Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.6.1.1 (adenylate cyclase)
 19,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously reported that a human small cell lung cancer (SCLC) cell line (COR L103) that expresses the proopiomelanocortin (POMC) gene and secretes ACTH precursor peptides is relatively resistant to glucocorticoid regulation. Using this model, we have now examined alternative regulatory mechanisms of the POMC gene and found that both the mRNA and ACTH precursor peptides were stimulated four- and two-fold, respectively, after 48 h incubation with db-cAMP. Next, we examined the dopamine agonist, bromocriptine, which acts predominantly through D2 receptors linked to adenyl cyclase to cause a reduction in intracellular cAMP. Bromocriptine suppressed cAMP levels and inhibited precursor peptide secretion within 24 h in a dose-dependent manner (0.15-15 microM). At the highest dose, peptide secretion was inhibited from 95 to 53 pmol/mg protein, and POMC mRNA was reduced by 50%, while beta-actin mRNA remained unchanged. This effect could not be mimicked by incubation of cells with the alpha-adrenergic antagonist, phenoxybenzamine, suggesting that the alpha-adrenergic effects of bromocriptine were not responsible for this observation. These cells also secrete estradiol, but the secretory rate was unaffected by bromocriptine, suggesting, with the beta-actin data, that the POMC inhibition was not a cytotoxic effect. No recovery in precursor peptide secretion was seen in a 48-h period after the removal of bromocriptine. However, when the postchallenge incubation was extended to 8 d, there was a recovery in secretory potential between day 3 and day 8 and normal growth kinetics in the 4 d after removal of the drug. In contrast to these findings, the mouse corticotroph cell line, AtT20, showed no response to bromocriptine, in keeping with reports that this agonist has no effect on anterior lobe corticotrophs. We conclude that bromocriptine effectively inhibits POMC expression in SCLC cells, and that this phenomenon might be of useful clinical application.
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PMID:Bromocriptine inhibits pro-opiomelanocortin mRNA and ACTH precursor secretion in small cell lung cancer cell lines. 132 94

The stimulation or inhibition of adenylate cyclase by hormones and chemicals is mediated by the stimulatory or inhibitory guanine nucleotide-binding proteins, Gs and Gi respectively. Although the presence of these G-proteins in the epidermis has been suggested, no direct information regarding their nature has been available. Using cDNAs for these G-proteins as a probe, we investigated the nature of the G-proteins of various keratinocytes. FRSK cells, a cell line derived from fetal rat epidermal cells, and SV-40-transformed human epidermal cells, both of which are highly proliferative keratinocytes, contained mRNAs for both Gs-alpha and two Gi-alpha proteins (Gi-2 alpha and -3 alpha). No evidence for the presence of Gi-1 alpha or Go-alpha was obtained. Normal human or pig epidermis had a relatively small amount of mRNAs for these G-proteins in the stable (hypoproliferative) condition. Tape-stripping-induced, and UVB-induced hyperproliferative epidermis contained an increased amount of these G-protein messages. However, all Gs-alpha, Gi-2 alpha and -3 alpha, as well as beta-actin mRNAs, were increased to a similar extent, and no specific expression of G-protein messages could be detected in the hyperproliferative epidermis.
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PMID:Expression of guanine nucleotide binding proteins, Gs and Gi, in mRNAs in epidermal keratinocytes. 217 80

The effects of recombinant human interleukin-1 alpha (IL-1) on procollagen gene expression were examined in the clonal mouse osteoblastic cell line MC3T3-E1. Cells were grown in Dulbecco's Modified Eagle's Medium containing 10% fetal calf serum and 50 micrograms/ml ascorbic acid. Collagen synthesis was assessed as [3H]proline incorporation into collagenase-digestible protein (CDP). Procollagen mRNA levels were determined by Northern blot analysis using a 32P-labeled alpha 1(I) cDNA. Transcription rates were determined by nuclear run-off assay. IL-1 at 1-1000 pg/ml caused a concentration-dependent inhibition of CDP, which was maximally reduced by 75-80%, and a parallel reduction of procollagen alpha 1(I) mRNA levels. The effects of IL-1 were mimicked by the tumor promoter phorbol 12-myristate 13-acetate (PMA) at 1-100 nM, which inhibited CDP and reduced procollagen alpha 1(I) mRNA levels to a similar extent. The effects of IL-1 and PMA were independent of prostaglandin production, since indomethacin did not alter the inhibitory effect of either agent on CDP. Neither IL-1 (up to 10 ng/ml) nor PMA (100 nM) affected adenylate cyclase activity, while forskolin (10 microM), PTH (10 nM) and prostaglandin E2 (1 microM) stimulated adenylate cyclase activity 3- to 5-fold. However, forskolin (10 microM) and (Bu)2cAMP (100 microM) failed to alter CDP or procollagen alpha 1(I) mRNA levels. IL-1 (1 ng/ml) and PMA (100 nM) reduced transcription of the alpha 1(I) procollagen gene by 70% and 80%, respectively, while alpha 2(I) transcription was decreased by 59% and 53%. Neither IL-1 nor PMA affected transcription of the beta-actin or beta-tubulin genes.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Interleukin-1 alpha and phorbol ester inhibit collagen synthesis in osteoblastic MC3T3-E1 cells by a transcriptional mechanism. 232 98

Neuroblastoma x glioma hybrid NG108-15 cells endogenously express at least three receptors which activate adenylate cyclase via the intermediacy of the stimulatory G-protein, Gs. Sustained exposure of the cells to agonists at the IP prostanoid receptor results in a substantial decrease in cellular levels of the alpha-subunit of Gs (Gs alpha) [McKenzie and Milligan (1990) J. Biol. Chem. 265, 17084-17093; Adie, Mullaney, McKenzie and Milligan (1992) Biochem J. 285, 529-536]. By contrast, equivalent treatments of the cells with agonists at either the A2 adenosine receptor or the secretin receptor have no measurable effect on cellular amounts of Gs alpha. To examine whether this is a feature specific to the IP prostanoid receptor or is related to the level of expression of the individual receptors, NG108-15 cells were transfected with a construct containing a human beta 2-adrenoceptor cDNA under the control of the beta-actin promoter. Two clones of these cells were examined in detail, beta N22, which expressed some 4000 fmol/mg of membrane protein, and clone beta N17, which expressed approx. 300 fmol/mg of membrane protein of the receptor. Exposure of beta N22 cells to the beta-adrenergic agonist isoprenaline resulted maximally in some 55% decrease in membrane-associated levels of Gs alpha, without effect on membrane levels of Gi2 alpha, Gi3 alpha, G(o) alpha or Gq alpha/G11 alpha. Dose-response curves to isoprenaline in beta N22 cells indicated that half-maximal down-regulation of Gs alpha was produced by approx. 1 nM agonist. Equivalent exposure of beta N17 cells to isoprenaline did not significantly modify levels of any of the G-protein alpha subunits, including Gs alpha. In beta N22 cells the IP prostanoid receptor was expressed at similar levels to those in wild-type NG108-15 cells, and treatment with iloprost resulted in a similar down-regulation of cellular Gs alpha levels. Iloprost was also effective in causing down-regulation of Gs alpha levels in clone beta N17. Concurrent addition of both isoprenaline and iloprost to clone beta N22 resulted in less than additive down-regulation of Gs alpha. These results demonstrate that the phenomenon of agonist-induced specific G-protein down-regulation is determined by the levels of expression of the receptor.
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PMID:Agonist regulation of cellular Gs alpha-subunit levels in neuroblastoma x glioma hybrid NG108-15 cells transfected to express different levels of the human beta 2 adrenoceptor. 751 55

Vasoactive intestinal peptide (VIP), the structurally homologous pituitary adenylate cyclase-activating peptide (PACAP) and the pituitary hormone, prolactin (PRL) enhance rapid eye movement sleep (REMS). VIP and PACAP are both inducers of PRL gene expression and release in the pituitary gland. Little is known about PRL regulation in the brain although it is hypothesized that the REMS-promoting activity of i.c.v. administered VIP may be mediated via the activation of cerebral PRL. To test whether VIP or PACAP in fact increase intracerebral mRNA, the peptides (VIP: 30 or 300 pmol; PACAP: 220 pmol) were injected i.c.v. into rats at dark onset. 1 h later, cDNA was synthesized from purified hypothalamic mRNA. Standardized amounts were analysed for PRL using the polymerase chain reaction followed by Southern blotting and hybridization. Compared with beta-actin mRNA levels, both VIP and PACAP increased PRL mRNA levels in a dose-dependent fashion though VIP was more effective on a molar basis. The previously reported alternatively spliced PRL mRNA (lacking exon 4) was not detected. The data support the hypothesis that the REMS-promoting activity of central VIP and PACAP might be mediated by cerebral PRL.
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PMID:Increase of prolactin mRNA in the rat hypothalamus after intracerebroventricular injection of VIP or PACAP. 782 Jun 99

The H(+)-K(+)-adenosinetriphosphatase (ATPase) is expressed in the parietal cell and is responsible for acid secretion by the stomach. Histamine binds to an H2 receptor and activates adenylate cyclase and intracellular calcium concentration ([Ca2+]i) elevation, stimulating acid secretion. It has been shown that omeprazole administered to rats increases serum gastrin and transiently increases the level of mRNA for the alpha-subunit of the pump, but this increase is blocked by the presence of the H2-receptor antagonist, famotidine [A. Tari, G. Yamamoto, K. Sumii, M. Sumii, Y. Takehara, K. Haruma, G. Kajiyama, V. Wu, G. Sachs, and J. H. Walsh. Am. J. Physiol. 265 (Gastrointest. Liver Physiol. 28): G752-G758, 1993]. These observations suggest that the release of histamine induced by gastrin is essential for the increase of the expression of mRNA induced by omeprazole. Infusion of histamine at 15 mumol.kg-1.h-1 i.v. for 1 h increased the alpha-subunit mRNA level by 144 +/- 2.4% and induced a stimulated morphological appearance of the parietal cell. These changes were inhibited completely by the competitive H2-receptor antagonist famotidine, which elevated gastric pH and serum gastrin. Famotidine also reduced the level of H(+)-K(+)-ATPase mRNA compared with control animals. No change in the expression of beta-actin mRNA was observed in any group of animals. These data provide direct evidence for histamine stimulation of H(+)-K(+)-ATPase alpha-subunit gene expression by activation of the H2 receptor.
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PMID:Effect of histamine on rat gastric H(+)-K(+)-ATPase alpha-subunit expression. 816 83

The possibility that alteration in stimulatory guanine nucleotide-binding protein (Gs) expression may contribute to the blunting of renal parathyroid hormone (PTH)-stimulated adenylate cyclase in aged rats was examined. Using rat cDNA probe, we identified a Gs alpha-subunit (Gs alpha) of 1.9 kb. Age did not alter the size of Gs alpha mRNA. The level of Gs alpha mRNA [normalized to poly(A)+ RNA] was decreased 23%, which was consistent with our previous report that Gs alpha protein decreased in senescence. In contrast, mRNA level of Gi alpha 2 increased with age. Level of beta-actin mRNA did not change with age. Nuclear runoff assay was performed to determine the transcription rate of Gs mRNA. Synthesis of poly(A)+ RNA and total RNA was reduced 39% and 37%, respectively, in nuclei prepared from old kidney, which suggested a general decline in RNA synthesis capacity in old rats. Our results also showed the transcription rate of Gs alpha mRNA in aged rats was reduced 89%, a decrease far exceeding that observed for total RNA or poly(A)+ RNA. We concluded that the decrease in steady-state level of Gs alpha mRNA was specific and probably was due to a reduction in the transcription activity. Thus alteration in Gs transcription may contribute, at least in part, to the impaired renal adenylate cyclase activation in aged rats.
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PMID:Decrease in Gs protein expression may impair adenylate cyclase activation in old kidneys. 849 29

Psoriatic hyperproliferative epidermis is characterized by a decreased beta 2-adrenergic adenylate cyclase response as well as by altered differentiation markers that include decreased loricrin and increased involucrin. Using a quantitative reverse transcription-polymerase chain reaction, we analysed the expression of beta 2-adrenergic receptor-mRNA, loricrin-mRNA, and involucrin-mRNA in the epidermis of five patients with psoriasis vulgaris. The mRNAs of the beta 2-adrenergic receptor and loricrin in the involved epidermis were significantly decreased, by 0.35-fold (P < 0.01) and 0.55-fold (P < 0.05) respectively, compared with uninvolved epidermis. In contrast, the involucrin mRNA expression of the involved epidermis was significantly increased, by 3.77-fold (P < 0.01). No significant difference in beta-actin mRNA transcripts was detected between the involved and the uninvolved epidermis. These results indicate that the altered expression of the beta 2-adrenergic receptor, loricrin, and involucrin, in the psoriatic involved epidermis, is associated with different amounts of each mRNA transcripts.
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PMID:Decreased beta 2-adrenergic receptor-mRNA and loricrin-mRNA, and increased involucrin-mRNA transcripts in psoriatic epidermis: analysis by reverse transcription-polymerase chain reaction. 876 26

Aromatase, a cytochrome P450, catalyzes three consecutive hydroxylation reactions converting C19 androgens to aromatic C18 estrogenic steroids. Aminoglutethimide (AG) is an aromatase inhibitor used to treat estrogen-dependent breast cancer. While AG is effective in inhibiting aromatase, it was found that aromatase activity in tumors of some breast cancer patients elevated after AG treatment (Miller and O'Neill, Steroids, 50: 245-252, 1987). These results may explain why some patients failed therapy after extensive AG treatment. Recently, we found that AG treatment increased aromatase activity in SK-BR-3, JAR, and HepG2 cell lines in a dose- and incubation time-dependent manner. AG induction is thought to occur at the transcriptional level because the aromatase mRNA level elevated after AG treatment in SK-BR-3 and HepG2 cells, as demonstrated by reverse transcription-polymerase chain reaction (RT-PCR) analysis, and AG treatment did not increase aromatase activity in aromatase cDNA transfected cell lines (driven by the beta-actin promoter). Our primer-specific RT-PCR analysis revealed that in SK-BR-3 cells, AG enhanced the action of a promoter which is different from promoter I.1, I.3, or II. Furthermore, since the AG induction was found to be suppressed by SQ 22536, an adenylate cyclase inhibitor, a cAMP-dependent mechanism might be involved. Our study provides an insight as to why some patients fail therapy after extensive AG treatment.
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PMID:Induction of aromatase expression by aminoglutethimide, an aromatase inhibitor that is used to treat breast cancer in postmenopausal women. 1047 Jan 47

Bacillus anthracis is the etiological agent of anthrax and the bacterium produces a tripartite anthrax toxin composed of protective antigen (PA), lethal factor (LF) and edema factor (EF). PA represents the binding domain of the toxin and acts in concert with either LF, a metalloprotease, or EF, an adenylate cyclase, to form lethal toxin (LeTx) or edema toxin (EdTx), respectively. We analyzed the proteomics response of two murine macrophage cell lines (J774.1A and RAW264.7) following B. anthracis LeTx treatment to detect unique host proteins involved in anthrax infection using difference in-gel electrophoresis (DIGE) followed by nanoLC-MS for identification of the proteins. The comparative proteomics approach identified a set of proteins in each cell line that was consistently upregulated when the two macrophage cell lines were treated with LeTx. The upregulated proteins include those involved in energy metabolism, cytoskeleton structure and stress response. A subset of five proteins (ATP synthase beta subunit, beta-actin, Hsp70, vimentin, and Hsp60 homolog) was identified that were commonly upregulated in both cell lines. The proteomic data suggest the involvement of reactive oxygen species (ROS) in cell lysis as seen by the upregulation of proteins that lead to the production of ROS in both the cell lines used in our study. However, proteins that afford protection against ROS may play an important role in the survival of the macrophage to LeTx infection as shown by the differences in proteomic responses of the two cell lines to the action of LeTx. These identified proteins may have the potential to be used as biomarkers for diagnostics and therapeutics.
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PMID:Proteomic analyses of murine macrophages treated with Bacillus anthracis lethal toxin. 1695 May 95


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