Discovery of a Potent and Selective TRPC5 Inhibitor, Efficacious in a Focal Segmental Glomerulosclerosis Model

Abstract

The nonselective Ca 2+ -permeable transient receptor potential (TRP) channels play important roles in diverse cellular processes, including actin remodeling and cell migration. TRP channel subfamily C, member 5 (TRPC5) helps regulate a tight balance of cytoskeletal dynamics in podocytes and is suggested to be involved in the pathogenesis of proteinuric kidney diseases, such as focal segmental glomerulosclerosis (FSGS). As such, protection of podocytes by inhibition of TRPC5 mediated Ca 2+ signaling may provide a novel therapeutic approach for the treatment of proteinuric kidney diseases. Herein, we describe the identification of a novel TRPC5 inhibitor, GFB-8438, by systematic optimization of a high-throughput screening hit, pyridazinone 1. GFB-8438 protects mouse podocytes from injury induced by protamine sulfate (PS) in vitro. It is also efficacious in a hypertensive deoxycorticosterone acetate (DOCA)-salt rat model of FSGS, significantly reducing both total protein and albumin concentrations in urine.

Cryo-EM structures of human TRPC5 reveal interaction of a xanthine-based TRPC1/4/5 inhibitor with a conserved lipid binding site

“…Physiological activation and modulation of TRPC1/4/5 channel activity is complex, [4][5][6] and may include mediation by endogenous and dietary lipids. 12,[19][20][21][22] In addition, structurally diverse pharmacological modulators have been reported, 5,10,18 including inhibitors suitable for studies of TRPC1/4/5 in cells, tissues and animal models such as the xanthines Pico145 (also called HC-608) [23][24][25] and HC-070, 24,25 the pyridazinone derivative GFB-8438, 26 and the benzimidazole ML204. 27 However, structural insight into the mode-of-action of small-molecule TRPC1/4/5 modulators is lacking, and no small-molecule binding sites have been identified.…”

Structural basis of TRPC4 regulation by calmodulin and pharmacological agents

“…The tri-fluoro benzyl ring engages in a hydrophobic interaction with L495 of helix S4, and the fluoride group is involved in a hydrogen bond with H369 of S1 and Y646 from the TRP helix. The residues interacting with the inhibitor are identical between TRPC4 and TRPC5 ( Figure S6) indicating a similar ligand binding mode in TRPC5, which is supported by their close IC50 values of 0.18 and 0.29 µM for TRPC5 and TRPC4, respectively (Yu et al, 2019).…”

“…The inhibitor GFB-8438 has been shown to be more specific for TRPC4/5 than TRPC6 (Yu et al, 2019). Comparison of the TRPC4/5 binding pocket with TRPC6 reveals a critical difference in ligand binding residues ( Figure 3D).…”

“…Recently, a novel class of small molecule modulators selective for TRPC4/5 was identified in a high-throughput screen, building up on a piperazinone/pyridazinone scaffold (Yu et al, 2019). Among this class of modulators are the activator GFB-9289 and the inhibitor GFB-8438.…”

“…In vitro, mouse podocytes were protected from protamine-induced injury when treated with the inhibitor. Importantly, GFB-8438 also demonstrated robust efficacy in a hypertensive deoxycorticosterone acetate (DOCA)-salt rat model of FSGS, in which both albumin concentration and total protein levels were significantly reduced (Yu et al, 2019).…”