title: Pitx2c is reactivated in the failing myocardium and stimulates myf5 expression in cultured cardiomyocytes.
abstract: BACKGROUND
  Pitx2 (paired-like homeodomain 2 transcription factor) is crucial for heart development, but its role in heart failure (HF) remains uncertain. The present study lays the groundwork implicating Pitx2 signalling in different modalities of HF.
  
  
  RESULTS
  A variety of molecular, cell-based, biochemical, and immunochemical assays were used to evaluate: (1) Pitx2c expression in the porcine model of diastolic HF (DHF) and in patients with systolic HF (SHF) due to dilated and ischemic cardiomyopathy, and (2) molecular consequences of Pitx2c expression manipulation in cardiomyocytes in vitro. In pigs, the expression of Pitx2c, physiologically downregulated in the postnatal heart, is significantly re-activated in left ventricular (LV) failing myocardium which, in turn, is associated with increased expression of a restrictive set of Pitx2 target genes. Among these, Myf5 was identified as the top upregulated gene. In vitro, forced expression of Pitx2c in cardiomyocytes, but not in skeletal myoblasts, activates Myf5 in dose-dependent manner. In addition, we demonstrate that the level of Pitx2c is upregulated in the LV-myocardium of SHF patients.
  
  
  CONCLUSIONS
  The results provide previously unrecognized evidence that Pitx2c is similarly reactivated in postnatal/adult heart at distinct HF phenotypes and suggest that Pitx2c is involved, directly or indirectly, in the regulation of Myf5 expression in cardiomyocytes.
authors.affiliation: Institute of Health Sciences, University of La Coruña, La Coruña, Spain.
authors.forename: Mario
authors.initials: M
authors.lastname: Torrado
authors.affiliation: Department of Experimental Biology, University of Jaen, Jaen, Spain.
authors.forename: Diego
authors.initials: D
authors.lastname: Franco
authors.affiliation: Department of Experimental Biology, University of Jaen, Jaen, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Hernández-Torres
authors.affiliation: University Hospital Center of La Coruña, La Coruña, Spain.
authors.forename: María G
authors.initials: MG
authors.lastname: Crespo-Leiro
authors.affiliation: University Hospital Center of La Coruña, La Coruña, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Iglesias-Gil
authors.affiliation: Institute of Health Sciences, University of La Coruña, La Coruña, Spain; University Hospital Center of La Coruña, La Coruña, Spain.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Castro-Beiras
authors.affiliation: Institute of Health Sciences, University of La Coruña, La Coruña, Spain.
authors.forename: Alexander T
authors.initials: AT
authors.lastname: Mikhailov
mesh_terms: D000818:Animals; D019556:COS Cells; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D005786:Gene Expression Regulation; D054144:Heart Failure, Diastolic / Q000235:genetics* / Q000473:pathology*; D006352:Heart Ventricles / Q000378:metabolism / Q000473:pathology; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D009206:Myocardium / Q000378:metabolism / Q000473:pathology*; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000473:pathology*; D051787:Myogenic Regulatory Factor 5 / Q000235:genetics*; D013552:Swine; D014157:Transcription Factors / Q000235:genetics*; D000097577:Homeobox Protein PITX2
chemical_list: D018398:Homeodomain Proteins; D051787:Myogenic Regulatory Factor 5; D014157:Transcription Factors; D000097577:Homeobox Protein PITX2; C497417:MYF5 protein, human