Repurposing Riociguat to Target a Novel Paracrine Nitric Oxide-TRPC6 Pathway to Prevent Podocyte Injury.

Daan ‘T Hart,Jinhua Li,Johan Van Der Vlag,Tom Nijenhuis

doi:10.3390/ijms222212485

Abstract

Increased expression and activity of the Ca2+ channel transient receptor potential channel 6 (TRPC6) is associated with focal segmental glomerulosclerosis, but therapeutic strategies to target TRPC6 are currently lacking. Nitric oxide (NO) is crucial for normal glomerular function and plays a protective role in preventing glomerular diseases. We investigated if NO prevents podocyte injury by inhibiting injurious TRPC6-mediated signaling in a soluble guanylate cyclase (sGC)-dependent manner and studied the therapeutic potential of the sGC stimulator Riociguat. Experiments were performed using human glomerular endothelial cells and podocytes. Podocyte injury was induced by Adriamycin incubation for 24 h, with or without the NO-donor S-Nitroso-N-acetyl-DL-penicillamine (SNAP), the sGC stimulator Riociguat or the TRPC6 inhibitor Larixyl Acetate (LA). NO and Riociguat stimulated cGMP synthesis in podocytes, decreased Adriamycin-induced TRPC6 expression, inhibited the Adriamycin-induced TRPC6-mediated Ca2+ influx and reduced podocyte injury. The protective effects of Riociguat and NO were blocked when sGC activity was inhibited with 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) or when TRPC6 activity was inhibited by LA. Our data demonstrate a glomerular (e)NOS-NO-sGC-cGMP-TRPC6 pathway that prevents podocyte injury, which can be translated to future clinical use by, e.g., repurposing the market-approved drug Riociguat.

Highlights

The glomerular filtration barrier (GFB) is essential in the filtration of blood by restricting the passage of blood proteins in a charge and size-selective manner
To evaluate the presence of the components for the suggested (e)nitric oxide synthase (NOS)-Nitric oxide (NO)-soluble guanylate cyclase (sGC)-transient receptor potential channel 6 (TRPC6) paracrine axis in glomerular endothelial cells (GEnC) and human podocytes (hPOD), we first addressed the expression of NO-producing enzymes in these cells
NO is produced by three different enzymes of the nitric oxide synthase (NOS) family; i.e., neuronal NOS, inducible NOS and endothelial

Summary

Introduction

The glomerular filtration barrier (GFB) is essential in the filtration of blood by restricting the passage of blood proteins in a charge and size-selective manner. Podocytes are visceral epithelial cells with interdigitating foot processes connected by slit diaphragm protein complexes that include transient receptor potential channel 6 (TRPC6), which is directly linked to the podocyte cytoskeleton. Podocyte injury is considered to play a key role in the pathogenesis of numerous glomerular diseases [2]. TRPC6 is known to be important for preserving normal renal filtration by adapting the podocyte cytoskeleton to changes in glomerular blood pressure [3]. The overexpression of TRPC6 is linked to acquired glomerular diseases, and causative gain-of-function mutations in TRPC6 cause hereditary forms of focal segmental glomerulosclerosis (FSGS) [4,5]. TRPC6 knock-out in mice or rats confers protection to the development of experimental diabetic nephropathy, puromycin aminonucleoside (PAN)-induced nephrosis and Angiotensin II-induced glomerular hyperfiltration [6,7,8] En-

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Conclusion