Extracellular matrix and kidney development

The basal lamina (BL) which is located underneath epithelial cells does not only provide structural support, but has an important function in the development and maintenance of renal epithelial tubules. The basal lamina is composed of different molecules which include integrins; they serve not only as the connection between the ECM and the epithelial cells but also as initiator of signal transduction pathways. Through activation of kinases such as ILK and FAK these signal pathways are responsible for the survival, differentiation, proliferation and the migration of cells; the maintenance of (epithelial) cells. The renal epithelial tubule cells originate from the mesoderm. Mesenchymal cells undergo significant expression changes to transform into epithelial cells, a process named MET (mesenchymal epithelial transition). During this process integrins and other BL components such as proteoglycans play a role. The expression of the integrin repertoire alters through out the entire MET; coinciding with the spatiotemporal expression of ECM ligand molecules. Despite the fact that integrin-ECM ligand communication is critical in the development of renal tubules there are two other vital communication types; GF and their receptors and proto-oncogenes and their ligands. In order to create interventions to restore the function of damaged renal tubules understanding of the development of these cells is necessary otherwise one would be clueless about what to do to restore the cell’s function.