Steps on the Alport path to proteinuria.

Using a mouse model of Alport disease, Dufek et al. report that endothelial cell-derived endothelin-1 activates mesangial cells, which deposit abnormal laminin isoforms in the Alport glomerular basement membrane. This study extends findings obtained previously by this laboratory implicating mesangial cells in the early pathogenesis of Alport disease. Together with abnormalities in matrix receptor expression, cytoskeletal architecture, and proteinase secretion in podocytes, a clearer picture is emerging on the inception of proteinuria in Alport disease.