title: Decreased levels of embryonic retinoic acid synthesis accelerate recovery from arterial growth delay in a mouse model of DiGeorge syndrome.
abstract: BACKGROUND
  Loss of Tbx1 and decrease of retinoic acid (RA) synthesis result in DiGeorge/velocardiofacial syndrome (DGS/VCFS)-like phenotypes in mouse models, including defects in septation of the outflow tract of the heart and anomalies of pharyngeal arch-derived structures including arteries of the head and neck, laryngeal-tracheal cartilage, and thymus/parathyroid. Wild-type levels of T-box transcription factor (Tbx)1 and RA signaling are required for normal pharyngeal arch artery development. Recent studies have shown that reduction of RA or loss of Tbx1 alters the contribution of second heart field (SHF) progenitor cells to the elongating heart tube.
  
  
  OBJECTIVE
  Here we tested whether Tbx1 and the RA signaling pathway interact during the deployment of the SHF and formation of the mature aortic arch.
  
  
  RESULTS
  Molecular markers of the SHF, neural crest and smooth muscle cells, were analyzed in Raldh2;Tbx1 compound heterozygous mutants. Our results revealed that the SHF and outflow tract develop normally in Raldh2(+/-);Tbx1(+/-) embryos. However, we found that decreased levels of RA accelerate the recovery from arterial growth delay observed in Tbx1(+/-) mutant embryos. This compensation coincides with the differentiation of smooth muscle cells in the 4th pharyngeal arch arteries, and is associated with severity of neural crest cell migration defects observed in these mutants.
  
  
  CONCLUSIONS
  Our data suggest that differences in levels of embryonic RA may contribute to the variability in great artery anomalies observed in DGS/VCFS patients.
authors.affiliation: INSERM UMR S910, Université de la Méditerranée, Faculté de Médecine, 27 Bd. Jean Moulin, Marseille, France.
authors.forename: Lucile
authors.initials: L
authors.lastname: Ryckebüsch
authors.forename: Nicolas
authors.initials: N
authors.lastname: Bertrand
authors.forename: Karim
authors.initials: K
authors.lastname: Mesbah
authors.forename: Fanny
authors.initials: F
authors.lastname: Bajolle
authors.forename: Karen
authors.initials: K
authors.lastname: Niederreither
authors.forename: Robert G
authors.initials: RG
authors.lastname: Kelly
authors.forename: Stéphane
authors.initials: S
authors.lastname: Zaffran
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001013:Aorta, Thoracic / Q000002:abnormalities / Q000378:metabolism*; D001934:Branchial Region / Q000002:abnormalities / Q000378:metabolism*; D002454:Cell Differentiation; D003433:Crosses, Genetic; D004062:DiGeorge Syndrome / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D015536:Down-Regulation; D004622:Embryo, Mammalian / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D005838:Genotype; D005865:Gestational Age; D006321:Heart / Q000196:embryology; D006579:Heterozygote; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D009131:Muscle, Smooth, Vascular / Q000002:abnormalities / Q000378:metabolism*; D009154:Mutation; D009432:Neural Crest / Q000002:abnormalities / Q000378:metabolism; D010641:Phenotype; D015398:Signal Transduction / Q000235:genetics; D020825:T-Box Domain Proteins / Q000235:genetics / Q000378:metabolism; D046509:Tissue Culture Techniques; D014212:Tretinoin / Q000378:metabolism*
chemical_list: D020825:T-Box Domain Proteins; C491573:Tbx1 protein, mouse; D014212:Tretinoin; D000445:Aldehyde Oxidoreductases; C470579:RALDH2 protein, mouse