Alteration in cell adhesion and extracellular matrix deposition is a hallma
rk of diabetic glomerulosclerosis. Integrin-linked kinase (ILK) is a recent
ly identified integrin cytoplasmic-binding protein that has been implicated
in the regulation of cell adhesion and extracellular matrix deposition. To
begin to investigate whether ILK is involved in the pathogenesis of diabet
ic glomerulosclerosis, we have analyzed the distribution and regulation of
ILK in normal and diabetic kidneys as well as in isolated mesangial cells.
We have found that ILK is normally expressed at high concentration in visce
ral epithelial cells. In diabetic glomeruli, ILK expression in the mesangiu
m. is dramatically increased. The increase in ILK level is associated with
diffuse mesangial expansion. In glomeruli where advanced nodular sclerosis
and global sclerosis were dominant, ILK level was reduced, suggesting that
the increase in ILK expression likely associates with relatively early glom
erulosclerosis. Additionally, we have found that exposure of mesangial cell
s to high concentrations of glucose significantly increased the ILK level.
Finally, we show that ILK localizes to regions of cell membranes that are i
n close contact with mesangial fibronectin matrix. These results suggest th
at ILK is likely involved in mesangial matrix expansion in response to hype
rglycemia in the pathogenesis of diabetic glomerulosclerosis.