Distinct Regulations of HO-1 Gene Expression for Stress Response and Substrate Induction

• Published in: Molecular and cellular biology 2021-11, Vol.41 (11), p.e0023621-e0023621
• Main Authors: Zhang, Anqi, Suzuki, Takafumi, Adachi, Saki, Naganuma, Eriko, Suzuki, Norio, Hosoya, Tomonori, Itoh, Ken, Sporn, Michael B., Yamamoto, Masayuki
• Format: Article
• Language: English
• Subjects: Animals; Antioxidants - metabolism; Bilirubin - metabolism; Biliverdine - metabolism; Gene Expression Regulation - genetics; Genetics and Molecular Biology; Heme - metabolism; Heme Oxygenase-1 - biosynthesis; Heme Oxygenase-1 - genetics; hemin; HO-1; Luminescent Proteins - genetics; Macrophages, Peritoneal - metabolism; Membrane Proteins - biosynthesis; Membrane Proteins - genetics; Mice; Mice, Inbred C57BL; Mice, Knockout; NF-E2-Related Factor 2 - genetics; NRF2; Oxidative Stress - genetics; Oxidative Stress - physiology; Research Article; Spotlight; stress response
• ISSN: 0270-7306; 1098-5549; 1098-5549
• DOI: 10.1128/MCB.00236-21

Heme oxygenase 1 (HO-1) is the key enzyme for heme catabolism and cytoprotection. Whereas HO-1 gene expression in response to various stresses has been investigated extensively, the precise mechanisms by which HO-1 gene expression is regulated by the HO-1 substrate heme remain elusive. To systematically examine whether stress-mediated induction and substrate-mediated induction of HO-1 utilize similar or distinct regulatory pathways, we developed an HO-1-DsRed-knock-in reporter mouse in which the HO-1 gene is floxed by loxP sites and the DsRed gene has been inserted. Myeloid lineage-specific recombination of the floxed locus led to fluorescence derived from expression of the HO-1-DsRed fusion protein in peritoneal macrophages. We also challenged general recombination of the locus and generated mice harboring heterozygous recombinant alleles, which enabled us to monitor HO-1-DsRed expression in the whole body in vivo and ex vivo. HO-1 inducers upregulated HO-1-DsRed expression in myeloid lineage cells isolated from the mice. Notably, analyses of peritoneal macrophages from HO-1-DsRed mice lacking NRF2, a major regulator of the oxidative/electrophilic stress response, led us to identify NRF2-dependent stress response-mediated HO-1 induction and NRF2-independent substrate-mediated HO-1 induction. Thus, the HO-1 gene is subjected to at least two distinct levels of regulation, and the available lines of evidence suggest that substrate induction in peritoneal macrophages is independent of CNC family-based regulation.