An analog of glibenclamide selectively enhances autophagic degradation of misfolded α1-antitrypsin Z

Abstract

The classical form of α1-antitrypsin deficiency (ATD) is characterized by intracellular accumulation of the misfolded variant α1-antitrypsin Z (ATZ) and severe liver disease in some of the affected individuals. In this study, we investigated the possibility of discovering novel therapeutic agents that would reduce ATZ accumulation by interrogating a C. elegans model of ATD with high-content genome-wide RNAi screening and computational systems pharmacology strategies. The RNAi screening was utilized to identify genes that modify the intracellular accumulation of ATZ and a novel computational pipeline was developed to make high confidence predictions on repurposable drugs. This approach identified glibenclamide (GLB), a sulfonylurea drug that has been used broadly in clinical medicine as an oral hypoglycemic agent. Here we show that GLB promotes autophagic degradation of misfolded ATZ in mammalian cell line models of ATD. Furthermore, an analog of GLB reduces hepatic ATZ accumulation and hepatic fibrosis in a mouse model in vivo without affecting blood glucose or insulin levels. These results provide support for a drug discovery strategy using simple organisms as human disease models combined with genetic and computational screening methods. They also show that GLB and/or at least one of its analogs can be immediately tested to arrest the progression of human ATD liver disease.

The molecular species responsible for α1‐antitrypsin deficiency are suppressed by a small molecule chaperone

“…The CHO cell model faithfully recapitulates the handling of mutant variants of α 1 ‐antitrypsin seen in other cellular models [23,53], with the benefits of inducible and titratable expression and robust characteristics in cell culture. We confirmed our findings using an iPSC model of Z α 1 ‐antitrypsin deficiency [35,36], which showed similar half‐times for the clearance of soluble and insoluble polymers.…”

Autophagy in liver diseases

“…Similarly, the induction of autophagy in mice by rapamycin reduced liver alpha1-ATZ aggregation and liver injury[ 582 , 586 - 589 ]. These findings have been repeated and verified when enhancement of autophagy[ 590 ] with either carbamazepine[ 591 ], gene transfer of the autophagy regulator TFEB[ 592 ] or an analog of glibenclamide[ 593 ] reduced the toxic protein. Recent preclinical studies have also demonstrated that an exogenous bile acid like norursodeoxycholicacid may be clinically useful in this condition[ 594 , 595 ].…”

Caenorhabditis elegans for rare disease modeling and drug discovery: strategies and strengths

“…Analogous to what has been observed in humans, the ATM model displayed normal secretion of the protein into the intestinal lumen, whereas the ATZ disease model developed protein accumulation in the ER as well as increased autophagy in these cells ( Gosai et al, 2010 ). Given its faithful recapitulation of disease phenotypes, this ATD model was used in a high-throughput, genome-wide RNAi screen to identify genes that, when depleted, significantly affected ATZ accumulation in the intestine of these animals ( O'Reilly et al, 2014 ; Wang et al, 2019 ). This screening strategy identified 54 modifier genes, which were also verified orthologs of human genes.…”