title: SWI/SNF chromatin-remodeling enzymes Brahma-related gene 1 (BRG1) and Brahma (BRM) are dispensable in multiple models of postnatal angiogenesis but are required for vascular integrity in infant mice.
abstract: BACKGROUND
  Mammalian SWItch/Sucrose NonFermentable (SWI/SNF) adenosine triphosphate (ATP)-dependent chromatin-remodeling complexes play important roles in embryonic vascular development by modulating transcription of specific target genes. We sought to determine whether SWI/SNF complexes likewise impact postnatal physiological and pathological angiogenesis.
  
  
  RESULTS
  Brahma-related gene 1 (BRG1) and Brahma gene (BRM) are ATPases within mammalian SWI/SNF complexes and are essential for the complexes to function. Using mice with vascular-specific mutations in Brg1 or with a global mutation in Brm, we employed 3 models to test the role of these ATPases in postnatal angiogenesis. We analyzed neonatal retinal angiogenesis, exercise-induced angiogenesis in adult quadriceps muscles, and tumor angiogenesis in control and mutant animals. We found no evidence of defective angiogenesis in Brg1 or Brm mutants using these 3 models. Brg1/Brm double mutants likewise show no evidence of vascular defects in the neonatal retina or tumor angiogenesis models. However, 100% of Brg1/Brm-double mutants in which Brg1 deletion is induced at postnatal day 3 (P3) die by P19 with hemorrhaging in the small intestine and heart.
  
  
  CONCLUSIONS
  Despite their important roles in embryonic vascular development, SWI/SNF chromatin-remodeling complexes display a surprising lack of participation in the 3 models of postnatal angiogenesis we analyzed. However, these complexes are essential for maintaining vascular integrity in specific tissue beds before weaning. These findings highlight the temporal and spatial specificity of SWI/SNF activities in the vasculature and may indicate that other chromatin-remodeling complexes play redundant or more essential roles during physiological and pathological postnatal vascular development.
authors.affiliation: Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK (M.M.W., V.M., C.T.G.).
authors.forename: Mandi M
authors.initials: MM
authors.lastname: Wiley
authors.affiliation: Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK (M.M.W., V.M., C.T.G.).
authors.forename: Vijay
authors.initials: V
authors.lastname: Muthukumar
authors.affiliation: Free Radical Biology and Aging Program, Oklahoma Medical Research Foundation, Oklahoma City, OK (T.M.G.) Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK (T.M.G.).
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Griffin
authors.affiliation: Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK (M.M.W., V.M., C.T.G.) Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK (C.T.G.).
authors.forename: Courtney T
authors.initials: CT
authors.lastname: Griffin
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000502:physiology; D001808:Blood Vessels / Q000254:growth & development; D004265:DNA Helicases / Q000502:physiology*; D005260:Female; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009389:Neovascularization, Pathologic / Q000503:physiopathology; D018919:Neovascularization, Physiologic / Q000502:physiology*; D009687:Nuclear Proteins / Q000502:physiology*; D010805:Physical Conditioning, Animal / Q000502:physiology; D012171:Retinal Vessels / Q000254:growth & development; D014157:Transcription Factors / Q000502:physiology*
chemical_list: D009687:Nuclear Proteins; C499503:Smarca2 protein, mouse; D014157:Transcription Factors; C513194:Smarca4 protein, mouse; D004265:DNA Helicases
keywords: BRG1; BRM; exercise‐induced angiogenesis; retinal angiogenesis; tumor angiogenesis