Adiponectin stimulates phosphorylation of AMP-activated protein kinase alpha in renal glomeruli.

Adiponectin receptor ADIPOR1 activates the intracellular second messenger AMP-activated protein kinase (AMPK) that participates in the control of the oxidative stress and apoptosis. This study reveals the presence of a functional ADIPOR1 receptor in all the cells of the renal glomeruli. Isolated glomeruli were incubated in vitro with adiponectin and proteins analysed by western blot. Electron microscopy using immunogold labeling was carried out on kidney sections. ADIPOR1 and catalytic AMPK sub-units alpha1 and alpha2 were revealed in normal rat glomeruli and incubation of freshly isolated rat glomeruli with either adiponectin or AICAR led to the activation by phosphorylation of catalytic AMPK. Electron microscopy localized with high resolution these proteins at the plasma membrane of the three glomerular cells, namely the endothelial, the mesangial and the podocyte cells, as well as on Bowman's capsule epithelial cells. It is concluded that glomerular cells express a functional adiponectin receptor ADIPOR1 which, through activation of AMPK, may play important roles in the control of oxidative stress and cell survival within the glomerulus.