A new platelet-derived growth factor-regulated genomic element which binds a serine/threonine phosphoprotein mediates induction of the slow immediate-early gene MCP-1.
The MCP-1 chemokine gene belongs to a cohort of immediate-early genes that are induced with slower kinetics than c-fos. In this study, we identified a cluster of four platelet-derived growth factor (PDGF)-responsive elements within a 240-bp enhancer found in the distal 5' flanking MCP-1 sequences. Two of the elements bind one or more forms of the transcription factor NF-kappa B. We focused on the other two elements which are hitherto unreported, PDGF-regulated genomic motifs. One of these novel elements, detected as a 28-mer by DNase I footprinting, restores PDGF inducibility when added in two copies to a 5' truncated MCP-1 gene. A single copy of the second novel element, a 27-mer, restores PDGF inducibility to a 5' truncated MCP-1 gene. The 27-base element interacts with a PDGF-activated serine/threonine phosphoprotein that is detected only within the nucleus of PDGF-treated 3T3 cells. DNA binding of this phosphoprotein is activated by PDGF treatment with slow kinetics that match the time course of MCP-1 gene expression, and activation is not inhibited by cycloheximide. PDGF-activated binding to the 27-mer is shown to involve a single 30-kDa protein by UV-cross-linking analysis.
Freter
R R
RR
Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts.
Alberta
J A
JA
Lam
K K
KK
Stiles
C D
CD
D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D018932:Chemokine CCL2; D002630:Chemotactic Factors / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation; D017781:Genes, Immediate-Early; D066298:In Vitro Techniques; D051379:Mice; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D010750:Phosphoproteins / Q000378:metabolism*; D010768:Phosphoserine; D010769:Phosphothreonine; D010982:Platelet-Derived Growth Factor / Q000502:physiology*; D014158:Transcription, Genetic
D018932:Chemokine CCL2; D002630:Chemotactic Factors; D004268:DNA-Binding Proteins; D016328:NF-kappa B; D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D010750:Phosphoproteins; D010982:Platelet-Derived Growth Factor; D010769:Phosphothreonine; D010768:Phosphoserine; D003513:Cycloheximide