Identification and characterization of Ref-1, a nuclear protein that facilitates AP-1 DNA-binding activity.

Abstract

Fos and Jun form a heterodimeric complex that regulates gene transcription by binding to the activator protein‐1 (AP‐1) DNA sequence motif. Previously, we demonstrated that the DNA‐binding activity of Fos and Jun is regulated in vitro by a novel redox (reduction‐oxidation) mechanism. Reduction of a conserved cysteine (cys) residue in the DNA‐binding domains of Fos and Jun by chemical reducing agents or by a nuclear redox factor stimulates DNA‐binding activity. Here, we describe purification and characterization of a 37 kDa protein (Ref‐1) corresponding to the redox factor. Although Ref‐1 does not bind to the AP‐1 site in association with Fos and Jun, it partially copurifies with a subset of AP‐1 proteins. Purified Ref‐1 protein stimulates AP‐1 DNA‐binding activity through the conserved Cys residues in Fos and Jun, but it does not alter the DNA‐binding specificity of Fos and Jun. Ref‐1 may represent a novel redox component of the signal transduction processes that regulate eukaryotic gene expression.

Protection of normal human reconstructed epidermis from UV by catalase overexpression

“…22 Thus, the protective effect of CAT overexpression may be due to the mitigation of DNA damage caused by the late increase in ROS levels. It is also likely that CAT affects the cellular redox status, leading to a modulation of gene expression through the activity of various transcription factors such as nuclear factor-kB, Fos, Jun, Myb 48 and p53. 49 Consistent with this hypothesis, it has been reported that UVB-induced ROS are involved in transcriptional activation of AP-1, 50 increased production of matrix metalloproteases 51 and also biosynthesis and activation of transforming growth factor-b.…”

Oxidative stress stimulates IL‐4 and IL‐6 production in mast cells by an APE/Ref‐1‐dependent pathway

“…[34,35], are present on the IL-4 promoter that are important for gene expression, while the transcriptional regulation of the IL-6 gene involves different transcriptional factors like NF-‹ B, AP-1 and CREB [36]. NF-‹ B and AP-1 are inducible transcription factors activated in response to oxidative stress and are both known to be redox-regulated through APE/Ref-1 activity [37,38]. Moreover, APE/Ref-1 was recently identified as a therapeutic target in allergic airway inflammation [39].…”

Human Apurinic/Apyrimidinic Endonuclease 1

“…Nearly a decade later, in the early 1990s, the transcript encoding the human AP endonuclease (at the time, termed APE, HAP1, and APEX, since named apurinic/apyrimidinic endonuclease 1 [APE1]/APEX1) was cloned by the Demple, Hickson, and Seki groups using one of two approaches: (i) a screen of a lambda phage expression library with an antibody against the purified protein (37) or (ii) a cross-hybridization screen of a human cDNA library using either the bovine or mouse AP endonuclease cDNA as a probe (171,182). Strikingly, around the same time, human APE1 was independently identified (and the gene subsequently cloned) by Curran and colleagues as the major nuclear protein (termed REF-1) to simulate the DNA-binding activity of the AP-1 (Fos/Jun) transcription factor complex (233). This activation was shown to be mediated through reduction of a conserved cysteine residue within the DNA binding domain of the target protein, and was also observed with factors such as NF-jB, Myb, and members of the ATF/ CREB family.…”