C/EBP-related sites in addition to a STAT site are necessary for ciliary neurotrophic factor-leukemia inhibitory factor-dependent transcriptional activation by the vasoactive intestinal peptide cytokine response element.
The neuropoietic cytokines ciliary neurotrophic factor (CNTF) and leukemia inhibitory factor (LIF) regulate VIP gene expression through a cytokine response element (CyRE) which interacts with members of the STAT transcription factor family. The CyRE STAT site is, however, insufficient to mediate full transcriptional activation by CNTF/LIF, suggesting that other sequences and nuclear proteins are also important. As C/EBP proteins participate in the transcriptional effects of the related cytokine, interleukin-6, we investigated the role of possible C/EBP-binding sites in the response of the VIP CyRE to CNTF/LIF. Using DNase I footprinting, transactivation studies, DNA mobility shift assays, and mutational analysis, three sites within the VIP CyRE were identified as C/EBP-related binding sites and shown to be important to CNTF/LIF-mediated transcriptional activation. The CyRE C/EBP-related sites interact with nuclear proteins from the human neuroblastoma cell line, NBFL, including a novel, protein synthesis-dependent, nuclear protein complex, induced by CNTF treatment. These nuclear proteins are not, however, recognized by antisera to known C/EBP proteins. Therefore, other nuclear proteins regulated by independent pathways act in concert with the JAK-STAT pathway to mediate CNTF/LIF regulation of VIP gene expression through the CyRE.
Symes
A J
AJ
Department of Neurology, Massachusetts General Hospital, Boston 02114, USA.
Rajan
P
P
Corpus
L
L
Fink
J S
JS
D001483:Base Sequence; D001665:Binding Sites; D022762:CCAAT-Enhancer-Binding Proteins; D020934:Ciliary Neurotrophic Factor; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D006131:Growth Inhibitors / Q000378:metabolism*; D006801:Humans; D015850:Interleukin-6; D053605:Leukemia Inhibitory Factor; D008222:Lymphokines / Q000378:metabolism*; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D009838:Oligodeoxyribonucleotides; D011485:Protein Binding; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured; D014660:Vasoactive Intestinal Peptide / Q000235:genetics* / Q000378:metabolism
D022762:CCAAT-Enhancer-Binding Proteins; D020934:Ciliary Neurotrophic Factor; D004268:DNA-Binding Proteins; D006131:Growth Inhibitors; D015850:Interleukin-6; C507837:LIF protein, human; D053605:Leukemia Inhibitory Factor; D008222:Lymphokines; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D014157:Transcription Factors; D014660:Vasoactive Intestinal Peptide