Lessons in congenital and acquired renal disease from alpha8 integrin mutant mice.

Cell-matrix interactions have been shown to be important during renal development and in various forms of kidney diseases. The alpha8 integrin chain is expressed during early nephrogenesis. In alpha8 gene mutated mice, lack of alpha8 results in unilateral or bilateral renal agenesis in part of the animals. No human disease with mutations in the alpha8 integrin gene locus has been described to date. However, similar renal defects are displayed in disorders with mutations affecting other adhesion molecules. In the kidneys of adult mice, alpha8 is expressed in vascular smooth muscle cells and mesangial cells of the glomerulus. Although alpha8-deficient mice surviving with reduced renal mass do not show any glomerular abnormalities, they have an increased susceptibility to glomerular damage upon mechanical or inflammatory stress of glomerular cells. Thus, alpha8 seems to be important for normal renal development and could help to maintain the structural integrity of the glomerulus following injury during various kidney diseases.