The BACH1 gene produces the transcription regulator protein BACH1 which contains 736 amino acids and is 88% identical to its mouse homolog. It contains basic leucine zipper and BTB-zinc finger domains (which are directly involved in DNA binding for transcription regulation) (Blouin et al, 1999).

The let-7 microRNA (miRNA) plays important roles in human liver development and diseases such as hepatocellular carcinoma, liver fibrosis and hepatitis wherein oxidative stress accelerates the progression of these diseases. It directly acts on the 3'-UTR of BACH1 and negatively regulates expression of this protein, and thereby up-regulates heme oxygenase (HMOX1) gene expression (Hou et al, 2012).

miR-155 is one of the TNFα-inducible endothelial microRNAs that bind to the BACH1 mRNA. Increased HMOX1 expression in endothelial cells by TNFα results from miR-155-induced repression of BACH1 rather than direct induction of HMOX1 via NF-κB. miR-155 is cytoprotective during inflammation by elevating HMOX1 expression in endothelial cells (Pulkkinen et al, 2011).

The microRNA miR‐196 directly acts on the 3′‐UTR of BACH1 messenger RNA and translationally represses the expression of this protein, and up‐regulates HMOX1 (Hou et al, 2010).