title: Autophagy is a regulator of TGF-β1-induced fibrogenesis in primary human atrial myofibroblasts.
abstract: Transforming growth factor-β(1) (TGF-β(1)) is an important regulator of fibrogenesis in heart disease. In many other cellular systems, TGF-β(1) may also induce autophagy, but a link between its fibrogenic and autophagic effects is unknown. Thus we tested whether or not TGF-β(1)-induced autophagy has a regulatory function on fibrosis in human atrial myofibroblasts (hATMyofbs). Primary hATMyofbs were treated with TGF-β(1) to assess for fibrogenic and autophagic responses. Using immunoblotting, immunofluorescence and transmission electron microscopic analyses, we found that TGF-β(1) promoted collagen type Iα2 and fibronectin synthesis in hATMyofbs and that this was paralleled by an increase in autophagic activation in these cells. Pharmacological inhibition of autophagy by bafilomycin-A1 and 3-methyladenine decreased the fibrotic response in hATMyofb cells. ATG7 knockdown in hATMyofbs and ATG5 knockout (mouse embryonic fibroblast) fibroblasts decreased the fibrotic effect of TGF-β(1) in experimental versus control cells. Furthermore, using a coronary artery ligation model of myocardial infarction in rats, we observed increases in the levels of protein markers of fibrosis, autophagy and Smad2 phosphorylation in whole scar tissue lysates. Immunohistochemistry for LC3β indicated the localization of punctate LC3β with vimentin (a mesenchymal-derived cell marker), ED-A fibronectin and phosphorylated Smad2. These results support the hypothesis that TGF-β(1)-induced autophagy is required for the fibrogenic response in hATMyofbs.
authors: 1] Department of Physiology, Manitoba Institute of Child Health, Winnipeg, Manitoba, Canada [2] Biology of Breathing Group, Manitoba Institute of Child Health, Winnipeg, Manitoba, Canada [3] Department of Physiology and Institute of Cardiovascular Sciences, St. Boniface Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada [4] Department of Human Anatomy and Cell Science, University of Manitoba, Winnipeg, Manitoba, Canada.
authors: S
authors: S
authors: Ghavami
authors: Department of Physiology and Institute of Cardiovascular Sciences, St. Boniface Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada.
authors: R H
authors: RH
authors: Cunnington
authors: Department of Physiology and Institute of Cardiovascular Sciences, St. Boniface Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada.
authors: S
authors: S
authors: Gupta
authors: 1] Department of Physiology, Manitoba Institute of Child Health, Winnipeg, Manitoba, Canada [2] Biology of Breathing Group, Manitoba Institute of Child Health, Winnipeg, Manitoba, Canada [3] Department of Physiology and Institute of Cardiovascular Sciences, St. Boniface Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada.
authors: B
authors: B
authors: Yeganeh
authors: Department of Physiology and Institute of Cardiovascular Sciences, St. Boniface Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada.
authors: K L
authors: KL
authors: Filomeno
authors: Department of Physiology and Institute of Cardiovascular Sciences, St. Boniface Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada.
authors: D H
authors: DH
authors: Freed
authors: Department of Physiology and Institute of Cardiovascular Sciences, St. Boniface Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada.
authors: S
authors: S
authors: Chen
authors: Department of Human Anatomy and Cell Science, University of Manitoba, Winnipeg, Manitoba, Canada.
authors: T
authors: T
authors: Klonisch
authors: 1] Department of Physiology, Manitoba Institute of Child Health, Winnipeg, Manitoba, Canada [2] Biology of Breathing Group, Manitoba Institute of Child Health, Winnipeg, Manitoba, Canada [3] Department of Internal Medicine, Manitoba Institute of Child Health, Winnipeg, Manitoba, Canada.
authors: A J
authors: AJ
authors: Halayko
authors: Department of Physiology and Institute of Cardiovascular Sciences, St. Boniface Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada.
authors: E
authors: E
authors: Ambrose
authors: Cardiac Sciences Program, St. Boniface General Hospital, Winnipeg, Manitoba, Canada.
authors: R
authors: R
authors: Singal
authors: Department of Physiology and Institute of Cardiovascular Sciences, St. Boniface Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada.
authors: I M C
authors: IM
authors: Dixon
mesh_terms: D000225:Adenine / Q000008:administration & dosage / Q000031:analogs & derivatives; D000818:Animals; D001343:Autophagy / Q000187:drug effects / Q000235:genetics*; D000071187:Autophagy-Related Protein 5; D000071193:Autophagy-Related Protein 7; D049109:Cell Proliferation / Q000187:drug effects; D024042:Collagen Type I / Q000378:metabolism; D005353:Fibronectins / Q000096:biosynthesis; D005355:Fibrosis / Q000235:genetics* / Q000473:pathology; D006325:Heart Atria / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D018942:Macrolides / Q000008:administration & dosage; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000235:genetics; D058628:Myofibroblasts / Q000378:metabolism* / Q000473:pathology; D061251:Primary Cell Culture; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects; D051899:Smad2 Protein / Q000096:biosynthesis / Q000235:genetics; D053773:Transforming Growth Factor beta1 / Q000096:biosynthesis* / Q000235:genetics
chemical_list: C495773:Atg5 protein, mouse; C502661:Atg7 protein, mouse; D000071187:Autophagy-Related Protein 5; D024042:Collagen Type I; D005353:Fibronectins; D018942:Macrolides; D008869:Microtubule-Associated Proteins; C497782:SMAD2 protein, human; D051899:Smad2 Protein; C508960:TGFB1 protein, human; D053773:Transforming Growth Factor beta1; C025946:3-methyladenine; C040929:bafilomycin A1; D000071193:Autophagy-Related Protein 7; D000225:Adenine