Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01275 (glucagon)
 26,492 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nuclear extracts from cultured rat hepatocytes were analyzed by gel mobility shift assay for protein binding to the cyclic AMP responsive elements CRE1 (-96/-77) and CRE2 (-152/-132) and the NF1-CTF binding site (-121/-99) of the phosphoenolpyruvate carboxykinase (PCK) promotor. Binding was very weak to the CRE2 and CRE1. The NF1-CTF site formed two complexes with nuclear protein. Protein binding was increased, when the NF1-CTF site was coupled to the CRE1, and further, when it was coupled to both the CRE1 and the CRE2. Complex formation was not altered by treatment of the hepatocytes with glucagon or with glucagon and insulin. Thus, protein binding was most efficient when all three elements were in context, which might be necessary for full transcriptional activation of the PCK gene.
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PMID:Interactions of nuclear protein from cultured rat hepatocytes with the cyclic AMP responsive elements and the NF1-CTF site in the promoter of the rat phosphoenolpyruvate carboxykinase gene. 183 77

The effects of glucagon and insulin on liver nuclear poly(ADP-ribose) polymerase activity and blood ketone body ratio after rat partial (68%) hepatectomy were examined. Liver weight regeneration rate was enhanced by glucagon and insulin after 5th posthepatectomy day. The maximal value of poly(ADP-ribose) polymerase activity without glucagon and insulin was revealed as 368 +/- 64 pmole/mg/min on 5 days after the hepatectomy. In contrast, the enzyme activity with glucagon and insulin reached to the peak value as 253 +/- 42 pmole/mg/min on 2 days after the hepatectomy. The amounts of DNA per nuclear protein showed similar changes with the changes of poly (ADP-ribose) polymerase activity after the hepatectomy. Blood ketone body ratio showed almost similar changes in both groups, except transitional decrease in the group without glucagon and insulin on 5th postoperative day. It is suggested that, to promote remnant liver regeneration, the combined therapy of glucagon and insulin may act directly to nucleic acid metabolism through the changes of poly(ADP-ribose) polymerase activity and preserve energy charge level by the suppression of NAD consumption by massive poly(ADP-ribose) formation.
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PMID:[Effects of glucagon and insulin on poly(ADP-ribose) polymerase activity and blood ketone body ratio after partial hepatectomy in rats]. 250 88

Treatment of rat superior cervical ganglia in culture with nerve growth factor (NGF) increases the amount of radioactive phosphate incorporated into a nuclear protein band. This band migrates coincidentally with H1 histone on 10% sodium dodecyl sulfate/polyacrylamide gels. The increase in phosphate incorporation is at least 70% and occurs only in tissues known to be responsive to NGF. It is not produced by treatment with related peptides, but is observed after the addition of dibutyryl cyclic AMP. An increase in phosphorylation can be detected after 1 h, and can be seen with as little as 10 ng/ml of NGF in the medium. Neither actinomycin D nor cycloheximide inhibits the effect. When the nuclei are extracted with 0.2 M H2SO4 and the extract analyzed on acid-urea/polyacrylamide gels, two NGF-responsive proteins can be detected. One protein again migrates with the H1 histone marker; the other migrates more slowly than H1. These two NGF-responsive proteins have molecular weights of approximately 30,000 and are chromatin-bound. They are not soluble in 5% perchloric acid, but can be extracted from the nuclei with 0.35 M NaCl. No increase in the phosphorylation of these proteins was seen in ganglia from 6-hydroxydopamine-treated rats. The phosphorylation of the proteins in both control and NGF-treated ganglia occurs almost exclusively on serine residues. The amino acid compositions of the two nuclear proteins show that they are different from the H1 histone and different from each other. Both nerve growth factor (NGF) and epidermal growth factor (EGF) increase the incorporation of radioactive phosphate into a specific nuclear protein in cultures of PC12, a clone of rat pheochromocytoma. Purified NGF antibody blocks the effect of NGF, but not that of EGF; EGF antiserum neutralizes the effect of EGF, but not that of NGF. Insulin, glucagon, and dexamethasone are without effect. The increase in phosphorylation due to NGF can be detected within 1 h. Dibutyryl cyclic AMP increases the phosphorylation of this protein, but dibutyryl cyclic GMP does not. Neither the uptake nor the overall incorporation of [32P]orthophosphate is altered by NGF, EGF, or dibutyryl cAMP under the present experimental conditions. The nuclear protein exhibiting increased radioactivity is similar in solubility, size, and amino acid composition to one of the NGF-responsive nuclear proteins from sympathetic ganglia.
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PMID:Increased phosphorylation of specific nuclear proteins in superior cervical ganglia and PC12 cells in response to nerve growth factor. 615 55

The cAMP response element (CRE)-binding transcription factor CREB can mediate induction of gene transcription in response to calcium as well as to cAMP. Since the rat insulin I gene 5'-flanking region contains a CRE with an octamer-like motif (TGACGTCC), CREB binding and cAMP/calcium responsiveness of the insulin CRE were investigated. In an electrophoretic mobility shift assay and in Southwestern blot experiments, bacterially expressed recombinant CREB bound to the insulin CRE as it did to the rat glucagon and rat somatostatin gene CREs. However, in nuclear extracts of the pancreatic islet cell line HIT, protein complexes binding to the insulin CRE did not contain proteins with CREB-like immunoreactivity, although these bound to the glucagon and somatostatin CREs. When reporter fusion genes were transfected into HIT cells, the isolated insulin CRE increased basal activity and mediated transcriptional activation by cAMP. However, cAMP stimulation of transcription through the insulin CRE was weak when compared with the response through the glucagon and somatostatin CREs. Furthermore, the insulin CRE did not confer responsiveness to membrane depolarization and calcium influx, in contrast to the glucagon and somatostatin CREs. These results demonstrate that the functional properties of the rat insulin I gene CRE are different from those of the rat glucagon and somatostatin CREs which may be explained by a distinct pattern of nuclear protein binding and suggest the existence of post-translational mechanisms that decrease the binding of cellular CREB to the insulin CRE.
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PMID:Distinct properties of the cAMP-responsive element of the rat insulin I gene. 792 45

In a subset of patients with non-insulin-dependent diabetes mellitus an 8-base pair (bp) repeat was found from -322 to -315 in the 5'-flanking region of the insulin gene. This 8-bp repeat is inserted into a sequence that is highly homologous to a sequence motif, called PISCES (pancreatic islet cell-specific enhancer sequences), found within cell-specific enhancer elements of the rat insulin I (Ins-E1, from -332 to -285), rat glucagon (Glu-G3) and rat somatostatin (SMS-UE) genes. The PISCES motif confers pancreatic islet-specific activity and is recognized by an islet-specific transcription factor (PISCES-BP). The consequences on functional activity and on protein binding of the 8-bp repeat sequence in the human insulin promoter was investigated. When fused to a reporter gene and transiently transfected into an insulin-producing islet cell line, the 8-bp repeat decreased basal transcriptional activity of the human insulin promoter (from -366 to +42) whereas the induction of promoter activity by cAMP was unaffected. The isolated rat Ins-E1 element was sufficient to confer basal transcriptional activity to a minimal promoter; the corresponding fragments of the normal and variant human insulin genes (from -329 to -288), however, were not. Using nuclear extracts in an electrophoretic mobility shift assay, it was found that PISCES-BP recognizes rat Ins-E1, but PISCES-BP binding to the corresponding normal and variant human insulin promoter fragments was not detectable and weak, respectively. However, a nuclear protein was found that binds to the variant but not normal human sequence. These data suggest that the 8-bp repeat in the variant human insulin promoter found in patients with non-insulin-dependent diabetes mellitus allows the binding of a nuclear protein that interferes with promoter function.
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PMID:Nuclear protein binding and functional activity of a variant insulin gene found in non-insulin-dependent diabetes mellitus. 881 39

The glucagon-dependent activation of the phosphoenolpyruvate carboxykinase (PCK) gene within two hours is modulated by O2 in rat hepatocytes. It was the aim of the present study to test if this short-term modulation by O2 of the glucagon induction might be influenced by long-term culture of hepatocytes for 24 hours under different O2 tensions prior to glucagon induction. Cells were precultured for 24 hours at arterial O2 (16% O2) or venous O2 (8% O2), then induced within two to four hours with 1 nM glucagon each at arterial or venous O2. In arterial O2 precultured cells PCK mRNA and activity were induced to 100% at arterial O2 and to about 60% at venous O2. In venous O2 precultured cells PCK mRNA and activity were induced only to about 70% at arterial O2 and to about 60% at venous O2. Transfected PCK promoter (-2500)-CAT constructs were activated by glucagon with the same long-term modulatory effects of oxygen as the endogenous PCK gene. Gel mobility shift assays with nuclear extracts prepared from hepatocytes and a PCK promoter fragment ranging from -149 to -42 bp revealed one complex with a higher DNA binding activity when extracts of cells precultured for 24 hours under venous O2 as compared to arterial O2 were used. Therefore, the short-term modulation by O2 of PCK gene activation by glucagon was widely lost during preculture at low O2. This diminution of O2 sensitivity of PCK induction may be due to a nuclear protein or proteins which are induced by perivenous O2 tensions and bind to the PCK promoter.
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PMID:Diminution of the O2 responsiveness of the glucagon-dependent activation of the phosphoenolpyruvate carboxykinase gene in rat hepatocytes by long-term culture at venous PO2. 902 35

To maintain glucose levels in blood within narrow limits, the synthesis and secretion of pancreatic islet hormones are controlled by a variety of neural, hormonal, and metabolic messengers that act through multiple signal transduction pathways. Glucagon gene transcription is stimulated by cyclic AMP and depolarization-induced calcium influx. In this study, the effect of protein kinase C on glucagon gene transcription was investigated. After transient transfection of a glucagon-reporter fusion gene into the glucagon-producing islet cell line alphaTC2, activation of protein kinase C by 12-O-tetradecanoylphorbol-13-acetate (TPA) stimulated glucagon gene transcription. By 5' deletions, 3' deletions, internal deletion, and oligonucleotide cassette insertion, the TPA-responsive element was mapped to the G2 element (from -165 to -200). Like TPA, overexpression of oncogenic Ras (V-12 Ras) stimulated G2-mediated transcription whereas overexpression of a dominant negative Ras mutant (N-17 Ras) blocked the effect of TPA. A mutational analysis of G2 function and nuclear protein binding indicated that protein kinase C and Ras responsiveness is conferred to the glucagon gene by HNF-3beta functionally interacting with a protein that binds to a closely associated site with sequence similarity to binding sites of Ets family proteins. HNF-3beta belongs to the winged-helix family of transcription factors and has been implicated in the control of cell-specific and developmental gene expression. The results of the present study show that the cell lineage-specific transcription factor HNF-3beta is an essential component of a novel protein kinase C response element in the glucagon gene.
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PMID:Characterization of a novel protein kinase C response element in the glucagon gene. 912 28

To maintain blood glucose levels within narrow limits, the synthesis and secretion of pancreatic islet hormones is controlled by a variety of extracellular signals. Depolarization-induced calcium influx into islet cells has been shown to stimulate glucagon gene transcription through the transcription factor cAMP response element-binding protein that binds to the glucagon cAMP response element. By transient transfection of glucagon-reporter fusion genes into islet cell lines, this study identified a second calcium response element in the glucagon gene (G2 element, from -165 to -200). Membrane depolarization was found to induce the binding of a nuclear complex with NFATp-like immunoreactivity to the G2 element. Consistent with nuclear translocation, a comigrating complex was found in cytosolic extracts of unstimulated cells, and the induction of nuclear protein binding was blocked by inhibition of calcineurin phosphatase activity by FK506. A mutational analysis of G2 function and nuclear protein binding as well as the effect of FK506 indicate that calcium responsiveness is conferred to the G2 element by NFATp functionally interacting with HNF-3beta binding to a closely associated site. Transcription factors of the NFAT family are known to cooperate with AP-1 proteins in T cells for calcium-dependent activation of cytokine genes. This study shows a novel pairing of NFATp with the cell lineage-specific transcription factor HNF-3beta in islet cells to form a novel calcium response element in the glucagon gene.
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PMID:Characterization of a novel calcium response element in the glucagon gene. 1002 8

We previously demonstrated that high glucose activates angiotensinogen (ANG) expression and that insulin inhibits this activation. The present studies aim to investigate whether insulin regulates ANG gene expression in kidney proximal tubular cells at the transcription level via interaction of the putative insulin-response element (IRE) with its binding protein(s) in the 5'-flanking region of the ANG gene. Fusion genes containing various lengths of the 5'-flanking region of the rat ANG gene fused to a human GH (hGH) gene as reporter were constructed and transiently introduced into rat immortalized renal proximal tubular cells (IRPTCs). The expression of the fusion genes was monitored by the amount of immunoreactive hGH secreted into the medium as assayed by a specific RIA for hGH. Insulin inhibited the expression of pOGH (rANG N-1498/+18), pOGH (rANG N-1120/+18) and pOGH (rANG N-882/+18) but not pOGH (rANG N-854/+18), pOGH (rANG N-820/+18), pOGH (rANG N-688/+18) and pOGH (rANG N-53/+18) in high-glucose (i.e. 25 mM) medium. Site-directed mutagenesis of nucleotides N-874 to N-867 (5' CCC GCC CT 3') in the 5'-flanking region of the rat ANG gene abolished the response to insulin. Insulin also inhibited the expression of the fusion gene containing the DNA fragment ANG N-882 to N-855 inserted upstream of the ANG gene promoter (N-53/+18), but had no effect on a mutant of N-882 to N-855. Gel mobility shift assays revealed that the labeled putative rat ANG-IRE motif (N-878 to N-864, 5' CCT TCC CGC CCT TCA 3') was bound to the nuclear proteins of IRPTCS: This binding was displaced by unlabeled ANG-IRE and IRE of human glyceraldehyde phosphate dehydrogenase but not by mutants of ANG-IRE and IRE of the rat glucagon gene. Southwestern blotting analysis revealed that the labeled putative ANG-IRE motif bound to a major nuclear protein with an apparent molecular mass of 48 kDA: Finally, high glucose levels enhanced 48-kDa nuclear protein expression and induced an additional 70-kDa nuclear protein expression in IRPTCs, as revealed by Southwestern blotting. Insulin inhibited both 48- and 70-kDa nuclear proteins expression induced by high glucose levels. Its inhibitory effect was reversed by the presence of PD98059 (an inhibitor of mitogen-activated protein kinase, MAPK) but not by wortmannin (an inhibitor of phosphatidylinositol 3- kinase). These studies demonstrate that insulin action on ANG gene expression is at the transcriptional level. The molecular mechanism (s) of insulin action is mediated, at least in part, via interaction of the functional IRE with unidentified 48- and 70- kDa nuclear proteins in the rat ANG gene and is MAPK dependent.
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PMID:Characterization of a putative insulin-responsive element and its binding protein(s) in rat angiotensinogen gene promoter: regulation by glucose and insulin. 1135 7

Multiple endocrine neoplasia type 1 (MEN1) is a hereditary syndrome linked to mutations in the MEN1 gene, which encodes a 610-amino-acid nuclear protein termed menin. Because of the lack of a suitable detection protocol, the in situ expression pattern of menin in human tissues remains to be determined. In this study, we have developed an antimenin monoclonal antibody and an indirect immunofluorescence/laser-scanning microscopy protocol for analyzing menin expression in frozen tissue sections. Because neuroendocrine pancreatic tumors represent a key feature of MEN1, we focused this study on nontumoral pancreas and a small panel of neuroendocrine pancreatic tumors. Results showed that menin was readily detected in nontumoral exocrine cells. In contrast, most islet cells expressing insulin, glucagon, or somatostatin showed considerably weaker levels of menin expression; however, a subpopulation of pancreatic polypeptide-positive cells exhibited a signal comparable with that detected in adjacent exocrine cells. Sporadic endocrine tumors showed variable levels of menin expression, whereas a MEN1-/- gastrinoma scored negative. This report thus provides the first description of the expression pattern of menin in human pancreas in situ and lays the groundwork for further studies of other tissues and tumors.
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PMID:In situ analysis of human menin in normal and neoplastic pancreatic tissues: evidence for differential expression in exocrine and endocrine cells. 1291 85


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