title: A cell-autonomous role of Cited2 in controlling myocardial and coronary vascular development.
abstract: OBJECTIVE
  Myocardial development is dependent on concomitant growth of cardiomyocytes and a supporting vascular network. The coupling of myocardial and coronary vascular development is partly mediated by vascular endothelial growth factor (VEGFA) signalling and additional unknown mechanisms. We examined the cardiomyocyte specific role of the transcriptional co-activator Cited2 on myocardial microstructure and vessel growth, in relation to Vegfa expression.
  
  
  RESULTS
  A cardiomyocyte-specific knockout of mouse Cited2 (Cited2(Nkx)) was analysed using magnetic resonance imaging and histology. Ventricular septal defects and significant compact layer thinning (P < 0.02 at right ventricular apex, P < 0.009 at the left ventricular apex in Cited2(Nkx) vs. controls, n = 11 vs. n = 7, respectively) were found. This was associated with a significant decrease in the number of capillaries to larger vessels (ratio 1.56 ± 0.56 vs. 3.25 ± 1.63, P = 2.7 × 10(-6) Cited2(Nkx) vs. controls, n = 11 vs. n = 7, respectively) concomitant with a 1.5-fold reduction in Vegfa expression (P < 0.02, Cited2(Nkx) vs. controls, n = 12 vs. n = 12, respectively). CITED2 was subsequently found at the Vegfa promoter in mouse embryonic hearts using chromatin immunoprecipitation, and moreover found to stimulate human VEGFA promoter activity in cooperation with TFAP2 transcription factors in transient transfection assays. There was no change in the myocardial expression of the left-right patterning gene Pitx2c, a previously known target of CITED2.
  
  
  CONCLUSIONS
  This study delineates a novel cell-autonomous role of Cited2 in regulating VEGFA transcription and the development of myocardium and coronary vasculature in the mouse. We suggest that coupling of myocardial and coronary growth in the developing heart may occur in part through a Cited2→Vegfa pathway.
authors.affiliation: Department of Cardiovascular Medicine, University of Oxford and Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford OX3 7BN, UK.
authors.forename: Simon T
authors.initials: ST
authors.lastname: MacDonald
authors.forename: Simon D
authors.initials: SD
authors.lastname: Bamforth
authors.forename: José
authors.initials: J
authors.lastname: Bragança
authors.forename: Chiann-Mun
authors.initials: CM
authors.lastname: Chen
authors.forename: Carol
authors.initials: C
authors.lastname: Broadbent
authors.forename: Jürgen E
authors.initials: JE
authors.lastname: Schneider
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Schwartz
authors.forename: Shoumo
authors.initials: S
authors.lastname: Bhattacharya
mesh_terms: D000818:Animals; D003331:Coronary Vessels / Q000196:embryology*; D005260:Female; D006321:Heart / Q000196:embryology*; D006345:Heart Septal Defects, Ventricular / Q000196:embryology; D018398:Homeodomain Proteins / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D018810:Magnetic Resonance Angiography; D051379:Mice; D018345:Mice, Knockout; D055806:Microvessels / Q000196:embryology; D032383:Myocytes, Cardiac / Q000502:physiology; D018919:Neovascularization, Physiologic / Q000502:physiology; D012097:Repressor Proteins / Q000502:physiology*; D015534:Trans-Activators / Q000502:physiology*; D050656:Transcription Factor AP-2 / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D000097577:Homeobox Protein PITX2
chemical_list: D018398:Homeodomain Proteins; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012097:Repressor Proteins; D015534:Trans-Activators; D050656:Transcription Factor AP-2; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; D000097577:Homeobox Protein PITX2; C110087:Cited2 protein, mouse; C497443:Hif1a protein, mouse