Matrix Metalloproteinases in Renal Development

Matrix metalloproteinases (MMPs) are enzymes with metal ion-dependent activity that degrade extracellular matrix (ECM) glycoproteins. MMPs play a vital role in various biological processes, such as embryogenesis, tissue remodeling, angiogenesis, and wound healing, and in certain disease processes, for example, metastasis of cancer cells. Following their activation, MMPs are believed to modulate both cell-cell and cell-matrix interactions, which in turn regulate cellular differentiation, migration, proliferation, and cell survival. Being involved in pericellular proteolysis, they maintain a gradient of ECM proteins by balancing ECM synthesis and degradation. Such a balance is critical for various mammalian developmental processes during embryonic life and also for the homeostasis of various organs and reparative processes in later life. During the past two decades the role of MMPs in the morphogenesis of various organs, including that of the metanephros, has been investigated extensively. Mammalian nephrogenesis comprises a series of intricate events characterized by a sustained remodeling and turnover of ECM, suggesting a potential role of MMPs in renal development. Conceivably, reciprocal inductive epithelial-mesenchymal interactions that take place at the very commencement of nephrogenesis are modulated by a number of ECM proteins. Their expression, especially at the epithelial-mesenchymal interface, are critical for metanephric development, and such a strategic expression is likely to be modified by a number of different macromolecules that exhibit spatiotemporal and stage-specific expression. Among them the most suitable candidate that could exert such a control would be MMPs. This review addresses the current status of our understanding of the functions and the role of MMPs in renal development.