenesis.

Bone development is a complex process in which several cell types interact, proliferate, differentiate, and die to give rise to skeletal structures. These processes are highly integrated and require continuous and coordinated regulation by soluble molecular signals and transcription factors to assure harmonious bone development and morphogenesis. In the bone, transcription factors often have multiple functions and control the differentiation of more than one skeletal cellular component. In particular, Distal-less (Dlx) homeobox transcription factors play a central role in regulating the proliferation and differentiation of the three major cell types that constitute bone: chondrocytes, osteoblasts, and osteoclasts. The aim of this review is to summarize what is known about the role of Dlx genes in osteogenesis and to emphasize their role as coordinators at different levels of skeletal development. The elucidation of these unifying roles could improve our understanding not only of bone development but also of adult bone anabolism and catabolism resulting in bone homeostasis and might thus help to further our understanding of the genetic factors responsible for predisposition to multifactorial conditions such as osteoporosis.