title: Impaired expression of uncoupling protein 2 causes defective postischemic angiogenesis in mice deficient in AMP-activated protein kinase α subunits.
abstract: OBJECTIVE
  The aim of the present study was to determine whether mitochondrial uncoupling protein (UCP) 2 is required for AMPK-dependent angiogenesis in ischemia in vivo.
  
  
  RESULTS
  Angiogenesis was assayed by monitoring endothelial tube formation (a surrogate for angiogenesis) in human umbilical vein endothelial cells (ECs), isolated mouse aortic endothelial cells (MAECs), and pulmonary microvascular endothelial cells or in ischemic thigh adductor muscles from wild-type (WT) mice or mice deficient in either AMPKα1 or AMPKα2. AMPK inhibition with pharmacological inhibitor (compound C) or genetic means (transfection of AMPKα-specific small interfering RNA) significantly lowered the tube formation in human umbilical vein ECs. Consistently, compared with WT mice, tube formation in MAECs isolated from either AMPKα1(-/-) or AMPKα2(-/-) mice, which exhibited oxidative stress and reduced expression of UCP2, was significantly impaired. In addition, adenoviral overexpression of UCP2, but not adenoviruses encoding green fluorescent protein, normalized tube formation in MAECs from either AMPKα1(-/-) or AMPKα2(-/-) mice. Similarly, supplementation with sodium nitroprusside, a nitric oxide (NO) donor, restored tube formation. Furthermore, ischemia significantly increased angiogenesis, serine 1177 phosphorylation of endothelial NO synthase, and UCP2 in ischemic thigh adductor muscles from WT mice but not in those from either AMPKα1(-/-) or AMPKα2(-/-) mice.
  
  
  CONCLUSIONS
  We conclude that AMPK-dependent UCP2 expression in ECs promotes angiogenesis in vivo.
authors: Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, 73104, USA.
authors: Ming-Jiang
authors: MJ
authors: Xu
authors: Ping
authors: P
authors: Song
authors: Najeeb
authors: N
authors: Shirwany
authors: Bin
authors: B
authors: Liang
authors: Junjie
authors: J
authors: Xing
authors: Benoit
authors: B
authors: Viollet
authors: Xian
authors: X
authors: Wang
authors: Yi
authors: Y
authors: Zhu
authors: Ming-Hui
authors: MH
authors: Zou
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