title: Different fatty acids inhibit apoB100 secretion by different pathways: unique roles for ER stress, ceramide, and autophagy.
abstract: Although short-term incubation of hepatocytes with oleic acid (OA) stimulates secretion of apolipoprotein B100 (apoB100), exposure to higher doses of OA for longer periods inhibits secretion in association with induction of endoplasmic reticulum (ER) stress. Palmitic acid (PA) induces ER stress, but its effects on apoB100 secretion are unclear. Docosahexaenoic acid (DHA) inhibits apoB100 secretion, but its effects on ER stress have not been studied. We compared the effects of each of these fatty acids on ER stress and apoB100 secretion in McArdle RH7777 (McA) cells: OA and PA induced ER stress and inhibited apoB100 secretion at higher doses; PA was more potent because it also increased the synthesis of ceramide. DHA did not induce ER stress but was the most potent inhibitor of apoB100 secretion, acting via stimulation of autophagy. These unique effects of each fatty acid were confirmed when they were infused into C57BL6J mice. Our results suggest that when both increased hepatic secretion of VLDL apoB100 and hepatic steatosis coexist, reducing ER stress might alleviate hepatic steatosis but at the expense of increased VLDL secretion. In contrast, increasing autophagy might reduce VLDL secretion without causing steatosis.
authors: Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY, USA.
authors: Jorge Matias
authors: JM
authors: Caviglia
authors: Constance
authors: C
authors: Gayet
authors: Tsuguhito
authors: T
authors: Ota
authors: Antonio
authors: A
authors: Hernandez-Ono
authors: Donna M
authors: DM
authors: Conlon
authors: Hongfeng
authors: H
authors: Jiang
authors: Edward A
authors: EA
authors: Fisher
authors: Henry N
authors: HN
authors: Ginsberg
mesh_terms: D000818:Animals; D053299:Apolipoprotein B-100 / Q000378:metabolism*; D001343:Autophagy / Q000187:drug effects*; D002460:Cell Line; D002518:Ceramides / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000187:drug effects* / Q000378:metabolism; D005227:Fatty Acids / Q000737:chemistry / Q000494:pharmacology*; D005229:Fatty Acids, Monounsaturated / Q000494:pharmacology; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018384:Oxidative Stress / Q000187:drug effects*; D010654:Phenylbutyrates / Q000494:pharmacology; D013230:Stearoyl-CoA Desaturase / Q000235:genetics / Q000378:metabolism
chemical_list: D053299:Apolipoprotein B-100; D002518:Ceramides; D005227:Fatty Acids; D005229:Fatty Acids, Monounsaturated; D010654:Phenylbutyrates; C075773:4-phenylbutyric acid; C490333:Scd1 protein, mouse; D013230:Stearoyl-CoA Desaturase; C001996:thermozymocidin