Modulation of BMP signalling by integrins

The bone morphogenetic protein (BMP) pathway is a major conserved signalling pathway with diverse roles in development and homeostasis. Given that cells exist in three-dimensional environments, one important area is to understand how the BMP pathway operates within such complex cellular environments. The extracellular matrix contains information regarding tissue architecture and its mechanical properties that is transmitted to the cell via integrin receptors. In this review, I describe various examples of modulation of the BMP pathway by integrins. In the case of the Drosophila embryo and some cell line-based studies, integrins have been found to enhance BMP responses through different mechanisms, such as enhancement of BMP ligand-receptor binding and effects on Smad phosphorylation or stability. In these contexts, BMP-dependent activation of integrins is a common theme. However, I also discuss examples where integrins inhibit the BMP pathway, highlighting the context-dependent nature of integrin-BMP cross-talk.