David Lomas; James A. Irving; Christopher Arico-Muendel; Svetlana Belyanskaya; Andy Brewster; Murray J. B. Brown; Chun-wa Chung; Hitesh Dave; Alexis Denis; Nerina Dodic; Anthony Dossang; Peter Eddershaw; Diana Klimaszewska; Imran Haq; Duncan Holmes; Jon Hutchinson; Alistair M. Jagger; Toral Jakhria; Emilie Jigorel; John Liddle; Ken Lind; Stefan John Marciniak; Jeff Messer; Margaret Neu; Allison Olszewski; Adriana Ordoñez; Riccardo Ronzoni; James Rowedder; Martin Rüdiger; Steven Skinner; Kate Smith; Rebecca Terry; Lionel Trottet; Iain Uings; Steve Wilson; Zhengrong Zhu; Andrew C. Pearce
bioRxiv, 2020
https://doi.org/10.1101/2020.07.26.217661

Abstract

Severe α1-antitrypsin deficiency results from the Z allele (Glu342Lys) that causes the accumulation of homopolymers of mutant α1-antitrypsin within the endoplasmic reticulum of hepatocytes in association with liver disease. We have used a DNA-encoded chemical library to undertake a high throughput screen to identify small molecules that bind to, and stabilise Z α1-antitrypsin. The lead compound blocks Z α1-antitrypsin polymerisation in vitro, reduces intracellular polymerisation and increases the secretion of Z α1-antitrypsin three-fold in mammalian cells including an iPSC model of disease. Crystallographic and biophysical analyses demonstrate that GSK716 and related molecules bind to a cryptic binding pocket, negate the local effects of the Z mutation and stabilise the bound state against progression along the polymerization pathway. Oral dosing of transgenic mice at 100 mg/kg three times a day for 20 days increased the secretion of Z α1-antitrypsin into the plasma by 7-fold. There was no observable clearance of hepatic inclusions with respect to controls. This study provides proof-of-principle that 'mutation ameliorating' small molecules are a viable approach to treat protein conformational diseases.