Lack of [alpha]8 integrin leads to morphological changes in renal mesangial cells, but not in vascular smooth muscle cells

Background Extracellular matrix receptors of the integrin family are known to regulate cell adhesion, shape and functions. The [alpha]8 integrin chain is expressed in glomerular mesangial cells and in vascular smooth muscle cells. Mice deficient for [alpha]8 integrin have structural alterations in glomeruli but not in renal arteries. For this reason we hypothesized that mesangial cells and vascular smooth muscle cells differ in their respective capacity to compensate for the lack of [alpha]8 integrin. Results Wild type and [alpha]8 integrin-deficient mesangial cells varied markedly in cell morphology and expression or localization of cytoskeletal molecules. In [alpha]8 integrin-deficient mesangial cells [alpha]-smooth muscle actin and CTGF were downregulated. In contrast, there were no comparable differences between [alpha]8 integrin-deficient and wild type vascular smooth muscle cells. Expression patterns of integrins were altered in [alpha]8 integrin-deficient mesangial cells compared to wild type mesangial cells, displaying a prominent overexpression of [alpha]2 and [alpha]6 integrins, while expression patterns of the these integrins were not different between wild type and [alpha]8 integrin-deficient vascular smooth muscle cells, respectively. Cell proliferation was augmented in [alpha]8 integrin-deficient mesangial cells, but not in vascular smooth muscle cells, compared to wild type cells. Conclusions Our findings suggest that [alpha]8 integrin deficiency has differential effects in mesangial cells and vascular smooth muscle cells. While the phenotype of vascular smooth muscle cells lacking [alpha]8 integrin is not altered, mesangial cells lacking [alpha]8 integrin differ considerably from wild type mesangial cells which might be a consequence of compensatory changes in the expression patterns of other integrins. This could result in glomerular changes in [alpha]8 integrin-deficient mice, while the vasculature is not affected in these mice.