Extracellular ATP modulates podocyte function through P2Y purinergic receptors and pleiotropic effects on AMPK and cAMP/PKA signaling pathways.

Podocytes and their foot processes interlinked by slit diaphragms, constitute a continuous outermost layer of the glomerular capillary and seem to be crucial for maintaining the integrity of the glomerular filtration barrier. Purinergic signaling is involved in a wide range of physiological processes in the renal system, including regulating glomerular filtration. We evaluated the role of nucleotide receptors in cultured rat podocytes using non-selective P2 receptor agonists and agonists specific for the P2Y ₁ , P2Y ₂ , and P2Y ₄ receptors. The results showed that extracellular ATP evokes cAMP-dependent pathways through P2 receptors and influences remodeling of the podocyte cytoskeleton and podocyte permeability to albumin via coupling with RhoA signaling. Our findings highlight the relevance of the P2Y ₄ receptor in protein kinase A-mediated signal transduction to the actin cytoskeleton. We observed increased cAMP concentration and decreased RhoA activity after treatment with a P2Y ₄ agonist. Moreover, protein kinase A inhibitors reversed P2Y ₄ -induced changes in RhoA activity and intracellular F-actin staining. P2Y ₄ stimulation resulted in enhanced AMPK phosphorylation and reduced reactive oxygen species generation. Our findings identify P2Y-PKA-RhoA signaling as the regulatory mechanism of the podocyte contractile apparatus and glomerular filtration. We describe a protection mechanism for the glomerular barrier linked to reduced oxidative stress and reestablished energy balance.
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