title: MiR-133a regulates collagen 1A1: potential role of miR-133a in myocardial fibrosis in angiotensin II-dependent hypertension.
abstract: MicroRNAs play an important role in myocardial diseases. MiR-133a regulates cardiac hypertrophy, while miR-29b is involved in cardiac fibrosis. The aim of this study was to evaluate whether miR-133a and miR-29b play a role in myocardial fibrosis caused by Angiotensin II (Ang II)-dependent hypertension. Sprague-Dawley rats were treated for 4 weeks with Ang II (200  ng/kg/min) or Ang II + irbesartan (50  mg/kg/day in drinking water), or saline by osmotic minipumps. At the end of the experimental period, cardiac miR-133a and miR-29b expression was measured by real-time PCR, and myocardial fibrosis was evaluated by morphometric analysis. A computer-based prediction algorithm led to the identification of collagen 1a1 (Col1A1) as a putative target of miR-133a. A reporter plasmid bearing the 3'-untranslated regions (UTRs) of Col1A1 mRNA was constructed and luciferase assay was performed. MiR-133a suppressed the activity of luciferase when the reporter gene was linked to a 3'-UTR segment of Col1A1 (P < 0.01). Mutation of miR-133a binding sites in the 3'-UTR of Col1A1 mRNA abolished miR-133a-mediated repression of reporter gene activity, showing that Col1A1 is a real target of miR-133a. In vivo, Ang II caused an increase in systolic blood pressure (P < 0.0001, tail cuff) and myocardial fibrosis in presence of a decrease in miR-133a (P < 0.01) and miR-29b (P < 0.01), and an increase in Col1A1 expression (P < 0.01). These effects were abolished by Ang II administration + irbesartan. These data demonstrate a relationship between miR-133a and Col1A1, suggesting that myocardial fibrosis occurring in Ang II-dependent hypertension is regulated by the down-regulation of miR-133a and miR-29b through the modulation of Col1A1 expression.
authors.affiliation: Clinica Nefrologica, Dipartimento di Medicina Clinica e Prevenzione, Az. Osp. San Gerardo, Università degli Studi di Milano-Bicocca, Monza, Italy. giovanna.castoldi@unimib.it
authors.forename: Giovanna
authors.initials: G
authors.lastname: Castoldi
authors.forename: Cira R T
authors.initials: CR
authors.lastname: Di Gioia
authors.forename: Camila
authors.initials: C
authors.lastname: Bombardi
authors.forename: Daniele
authors.initials: D
authors.lastname: Catalucci
authors.forename: Barbara
authors.initials: B
authors.lastname: Corradi
authors.forename: Maria Giovanna
authors.initials: MG
authors.lastname: Gualazzi
authors.forename: Martina
authors.initials: M
authors.lastname: Leopizzi
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Mancini
authors.forename: Gianpaolo
authors.initials: G
authors.lastname: Zerbini
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Condorelli
authors.forename: Andrea
authors.initials: A
authors.lastname: Stella
mesh_terms: D000804:Angiotensin II / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism*; D000090602:Collagen Type I, alpha 1 Chain; D005355:Fibrosis / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D006331:Heart Diseases / Q000378:metabolism*; D006973:Hypertension / Q000378:metabolism*; D008297:Male; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D024042:Collagen Type I; D000090602:Collagen Type I, alpha 1 Chain; C549446:MIRN133 microRNA, rat; D035683:MicroRNAs; D000804:Angiotensin II