Nrf1 in a complex with fosB, c-jun, junD and ATF2 forms the AP1 component at the TNF  promoter in stimulated mast cells

By the 4-cell stage of C. elegans embryogenesis, a ventral blastomere, called EMS, is already committed to producing pharyngeal and intestinal cell types. Recessive, maternal-effect mutations in the gene skn-1 prevent EMS from producing both pharyngeal and intestinal cells. In skn-1 mutant embryos, EMS instead produces hypodermal cells and body wall muscle cells, much like its sister blastomere. Genetic analysis suggests that the skn-1 gene product is also required post-embryonically for development of the intestine. We have cloned and sequenced the skn-1 gene and describe sequence similarities to the basic regions of bZIP transcription factors. We propose that the maternally expressed skn-1 gene product acts to specify the fate of the EMS blastomere.

The CNC-basic leucine zipper (CNC-bZIP) family is a subfamily of bZIP proteins identified from independent searches for factors that bind the AP-1-like cis-elements in the beta-globin locus control region. Three members, p45-Nf-e2, Nrf-1 and Nrf-2 have been identified in mammals. Expression of p45-Nf-e2 is largely restricted to hematopoietic cells while Nrf-1 and Nrf-2 are expressed in a wide range of tissues. To determine the function of Nrf-1, targeted disruption of the Nrf-1 gene was carried out. Homozygous Nrf-1 mutant mice are anemic due to a non-cell autonomous defect in definitive erythropoiesis and die in utero.