?-1-antitrypsin (AT) deficiency is prototypic of an expanding number of conformational diseases characterized by tissue damage from misfolded/aggregated proteins. The classical form of AT deficiency involves a mutation that enhances self-polymerization and aggregation of the mutant protein, ATZ. ATZ is poorly secreted and accumulates within the endoplasmic reticulum (ER) of liver cells. Decreased circulating AT leads to a loss of protease inhibitor function in the lung and predisposition to emphysema. In contrast, accumulation of ATZ in the ER of liver cells leads to a toxic gain-of-function as evidenced by liver failure and carcinoma. AT deficiency is an attractive target for chemoprophylaxis as the disease predominantly involves an ER translocation defect. Although minimally secreted, ATZ still retains some of its anti-elastase activity. Thus, small molecules that increase ATZ secretion could theoretically prevent tissue damage in both lung and liver. Also, the severity of ATZ-induced tissue injury is influenced by genetic and environmental modifiers that regulate endogenous quality control mechanisms for disposal of misfolded proteins. Compounds that enhance these degradative processes, could be used in patients to prevent liver damage in combination with strategies designed to prevent lung injury. A tractable genetic model of this disease would greatly enhance our ability to elucidate the mechanism of tissue damage and the endogenous mechanisms that protect against protein misfolding. Our preliminary results show that the toxic ER translocation defect of AT deficiency can be modeled in C. elegans. Animals expressing wild-type AT secrete the protein. In contrast, animals expressing ATZ develop intracellular inclusions, and show slow growth and larval arrest. Further, in collaboration with the Drug Discovery Institute of the U of Pittsburgh, we show the development of an assay using this model that can easily be adapted to automated high throughput screening. The goals of this project include using the power of genome-wide forward and reverse genetic screens in C. elegans to identify molecular pathways that modulate ATZ aggregation and alter the survival of affected animals, therein providing a framework for designing mechanism-based therapeutics. The C. elegans model will also be adapted for high-throughput screening of drug libraries, thereby providing an unbiased method for chemoprophylaxis of liver and lung disease in AT deficiency.
The specific aims are: 1) provide detailed characterization and validation of the C. elegans model of AT deficiency, 2) elucidate the underlying genetic program(s) that modify the cellular fate and pathogenic effects of ATZ in vivo, and 3) identify drugs that prevent intracellular accumulation of ATZ or eliminate its toxic effects in vivo. Relevance to public health: The major goal of this proposal is to discover new drugs for AT deficiency, the most common genetic cause of liver disease in childhood and the most frequent genetic liver disease necessitating liver transplantation.
|Cummings, Erin E; O'Reilly, Linda P; King, Dale E et al. (2015) Deficient and Null Variants of SERPINA1 Are Proteotoxic in a Caenorhabditis elegans Model of ?1-Antitrypsin Deficiency. PLoS One 10:e0141542|
|Hidvegi, Tunda; Stolz, Donna B; Alcorn, John F et al. (2015) Enhancing Autophagy with Drugs or Lung-directed Gene Therapy Reverses the Pathological Effects of Respiratory Epithelial Cell Proteinopathy. J Biol Chem 290:29742-57|
|Silverman, Richard M; Cummings, Erin E; O'Reilly, Linda P et al. (2015) The aggregation-prone intracellular serpin SRP-2 fails to transit the ER in Caenorhabditis elegans. Genetics 200:207-19|
|Miedel, Mark T; Zeng, Xuemei; Yates, Nathan A et al. (2014) Isolation of serpin-interacting proteins in C. elegans using protein affinity purification. Methods 68:536-41|
|O'Reilly, Linda P; Perlmutter, David H; Silverman, Gary A et al. (2014) ?1-antitrypsin deficiency and the hepatocytes - an elegans solution to drug discovery. Int J Biochem Cell Biol 47:109-12|
|O'Reilly, Linda P; Long, Olivia S; Cobanoglu, Murat C et al. (2014) A genome-wide RNAi screen identifies potential drug targets in a C. elegans model of ?1-antitrypsin deficiency. Hum Mol Genet 23:5123-32|
|Long, Olivia S; Benson, Joshua A; Kwak, Joon Hyeok et al. (2014) A C. elegans model of human ?1-antitrypsin deficiency links components of the RNAi pathway to misfolded protein turnover. Hum Mol Genet 23:5109-22|
|Luke, Cliff J; Niehaus, Jason Z; O'Reilly, Linda P et al. (2014) Non-microfluidic methods for imaging live C. elegans. Methods 68:542-7|
|O'Reilly, Linda P; Luke, Cliff J; Perlmutter, David H et al. (2014) C. elegans in high-throughput drug discovery. Adv Drug Deliv Rev 69-70:247-53|
|Li, Jie; Pak, Stephen C; O'Reilly, Linda P et al. (2014) Fluphenazine reduces proteotoxicity in C. elegans and mammalian models of alpha-1-antitrypsin deficiency. PLoS One 9:e87260|
Showing the most recent 10 out of 19 publications