Targeting Hepatic Glutaminase 1 Ameliorates Non-alcoholic Steatohepatitis by Restoring Very-Low-Density Lipoprotein Triglyceride Assembly
Jorge Simón, Maitane Núñez-García, Pablo Fernández‐Tussy, Lucía Barbier‐Torres, David Fernández‐Ramos, Beatriz Gómez‐Santos, Xabier Buqué, Fernando Lopitz‐Otsoa, Naroa Goikoetxea‐Usandizaga, Marina Serrano‐Maciá, Rubén Rodríguez‐Agudo, Maider Bizkarguenaga, Imanol Zubiete‐Franco, Virginia Gutiérrez‐de Juan, Diana Cabrera, Cristina Alonso, Paula Iruzubieta, Manuel Romero‐Gómez, Sebastiaan van Liempd, Azucena Castro, Rubén Nogueiras, Marta Varela‐Rey, Juan Manuel Falcón‐Pérez, Erica Villa, Javier Crespo, Shelly C. Lu, José M. Mato, Patricia Aspichueta, Teresa C. Delgado, Maria Luz Martínez‐Chantar
Abstract
Non-alcoholic steatohepatitis (NASH) is characterized by the accumulation of hepatic fat in an inflammatory/fibrotic background. Herein, we show that the hepatic high-activity glutaminase 1 isoform (GLS1) is overexpressed in NASH. Importantly, GLS1 inhibition reduces lipid content in choline and/or methionine deprivation-induced steatotic mouse primary hepatocytes, in human hepatocyte cell lines, and in NASH mouse livers. We suggest that under these circumstances, defective glutamine fueling of anaplerotic mitochondrial metabolism and concomitant reduction of oxidative stress promotes a reprogramming of serine metabolism, wherein serine is shifted from the generation of the antioxidant glutathione and channeled to provide one-carbon units to regenerate the methionine cycle. The restored methionine cycle can induce phosphatidylcholine synthesis from the phosphatidylethanolamine N-methyltransferase-mediated and CDP-choline pathways as well as by base-exchange reactions between phospholipids, thereby restoring hepatic phosphatidylcholine content and very-low-density lipoprotein export. Overall, we provide evidence that hepatic GLS1 targeting is a valuable therapeutic approach in NASH.