Optimizing small molecule SWELL1-LRRC8 modulators to treat Type 2 diabetes

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Project Summary/Abstract Type 2 diabetes (T2D) is characterized by both a loss of insulin sensitivity of target and ultimately, impaired insulin secretion from the pancreatic b-cell. We have identified a novel SWELL1-mediated signaling pathway that regulates both insulin sensitivity and insulin secretion, whereby SWELL1 loss-of-function can both down- regulate insulin signaling in target tissues, and insulin secretion from the pancreatic b-cell. We have identified a small molecule modulator, DCPIB (renamed SN-401), as a tool compound that binds the SWELL1-LRRC8 complex and functions as a molecular chaperone to augment SWELL1 expression, plasma membrane trafficking and signaling. In vivo, SN-401 normalizes glucose tolerance by increasing insulin sensitivity and secretion in murine T2D models. SN-401 also augments glucose uptake into adipose tissue and myocardium, suppresses hepatic glucose production in KKAy mice, and protects against hepatic steatosis in HFD fed mice. We propose that small molecule SWELL1 modulators represent a “first-in-class” therapeutic approach to treat metabolic syndrome and associated diseases by restoring SWELL1 signaling across multiple organ system that are dysfunctional in T2D. Combining recent cryo-EM data of SN-401 bound to its target SWELL1/LRRC8a with molecular docking simulations we have validated a structure-activity relationship (SAR) based approach to generate novel SN-401 congeners with either enhanced or reduced on-target activity. The objectives are: 1. To establish the optimal dosing regimen and mode of administration for the newly synthesized, SAR-inspired SN-401 congeners synthesized to date to achieve a therapeutic effect for T2D; 2. To evaluate for putative beneficial cardiovascular effects; 3. To determine the primary tissue-site(s) of action of SN-401 in vivo; 4. SAR-based compound synthesis to refine and optimize the leads based on in vitro ADMET and selectivity screens, and efficacy studies in vivo. We propose the following specific AIMs AIM#1: Determine optimal dosing regimen, therapeutic effect and target tissue(s) of novel SAR-inspired SN-401 congeners. AIM#2: SAR-directed SN-401 optimization and characterization in vitro and in vivo to identify preclinical lead structures. This proposal seeks to use a validated chemical biology approach to expand a pipeline of novel, bioactive pharmacological SWELL1 signaling modulators for the treatment of T2D, metabolic syndrome and associated diseases to ultimately take into man in the form of a clinical trial for efficacy in humans.