Biomaterial Database

Transcription factor AP-2 regulates human insulin-like growth factor binding protein-5 gene expression. 1995

C Duan, and D R Clemmons

Department of Medicine, University of North Carolina at Chapel Hill 27599, USA.

Insulin-like growth factor binding protein-5 (IG-FBP-5) is an important modulator of IGF actions. IG-FBP-5 mRNA is abundant in human fibroblasts and is regulated by cAMP. To understand the molecular mechanism underlying this cell type-specific expression and regulation, we isolated the 5'-flanking region of the human IGFBP-5 gene and fused it to a promoter-less reporter plasmid encoding luciferase. Transient transfection of the construct into fibroblasts displayed both constitutive and cAMP-induced promoter activity in an orientation-specific manner. Sequence analysis revealed the existence of distal and proximal consensus AP-2 recognition sites located 5' from the TATA box. Both sequences bound specifically to human AP-2 in vitro by gel shift mobility assay. The possible role of AP-2 was examined by cotransfection of AP-2-deficient HepG2 cells with the IGFBP-5 promoter construct and a human AP-2 expression construct. Cotransfection with AP-2 significantly elevated IGFBP-5 promoter activity. This trans-activation was IGFBP-5 promoter and AP-2 specific. In AP-2 abundant fibroblasts, expression of AP-2B, a dominant-negative inhibitor of AP-2, suppressed IGFBP-5 promoter activity. In HepG2 cells, AP-2B alone had no significant effect, but the AP-2-induced activation of promoter activity was inhibited by AP-2B in a dose-dependent manner. The relative functional importance of the putative AP-2 binding sites was examined using a number of deletion mutants and point mutations. When the first two distal CCCCACCC-like putative AP-2 sites were deleted or mutated, there was no change in AP-2-induced trans-activation. Deletion or mutation of the proximal GCCNNNGGC-like sequences, however, abolished the AP-2-induced activation. These results suggest that AP-2 regulates the IGFBP-5 gene expression through the proximal GCCNNNGGC-like sequences. This AP-2-mediated trans-activation contributes at least in part to the constitutively high expression of IGFBP-5 in fibroblasts and to the cAMP responsiveness of this gene.

UI	MeSH Term	Description	Entries
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D004268	DNA-Binding Proteins	Proteins which bind to DNA. The family includes proteins which bind to both double- and single-stranded DNA and also includes specific DNA binding proteins in serum which can be used as markers for malignant diseases.	DNA Helix Destabilizing Proteins,DNA-Binding Protein,Single-Stranded DNA Binding Proteins,DNA Binding Protein,DNA Single-Stranded Binding Protein,SS DNA BP,Single-Stranded DNA-Binding Protein,Binding Protein, DNA,DNA Binding Proteins,DNA Single Stranded Binding Protein,DNA-Binding Protein, Single-Stranded,Protein, DNA-Binding,Single Stranded DNA Binding Protein,Single Stranded DNA Binding Proteins
D005786	Gene Expression Regulation	Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation.	Gene Action Regulation,Regulation of Gene Expression,Expression Regulation, Gene,Regulation, Gene Action,Regulation, Gene Expression
D005809	Genes, Regulator	Genes which regulate or circumscribe the activity of other genes; specifically, genes which code for PROTEINS or RNAs which have GENE EXPRESSION REGULATION functions.	Gene, Regulator,Regulator Gene,Regulator Genes,Regulatory Genes,Gene, Regulatory,Genes, Regulatory,Regulatory Gene
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D001483	Base Sequence	The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.	DNA Sequence,Nucleotide Sequence,RNA Sequence,DNA Sequences,Base Sequences,Nucleotide Sequences,RNA Sequences,Sequence, Base,Sequence, DNA,Sequence, Nucleotide,Sequence, RNA,Sequences, Base,Sequences, DNA,Sequences, Nucleotide,Sequences, RNA
D013002	Somatomedins	Insulin-like polypeptides made by the liver and some fibroblasts and released into the blood when stimulated by SOMATOTROPIN. They cause sulfate incorporation into collagen, RNA, and DNA synthesis, which are prerequisites to cell division and growth of the organism.	Sulfation Factor,Somatomedin,Factor, Sulfation
D014157	Transcription Factors	Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process.	Transcription Factor,Factor, Transcription,Factors, Transcription
D015533	Transcriptional Activation	Processes that stimulate the GENETIC TRANSCRIPTION of a gene or set of genes.	Gene Activation,Genetic Induction,Transactivation,Induction, Genetic,Trans-Activation, Genetic,Transcription Activation,Activation, Gene,Activation, Transcription,Activation, Transcriptional,Genetic Trans-Activation,Trans Activation, Genetic
D050656	Transcription Factor AP-2	A family of DNA binding proteins that regulate expression of a variety of GENES during CELL DIFFERENTIATION and APOPTOSIS. Family members contain a highly conserved carboxy-terminal basic HELIX-TURN-HELIX MOTIF involved in dimerization and sequence-specific DNA binding.	AP-2 Enhancer Binding Protein,AP-2 alpha Protein,AP-2 beta Protein,AP-2 epsilon Protein,AP-2 gamma Protein,AP-2delta Protein,Activator Protein AP-2,Enhancer-Binding Protein AP-2,TFAP2B Protein,TFAP2alpha Protein,Transcription Factor AP-2 alpha Protein,Transcription Factor AP-2 beta Protein,Transcription Factor AP-2 delta Protein,Transcription Factor AP-2 epsilon Protein,Transcription Factor AP-2 gamma Protein,Transcription Factor AP-2alpha,Transcription Factor AP-2beta,Transcription Factor AP-2epsilon,Transcription Factor AP-2gamma,Transcription Factor AP2,Transcription Factor Ap-2delta,AP 2 Enhancer Binding Protein,AP 2 alpha Protein,AP 2 beta Protein,AP 2 gamma Protein,AP 2delta Protein,AP-2, Activator Protein,AP-2, Enhancer-Binding Protein,AP-2, Transcription Factor,AP-2alpha, Transcription Factor,AP-2beta, Transcription Factor,AP-2epsilon, Transcription Factor,AP-2gamma, Transcription Factor,Activator Protein AP 2,Ap-2delta, Transcription Factor,Enhancer Binding Protein AP 2,Transcription Factor AP 2,Transcription Factor AP 2 alpha Protein,Transcription Factor AP 2 beta Protein,Transcription Factor AP 2 delta Protein,Transcription Factor AP 2 epsilon Protein,Transcription Factor AP 2 gamma Protein,Transcription Factor AP 2alpha,Transcription Factor AP 2beta,Transcription Factor AP 2epsilon,Transcription Factor AP 2gamma,Transcription Factor Ap 2delta