Extracellular microfibrils: contextual platforms for TGFbeta and BMP signaling.

The extracellular matrix plays a key role in organ formation and tissue homeostasis. Recent studies have revealed that fibrillin assemblies (microfibrils) confer both tissue integrity and regulate signaling events that instruct cell performance and that perturbation of either function manifests in disease. These analyses have also indicated that fibrillin assemblies impart contextual specificity to TGFbeta and BMP signaling. Moreover, correlative evidence suggests functional coupling between cell-directed assembly of microfibrils and targeting of TGFbeta and BMP complexes to fibrillins. Hence, the emerging view is that fibrillin-rich microfibrils are molecular integrators of structural and instructive signals with TGFbetas and BMPs as nodal points that convert extracellular inputs into discrete and context-dependent cellular responses.