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1Free Radical and Radiation Biology Program, Department of Radiation Oncology, 2Department of Internal Medicine, The University of Iowa, Iowa City, Iowa 52242
Submitted 12 December 2002 ; accepted in final form 28 April 2003
Redox factor-1 (Ref-1/APE), a multifunctional DNA base excision repair and
redox regulation enzyme, plays an important role in oxidative signaling,
transcription factor regulation, and cell cycle control. We hypothesized that
Ref-1 plays a regulatory role in smooth muscle cell (SMC) proliferation
induced by PDGF. Ref-1 antisense oligodeoxynucleotides (AODN), which
diminished the level of Ref-1 protein in SMCs by
50%, inhibited PDGF-BB
(composed of the homodimer of B-polypeptide chain)-induced
[3H]thymidine incorporation compared with control
oligodeoxynucleotides. Ref-1 AODN inhibited PDGF-BB-induced S phase
entry by
63%, which was overcome by overexpression of Ref-1 by
adenoviral-mediated gene transfer. Overexpression of Ref-1 alone without PDGF
enhanced SMC entry into the S phase. Furthermore, decreasing Ref-1 protein by
treatment of SMCs with Ref-1 AODN, or by immunodepletion of Ref-1 from nuclear
extracts, inhibited PDGF-BB-induced activator protein-1 (AP-1) DNA binding
activity. Chemical reduction restored the AP-1 DNA binding in Ref-1-depleted
nuclear extracts. These results suggest that Ref-1 contributes to the
regulation of PDGF-BB-stimulated cell cycle progression from
G0/G1 to S in SMCs, with one of the possible steps being
redox-regulation of AP-1 by Ref-1 protein.
activator protein-1; cell cycle; antisense
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