Signaling cross-talk by bone morphogenetic proteins

Bone morphogenetic proteins (BMPs) have diverse effect on different cell types and, for many, BMPs play essential role in their survival and differentiation. BMPs are conserved across the animal kingdom and participate in the development of a wide variety of organisms including vertebrates, arthropods and nematodes. In the growing family of BMPs, more than 30 members have been described so far. In vertebrates, BMPs regulate development of many organs, including heart, kidney and bone, by regulating proliferation, differentiation and apoptotic pathways [1, 2, 3]. The wide spectrum of biological responses elicited by BMPs in different cellular set ups are dictated by tightly controlled signaling cross-talk between BMPinduced signaling pathways and interaction of divergent intracellular cofactors. In this review, we describe the signal transduction pathways induced by BMPs and discuss the possible cross-talk between them. We focus mainly on BMP signaling in bone with a brief discussion of other cell types that are regulated by BMPs. Figure 1 summarizes the pathways for BMP-induced signal transduction pathways discussed in this review.