Involvement of JunD in transcriptional activation of the orphan receptor gene nur77 by nerve growth factor and membrane depolarization in PC12 cells.
nur77, an immediate-early gene that encodes an orphan nuclear receptor, is rapidly and transiently induced by nerve growth factor (NGF) stimulation or membrane depolarization in the rat pheochromocytoma-derived cell line PC12. The Nur77 protein can act as a potent transcription activator and may function to regulate the expression of downstream genes in response to extracellular stimuli. We show here that activation of nur77 by NGF treatment and membrane depolarization is signalled through distinct pathways. These distinct signals appear to converge on the same transcription factors acting on the same promoter elements. We show that nur77 activation by both processes requires two cis-acting AP1-like elements, NAP1 and NAP2, which contain the core sequence TGCGTCA centered at 67 and 38 nucleotides upstream of the transcription start site. The NAP elements can confer inducibility by NGF and membrane depolarization on an otherwise unresponsive heterologous promoter. We identified JunD as a key mediator of nur77 activation by reason of the following observations. (i) JunD, but not CREB or other members of the Fos/Jun family, is a component of NAP binding activity in PC12 cell nuclear extracts. (ii) JunD, but not other Fos/Jun family members, specifically transactivates the nur77 promoter through the NAP elements (iii) A dominant-negative mutant of JunD effectively abolishes the activation of nur77 by either NGF treatment or membrane depolarization. These data draw a contrast between the regulation of nur77 with that of c-fos, in which the sequence requirements for activation by NGF treatment and membrane depolarization appear separable, and CREB appears to play a role in activation by both NGF and membrane depolarization.
Department of Genetics, University of Illinois College of Medicine, Chicago 60612.
J K
JK
Yoon
L F
LF
Lau
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D005576:Colforsin / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000235:genetics*; D005786:Gene Expression Regulation; D017781:Genes, Immediate-Early; D008564:Membrane Potentials; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009414:Nerve Growth Factors / Q000494:pharmacology*; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D016716:PC12 Cells; D011189:Potassium Chloride / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D016755:Proto-Oncogene Proteins c-jun / Q000502:physiology*; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D004268:DNA-Binding Proteins; D009414:Nerve Growth Factors; C539820:Nr4a1 protein, rat; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D009838:Oligodeoxyribonucleotides; D016755:Proto-Oncogene Proteins c-jun; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D014157:Transcription Factors; D005576:Colforsin; D011189:Potassium Chloride