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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In human cells infected with herpes simplex virus (HSV), viral gene expression is initiated by the virion protein VP16. VP16 does not bind DNA directly but forms a multiprotein complex on the viral immediate-early gene promoters with two cellular proteins: the POU domain protein Oct-1 and host cell factor (HCF; also called C1, VCAF, and CFF). Despite its apparent role in stabilizing the VP16-induced transcription complex, the natural biological role of HCF is unclear. Only recently HCF has been implicated in control of the cell cycle. To determine the role of HCF in cells and answer why HSV has evolved an HCF-dependent mechanism for the initiation of the lytic cycle, we identified the first human ligand for HCF (R. Lu et al., Mol. Cell. Biol. 17:5117-5126, 1997). This protein, Luman, is a member of the CREB/ATF family of transcription factors that can activate transcription from promoters containing cyclic AMP response elements (CRE). Here we provide evidence that Luman and VP16 share two important structural features: an acidic activation domain and a common mechanism for binding HCF. We found that Luman, its homolog in Drosophila, dCREB-A (also known as BBF-2), and VP16 bind to HCF by a motif, (D/E)HXY(S/A), present in all three proteins. In addition, a mutation (P134S) in HCF that prevents VP16 binding also abolishes its binding to Luman and dCREB-A. We also show that while interaction with HCF is not required for the ability of Luman to activate transcription when tethered to the GAL4 promoter, it appears to be essential for Luman to activate transcription through CRE sites. These data suggest that the HCF-Luman interaction may represent a conserved mechanism for transcriptional regulation in metazoans, and HSV mimics this interaction with HCF to monitor the physiological state of the host cell.
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PMID:The herpesvirus transactivator VP16 mimics a human basic domain leucine zipper protein, luman, in its interaction with HCF. 965 67

The murine epididymal retinoic acid-binding protein (mE-RABP) is specifically synthesized in the mouse mid/distal caput epididymidis and secreted in the lumen. In this report, we have demonstrated by Southern blot analysis of genomic DNA that mE-RABP is encoded by a single-copy gene. A mouse 129/SvJ genomic bacterial artificial chromosome (BAC) library was screened using a cDNA encoding the minor form of mE-RABP. One positive BAC clone was characterized and sequenced to determine the nucleotide sequence of the entire mE-RABP gene. The molecular cloning of the mE-RABP gene completes the characterization of the 20.5-kDa-predicted preprotein leading to the minor and major forms of mE-RABP. Comparison of the DNA sequence of the promoter and coding regions with that of the rat epididymal secretory protein I (ESP I) gene showed that the mE-RABP gene is the orthologue of the ESP I gene that encodes a rat epididymal retinoic acid-binding protein. Several regulatory elements, including a putative androgen receptor binding site, "CACCC-boxes," NF-1, Oct-1, and SP-1 recognition sites, are conserved in the proximal promoter. Analysis of the nucleotide sequence of the mE-RABP gene revealed the presence of seven exons and showed that the genomic organization is highly related to other genes encoding lipocalins. The mE-RABP gene was mapped by fluorescent in situ hybridization to the [A3-B] region of the murine chromosome 2. Our data, combined with that of others, suggest that the proximal segment of the mouse chromosome 2 may be a rich region for genes encoding lipocalins with a genomic organization highly related to the mE-RABP gene.
Mol Reprod Dev 1998 Aug
PMID:Genomic organization and chromosomal localization of the murine epididymal retinoic acid-binding protein (mE-RABP) gene. 966 22

The Rho family of small GTP-binding proteins is involved in the regulation of cytoskeletal structure, gene transcription, specific cell fate development, and transformation. We demonstrate in this report that overexpression of an activated form of Rho enhances AP-1 activity in Jurkat T cells in the presence of phorbol myristate acetate (PMA), but activated Rho (V14Rho) has little or no effect on NFAT, Oct-1, and NF-kappaB enhancer element activities under similar conditions. Overexpression of a V14Rho construct incapable of membrane localization (CAAX deleted) abolishes PMA-induced AP-1 transcriptional activation. The effect of Rho on AP-1 is independent of the mitogen-activated protein kinase pathway, as a dominant-negative MEK and a MEK inhibitor (PD98059) did not affect Rho-induced AP-1 activity. V14Rho binds strongly to protein kinase Calpha (PKCalpha) in vivo; however, deletion of the CAAX site on V14Rho severely diminished this association. Evidence for a role for PKCalpha as an effector of Rho was obtained by the observation that coexpression of the N-terminal domain of PKCalpha blocked the effects of activated Rho plus PMA on AP-1 transcriptional activity. These data suggest that Rho potentiates AP-1 transcription during T-cell activation.
Mol Cell Biol 1998 Sep
PMID:The small GTP-binding protein Rho potentiates AP-1 transcription in T cells. 971 May 82

The lymphoid-specific transcriptional coactivator OBF-1 (also known as OCA-B or Bob-1) is recruited to octamer site-containing promoters by interacting with Oct-1 or Oct-2 and thereby enhances the transactivation potential of these two Oct factors. For this interaction the POU domain is sufficient. By contrast, OBF-1 does not interact with the POU domains of other POU proteins, such as Oct-4, Oct-6, or Pit-1, even though these factors bind efficiently to the octamer motif. Here we examined the structural requirements for selective interaction between the POU domain and OBF-1. Previous data have shown that formation of a ternary complex among OBF-1, the POU domain, and the DNA is critically dependent on residues within the octamer site. By methylation interference analysis we identified bases that react differently in the presence of OBF-1 compared to the POU domain alone, and using phosphothioate backbone-modified probes in electrophoretic mobility shift assays, we identified several positions influencing ternary complex formation. We then used Oct-1/Pit-1 POU domain chimeras to analyze the selectivity of the interaction between OBF-1 and the POU domain. This analysis indicated that both the POU specific domain (POUS) and the POU homeodomain (POUH) contribute to complex formation. Amino acids that are different in the Pit-1 and Oct-1 POU domains and are considered to be solvent accessible based on the Oct-1 POU domain/DNA cocrystal structure were replaced with alanine residues and analyzed for their influence on complex formation. Thereby, we identified residues L6 and E7 in the POUS and residues K155 and I159 in the POUH to be critical in vitro and in vivo for selective interaction with OBF-1. Furthermore, in an in vivo assay we could show that OBF-1 is able to functionally recruit two artificially separated halves of the POU domain to the promoter DNA, thereby leading to transactivation. These data allow us to propose a model of the interaction between OBF-1 and the POU domain, whereby OBF-1 acts as a molecular clamp holding together the two moieties of the POU domain and the DNA.
Mol Cell Biol 1998 Dec
PMID:Coactivator OBF-1 makes selective contacts with both the POU-specific domain and the POU homeodomain and acts as a molecular clamp on DNA. 981 26

PRL gene transcription is primarily regulated by dopamine, which lowers cAMP levels and inhibits protein kinase A (PKA) activity. Current data indicate that the cAMP/PKA response maps to the most proximal Pit-1/Pit-1beta binding site footprint I (FP I) on the rat PRL (rPRL) promoter. Pit-1, a POU-homeo domain transcription factor, is specifically expressed in the anterior pituitary and is required both for the normal development of anterior pituitary cell types, somatotrophs, lactotrophs, and thyrotrophs, and for the expression of their hormones: GH, PRL, and TSHbeta. Pit-1 has been shown to functionally interact, via FP I, with several transcription factors, including Oct-1, a ubiquitous homeobox protein, and thyrotroph embryonic factor, which is found in lactotrophs, to activate basal rPRL promoter activity. Pit-1beta/GHF-2, a distinct splice isoform of Pit-1, acts to inhibit Ras-activated transcription from the rPRL promoter, which is mediated by a functional interaction between Pit-1 and Ets-1 at the most distal Pit-1 binding site (FP IV). In this manuscript we show 1) that the Pit-1beta isoform not only fails to block PKA activation, but is, in fact, a superior mediator of the PKA response; 2) that the PKA response requires intact POU-specific and POU-homeo domains of Pit-1; and 3) that Oct-1, but not thyrotroph embryonic factor, functions as a Pit-1-interacting factor to mediate an optimal PKA response.
Mol Endocrinol 1999 Feb
PMID:Reconstitution of the protein kinase A response of the rat prolactin promoter: differential effects of distinct Pit-1 isoforms and functional interaction with Oct-1. 997 53

The promoter of the mouse inducible nitric oxide synthase (iNOS) has a putative octamer motif (ATGCAAAA) which exists 24 bp upstream from the TATA box and is mismatched at a single residue from the consensus octamer motif. To examine whether this site is involved in iNOS expression, we constructed various deletions and site-directed mutants of the iNOS promoter linked to the chloramphenicol acetyltransferase (CAT) reporter gene, transfected the constructs into RAW 264.7 macrophages, and stimulated the cells with interferon-gamma (IFN-gamma) and/or lipopolysaccharide (LPS). CAT activity was not induced by LPS in constructs containing only the octamer motif (-71 to +82), but was induced with constructs containing the octamer motif and the upstream sequences of the NF-kappaB site (-91 to +82). However, a site-directed mutation of the octamer motif in the context of the -91 to +82 promoter construct or an extended promoter construct (-1542 to +82) abolished IFN-gamma and/or LPS-induced CAT activity. Similar results were obtained from site-directed mutants at either the NF-kappaB site or both the NF-kappaB site and octamer motif in these two constructs. In addition, we demonstrated that the conversion of the iNOS octamer motif into a consensus sequence increased CAT activity. Electrophoretic mobility shift assay (EMSA) performed with the NF-kappaB site or the octamer motif-containing oligonucleotide probe revealed that NF-kappaB binding was induced by LPS treatment, while the Oct-1 binding was constitutive. Competition assays performed with octamer-related oligonucleotide competitors derived from the immunoglobulin-kappaB or SV40 promoter confirmed the identity of the iNOS promoter sequence as being a Oct-1 binding site. EMSA carried out using a probe containing both the NF-kappaB site and the octamer motif identified two LPS-induced complexes. Competition assays with each NF-kappaB site or octamer motif competitor revealed that NF-kappaB and Oct-1 were present in these two complexes. These data suggest that, besides the NF-kappaB site, the octamer motif is essential for the maximal expression of the iNOS gene in murine macrophages, and the direct interaction of Oct-1 and NF-kappaB is important for the regulation of this gene.
Mol Cells 1999 Feb 28
PMID:Octamer motif is required for the NF-kappaB-mediated induction of the inducible nitric oxide synthase gene expression in RAW 264.7 macrophages. 1010 79

Motifs for sequence specific-protein-DNA interactions, such as helix-turn-helix, zinc finger and leucine zipper, are now better understood as a result of extensive studies of three-dimensional (3D) structures of transcription factors. On the other hand, little attention has been paid to motifs for sequence nonspecific binding, namely DNA-phosphate binding. To address the question whether different transcription factors and DNA manipulation enzymes, that is enzymes that work on DNA, share a similar mode of phosphate binding, we surveyed interactions between DNA and protein module, a structural unit of a globular protein. We analyzed the modular organization of DNA polymerase beta and found that residues making contact with DNA phosphates were localized to five modules. Structural comparison of these phosphate-binding modules against others in transcription factors and DNA manipulation enzymes revealed that DNA polymerase beta, the Oct-1 POU domain, 434 Cro and the Arc repressor have a phosphate-binding module with 3D structures similar to one another. This newly detected module, the phosphate-binding helix-turn-helix (pbHTH) module, named for its function and 3D structure, interacts with DNA by (i) making hydrogen bonds between a DNA phosphodiester oxygen and an amino hydrogen of the main chain located at the N-terminus of a C-terminal alpha-helix, and (ii) making electrostatic interactions between DNA phosphates and side chains of lysine or arginine. Finding structurally and functionally similar phosphate-binding units in different transcription factors and DNA manipulation enzymes suggests that shuffling of modules is not limited to the DNA base-recognition motif. Phosphate-binding modules are apparently also shuffled in DNA-binding proteins.
Cell Mol Life Sci 1999 Mar
PMID:Repetitive use of a phosphate-binding module in DNA polymerase beta, Oct-1 POU domain and phage repressors. 1022 61

The expression of immunoglobulin genes is controlled in part by the DNA-binding protein Oct-1 and the B cell-specific transcription co-activator, Bob1 (also known as OCA-B or OBF-1) that together form a complex on the Igkappa promoter. We have characterised the assembly of the ternary complex using biophysical methods. Bob1 binds specifically as a monomer to the complex of the Oct-1 DNA-binding domain (Oct-1 POU) and the Igkappa promoter, but binds weakly to either Oct-1 POU or the Igkappa promoter alone, indicating that both are required to make an avid complex. Ternary complex formation requires a defined DNA sequence, as the stability of the complex can be strongly affected by a single base-pair change or by removing 5-methyl groups from selected thymine bases.In isolation, Bob1 appears to have little secondary structure, but may become partially structured upon recruitment into the ternary complex as demonstrated by circular dichroism spectra and calorimetry. These and other findings suggest that ternary complex formation requires a defined geometry of the POU/DNA complex, and that the co-activator makes stereo-specific contacts to both the POU protein and the major groove of the DNA that induces its fold.
J Mol Biol 1999 May 21
PMID:Oct-1 POU and octamer DNA co-operate to recognise the Bob-1 transcription co-activator via induced folding. 1032 90

Eukaryotic transcriptional activators generally comprise both a DNA-binding domain that recognizes specific cis-regulatory elements in the target genes and an activation domain which is essential for transcriptional stimulation. Activation domains typically behave as structurally and functionally autonomous modules that retain their intrinsic activities when directed to a promoter by a variety of heterologous DNA-binding domains. Here we report that OBF-1, a B-cell-specific coactivator for transcription factor Oct-1, challenges this traditional view in that it contains an atypical activation domain that exhibits two unexpected functional properties when tested in the yeast Saccharomyces cerevisiae. First, OBF-1 by itself has essentially no intrinsic activation potential, yet it strongly synergizes with other activation domains such as VP16 and Gal4. Second, OBF-1 exerts its effect in association with DNA-bound Oct-1 but is inactive when attached to a heterologous DNA-binding domain. These findings suggest that activation by OBF-1 is not obtained by simple recruitment of the coactivator to the promoter but requires interaction with DNA-bound Oct-1 to stimulate a step distinct from those regulated by classical activation domains.
Mol Cell Biol 1999 Jun
PMID:B-Cell coactivator OBF-1 exhibits unusual transcriptional properties and functions in a DNA-bound Oct-1-dependent fashion. 1033 Jan 65

UTF1 is a transcriptional coactivator which has recently been isolated and found to be expressed mainly in pluripotent embryonic stem (ES) cells (A. Okuda, A. Fukushima, M. Nishimoto, et al., EMBO J. 17:2019-2032, 1998). To gain insight into the regulatory network of gene expression in ES cells, we have characterized the regulatory elements governing UTF1 gene expression. The results indicate that the UTF1 gene is one of the target genes of an embryonic octamer binding transcription factor, Oct-3/4. UTF1 expression is, like the FGF-4 gene, regulated by the synergistic action of Oct-3/4 and another embryonic factor, Sox-2, implying that the requirement for Sox-2 by Oct-3/4 is not limited to the FGF-4 enhancer but is rather a general mechanism of activation for Oct-3/4. Our biochemical analyses, however, also reveal one distinct difference between these two regulatory elements: unlike the FGF-4 enhancer, the UTF1 regulatory element can, by its one-base difference from the canonical octamer-binding sequence, selectively recruit the complex comprising Oct-3/4 and Sox-2 and preclude the binding of the transcriptionally inactive complex containing Oct-1 or Oct-6. Furthermore, our analyses reveal that these properties are dictated by the unique ability of the Oct-3/4 POU-homeodomain that recognizes a variant of the Octamer motif in the UTF1 regulatory element.
Mol Cell Biol 1999 Aug
PMID:The gene for the embryonic stem cell coactivator UTF1 carries a regulatory element which selectively interacts with a complex composed of Oct-3/4 and Sox-2. 1040 35


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