title: Heart failure and angiotensin II modulate atrial Pitx2c promotor methylation.
abstract: Heart failure (HF) can increase atrial fibrillation and induce cardiac hypermethylation. The homeobox gene Pitx2c plays important roles in the genesis of atrial fibrillation and the promoter region of Pitx2c contains cytosine-phosphate-guanine islands. Therefore, epigenetic modification by hypermethylation may reduce Pitx2c expression in atrial myocytes. The aim of the present study were to evaluate whether HF can modulate DNA methylation of Pitx2c and the potential mechanisms involved. We used real-time polymerase chain reaction, immunoblotting and pyrosequencing to investigate RNA and protein expression, as well as the methylation of Pitx2c, in isoproterenol-induced HF, healthy rat left atria and in HL-1 cells with and without (control) exposure to angiotensin (Ang) II (0.1 and 1 μmol/L) or isoproterenol (1 or 10 μmol/L) for 24 h. The HF atrium exhibited increased Pitx2c promoter methylation with increased DNA methyltransferase (DNMT) 1 and decreased Pitx2c protein levels compared with the normal atrium. Angiotensin II (0.1 and 1 μmol/L), increased Pitx2c promoter methylation in HL-1 cells with increased DNMT1 and decreased Pitx2c and Kir2.1 protein levels compared with control cells. These effects were attenuated by the methylation inhibitor 5-aza-2'-deoxycytidine (0.1 μmol/L) and by the AngII receptor blocker losartan (10 μmol/L). However, isoproterenol (1 and 10 μmol/L) did not change the expression of the Pitx2c, DNMT1 and Kir2.1 proteins. In conclusion, HF induces Pitx2c promoter hypermethylation and AngII may contribute to the hypermethylation in HF.
authors.affiliation: Department of Medical Education and Research, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan.
authors.forename: Yu-Hsun
authors.initials: YH
authors.lastname: Kao
authors.forename: Yao-Chang
authors.initials: YC
authors.lastname: Chen
authors.forename: Chen-Chih
authors.initials: CC
authors.lastname: Chung
authors.forename: Gi-Shih
authors.initials: GS
authors.lastname: Lien
authors.forename: Shih-Ann
authors.initials: SA
authors.lastname: Chen
authors.forename: Ching-Chuan
authors.initials: CC
authors.lastname: Kuo
authors.forename: Yi-Jen
authors.initials: YJ
authors.lastname: Chen
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology*; D057911:Angiotensin Receptor Antagonists / Q000494:pharmacology; D000818:Animals; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D045744:Cell Line, Tumor; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects*; D000077209:Decitabine; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006325:Heart Atria / Q000378:metabolism*; D006333:Heart Failure / Q000139:chemically induced / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000235:genetics*; D007545:Isoproterenol; D019808:Losartan / Q000494:pharmacology; D008297:Male; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012313:RNA / Q000378:metabolism; D051381:Rats; D014157:Transcription Factors / Q000235:genetics*; D000097577:Homeobox Protein PITX2
chemical_list: D000804:Angiotensin II; D057911:Angiotensin Receptor Antagonists; D001374:Azacitidine; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D000077209:Decitabine; D004791:Enzyme Inhibitors; D018398:Homeodomain Proteins; D007545:Isoproterenol; D019808:Losartan; D012313:RNA; D014157:Transcription Factors; D000097577:Homeobox Protein PITX2; C000619382:Dnmt1 protein, rat