JunB and JunD Regulate Human Heme Oxygenase-1 Gene Expression in Renal Epithelial Cells

Abstract

Heme oxygenase-1 is a highly inducible gene, the product of which catalyzes breakdown of the prooxidant heme. The purpose of this study was to investigate the regulation of the human heme oxygenase-1 gene in renal epithelial cells. DNase I hypersensitivity studies identified three distal sites (HS-2, -3, and -4) corresponding to approximately ؊4.0, ؊7.2, and ؊9.2 kb, respectively, of the heme oxygenase-1 promoter in addition to one proximal region, HS-1, which we have shown previously to be an E box. In vivo dimethyl sulfate footprinting of the HS-2 region revealed six individual protected guanines. Two mutations within HS-2 combined with a third mutation of the proximal E box abolished hemin-and cadmium-driven heme oxygenase-1 promoter activation, suggesting that these three sites synergized for maximal heme oxygenase-1 induction. Jun proteins bound to the antioxidant response element in the HS-2 region in vitro and associated with the heme oxygenase-1 promoter in vivo. JunB and JunD contribute opposing effects; JunB activated whereas JunD repressed heme oxygenase-1 expression in human renal epithelial cells, results that were corroborated in junB ؊/؊ and junD ؊/؊ cells. We propose that heme oxygenase-1 induction is controlled by a dynamic interplay of regulatory proteins, and we provide new insights into the molecular control of the human heme oxygenase-1 gene.

Ethanol-induced HO-1 and NQO1 Are Differentially Regulated by HIF-1α and Nrf2 to Attenuate Inflammatory Cytokine Expression

“…These results show that JunD and JunB have opposing roles in regulating ethanol-mediated HO-1 transcription. Previous studies in HK-2 cells, an immortalized human renal epithelial cell line, show that hemin-induced HO-1 promoter activity is augmented by c-Jun and JunB but repressed by JunD (27). These results and data from our studies implicate differential roles of JunD and JunB in regulating HO-1 gene expression and are context-sensitive to the nature of stimuli and cell type.…”

“…The targets of the inhibitors and siRNA mentioned are described in supplemental Table I. The human Ϫ9.2-kb HO-1-pGL3, Ϫ4.5-kb HO-1-pGL3, and mutant construct of the Ϫ4.5-kb HO-1-pGL3 promoter with a deletion of the ARE enhancer region E1 and the JunB expression plasmid were generously provided by Dr. Anupam Agarwal (University of Alabama, Birmingham, AL) (27,36). Mutant constructs of the HO-1-luc promoter were generated using wild-type Ϫ4.5-kb HO-1 construct as a template with the QuikChange site-directed mutagenesis kit (Stratagene, Cedar Creek, TX) using the primers shown in Table 1.…”

“…The ARE core sequence is present in mouse and human HO-1 promoters (26) as well as other phase II enzymes, which have an AP-1 or AP-1 like motif (8). Recent studies have shown that JunB binding to the AP-1 site activates, whereas JunD represses human HO-1 gene expression (27). LPS and cytokine-mediated induction of HO-1 has been shown to involve AP-1 transcription factors (28).…”

Placenta Growth Factor (PlGF), a Novel Inducer of Plasminogen Activator Inhibitor-1 (PAI-1) in Sickle Cell Disease (SCD)

“…Additionally, studies have shown that there are at least five putative HRE-1 to -5 in the human PAI-1 promoter and that HIF-1␣ interacts only with HRE-2 to regulate PAI-1 transcription in response to hypoxia (17). Our study shows that PlGF induces activity of the human PAI-1 promoter via HRE-1 and -2 (but not HRE-3, -4, or -5 (48). In contrast, we show that PlGF-mediated PAI-1 transcription is activated by JunD, and overexpression of JunB has no effect.…”

Polyamines Regulate the Stability of JunD mRNA by Modulating the Competitive Binding of Its 3′ Untranslated Region to HuR and AUF1

“…Jun proteins can form AP-1 homodimers or heterodimers among themselves or with members of the related Fos or ATF (activating transcription factor) protein families and regulate the transcription of target genes by binding to specific promoter DNA elements such as TGAGTCA and TGACGTCA (17,41,58,59). All three Jun proteins (c-Jun, JunB, and JunD) are similar in DNA-binding affinity, but their patterns of expression vary in response to stress and during cell proliferation and transformation (6,10,17,48,56,59). Although c-Jun and JunB behave as immediate-early response genes and enhance the G 1 -to-S-phase transition upon mitogenic stimulation, the overexpression of JunD inhibits cell proliferation (14,29,38).…”