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At least 1,495 records · Page 83Linked to original sources
PubMed1997

Diverse transcription factors are involved in the quantitative regulation of transcriptional activation of kappa promoters.

Immunoglobulin kappa promoters show sequence divergence but conserved function between different subgroups. Here we show that three separate 5' elements are required for synergistic stimulation of transcription with the decamer in a kappa promoter. These sites are a 5' E-box, a 3' AT-rich region in the pentadecamer (pd) element, and the kappa-Y element. Elf-1 is a novel kappa-Y element ligand induced upon mitogenic stimulation of resting B lymphocytes. Furthermore, the 5' E2A-like E-box in the pd element could be substituted by an upstream stimulatory factor motif with conservation of function. Thus, the synergistic activation requirements of kappa transcription is strictly dependent on the quantitative presence of transcription factor-binding motifs 5' of the decamer, but these differ qualitatively in that they may bind an array of proteins with conserved function.

Animals↗
PubMed2001

Transcription factor BACH2 is transcriptionally regulated by the BCR/ABL oncogene.

Expression of BCR/ABL, a constitutively active tyrosine kinase, is a primary event in the pathogenesis of chronic myeloid leukemia (CML) and Ph-positive acute lymphoblastic leukemia (Ph+ALL). Inhibition of the BCR/ABL kinase activity in the BV173 CML cell line with STI571 resulted in a significant overexpression of a 10-kb novel mRNA, found to be the human ortholog of the murine Bach2, a B-cell-specific transcription factor. The human BACH2 cDNA is >9,120 bp long and includes an open reading frame of 2,526 bp encoding a protein with a basic leucine zipper (bZip) and a BTB/POZ domain, mediating DNA-binding and heterodimerization. BACH2 was consistently upregulated (2-10-fold) in all 10 Ph+ lymphoid lines tested following BCR/ABL inhibition. In CML myeloid cell lines (n = 8) and BCR/ABL-negative lines (n = 6), BACH2 was either undetectable by Northern blotting or did not change in response to STI571, suggesting that BACH2 repression by BCR/ABL may be specifically relevant to lymphoid transformation. Quantitative RT/PCR revealed a significantly lower level of BACH2 expression in leukocytes from patients with CML (n = 24) as compared to normal individuals (n = 23) (P < 0.0005). Moreover, CD34+ cells treated in vitro with STI571 exhibited a consistent upregulation of BACH2 in 8 of 10 CMLs but in none of the 9 normal individuals tested. Transcription regulation of BACH2 in BCR/ABL-positive cells was exerted via the MEK pathways, as shown by their responses to the U0126-specific inhibitor. Radiation hybrid mapping and FISH revealed that BACH2 is located on chromosome 6, band q15, a region frequently associated with deletions in ALL and non-Hodgkin's lymphoma, suggesting its possible role as a tumor suppressor gene. However, no rearrangement or loss of signal was observed by Southern blotting in 34 lymphomas, 10 B-cell ALLs, or seven reactive lymph nodes. The pattern of BACH2 expression in BCR/ABL-positive cells suggests that transcriptional repression by this regulator is impaired in CML and may contribute to the emergence of lymphoid blast crisis.

Adult↗
PubMed1993

Characterization of the transcription activation function and the DNA binding domain of transcriptional enhancer factor-1.

The regions of transcriptional enhancer factor-1 (TEF-1) required for its activation function and sequence-specific DNA binding have been determined. Deletion analysis of a chimera between TEF-1 and the GAL4 DNA binding domain (DBD) indicated that at least three regions of TEF-1 were involved in transactivation. However, none of these regions functioned as independent activating domains. Moreover, none of the GAL4 chimeras containing individual TEF-1 regions interfered with the activity of endogenous HeLa cell TEF-1, while interference was observed with the GAL4-TEF-1 chimeras which functioned as transactivators. These results indicate that there is a general correlation between the abilities of a given GAL4-TEF-1 chimera to function in transcriptional activation and interference, thus supporting the idea that transactivation by TEF-1 is mediated by a limiting transcriptional intermediary factor. In addition, we show experimentally that the TEA/ATTS domain is a novel class of DBD involved in the sequence-specific DNA binding of TEF-1 and its Drosophila homologue scalloped. Two other regions of TEF-1 are also required for DNA binding. These regions are not part of the minimum DBD, but may function by antagonizing the effect of sequences which negatively regulate DNA binding mediated by both the TEF-1 TEA/ATTS domain and the GAL4 DBD. In addition, analysis of TEF-1 and scalloped derivatives in which their TEA/ATTS domains have been interchanged further indicates that the TEA/ATTS domain is not the only determinant of DNA binding specificity.

Amino Acid Sequence↗
PubMed1994

The heat shock transcription factor in liver exists in a form that has DNA binding activity but no transcriptional activity.

The binding activity of the heat shock transcription factor (HSF) to the heat shock element (HSE) is observed in non-stressed liver and freshly isolated hepatocytes when the expression of hsp70 is undetectable. HSF binding activity in non-stressed liver/hepatocytes is specific for HSE and similar to the HSF binding activity observed in heat shocked hepatocytes that is associated with hsp70 transcription. However, the HSF binding activity in non-stressed and heat shock cells can be distinguished on the basis of the thermal stability in vitro. The HSE binding activity of cell extracts isolated from non-stressed liver/hepatocytes was lost rapidly when the extracts were incubated at 37 degrees C. In contrast, the HSF binding activity of cell extracts isolated from heat shocked hepatocytes was relatively stable at 37 degrees C. Based on our observations, we propose that the activation of HSF is a multistep process that involves a change in conformation after oligomerization and the acquisition of DNA binding to a form that is more thermostable and is associated with increased hsp70 transcription.

Animals↗
PubMed2000

Transcriptional factor AP-2gamma increases human cystatin A gene transcription of keratinocytes.

The transcriptional activator protein-2 (AP-2) has been suggested to participate in keratinocyte gene regulation. Cystatin A, a cysteine proteinase inhibitor, is one of the cornified cell envelope constituents and is expressed in the upper epidermis. We report AP-2-dependent transcriptional regulation of cystatin A gene expression of keratinocytes. At least three isoforms of AP-2 (AP-2 alpha, beta, gamma) have been described. Transfection of AP-2alpha, beta and gamma expression vectors into cultured normal human keratinocytes (NHK) resulted in increased cystatin A expression in both mRNA and protein levels. Among the three isoforms AP-2gamma was most potent in inducing cystatin A expression. In contrast, transfection of antisense oriented AP-2gamma expression vector decreased basal AP-2 expression, accompanied by decreased cystatin A mRNA. The fragment, +77 to -478 of 5'-flanking region of human cystatin A gene, was subcloned into chloramphenicol acetyltransferase (CAT) reporter vector (p478CAT). Cotransfection of p478CAT vector with AP-2alpha, beta, and gamma expression vectors resulted in three-, three-, and sixfold increase in the CAT activity, respectively. Transfection of the deleted construct (p478DeltaAP-2CAT, devoid of AP-2-like binding site (-75 to -84)) decreased CAT activity by one-third compared to p478CAT promoter activity. Cotransfection of p478DeltaAP-2CAT with AP-2alpha, beta, and gamma expression vectors had no effect on the decreased promoter activity. Immunohistochemical analysis of human skin showed that AP-2alpha is exclusively expressed in the nuclei of basal cell layer. AP-2gamma is expressed in the nuclei of basal, spinous, and granular cell layers. AP-2beta expression was not observed in the epidermis. Gel mobility shift assay revealed that the AP-2gamma protein specifically binds to oligonucleotides containing AP-2-like binding site of cystatin A gene. These results indicate that AP-2gamma regulates the cystatin A gene expression of epidermal keratinocytes at the transcriptional level.

5' Untranslated Regions↗
PubMed1994

Isolation of yeast transcription factor IIA using a functional transcription assay.

TFIIA was extensively purified from a whole-cell transcription extract from yeast. Activity was followed throughout isolation utilizing a functional transcription assay. Transcription activity was found to copurify with polypeptides of 43 and 12.5 kDa, consistent with a previous purification that utilized a TBP/DNA gel mobility shift assay (J. Ranish and S. Hahn, J. Biol. Chem. 266, 19320-19327, 1991). The Stoke's radius of the purified protein was determined by gel filtration chromatography to be 44 A under native conditions. The solution molecular weight derived from this measurement, 110 kDa, is consistent with a heterotetrameric structure of TFIIA.

Chromatography, Gel↗
PubMed1996

Determination of occupancies of the SPH and GT-IIC transcription factor binding motifs in SV40: evidence for two forms of transcription elongation complex.

Occupancies of the SPH and GT-IIC sequence motifs in the native SV40 late transcription elongation complex were determined by assessing blockage to restriction enzyme cleavage. Cleavages specific to the transcription elongation complex were quantified by radioactive extension labeling and polymerase run-off analysis. The SPH motif was assayed by Sphl digestion and found to be unoccupied. In contrast, digestion with Pvull at the GT-IIC site was blocked in 36% of the complexes, indicating that approximately a third of the complexes are occupied by factor. This fractional occupancy indicates that there are at least two forms of SV40 late transcription elongation complexes, one form with the GT-IIC site occupied by a factor and another with the site vacant.

Animals↗
PubMedDate not supplied

MCEF, the newest member of the AF4 family of transcription factors involved in leukemia, is a positive transcription elongation factor-b-associated protein.

Positive transcription elongation factor-b (P-TEFb) contains CDK9 and cyclin T(1). P-TEFb was affinity purified from a stably transfected cell line that expresses epitope-tagged CDK9, and proteins that appeared to be specifically bound were sequenced. In addition to CDK9, previously identified isoforms of cyclin T (including T(1), T(2A) and T(2B)), HSP90 and CDC37, this analysis identified a novel protein named MCEF. Cloning of its cognate cDNA revealed that MCEF is the newest member of the AF4 family of transcription factors involved in acute lymphoblastic leukemia. MCEF RNA was expressed in all human tissues examined, and antisera directed against recombinant MCEF specifically immunoprecipitated P-TEFb. Ectopic expression of MCEF did not activate HIV-1 replication, and tethering of MCEF to a promoter did not activate transcription.

Amino Acid Sequence↗
PubMed2005

Transcriptional regulation by abscisic acid in barley (Hordeum vulgare L.) seeds involves autoregulation of the transcription factor HvABI5.

The barley bZIP transcription factor HvABI5 mediates abscisic acid (ABA)-upregulated gene expression in barley (Hordeum vulgare L.) seeds. HvABI5 specifically recognizes cis-elements of the ABA response complexes present in the promoters of the ABA-induced genes HVA1 and HVA22. HvABI5 together with another transcription factor, HvVP1, are required for the transactivation of these promoters, and this transactivation process is insensitive to the negative regulator abi1-1. The expression of HvABI5 itself appeared to be induced by ABA and can be suppressed by abi1-1. Gain- and loss-of-function studies in barley aleurone cells show that HvABI5 expression is positively regulated by a feed-forward circuit that involves HvABI5 itself and HvVP1. Mutation of the Ser residue in HvABI5, which has been shown to be phosphorylated in an ABA-dependent manner in the rice orthologue of HvABI5, reduces the transactivation activity of the factor by 50%. Although levels of HvABI5 and its transcript are enhanced by ABA treatment, the nuclear localization of HvABI5 is not affected by ABA. A model based on these observations is presented to explain the ABA upregulation of gene expression.

Abscisic Acid↗
PubMed1990

A specific member of the ATF transcription factor family can mediate transcription activation by the adenovirus E1a protein.

The adenovirus E1a protein stimulates transcription of viral early genes. Recent experiments indicate that E1a contains a transcriptional activating region, which functions when directed to a promoter. Because E1a is not a sequence-specific DNA binding protein, how it targets to viral promoters has been a question. Several of the viral early promoters contain one or more binding sites for ATFs, a family of cellular transcription factors. Here we show that E1a can function through a specific ATF protein, designated ATF-2. We provide evidence that E1a interacts with a discrete region of promoter-bound ATF-2, thereby positioning the E1a activating region at a viral promoter.

Activating Transcription Factors↗
PubMed2004

Characterization of Bcl10 as a potential transcriptional activator that interacts with general transcription factor TFIIB.

The importance of aberrant Bcl10 nuclear expression implicated in lymphomagenesis is becoming increasingly apparent. Our previous works indicate that Bcl10 can transactivate gene expression in yeast, nevertheless, little is known about the activities of nuclear Bcl10 in the mammalian cells and the mechanisms by which it modulates transcription. To understand it better, we mapped the location of the activation domain of Bcl10. This was done in the context of its interaction with TFIIB, as well as its ability to activate transcription as a fusion protein linked to the DNA-binding domain of Gal4 in the mammalian cells. Both approaches demonstrated that Bcl10 contains an activation domain in its N-terminal 13 amino acids. Together, these findings suggest that Bcl10 nuclear expression may modulate gene expression and Bcl10 is a potential transcriptional activator apart from its traditional roles that have been found.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Alternative splicing regulates the transcriptional activity of Drosophila heat shock transcription factor in response to heat/cold stress.

Heat shock transcription factor 1 (HSF1) mediates the induction of heat shock proteins in response to various types of stress. Although HSF1 activity is regulated by its post-translational modifications, alterations in mRNA expression have also been suggested. We here identified three new alternatively spliced isoforms of Drosophila HSF (dHSF) mRNA, named dHSFb, dHSFc, and dHSFd. We found that the ratio of dHSFb increases upon heat exposure, while that of dHSFd increases upon cold exposure. The dHSFc and dHSFd isoforms showed greater transcriptional activity than the other isoforms. Our findings suggest that alternative splicing regulates the transcriptional activity of dHSF.

Alternative Splicing↗
PubMed2005

Recognition of RNA polymerase II and transcription bubbles by XPG, CSB, and TFIIH: insights for transcription-coupled repair and Cockayne Syndrome.

Loss of a nonenzymatic function of XPG results in defective transcription-coupled repair (TCR), Cockayne syndrome (CS), and early death, but the molecular basis for these phenotypes is unknown. Mutation of CSB, CSA, or the TFIIH helicases XPB and XPD can also cause defective TCR and CS. We show that XPG interacts with elongating RNA polymerase II (RNAPII) in the cell and binds stalled RNAPII ternary complexes in vitro both independently and cooperatively with CSB. XPG binds transcription-sized DNA bubbles through two domains not required for incision and functionally interacts with CSB on these bubbles to stimulate its ATPase activity. Bound RNAPII blocks bubble incision by XPG, but an ATP hydrolysis-dependent process involving TFIIH creates access to the junction, allowing incision. Together, these results implicate coordinated recognition of stalled transcription by XPG and CSB in TCR initiation and suggest that TFIIH-dependent remodeling of stalled RNAPII without release may be sufficient to allow repair.

Adenosine Triphosphatases↗
PubMed2000

Regulation of CD34 transcription by Sp1 requires sites upstream and downstream of the transcription start site.

CD34 is a cell surface glycoprotein expressed on hematopoietic stem and progenitor cells, but not on fully differentiated cells in the peripheral blood. To better understand the molecular regulation of early hematopoiesis, we are elucidating the mechanisms of CD34 transcriptional regulation. By deletion analysis we identify a 39-bp element in the proximal region of murine CD34 promoter that is critical for promoter activity. Electromobility shift assays indicate that nuclear proteins of hematopoietic cells bind to this domain; however, the presence of this binding activity does not correlate directly with CD34 expression.Using methylation interference, the DNA binding site for this activity was localized to four guanine residues within the GGGGTCGG sequence from -48 to -54 bp. When the four contact guanines were mutated, both protein binding and promoter activity were abolished. Although this sequence does not contain a standard consensus for Sp1, this transcription factor binds specifically to the 39-bp region and stimulates promoter activity in both hematopoietic cells and in Sp1 null Drosophila S2 cells. In addition, Ku binds to this domain in a sequence-specific manner. Activation of the CD34 promoter by Sp1 requires the presence of a binding domain at -48 bp as well as the 5' untranslated region, which also binds Sp1.A functional interaction between regulatory regions upstream and downstream of the transcription start site is required for CD34 gene expression.

Animals↗
PubMed1995

Transcriptional activation. Tuning-up transcription.

Eukaryotic transcription is a complex process, and recent results identify multiple steps that need to be stimulated to activate transcription, one of which is a change in conformation of the general transcription factor TFIIB.

Animals↗
PubMed2000

Concerted dephosphorylation of the transcription factor NFAT1 induces a conformational switch that regulates transcriptional activity.

NFAT transcription factors are highly phosphorylated proteins that are regulated by the calcium-dependent phosphatase calcineurin. We show by mass spectrometry that NFAT1 is phosphorylated on fourteen conserved phosphoserine residues in its regulatory domain, thirteen of which are dephosphorylated upon stimulation. Dephosphorylation of all thirteen residues is required to mask a nuclear export signal (NES), cause full exposure of a nuclear localization signal (NLS), and promote transcriptional activity. An inducible phosphorylation site in the transactivation domain contributes to transcriptional activity. Our data suggest that dephosphorylation promotes NFAT1 activation by increasing the probability of an active conformation, in a manner analogous to that by which depolarization increases the open probability of voltage-gated ion channels. This conformational switch paradigm may explain modification-induced functional changes in other heavily phosphorylated proteins.

Animals↗
PubMed2003

ERK-dependent phosphorylation of the transcription initiation factor TIF-IA is required for RNA polymerase I transcription and cell growth.

Phosphorylation of transcription factors by mitogen-activated protein kinase (MAPK) cascades links cell signaling with the control of gene expression. Here we show that growth factors induce rRNA synthesis by activating MAPK-dependent signaling cascades that target the RNA polymerase I-specific transcription initiation factor TIF-IA. Activation of TIF-IA and ribosomal gene transcription is sensitive to PD98059, indicating that TIF-IA is targeted by MAPK in vivo. Phosphopeptide mapping and mutational analysis reveals two serine residues (S633 and S649) that are phosphorylated by ERK and RSK kinases. Replacement of S649 by alanine inactivates TIF-IA, inhibits pre-rRNA synthesis, and retards cell growth. The results provide a link between growth factor signaling, ribosome production, and cell growth, and may have a major impact on the mechanism of cell transformation.

3T3 Cells↗
PubMed1997

Cross-talk between transcription factors NF-kappa B and C/EBP in the transcriptional regulation of genes.

The study of the acute phase response has attracted substantial interest, not only for its medical implication, but also its provision as an excellent system with which to elucidate the molecular mechanisms involved in the modulation of gene expression. Our previous data suggest that the synergistic induction of the major acute phase reactant serum amyloid A2 (SAA2) expression by interleukin-1 (IL-1) and interleukin-6 (IL-6) is mediated by two families of transcription factors, namely NF-kappa B and C/EBP. To understand the molecular mechanisms of this synergy, we have undertaken a molecular dissection of the factors involved in the formation of the regulatory complex. Electrophoretic mobility shift analysis indicates that NF-kappa B p65 (RelA) and p50, but not p52 or c-Rel, bind specifically to the NF-kappa B site of the SAA2 promoter in response to IL-1 stimulation. In addition, C/EBP beta and C/EBP delta, but not C/EBP alpha, bind specifically to the C/EBP site of SAA2 in response to IL-6 stimulation. Transient co-transfection analysis indicates that co-operative association of NF-kappa B p65 with C/EBP beta and, in particular, with C/EBP delta, results in synergistic transcriptional activation of the SAA2 promoter. When incubated together, NF-kappa B p65 and C/EBP beta form a ternary complex by direct protein/protein interaction. Mutational analysis demonstrates that the C-terminus region of the Rel homology domain (RHD) and the C-terminus of the activation domain of p65 are important for its interaction with C/EBP beta. These results suggest the NF-kappa B and C/EBP may form a new complex of transcription factors that mediates the synergistic induction of SAA2 by IL-1 and IL-6.

Acute-Phase Reaction↗