title: β-Adrenergic agonist and antagonist regulation of autophagy in HepG2 cells, primary mouse hepatocytes, and mouse liver.
abstract: Autophagy recently has been shown to be involved in normal hepatic function and in pathological conditions such as non-alcoholic fatty liver disease. Adrenergic signalling also is an important regulator of hepatic metabolism and function. However, currently little is known about the potential role of adrenergic signaling on hepatic autophagy, and whether the β-adrenergic receptor itself may be a key regulator of autophagy. To address these issues, we investigated the actions of the β2-adrenergic receptor agonist, clenbuterol on hepatic autophagy. Surprisingly, we found that clenbuterol stimulated autophagy and autophagic flux in hepatoma cells, primary hepatocytes and in vivo. Similar effects also were observed with epinephrine treatment. Interestingly, propranolol caused a late block in autophagy in the absence and presence of clenbuterol, both in cell culture and in vivo. Thus, our results demonstrate that the β2-adrenergic receptor is a key regulator of hepatic autophagy, and that the β-blocker propranolol can independently induce a late block in autophagy.
authors.affiliation: Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School Singapore, Singapore.
authors.forename: Benjamin L
authors.initials: BL
authors.lastname: Farah
authors.affiliation: Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School Singapore, Singapore.
authors.forename: Rohit A
authors.initials: RA
authors.lastname: Sinha
authors.affiliation: Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
authors.forename: Yajun
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School Singapore, Singapore.
authors.forename: Brijesh K
authors.initials: BK
authors.lastname: Singh
authors.affiliation: Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School Singapore, Singapore.
authors.forename: Jin
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
authors.forename: Boon-Huat
authors.initials: BH
authors.lastname: Bay
authors.affiliation: Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School Singapore, Singapore; Sarah W. Stedman Nutrition and Metabolism Center, Departments of Medicine and Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, United States of America.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Yen
mesh_terms: D000318:Adrenergic beta-Agonists / Q000008:administration & dosage; D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage; D000818:Animals; D001343:Autophagy / Q000235:genetics*; D002976:Clenbuterol / Q000008:administration & dosage; D004837:Epinephrine / Q000008:administration & dosage; D056945:Hep G2 Cells; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D011433:Propranolol / Q000008:administration & dosage; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism*
chemical_list: D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D018343:Receptors, Adrenergic, beta-2; D011433:Propranolol; D002976:Clenbuterol; D004837:Epinephrine