Ischemia-induced angiogenesis is impaired in aminopeptidase A deficient mice via down-regulation of HIF-1α.
Aminopeptidase A (APA; EC 3.4.11.7) is a transmembrane metalloprotease with several functions in tumor angiogenesis. To investigate the role of APA in the process of ischemia-induced angiogenesis, we evaluated the cellular angiogenic responses under hypoxic conditions and the process of perfusion recovery in the hindlimb ischemia model of APA-deficient (APA-KO; C57Bl6/J strain) mice. Western blotting of endothelial cells (ECs) isolated from the aorta of APA-KO mice revealed that the accumulation of hypoxia-inducible factor-1α (HIF-1α) protein in response to hypoxic challenge was blunted. Regarding the proteasomal ubiquitination, a proteasome inhibitor MG-132 restored the reduced accumulation of HIF-1α in ECs from APA-KO mice similar to control mice under hypoxic conditions. These were associated with decreased growth factor secretion and capillary formation in APA-KO mice. In the hindlimb ischemia model, perfusion recovery in APA-KO mice was decreased in accordance with a significantly lower capillary density at 2weeks. Regarding vasculogenesis, no differences were observed in cell populations and distribution patterns between wild type and APA-KO mice in relation to endothelial progenitor cells. Our results suggested that Ischemia-induced angiogenesis is impaired in APA-KO mice partly through decreased HIF-1α stability by proteasomal degradation and subsequent suppression of HIF-1α-driven target protein expression such as growth factors. APA is a functional target for ischemia-induced angiogenesis.
Department of Cardiology, Nagoya University, Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya 466-8550, Japan.
Ryuji
R
Kubota
Yasushi
Y
Numaguchi
Masakazu
M
Ishii
Manabu
M
Niwa
Kenji
K
Okumura
Keiji
K
Naruse
Toyoaki
T
Murohara
D000818:Animals; D015687:Cell Hypoxia; D015536:Down-Regulation; D043384:Glutamyl Aminopeptidase / Q000235:genetics / Q000378:metabolism*; D006614:Hindlimb / Q000098:blood supply; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007511:Ischemia / Q000150:complications*; D051379:Mice; D018345:Mice, Knockout; D009389:Neovascularization, Pathologic / Q000201:enzymology* / Q000209:etiology / Q000235:genetics
D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D043384:Glutamyl Aminopeptidase