Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.1 (protein kinase)
 81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hormonally induced increases in cyclic AMP levels induce phosphorylation of the transcription factor CREB at a serine residue at position 133 by protein kinase A (ref. 1), enhancing its ability to activate transcription without affecting its intracellular location or DNA-binding activity. This effect is dependent on a 60-amino-acid region of CREB that contains Ser133 and is termed the kinase-inducible domain (KID)2, which also occurs in the CREB-related CREM-alpha and -beta proteins, although these are transcriptional repressors. Here we show that the KID domain confers a cAMP-inducible increase on the activity of the Q2 activation domain from CREB and the acidic activation domains from the yeast proteins GAL4 and GCN4. Remarkably, it retains this ability even when attached to a separate polypeptide bound to an adjacent site in the promoter. KID may therefore be the first of a new class of conditional activators that work through other promoter-bound factors to stimulate gene expression in response to hormonal stimuli.
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PMID:Protein-kinase-A-dependent activator in transcription factor CREB reveals new role for CREM repressors. 810 91

Transcription of the phosphoenolpyruvate carboxykinase (PEPCK) and PEPCK-chloramphenicol acetyltransferase (CAT) genes is induced by cAMP and glucocorticoids and is inhibited by insulin in H4IIE cells, as it is in liver. In contrast, PEPCK-CAT expression in HepG2 cells is not affected by insulin but is induced by cAMP, which in turn is repressed by glucocorticoids. Mutations were introduced into well defined transcription factor binding sites to investigate possible interactions between the cAMP regulatory element (CRE) binding protein (CREB) and glucocorticoid response unit (GRU) binding proteins. H4IIE rat hepatoma cells were transfected with PEPCK-CAT plasmids with or without an expression vector for protein kinase A (PKA). Glucocorticoid-induced CAT activity was dependent upon the GRU and was decreased in plasmids lacking the CRE. To determine the direct effects of CREB, the DNA binding and dimerization domain of GAL4 was substituted for that of CREB (CRG), and the PEPCK CRE was replaced with a GAL4 binding site (G4PEPCK-CAT). CRG elevated basal and glucocorticoid-induced activities of G4PEPCK-CAT equally and restored responsiveness to PKA. The basal activity of CRG was not diminished by concomitant treatment with PKA plus its inhibitor peptide, PKI, or by mutation of the PKA phosphorylation. Deletion of C-terminal regions of the CREB activation domain from CRG diminished basal activation without affecting induction by PKA. The glucocorticoid-induced level of CAT activity decreased in proportion to the reduced ability of CREB to activate basal transcription. Induction by glucocorticoid, in the absence or presence of PKA, was not affected by CRG, indicating that interaction of GRU-bound factors with CREB is not required for glucocorticoid induction of PEPCK. These results indicate that CREB is directly involved in basal and PKA-induced expression of PEPCK, and that CREB supports glucocorticoid-induced PEPCK expression through its positive effect on basal transcription.
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PMID:Involvement of 3',5'-cyclic adenosine monophosphate regulatory element binding protein (CREB) in both basal and hormone-mediated expression of the phosphoenolpyruvate carboxykinase (PEPCK) gene. 811 62

Lactoferrin is present in a variety of tissues and biological fluids; however, the amount differs significantly due to differential expressions. We have previously demonstrated that the mouse lactoferrin gene is regulated by estrogen through an estrogen-response DNA element located at -349, upstream from the transcription start site (+1). In this report, we characterized by deletion and mutation analyses a cluster of mitogen-response elements located between -80 and -40 of the mouse lactoferrin promoter. We demonstrated that the chimeric chloramphenicol acetyltransferase reporter constructs (the -103 to +1 sequence of the mouse lactoferrin gene) containing the mitogen-response unit of the lactoferrin gene were stimulated by cAMP, forskolin, 12-O-tetradecanoylphorbol-13-acetate, and epidermal growth factor/recombinant transforming growth factor-alpha (EGF/TGF-alpha) in a time- and dose-dependent manner. The sequence at position -52 to -40 (mLF-CRE) of the gene conferred transcriptional activation in the presence of forskolin, cyclic AMP, and 12-O-tetradecanoylphorbol-13-acetate in transiently transfected human endometrium carcinoma RL95-2 cells, whereas the region at -80 to -60 responded to EGF/TGF-alpha stimulation. Overexpression of the catalytic unit of protein kinase C or protein kinase A in the RL95-2 cells elevated the chloramphenicol acetyl-transferase activity of the reporter construct 5-6-fold. The mobility shift assay suggested that AP1 and CREB or related proteins participated in complex formation with the mLF-CRE, whereas different proteins bound to the EGF/TGF-alpha-response element.
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PMID:Characterization of a mitogen-response unit in the mouse lactoferrin gene promoter. 817 15

The cyclic AMP-response element (CRE), a transcriptional enhancer, is regulated by CREB (CRE-binding protein) which is the leucine zipper protein phosphorylated by protein kinase A in response to cAMP signal. The highly homologous protein CREM (CRE-modulator) is thought to modulate CREB-stimulated transcription, and is also involved in transcriptional control during spermatogenesis. In this paper, we report two types of cDNAs of human CREM (hCREM), type 1 and type 2; type 1 is a group of human counterparts of the mouse CREM alpha and type 2 is a novel form having a distinct 5' exon which is unrelated to any species of the CREB and CREM isoforms so far described. This unique 5' region of type 2 hCREM may suggest its independent expression from type 1 CREM. The specific 5' region of type 2 hCREM consisted of 88 bp, containing an initiation codon for translation, but no possible phosphorylation site, suggesting different roles from type 1 CREM. Both type 1 and 2 hCREMs are expressed in lymphoid and non-lymphoid cell lines. Their excess expression by transfection induced suppression of cAMP-mediated activation of transcription, suggesting their negative regulation of CRE-mediated transcription.
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PMID:Novel isoforms of human cyclic AMP-responsive element modulator (hCREM) mRNA. 820 79

Hormones and cytokines regulate many cellular functions by activating the ubiquitous cAMP-dependent protein kinase (A kinase) system. Newly synthesized cAMP molecules bind to regulatory (R) subunits in A kinase holoenzymes, causing them to release their catalytic (C) subunits. These free C subunits then phosphorylate proteins until the cAMP level falls, whereupon the R subunits regain their affinity for free C subunits, and thus form inactive holoenzymes again. However if cAMP levels remain persistently elevated, many cells change their A kinase system. Some cells alter the rate of degradation of subunits, and some cells change the level or stability of the messages encoding subunits. Cellular behavior often changes if cAMP levels remain elevated: many cells differentiate, some cells proliferate, and some cells die, depending on the stage of the cell cycle. The two forms of A kinase holoenzyme (type I and type II) contain identical C subunits, but contain either an RI dimer or an RII dimer. In some tissues, type II holoenzyme is compartmentalized to subcellular organelles via specific anchoring proteins, whereas type I holoenzyme is generally cytosolic. Free RI subunits turn over more rapidly than free RII subunits in most cells, but all free subunits are degraded more rapidly than when they are associated together in holoenzymes. Free C subunits can phosphorylate a broad spectrum of proteins in both the cytoplasm and nucleus, depending on the type of cell, its state of differentiation, and the hormonal milieux. If free C subunit is microinjected into the cytoplasm of some intact cells, it migrates to the nucleus, whereas if free R subunit is microinjected, it remains in the cytoplasm. If both subunits are coinjected, R subunit blocks the nuclear migration of the C subunit. A major nuclear target for free C subunits is the CREB family of nuclear proteins, which bind to cAMP response elements (CREs) in the promoter regions of cAMP-responsive genes. Phosphorylation of CREB proteins alters their ability to form dimers and to interact with CREs. Many CREB proteins can be phosphorylated by other kinases as well, indicating this is one means by which cells coordinate cAMP- and non-cAMP-mediated gene responses. However, interactions between CREB and a number of other nuclear proteins with which they can dimerize, especially proteins whose levels are rapidly altered in response to hormones, provide an even higher degree of complexity of gene regulation than is possible from various kinases phosphorylating the different sites in CREB proteins.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The ways in which hormones change cyclic adenosine 3',5'-monophosphate-dependent protein kinase subunits, and how such changes affect cell behavior. 826 10

Cyclic AMP (cAMP) regulates a number of eukaryotic genes by mediating the protein kinase A (PKA)-dependent phosphorylation of the CREB transcription factor at Ser-133. In this study, we test the hypothesis that the stoichiometry and kinetics of CREB phosphorylation are determined by the liberation and subsequent translocation of PKA catalytic subunit (C subunit) into the nucleus. Using fluorescence imaging techniques, we observed that PKA was activated in a stimulus-dependent fashion that led to nuclear entry of C subunit over a 30-min period. The degree of CREB phosphorylation, assessed with antiserum specific for CREB phosphorylated at Ser-133, correlated with the amount of PKA liberated. The time course of phosphorylation closely paralleled the nuclear entry of the catalytic subunit. There was a linear relationship between the subsequent induction of the cAMP-responsive somatostatin gene and the degree of CREB phosphorylation, suggesting that each event--kinase activation, CREB phosphorylation, and transcriptional induction--was tightly coupled to the next. In contrast to other PKA-mediated cellular responses which are rapid and quantitative, the slow, incremental regulation of CREB activity by cAMP suggests that multifunctional kinases like PKA may coordinate cellular responses by dictating the kinetics and stoichiometry of phosphorylation for key substrates like CREB.
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PMID:Coupling of hormonal stimulation and transcription via the cyclic AMP-responsive factor CREB is rate limited by nuclear entry of protein kinase A. 833 22

We have identified in mammalian cells a novel cyclic AMP response element (CRE)-binding protein of molecular mass 47 kDa. This protein was not recognized by either the CREB-327/341 or c-Jun antisera, and its tissue distribution did not overlap with those of the CREB and Jun families. For example, hepatoma and placental tissue did not contain the 47-kDa DNA-binding protein, but did contain the CREB isoforms. On the other hand, S49 lymphoma cells contained a high level of the 47-kDa DNA-binding protein but did not contain a 47-kDa Jun-related protein which was found in normal liver and hepatoma. This new 47-kDa factor bound to the CRE in the dephosphorylated form, and phosphorylation of the protein by the catalytic subunit of protein kinase A completely abolished its DNA-binding activity. The isoforms of the CREB-327/341 family, on the other hand, bound to DNA in the phosphorylated form, and alkaline phosphatase treatment reduced significantly their interaction with CRE sequence. This reverse effect of phosphorylation/dephosphorylation on the DNA-binding property of this new 47-kDa protein in particular distinguishes it from other known CREB factors and suggests that the protein might play a unique role in the regulation of cAMP-mediated transcription.
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PMID:Identification of a new cAMP response element-binding factor by southwestern blotting. 836 1

We demonstrate that granular cerebellar neurons express functional corticotropin-releasing hormone (CRH) receptors. Activation of these receptors with CRH receptor agonists leads to a dose-dependent increase in cyclic AMP (cAMP) levels with an apparent EC50 close to 10(-9) M. Using the c-fos protooncogene as a system to evaluate genomic effects of CRH, we show that activation of CRH receptors regulates gene expression at the transcriptional level. CRH rapidly induced c-fos mRNA accumulation. Genetic studies, using chimera genes containing human c-fos promoter sequences coupled to a chloramphenicol acetyltransferase (CAT) reporter gene, confirmed and extended this observation. When protein kinase A (PKA) was specifically inactivated by gene transfer of a mutated regulatory subunit of PKA lacking cAMP binding sites, CRH-stimulated c-fos transcription was suppressed but the increase in cAMP level was not affected, indicating a key role of PKA in mediating CRH-stimulated transcription. As CRH clearly modulates gene expression via the cAMP pathway, we analyzed the genomic effect of this neurohormone on a deleted c-fos-CAT construct containing only the cAMP-responsive element (CRE) and on a heterologous promoter construct bearing the minimal palindromic consensus CRE (core sequence TGACGTCA). These minimal cAMP-responsive genes are induced by CRH. These inductions are dependent on functional PKA. Taken together, our results demonstrate the presence of functional CRH receptors in primary cerebellar cultures. Activation of these receptors stimulates gene expression via the cAMP/PKA pathway and the transacting factor CREB (cAMP-responsive element binding protein).
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PMID:Characterization and genetic analysis of functional corticotropin-releasing hormone receptors in primary cerebellar cultures. 838 Apr 41

Pituitary-derived trophic hormones regulate cell-type-specific expression of VL30 retrotransposons in tissues that are engaged in steroidogenesis. We show that adrenocorticotropic hormone and forskolin induced VL30 transcription in the steroidogenic adrenal cell line Y1 and that the transcriptional activation was cell type- and protein kinase A-dependent. Three novel cAMP-responsive elements (CREs), within the VL30 long terminal repeat, were identified and shown to activate transcription synergistically when templates bearing multiple sites were compared with templates bearing a single site. This type of regulation was evident only in forskolin-treated cells, and the response elements were found to be inactive as mediators of constitutive transcription. In vitro binding analyses indicated that a consensus CRE and the nonconsensus VL30 CREs differ with respect to binding affinity and specificity to a number of nuclear factors that were identified to be related to proteins within the CREB, Jun, and C/EBP families of transcription factors. The relatively low affinity and/or a restricted binding specificity of the VL30 CREs made it possible to detect forskolin-induced binding of CREB- and Jun-related proteins to these sequences. We suggest that cAMP-induced transcription, specific for steroidogenic cells, can be mediated by a novel type of nonconsensus CREs and that the mechanism for this type of gene regulation is distinct from that mediated through a consensus CRE. We also report the identification of a novel factor, distinct from previously characterized CRE-binding proteins, that constitutively binds to the identified CREs.
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PMID:Cooperating nonconsensus cAMP-responsive elements are mediators of adrenocorticotropin-induced VL30 transcription in steroidogenic adrenal cells. 838 84

Interleukin-6 (IL-6) activation of the immediate-early gene junB has been shown to require both a tyrosine kinase and an unknown 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H7)-sensitive pathway. Here we report the identification and characterization of an IL-6 immediate-early response element in the junB promoter (designated JRE-IL6) in HepG2 cells. The JRE-IL6 element, located at -149 to -124, contains two DNA motifs, an Ets-binding site (EBS) (CAGGAAGC) and a CRE-like site (TGACGCGA). Functional studies using variously mutated JRE-IL6 elements showed that both motifs were necessary and sufficient for IL-6 response of the promoter. The EBS of the JRE-IL6 element (JEBS) appears to bind a protein in the Ets family or a related protein which could also form a major complex with the EBSs of the murine sarcoma virus long terminal repeat or human T-cell leukemia virus type 1 long terminal repeat. The CRE-like site appears to weakly bind multiple CREB-ATF family proteins. Despite the similarity in the structure between the JRE-IL6 element and the polyomavirus enhancer PyPEA3, composed of an EBS and an AP1-binding site and known to be activated by a variety of oncogene signals, JRE-IL6 could not be activated by activated Ha-Ras, Raf-1, or 12-O-tetradecanoylphorbol-13-acetate. We show that IL-6 activates JRE-IL6 through an H7-sensitive pathway that does not involve protein kinase C, cyclic AMP-dependent kinase, Ca(2+)- or calmodulin-dependent kinases, Ras, Raf-1, or NF-IL6 (C/EBP beta). The combination of JEBS and the CRE-like site appears to form the basis for the selective and efficient response of JRE-IL6 to IL-6 signals, but not to signals generated by activated Ha-Ras, Raf-1, or protein kinase C.
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PMID:Identification of a novel interleukin-6 response element containing an Ets-binding site and a CRE-like site in the junB promoter. 838 18


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