Synergy of activin and ciliary neurotrophic factor signaling pathways in the induction of vasoactive intestinal peptide gene expression.
Activin, a member of the transforming growth factor-beta superfamily, can regulate neuropeptide gene expression in the nervous system and in neuroblastoma cells. Among the neuropeptide genes whose expression can be regulated by activin is the gene encoding the neuropeptide vasoactive intestinal peptide (VIP). To investigate the molecular mechanisms by which activin regulates neuronal gene expression, we have examined activin's regulation of VIP gene expression in NBFL neuroblastoma cells. We report here that NBFL cells respond to activin by increasing expression of VIP mRNA. Activin regulates VIP gene transcription in NBFL cells through a 180-bp element in the VIP promoter that was previously characterized to be necessary and sufficient to mediate the induction of VIP by the neuropoietic cytokines and termed the cytokine response element (CyRE). We find that the VIP CyRE is necessary and sufficient to mediate the transcriptional response to activin. In addition, ciliary neurotrophic factor (CNTF), a neuropoietic cytokine, synergizes with activin to increase VIP mRNA expression and transcription through the VIP CyRE. Mutations in either the Stat (signal transducer and activator of transcription) or AP-1 sites within the CyRE that reduce the response to CNTF, also reduce the response to activin. However, mutating both the Stat and AP-1 sites within the wild-type CyRE, while reducing the separate responses to either activin or CNTF, eliminates the synergy between them. These data suggest that activin and CNTF, two factors that appear to signal though distinct pathways, activate VIP gene transcription through a common transcriptional element, the VIP CyRE.
Symes
A J
AJ
Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, USA. asymes@usuhs.mil
Pitts
R L
RL
Conover
J
J
Kos
K
K
Coulombe
J
J
D028341:Activins; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002645:Chickens; D020934:Ciliary Neurotrophic Factor / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004357:Drug Synergism; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007265:Inhibins / Q000494:pharmacology*; D009154:Mutation; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics; D009447:Neuroblastoma / Q000378:metabolism / Q000473:pathology; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D050794:STAT1 Transcription Factor; D015398:Signal Transduction / Q000187:drug effects*; D015534:Trans-Activators / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000187:drug effects; D014660:Vasoactive Intestinal Peptide / Q000096:biosynthesis* / Q000235:genetics
D020934:Ciliary Neurotrophic Factor; D004268:DNA-Binding Proteins; D009363:Neoplasm Proteins; D011993:Recombinant Fusion Proteins; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D015534:Trans-Activators; D018808:Transcription Factor AP-1; D016212:Transforming Growth Factor beta; D028341:Activins; D014660:Vasoactive Intestinal Peptide; D007265:Inhibins