The heme-Bach1 pathway in the regulation of oxidative stress response and erythroid differentiation

Kazuhiko Igarashi, Jiying Sun

Research output: Contribution to journalReview articlepeer-review

202 Citations (Scopus)


Heme-as a prosthetic group of proteins required for oxygen transport and storage, respiration, and biosynthetic pathways-is essential for practically all forms of life. Additionally, the degradation products of heme (i.e., carbon monoxide, biliverdin, and bilirubin) produced by the enzymatic actions of heme oxygenase (HO) and biliverdin reductase, possess various biological activities in vivo. In mammalian cells, heme also functions as an intracellular regulator of gene expression by virtue of its ability to bind to Bach1, a transcription factor that functions in association with small Maf proteins. Normally, such complexes function as repressors by binding to specific target sequences, the Maf recognition element (MARE), within enhancers of genes encoding proteins such as HO-1 and β-globin. By binding to Bach1, heme induces selective removal of the repressor from the gene enhancers permitting subsequent occupancy of the MAREs by activators that, interestingly, also contain small Maf proteins. Thus small Maf proteins play dual functions in gene expression: complexes with Bach1 repress MARE-dependent gene expression, whereas heterodimers with NF-E2 p45 or related factors (Nrf1, Nrf2, and Nrf3) activate MARE-driven genes. By modulating the equilibrium of the small Maf heterodimer network, heme regulates expression of the cytoprotective enzyme HO-1 during the stress response and of β-globin during erythroid differentiation. Implications of such heme-regulated gene expression in human diseases including atherosclerosis are discussed.

Original languageEnglish
Pages (from-to)107-118
Number of pages12
JournalAntioxidants and Redox Signaling
Issue number1-2
Publication statusPublished - 2006 Jan

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Molecular Biology
  • Clinical Biochemistry
  • Cell Biology


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