Korean J Nephrol.  2006 Sep;25(5):705-715.

Angiotensin II Effect on alpha-Actinin in Glomerular Epithelial Cells

• Kwon SK
• Ha TS

Abstract

BACKGROUND: Angiotensin II plays a potential role in renal injury not only by its vasoconstrictive effects but also its biochemical effects. alpha-Actinin, an actin-linked glycoprotein, is expressed in podocytes and known to be rearranged and changed in various glomerular diseases. We investigated the effect of angiotensin II on the alpha-actinin in the glomerular epithelial cells to find out the fact that it could be prevented by losartan, a type 1 angiotensin receptor antagonist.
METHODS
Glomerular epithelial cells were treated with various concentrations of angiotensin II in culture media, and then we compared the localization and amount of alpha-actinin by confocal microscopy and Western blot analysis, respectively. We also compared the differences in the localization and protein amount of alpha-actinin by various concentrations of losartan in the presence of angiotensin II. In addition, we tried to observe the mRNA expression of alpha-actinin via RT-PCR.
RESULTS
The fluorescent and band intensities of alpha-actinin were decreased by angiotensin II in a dose-dependent manner by confocal microscopy and Western blot analysis, respectively. These changes of alpha-actinin by angiotensin II were reversed by losartan in dose dependent manner. Angiotensin II also changed the distribution of alpha-actinin from peripheral to inner cytoplasm in dose-dependent manner, which was also reversed by losartan. The different expression of alpha-actinin m-RNA by RT-PCR were unremarkable.
CONCLUSIONS
Angiotensin II decreases the amount of alpha-actinin protein and and makes cytoskeletal changes in glomerular epithelial cells, which could be reversed by losartan. It suggests that it could be prevented by angiotensin II AT1 receptor blockers.

Keyword

Angiotensin II; alpha-actinin; Glomerular epithelial cell; Angiotensin receptor blocker