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Transcription Factor AP-2Transcription FactorsTranscription, GeneticDNA-Binding ProteinsTranscription Factor AP-1Promoter Regions, GeneticMolecular Sequence DataBase SequenceGene Expression RegulationSp1 Transcription FactorTranscriptional ActivationBinding SitesProto-Oncogene Proteins c-junTrans-ActivatorsBasic Helix-Loop-Helix Transcription FactorsRNA, MessengerProtein BindingNuclear ProteinsRepressor ProteinsCell LineForkhead Transcription FactorsHomeodomain ProteinsGene Expression Regulation, DevelopmentalSignal TransductionAmino Acid SequenceDNABasic-Leucine Zipper Transcription FactorsMutationCell NucleusCell DifferentiationTransfectionKruppel-Like Transcription FactorsTranscription Factors, TFIIChromatin ImmunoprecipitationGenes, ReporterHeLa CellsYY1 Transcription FactorSTAT3 Transcription FactorCells, CulturedGATA4 Transcription FactorTranscription Factor TFIIDNFATC Transcription FactorsActivating Transcription Factor 3Sp3 Transcription FactorNF-kappa BTranscription Initiation SiteReverse Transcriptase Polymerase Chain ReactionZinc FingersPaired Box Transcription FactorsElectrophoretic Mobility Shift AssayActivating Transcription Factor 2Transcription Factor TFIIBEnhancer Elements, GeneticRegulatory Sequences, Nucleic AcidE2F1 Transcription FactorGene Expression ProfilingRNA Polymerase IICloning, MolecularRecombinant Fusion ProteinsBasic Helix-Loop-Helix Leucine Zipper Transcription FactorsPlasmidsMEF2 Transcription FactorsGATA3 Transcription FactorGATA1 Transcription FactorGene ExpressionGATA2 Transcription FactorGene Expression Regulation, FungalTCF Transcription FactorsGATA Transcription FactorsMicrophthalmia-Associated Transcription FactorProtein Structure, TertiaryLuciferasesSTAT1 Transcription FactorActivating Transcription FactorsCell Line, TumorPhosphorylationTranscription Factor RelAE2F Transcription FactorsSaccharomyces cerevisiaeHelix-Loop-Helix MotifsChromatinGene Expression Regulation, PlantOligonucleotide Array Sequence AnalysisSaccharomyces cerevisiae ProteinsModels, BiologicalSequence Homology, Amino AcidGATA6 Transcription FactorActivating Transcription Factor 4Transcription Factor 7-Like 1 ProteinCyclic AMP Response Element-Binding ProteinActivating Transcription Factor 1Proto-Oncogene ProteinsTranscription Factor TFIIIABlotting, WesternMice, KnockoutTATA BoxNFI Transcription FactorsTumor Cells, CulturedDown-RegulationModels, Genetic

SELEX and missing phosphate contact analyses reveal flexibility within the AP-2[alpha] protein: DNA binding complex. (9/687)

The AP-2 family of transcription factors are defined by the presence of a novel DNA binding domain, termed a 'basic helix-span-helix' motif. The AP-2 genes regulate important aspects of vertebrate embryogenesis and have also been linked to the control of cell proliferation and tumorigenesis, but the cellular targets that the AP-2 proteins control are largely undefined. In particular, since only a limited number of sequences have previously been utilized to define the nature of the AP-2 binding site, the range of DNA sequences recognized by the AP-2 proteins remains unknown. We have therefore utilized a SELEX analysis to identify multiple new AP-2[alpha] binding sites. Moreover, we have devised a novel missing phosphate and nucleotide competition analysis to characterize the residues in the binding site required for AP-2[alpha] protein:DNA contact. These studies suggest that the AP-2[alpha] protein:DNA complex is flexible and indicate that AP-2[alpha] can bind three related sequence motifs: GCC N3 GGC, GCC N4 GGC and GCC N3/4 GGG. The availability of these more refined consensus sequences should assist in the identification of target genes for this critical transcription factor.  (+info)

AP-2 enhances Sp1-dependent activation of the growth-regulated human ATP/ADP translocator. (10/687)

The mammalian ATP/ADP translocator isoform-2 (ANT2) gene is growth-activated. Regulation of the gene appears to involve Sp1, as an essential activator, and a suppressor through an Sp1 core element next to the transcription start. We show here that the proximal promoter also binds AP-2 strongly and specifically to two sites, one of which overlaps the Sp1 proximal suppressor site. AP-2 binds with an affinity of 10 to15 fold higher than that of Sp1. AP-2 alone does not alter the ANT2 promoter activity in transfected SL2 cells, but enhances the Sp1-dependent activation of the promoter several fold. Enhancement by AP-2 is observed only when Sp1 is limiting for transcription activation. These data suggest that the cellular AP-2/Sp1 ratio might influence ANT2 expression in developing or differentiating cells.  (+info)

Synergy of PEBP2/CBF with mi transcription factor (MITF) for transactivation of mouse mast cell protease 6 gene. (11/687)

The mi locus encodes a member of the basic - helix - loop - helix - leucine zipper (bHLH-Zip) protein family of transcription factors (hereafter called MITF). Although the bHLH-Zip family transcription factors generally recognize and bind CANNTG motifs, the expression of mouse mast cell protease 6 (MMCP-6) gene is regulated by MITF through the GACCTG motif in the promoter region. The GACCTG motif was partly overlapped the TGTGGTC sequence, which was bound by polyomavirus enhancer binding protein 2 (PEBP2). In the present study, the effect of PEBP2 on the expression of MMCP-6 gene was examined. PEBP2 that is composed of alpha and beta subunits was expressed by mast cell lines and cultured mast cells derived from spleen. The overexpression of dominant negative PEBP2 cDNA reduced the expression of MMCP-6. Moreover, the simultaneous transfection of the plasmid containing MITF cDNA and the plasmid containing PEBP2 cDNA increased the MMCP-6 promoter activity. For the synergistic action of PEBP2 and MITF, the intact GACCTG and TGTGGTC motifs were prerequisite. The PEBP2alphaB1 mutant which lacked the region downstream from the Runt domain did not bind MITF and lost the synergistic function. These results indicated that PEBP2 and MITF synergistically transactivated the MMCP-6 gene and that the region downstream from the Runt domain of PEBP2alphaB1 was essential for the physical and functional interactions with MITF.  (+info)

Cutting edge: SIV Nef protein utilizes both leucine- and tyrosine-based protein sorting pathways for down-regulation of CD4. (12/687)

The Nef protein is unique to primate lentiviruses and is closely linked to accelerated pathogenesis in both human and monkey hosts. Nef acts to down-regulate CD4 and MHC class I, two receptors important for immune function. A recent report demonstrated the presence of two tyrosine motifs in SIV Nef that contribute to its ability to down-regulate CD4 and to associate with clathrin adaptors. These tyrosine motifs are not present in HIV-1 Nef, which instead utilizes a leucine-based motif for its down-regulation of CD4. We now report that SIV Nef also contains a conserved leucine-based motif that contributes to CD4 down-regulation, functions to stimulate internalization, and contributes to the association of SIV Nef with clathrin adaptors AP-1 and AP-2. These results demonstrate that SIV Nef differs from HIV-1 Nef by its ability to use two parallel pathways of the protein-sorting machinery based on either tyrosine or leucine motifs.  (+info)

Regulation of a cell type-specific silencer in the human interleukin-3 gene promoter by the transcription factor YY1 and an AP2 sequence-recognizing factor. (13/687)

Negative regulation of cytokine gene transcription is an important mechanism in maintaining homeostasis of immune function. In this study, we characterized a silencer element in the human interleukin-3 gene promoter that is responsible for the cell-specific expression of interleukin-3. This silencer activity was proposed to be mediated by an unidentified nuclear inhibitory protein (NIP). In this study, we have identified two nuclear factors that are responsible for the silencer activity in T cells. The NIP element forms four specific DNA-protein complexes (designated as complexes A-D) with the Jurkat nuclear proteins. Complex A contains a nuclear protein that shares DNA-binding specificity with the transcription factor AP2 (designated as an AP2 sequence-recognizing factor (ASRF)). Formation of this ASRF complex is required for the NIP silencer function, as mutation of the ASRF-binding site abrogated the silencer activity. Complex B contains the nuclear factor YY1 (Yin-Yang 1), whose function is to down-regulate ASRF activity in the silencer. YY1 activity is supported by data from mutation and cotransfection analyses. Complexes C and D are formed by nonspecific binding proteins and do not express any regulatory activity in the NIP element. These data indicate that a cell type-specific silencer activity might be determined by a unique profile of ubiquitous transcription factors.  (+info)

p22/WAF1 expression in human colorectal carcinoma: association with p53, transcription factor AP-2 and prognosis. (14/687)

p21/WAF1 expression was studied in a series of 162 colorectal carcinoma patients and its relation to p53- and activator protein (AP)-2 expressions and to stage as well as survival was assessed. p21 expression was moderate or intense in 33% of the tumours, and 53% of the tumours had moderate or strong p53 staining intensity. Eighty-nine percent of the tumours showed a weak cytoplasmic AP-2 signal. As expected, p21 and p53 stainings were inversely related to each other (P < 0.001). There was a significant positive association between p21 and AP-2 expression levels (P= 0.01). p21 intensity and percentage were higher in Dukes' A and B stages (P< 0.001). The cancer-related survival and recurrence-free survival (RFS) rates were significantly lower among patients with a low signal for p21 (P< 0.001) and low p21 percentage in tumour epithelium (P < 0.001). High p53 staining intensity in tumour epithelium predicted poor survival (P = 0.01) and RFS (P = 0.003). In the multivariate analysis, p21 percentage distribution independently predicted cancer-related survival in all cases, and p21 expression intensity in T1-4/N0-3/M0 and T1-3/N0/M0 cases. p21 percentage distribution was an independent predictor of RFS in all and T1-3/N0/M0 cases. AP-2 staining did not reach any prognostic significance. These results suggest that the immunohistochemical detection of cyclin-dependent kinase inhibitor p21 could be used to predict more precisely the outcome of colorectal cancer patients.  (+info)

Expression of MXI1, a Myc antagonist, is regulated by Sp1 and AP2. (15/687)

MXI1, a member of the MAD family of Myc antagonists, encodes a transcription factor whose expression must be tightly regulated to maintain normal cell growth and differentiation. To more closely investigate the transcriptional regulation of the human MXI1 gene, we have cloned and characterized the MXI1 promoter. After clarification of the 5'- and 3'-untranslated regions of the cDNA (indicating that the true length of the MXI1 transcript is 2643 base pairs), we identified two transcription initiation sites. We subsequently isolated the MXI1 promoter, which is GC-rich and lacks a TATA box. Although it contains at least six potential initiator sequences, functional studies indicate the proximal two initiator sequences in combination with nearby Sp1 and MED-1 sites together account for virtually all promoter activity. We also demonstrate that MXI1 promoter activity is repressed by high levels of AP2. These studies provide further insight into the complex regulatory mechanisms governing MXI1 gene expression and its role in cellular differentiation and tumor suppression.  (+info)

AP2alpha and AP2gamma: a comparison of binding site specificity and trans-activation of the estrogen receptor promoter and single site promoter constructs. (16/687)

The AP2 transcription factors exhibit a high degree of homology in the DNA binding and dimerization domains. In this study, we methodically compared the binding specificity of AP2alpha and AP2gamma using PCR-assisted binding site selection and competitive gel shift assay and determined that the consensus binding site for both factors is(G)/(C)CCNN(A/)C(/G)(G)/(A)G(G/)C(/T.)The use of single site promoter constructs with either a high or low affinity site demonstrated a direct relationship between site affinity and transcriptional activation. Overexpression of AP2alpha and AP2gamma resulted in the activation of a low affinity binding site construct to levels comparable to those seen with a high affinity site construct at lower amounts of protein expression. Both AP2alpha and AP2gamma were able to trans-activate the cloned human estrogen receptor alpha promoter in ER-negative MDA-MB-231 cells through high affinity AP2 sites in the untranslated leader sequence. This provides a functional mechanism to explain the correlation between AP2 activity and estrogen receptor expression in breast cancer. Since there is overexpression of AP2 factors in breast cancer compared to normal breast epithelium, our results suggest that increased factor expression may activate a set of target genes containing lower affinity binding sites that would normally not be expressed in normal breast epithelium.  (+info)