title: miR-182 attenuates atrophy-related gene expression by targeting FoxO3 in skeletal muscle.
abstract: Skeletal muscle atrophy occurs in response to a variety of conditions including chronic kidney disease, diabetes, cancer, and elevated glucocorticoids. MicroRNAs (miR) may play a role in the wasting process. Activation of the forkhead box O3 (FoxO3) transcription factor causes skeletal muscle atrophy in patients, animals, and cultured cells by increasing the expression of components of the ubiquitin-proteasome and autophagy-lysosome proteolytic systems. To identify microRNAs that potentially modulate the atrophy process, an in silico target analysis was performed and miR-182 was predicted to target FoxO3 mRNA. Using a combination of immunoblot analysis, quantitative real-time RT-PCR, and FoxO3 3'-UTR luciferase reporter genes, miR-182 was confirmed to regulate FoxO3 expression in C2C12 myotubes. Transfection of miR-182 into muscle cells decreased FoxO3 mRNA 30% and FoxO3 protein 67% (P < 0.05) and also prevented a glucocorticoid-induced upregulation of multiple FoxO3 gene targets including MAFbx/atrogin-1, autophagy-related protein 12 (ATG12), cathepsin L, and microtubule-associated protein light chain 3 (LC3). Treatment of C2C12 myotubes with dexamethasone (Dex) (1 μM, 6 h) to induce muscle atrophy decreased miR-182 expression by 63% (P < 0.05). Similarly, miR-182 was decreased 44% (P < 0.05) in the gastrocnemius muscle of rats injected with streptozotocin to induce diabetes compared with controls. Finally, miR-182 was present in exosomes isolated from the media of C2C12 myotubes and Dex increased its abundance. These data identify miR-182 as an important regulator of FoxO3 expression that participates in the control of atrophy-inducing genes during catabolic diseases.
authors.affiliation: Department of Medicine, Renal Division, Emory University, Atlanta, Georgia; mbhudson@emory.edu.
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Hudson
authors.affiliation: Department of Medicine, Renal Division, Emory University, Atlanta, Georgia;
authors.forename: Jill A
authors.initials: JA
authors.lastname: Rahnert
authors.affiliation: Department of Medicine, Renal Division, Emory University, Atlanta, Georgia;
authors.forename: Bin
authors.initials: B
authors.lastname: Zheng
authors.affiliation: Nutrition and Health Sciences Ph.D. Program, Graduate Division of Biological and Biomedical Sciences, Emory University, Atlanta, Georgia;
authors.forename: Myra E
authors.initials: ME
authors.lastname: Woodworth-Hobbs
authors.affiliation: Department of Medicine, Renal Division, Emory University, Atlanta, Georgia;
authors.forename: Harold A
authors.initials: HA
authors.lastname: Franch
authors.affiliation: Department of Medicine, Renal Division, Emory University, Atlanta, Georgia; Biomedical Laboratory Research and Development Service, Atlanta VA Medical Center, Decatur, Georgia.
authors.forename: S Russ
authors.initials: SR
authors.lastname: Price
mesh_terms: D020413:3' Untranslated Regions; D000818:Animals; D001284:Atrophy; D001665:Binding Sites; D002460:Cell Line; D019295:Computational Biology; D030541:Databases, Genetic; D003907:Dexamethasone / Q000494:pharmacology; D004195:Disease Models, Animal; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D005938:Glucocorticoids / Q000494:pharmacology; D008297:Male; D051379:Mice; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology; D009133:Muscular Atrophy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D032448:Myoblasts, Skeletal / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D014162:Transfection
chemical_list: D020413:3' Untranslated Regions; C499515:FOXO3 protein, rat; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; C474033:FoxO3 protein, mouse; D005938:Glucocorticoids; C577631:MIRN182 microRNA, rat; D035683:MicroRNAs; C540524:Mirn182 microRNA, mouse; D012333:RNA, Messenger; D003907:Dexamethasone
keywords: FoxO3; atrophy; glucocorticoids; microRNA; muscle