NRF-1, an activator involved in nuclear-mitochondrial interactions, utilizes a new DNA-binding domain conserved in a family of developmental regulators.

Abstract

Nuclear respiratory factor 1 (NRF-1) was first discovered as an activator of the cytochrome c gene and was subsequently found to play a broader role in nuclear-mitochondrial interactions. We have now cloned a HeLa cDNA encoding NRF-1 using degenerate oligomers derived from tryptic peptide sequences for PCR amplification. The cDNA-encoded protein was indistinguishable from the authentic HeLa cell factor on denaturing gels, displayed the expected NRF-1 DNA-binding specificity, and made the same guanine nucleotide contacts as HeLa NRF-1 on binding known NRF-1 recognition sites. Antiserum raised against the highly purified recombinant protein recognized the identical DNA-protein complex formed using either a crude nuclear fraction or nearly homogeneous HeLa NRF-1. Recombinant NRF-1 also activated transcription through specific sites from several NRF-l-responsive promoters, confirming both the transcriptional activity and specificity of the cDNA product. Portions of NRF-1 are closely related to sea urchin P3A2 and the erect wing (EWG) protein of Drosophila. Both are recently identified developmental regulatory factors. The region of highest sequence identity with P3A2 and EWG was in the amino-terminal half of the molecule, which was found by deletion mapping to contain the DNA-binding domain, whereas the carboxy-terminal half of NRF-1 was highly divergent from both proteins. The DNA-binding domain in these molecules is unrelated to motifs found commonly in DNA-binding proteins; thus, NRF-1, P3A2, and EWG represent the founding members of a new class of highly conserved sequence-specific regulatory factors.

Electrical stimulation of neonatal cardiomyocytes results in the sequential activation of nuclear genes governing mitochondrial proliferation and differentiation

“…If this is the case, induction of Cyt c mRNA may be preceded by induction of transcriptional activators that control its expression. One such factor is NRF-1, originally identified as an activator of Cyt c gene transcription (23) found to act on many nuclear genes required for mitochondrial respiratory function (8,10,12). In addition, the Cyt c promoter has functional binding sites for the activating transcription factor͞cAMP response element binding protein (ATF͞ CREB) family of transcription factors.…”

“…9). These nuclear transcription factors also act on genes encoding key components of the mitochondrial transcription, replication (8,10) and heme biosynthetic machinery (11), suggesting that they play a role in nuclear-mitochondrial interactions (12). Although the contribution of transcriptional and posttranscriptional mechanisms has not been established, increases in mitochondrial protein expression in response to electrical stimulation may be mediated in part through these and possibly other transcriptional activators.…”

CD30 triggering by agonistic antibodies regulates CXCR4 expression and CXCL12 chemotactic activity in the cell line L540

“…35,49 Putative NRF-1 binding sites have been identified in several cell growth genes, including bcl-2 and murine GM-CSF. 64,65 CD30 signaling leads to activation of at least NF-B through a TRAF-dependent mechanism 65 and AP-1 through jun N-terminal kinases. TRAF2 and related proteins are rapidly depleted by proteolysis after binding to the cytoplasmic domain of CD30, 3,66,67 resulting in down-modulation of the proliferative potential and sensitization to TNFR1-mediated proapoptotic effects.…”

“…Elements regulating the transcription unit of the human CXCR4 gene include NRF-1, Sp1, and AP-1, but no NF-B-related complexes. 35,48,49 NRF-1 is a nuclear-encoded gene product important for the transcriptional regulation of mitochondrial cellular respiration genes 64,65 and related to constitutive transcription of CXCR4 mRNA. 35,49 Putative NRF-1 binding sites have been identified in several cell growth genes, including bcl-2 and murine GM-CSF.…”

The role of c-myc in cellular growth control

“…The eIF2a promoter contained a non-canonical CGCATG site known to be a preferred in vivo target for c-myc (Blackwell et al, 1993;Humbelin et al, 1989;Rosenwald et al, 1993b). Furthermore, max binds to this site as a heterodimer with an interesting transcription factor called either a-PAL or NRF (E®ok et al, 1994;Shors et al, 1998;Virbasius et al, 1993). Moreover, this factor, Nuclear Regulatory Factor (NRF) coordinates the transcription of nuclear mRNAs needed to make cellular mitochondrial proteins (Evans and Scarpulla, 1990).…”