title: Ethanol Enhances TGF-β Activity by Recruiting TGF-β Receptors From Intracellular Vesicles/Lipid Rafts/Caveolae to Non-Lipid Raft Microdomains.
abstract: Regular consumption of moderate amounts of ethanol has important health benefits on atherosclerotic cardiovascular disease (ASCVD). Overindulgence can cause many diseases, particularly alcoholic liver disease (ALD). The mechanisms by which ethanol causes both beneficial and harmful effects on human health are poorly understood. Here we demonstrate that ethanol enhances TGF-β-stimulated luciferase activity with a maximum of 0.5-1% (v/v) in Mv1Lu cells stably expressing a luciferase reporter gene containing Smad2-dependent elements. In Mv1Lu cells, 0.5% ethanol increases the level of P-Smad2, a canonical TGF-β signaling sensor, by ∼ 2-3-fold. Ethanol (0.5%) increases cell-surface expression of the type II TGF-β receptor (TβR-II) by ∼ 2-3-fold from its intracellular pool, as determined by I(125) -TGF-β-cross-linking/Western blot analysis. Sucrose density gradient ultracentrifugation and indirect immunofluorescence staining analyses reveal that ethanol (0.5% and 1%) also displaces cell-surface TβR-I and TβR-II from lipid rafts/caveolae and facilitates translocation of these receptors to non-lipid raft microdomains where canonical signaling occurs. These results suggest that ethanol enhances canonical TGF-β signaling by increasing non-lipid raft microdomain localization of the TGF-β receptors. Since TGF-β plays a protective role in ASCVD but can also cause ALD, the TGF-β enhancer activity of ethanol at low and high doses appears to be responsible for both beneficial and harmful effects. Ethanol also disrupts the location of lipid raft/caveolae of other membrane proteins (e.g., neurotransmitter, growth factor/cytokine, and G protein-coupled receptors) which utilize lipid rafts/caveolae as signaling platforms. Displacement of these membrane proteins induced by ethanol may result in a variety of pathologies in nerve, heart and other tissues.
authors.affiliation: Auxagen, Inc., St. Louis, Missouri, 63132.
authors.forename: Shuan Shian
authors.initials: SS
authors.lastname: Huang
authors.affiliation: Department of Biological Science, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.|Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University and Academia Sinica, Kaohsiung, 804, Taiwan.
authors.forename: Chun-Lin
authors.initials: CL
authors.lastname: Chen
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, 02115.|Harvard Medical School, Boston, Massachusetts, 02115.
authors.forename: Franklin W
authors.initials: FW
authors.lastname: Huang
authors.affiliation: Department of Surgery, Saint Louis University School of Medicine, St. Louis, Missouri, 63104.
authors.forename: Frank E
authors.initials: FE
authors.lastname: Johnson
authors.affiliation: Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Doisy Research Center, St. Louis, Missouri, 63104.
authors.forename: Jung San
authors.initials: JS
authors.lastname: Huang
mesh_terms: D000818:Animals; D021941:Caveolae / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D051242:Caveolin 1 / Q000235:genetics / Q000378:metabolism; D002458:Cell Fractionation; D002461:Cell Line, Transformed; D022162:Cytoplasmic Vesicles / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D000431:Ethanol / Q000494:pharmacology*; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008168:Lung / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D021962:Membrane Microdomains / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D008907:Mink; D010766:Phosphorylation; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D051899:Smad2 Protein / Q000235:genetics / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000235:genetics* / Q000378:metabolism
chemical_list: D051242:Caveolin 1; D020033:Protein Isoforms; D018125:Receptors, Transforming Growth Factor beta; D051899:Smad2 Protein; D016212:Transforming Growth Factor beta; D000431:Ethanol; D008156:Luciferases
keywords: CANONICAL TGF-β SIGNALING; NON-LIPID RAFT MICRODOMAINS; TGF-β ENHANCER; TGF-β RECEPTORS