Jie Li , Francesca Moretti , Tunda Hidvegi , Sanja Sviben , James A.J. Fitzpatrick , Hemalatha Sundaramoorthi , Stephen C. Pak , Gary A. Silverman , Britta Knapp , Ireos Filipuzzi , John Alford , John Reece-Hoyes , Florian Nigsch , Leon O. Murphy , Beat Nyfeler , David H. Perlmutter
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引用次数: 0
Abstract
Background & Aims
In the classic form of α1-antitrypsin deficiency (ATD), the misfolded α1-antitrypsin Z (ATZ) variant accumulates in the endoplasmic reticulum (ER) of liver cells. A gain-of-function proteotoxic mechanism is responsible for chronic liver disease in a subgroup of homozygotes. Proteostatic response pathways, including conventional endoplasmic reticulum–associated degradation and autophagy, have been proposed as the mechanisms that allow cellular adaptation and presumably protection from the liver disease phenotype. Recent studies have concluded that a distinct lysosomal pathway called endoplasmic reticulum–to-lysosome completely supplants the role of the conventional macroautophagy pathway in degradation of ATZ. Here, we used several state-of-the-art approaches to characterize the proteostatic responses more fully in cellular systems that model ATD.
Methods
We used clustered regularly interspaced short palindromic repeats (CRISPR)-mediated genome editing coupled to a cell selection step by fluorescence-activated cell sorter to perform screening for proteostasis genes that regulate ATZ accumulation and combined that with selective genome editing in 2 other model systems.
Results
Endoplasmic reticulum–associated degradation genes are key early regulators and multiple autophagy genes, from classic as well as from ER-to-lysosome and other newly described ER-phagy pathways, participate in degradation of ATZ in a manner that is temporally regulated and evolves as ATZ accumulation persists. Time-dependent changes in gene expression are accompanied by specific ultrastructural changes including dilation of the ER, formation of globular inclusions, budding of autophagic vesicles, and alterations in the overall shape and component parts of mitochondria.
Conclusions
Macroautophagy is a critical component of the proteostasis response to cellular ATZ accumulation and it becomes more important over time as ATZ synthesis continues unabated. Multiple subtypes of macroautophagy and nonautophagic lysosomal degradative pathways are needed to respond to the high concentrations of misfolded protein that characterizes ATD and these pathways are attractive candidates for genetic variants that predispose to the hepatic phenotype.
期刊介绍:
"Cell and Molecular Gastroenterology and Hepatology (CMGH)" is a journal dedicated to advancing the understanding of digestive biology through impactful research that spans the spectrum of normal gastrointestinal, hepatic, and pancreatic functions, as well as their pathologies. The journal's mission is to publish high-quality, hypothesis-driven studies that offer mechanistic novelty and are methodologically robust, covering a wide range of themes in gastroenterology, hepatology, and pancreatology.
CMGH reports on the latest scientific advances in cell biology, immunology, physiology, microbiology, genetics, and neurobiology related to gastrointestinal, hepatobiliary, and pancreatic health and disease. The research published in CMGH is designed to address significant questions in the field, utilizing a variety of experimental approaches, including in vitro models, patient-derived tissues or cells, and animal models. This multifaceted approach enables the journal to contribute to both fundamental discoveries and their translation into clinical applications, ultimately aiming to improve patient care and treatment outcomes in digestive health.