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Novel Role of Antioxidant‐1 in Neovascularization in Response to Hindlimb Ischemia
Author(s) -
Fukai Tohru,
Kim Ha Won,
Fukai Masuko Ushio
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.lb98-b
Subject(s) - neovascularization , angiogenesis , chemistry , cyclin d1 , hindlimb , microbiology and biotechnology , cancer research , biology , endocrinology , cell , cell cycle , biochemistry
Copper plays a fundamental role in regulating cell proliferation involved in angiogenesis; however, underlying molecular mechanisms remain unknown. Recently, we found that antioxidant‐1 (Atox1), previously appreciated as a copper chaperone, functions as a novel copper dependent transcription factor that mediates copper‐induced cell proliferation. We performed present study to test the hypothesis that Atox1 play an important role in postnatal neovascularization. Using mouse ischemia hindlimb model, we found that neovascular formation in the ischemic hindlimb was significantly impaired in Atox1−/− mice as compared with WT (35.9±6.7% decrease) as evaluated by laser Doppler blood flow. Capillary density in ischemic hindlimb at 7 days after ischemia was markedly reduced in Atox1−/− mice as compared to WT mice (27.8±4.7% decrease). Interestingly, the numbers of CD34/CD31‐ and c‐kit/CD31‐ double positive endothelial progenitor cells (EPCs) derived from bone marrow and peripheral blood were markedly decreased in Atox1−/− mice after ischemia as compare to WT (37.5‐ and 22.4% decrease, respectively) as analyzed by FACS. To gain insight into the molecular mechanism, we performed EMSA and CHIP assays and found that Atox1 binds to the promotor region of cyclin D1 in a copper dependent manner. Moreover, copper‐induced increase in cell proliferation and protein levels of cyclin D1 is markedly inhibited in Atox1 deficient mouse fiblobrasts and by knockdown of Atox1 using siRNA. Taken together, we provide the first evidence that Atox1 functions as a copper dependent transcription factor for cyclin D1 and thus stimulates cell proliferatioin, thereby promoting neovascularization induced by tissue ischemia.