title: Loss of methyl-CpG-binding domain protein 2 enhances endothelial angiogenesis and protects mice against hind-limb ischemic injury.
abstract: BACKGROUND
  Despite intensive investigation, how DNA methylation influences endothelial function remains poorly understood. We used methyl-CpG-binding domain protein 2 (MBD2), an interpreter for DNA methylome-encoded information, to dissect the impact of DNA methylation on endothelial function in both physiological and pathophysiological states.
  
  
  RESULTS
  Human umbilical vein endothelial cells under normal conditions express moderate levels of MBD2, but knockdown of MBD2 by siRNA significantly enhanced angiogenesis and provided protection against H(2)O(2)-induced apoptosis. Remarkably, Mbd2(-/-) mice were protected against hind-limb ischemia evidenced by the significant improvement in perfusion recovery, along with increased capillary and arteriole formation. Loss of MBD2 activated endothelial survival and proangiogenic signals downstream of vascular endothelial growth factor signaling characterized by an increase in endothelial nitric oxide synthase (eNOS) and vascular endothelial growth factor receptor 2 expression, along with enhanced extracellular signal-regulated kinase 1/2 activation and BCL-2 expression. Mechanistic studies confirmed the methylation of CpG elements in the eNOS and vascular endothelial growth factor receptor 2 promoter. MBD2 binds to these methylated CpG elements and suppresses eNOS promoter activity. On ischemic insult, key endothelial genes such as eNOS and vascular endothelial growth factor receptor 2 undergo a DNA methylation turnover, and MBD2 interprets the changes of DNA methylation to suppress their expressions. Moreover, MBD2 modulation of eNOS expression is likely confined to endothelial cells because nonendothelial cells such as splenocytes fail to express eNOS after loss of MBD2.
  
  
  CONCLUSIONS
  We provided direct evidence supporting that DNA methylation regulates endothelial function, which forms the molecular basis for understanding how environmental insults (epigenetic factor) affect the genome to modify disease susceptibility. Because MBD2 itself does not affect the methylation of DNA and is dispensable for normal physiology in mice, it could be a viable epigenetic target for modulating endothelial function in disease states.
authors.affiliation: Center for Biomedical Research, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Ave., Wuhan, China.
authors.forename: Xiaoquan
authors.initials: X
authors.lastname: Rao
authors.forename: Jixin
authors.initials: J
authors.lastname: Zhong
authors.forename: Shu
authors.initials: S
authors.lastname: Zhang
authors.forename: Yushan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Qilin
authors.initials: Q
authors.lastname: Yu
authors.forename: Ping
authors.initials: P
authors.lastname: Yang
authors.forename: Mong-Heng
authors.initials: MH
authors.lastname: Wang
authors.forename: David J
authors.initials: DJ
authors.lastname: Fulton
authors.forename: Huidong
authors.initials: H
authors.lastname: Shi
authors.forename: Zheng
authors.initials: Z
authors.lastname: Dong
authors.forename: Daowen
authors.initials: D
authors.lastname: Wang
authors.forename: Cong-Yi
authors.initials: CY
authors.lastname: Wang
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002470:Cell Survival / Q000502:physiology; D019175:DNA Methylation / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology*; D044127:Epigenesis, Genetic / Q000502:physiology; D006614:Hindlimb / Q000098:blood supply*; D006861:Hydrogen Peroxide / Q000009:adverse effects / Q000494:pharmacology; D007511:Ischemia / Q000503:physiopathology / Q000517:prevention & control*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D023421:Models, Animal; D018919:Neovascularization, Physiologic / Q000502:physiology*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; C489326:Mbd2 protein, mouse; D006861:Hydrogen Peroxide; D052250:Nitric Oxide Synthase Type III; D040301:Vascular Endothelial Growth Factor Receptor-2