FRET-based visualization of cGMP signaling in glomerular endothelial cells and podocytes

Background: Drugs targeting the cGMP pathway have been successful in the treatment of vascular diseases and sparked interest in translation to renal diseases. In the kidney field, the literature relies on methods lacking both temporal and spatial resolution to reveal the dynamic and regulatory differences in the synthesis of cGMP in glomerular endothelial cells (GECs) and podocytes. Methods: Acute kidney slices from mice expressing the genetically encoded fluorescent FRET-based cGMP biosensor cGi500 exclusively in the cytosol of endothelial cells or podocytes were prepared. Slices were stimulated with the atrial natriuretic peptide (ANP) or/and SNAP (NO donor) without or with several phosphodiesterase (PDE) inhibitors. Results: Both GECs and podocytes respond to stimulation with ANP (via pGC) and SNAP (via sGC) with an increase in cytosolic cGMP concentrations. GECs exhibited a transient cGMP signaling in response to the activation of both signaling pathways. Podocytes, however, showed a prolonged cGMP signal after activation of the pGC pathway. Simultaneous stimulation with ANP and SNAP led to an additive response in GECs, whereas cGMP levels in podocytes were less elevated compared to ANP stimulation alone. The use of PDE inhibitors revealed a lower PDE activity in podocytes (predominated by PDE3 and PDE5) compared to GECs (predominated by PDE2a). Conclusion: Both cGMP signaling pathways are present in GECs and podocytes and show cell-specific differences in synthesis and degradation. Further insights into cell-specific cGMP signaling could provide new therapeutic options for treating kidney diseases.