Novel Hematopoietic Target Genes in the NRF2-Mediated Transcriptional Pathway

Abstract

Nuclear factor- (erythroid-derived 2) like 2 (NFE2L2, NRF2) is a key transcriptional activator of the antioxidant response pathway and is closely related to erythroid transcription factor NFE2. Under oxidative stress, NRF2 heterodimerizes with small Maf proteins and binds cis-acting enhancer sequences found near oxidative stress response genes. Using the dietary isothiocyanate sulforaphane (SFN) to activate NRF2, chromatin immunoprecipitation sequencing (ChIP-seq) identified several hundred novel NRF2-mediated targets beyond its role in oxidative stress. Activated NRF2 bound the antioxidant response element (ARE) in promoters of several known and novel target genes involved in iron homeostasis and heme metabolism, including known targets FTL and FTH1, as well as novel binding in the globin locus control region. Five novel NRF2 target genes were chosen for followup: AMBP, ABCB6, FECH, HRG-1 (SLC48A1), and TBXAS1. SFN-induced gene expression in erythroid K562 and lymphoid cells were compared for each target gene. NRF2 silencing showed reduced expression in lymphoid, lung, and hepatic cells. Furthermore, stable knockdown of NRF2 negative regulator KEAP1 in K562 cells resulted in increased NQO1, AMBP, and TBXAS1 expression. NFE2 binding sites in K562 cells revealed similar binding profiles as lymphoid NRF2 sites in all potential NRF2 candidates supporting a role for NRF2 in heme metabolism and erythropoiesis.

miR-214 protects erythroid cells against oxidative stress by targeting ATF4 and EZH2

“…The important role of Nrf2 in anti-stress responses has also been documented in erythroid cells [14,71]. Although evidence suggested that ATF4 could interact with Nrf2 to regulate the expression of antioxidant enzymes (e.g.…”

Regulation of Ahr signaling by Nrf2 during development: Effects of Nrf2a deficiency on PCB126 embryotoxicity in zebrafish (Danio rerio)

“…However, these are putative AREs and thus confirmation of Nrf2 transcription factor binding and activation of these targets would be required in order to determine whether Nrf2 does activate or repress transcription of these genes. Several other groups have performed ChIP-seq in various tissues and cell lines in order to discern whether basal and/or induced NRF2 has any novel targets in various tissues (Campbell et al ., 2013; Chorley et al ., 2012; Malhotra, et al, 2010). Though these studies confirmed NRF2 binding to a similar core of genes associated with the antioxidant response, such as those included in glutathione synthesis and phase II metabolism, these studies also identified novel targets for each cell line or tissue.…”

Macrophages and iron trafficking at the birth and death of red cells

“…The heme importer HRG1 is expressed in early erythroid cells. 47 Studies have shown that heme can be exported by macrophages, and macrophages indeed express the plasma membrane heme exporter FLVCR1 48,49 ( Figure 1, heme transport pathway). FLVCR1a, the first reported isoform, was initially discovered as a plasma membrane heme exporter, although recently a second isoform, FLVCR1b, has been shown to function as a mitochondrial heme exporter.…”