Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:4.6.1.1 (adenylate cyclase)
19,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The chemotactic effect of calcitonin (CT) gene products was tested on F9 teratocarcinoma cells, which are an in vitro model of early embryonic development. CT and CT gene-related peptide (CGRP) induce a significant chemotactic response (chemotactic index, 40-50). The order of potency is: chicken CGRP greater than or equal to salmon CT greater than or equal to human CGRP. Human CT is a less potent chemotactic agent (chemotactic index, 15). Compared to other well known peptides with chemotactic activity, such as platelet-derived growth factor (no activity) and transforming growth factor-beta (chemotactic index, 5), CGRP and CT appear to be very active in attracting F9 cells in the Boyden chamber assay. Interestingly, CT and CGRP exhibit little chemotactic effect toward differentiated teratocarcinoma cells (i.e. retinoic acid-treated F9 cells or parietal endodermal PYS cells). While salmon CT and chicken CGRP activate adenylate cyclase activity in F9 cell membranes by 7- to 8-fold, higher concentrations (greater than 10(-10) M) of these peptides are required to stimulate cAMP formation than are required to mediate the chemotactic effect of these peptides. These data imply the possible involvement of CT gene products in regulating cell migration during early embryonic development.
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PMID:Calcitonin and calcitonin gene-related peptide are chemotactic for F9 embryonal carcinoma cells. 193 83

Stimulation of human arterial endothelial cells with heparin-binding growth factor-1 (HBGF-1) resulted in a 40% to 60% increase in the cellular adenylate cyclase activity and intracellular cAMP content. The stimulatory effect of HBGF-1 was effectively suppressed by pretreating the cells with transforming growth factor-beta (TGF-beta), an endothelial cell growth inhibitor. The inhibition of the adenylate cyclase activity precedes growth inhibition by at least 24 h. The half maximal inhibitory dose was calculated to be 0.2 ng/ml for the inhibition of both cyclase activity and cell growth. The possible role of the adenylate cyclase suppression in growth inhibition by TGF-beta is discussed.
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PMID:Transforming growth factor-beta inhibits cellular adenylate cyclase activity in cultured human arterial endothelial cells. 246 71

It is the objective of the experiments reported herein to examine the possible relevance of transforming growth factor-beta (TGF beta) to theca-interstitial cell function, and to further characterize the established interaction of TGF beta with the granulosa cell. In examining the interaction of TGF beta (10 ng/ml) with murine theca-interstitial cells, no significant effect was observed on either basal or human chorionic gonadotropin (hCG)-stimulated androsterone accumulation. In contrast, given murine granulosa cells, TGF beta (10 ng/ml) produced dose- and time-dependent augmentation of follicle-stimulating hormone (FSH)-supported aromatase activity with a minimal and median effective doses of 20 +/- 3 and 123 +/- 24 pg/ml, respectively and a minimal time requirement of less than or equal to 48 h. The ability of TGF beta to augment FSH hormonal action could not be accounted for by alteration(s) of specific FSH binding (13965 +/- 298 and 12614 +/- 694 cpm/4 X 10(5) cells for FSH and FSH + TGF beta). However, TGF beta proved capable of exerting a direct upregulatory effect on stimulatable adenylate cyclase activity, further enhancement occurring at site(s) distal to cAMP generation (dibutyryl cyclic AMP (Bt2cAMP) = 1.4 +/- 0.2 ng/culture; Bt2cAMP + TGF beta = 4.1 +/- 0.6 ng/culture). Taken together, our findings are in keeping with the notion that TGF beta, possibly of intraovarian origin, comprises the central signal of autocrine or paracrine loop(s) capable of amplifying gonadotropin action at the level of the granulosa, but not theca-interstitial cell.
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PMID:Ovarian transforming growth factor-beta (TGF beta): cellular site(s), and mechanism(s) of action. 249 58

Numerous reports have appeared in the literature indicating phenotypic heterogeneity among cells of the osteoblastic lineage. This diversity may be due to either certain stages of differentiation or a subspecialization of already terminally differentiated osteoblasts. To obtain answers to this question, we report on studies undertaken to clone bone cell populations from 1 day postnatal rat calvaria which express well defined differences in phenotype. To achieve this goal, we have used the soft agarose cloning technique which previously has almost exclusively been applied to clone cells of neoplastic origin. The reason for being able to employ this method is based on the fact that bone cells can be induced by transforming growth factor-beta to reversibly acquire the transformed phenotype, an event expressed by anchorage-dependent bone cells to form progressively growing colonies in soft agarose. Individual colonies, harvested from agarose, were expanded to clonal bone cell populations. Characterizing 48 cell clones by detection of osteoblastic cell markers such as alkaline phosphatase activity, PTH- and prostaglandin-E2-induced adenylate cyclase activity, osteocalcin mRNA synthesis, as well as collagen synthesis, 7 subsets of osteoblastic cell types were identified. Each subset was found to express a distinct phenotype, indicated by the absence or presence of osteoblastic cell markers. Some clones, previously found not to exhibit any osteoblastic traits, developed PTH responsiveness when treated with insulin-like growth factor-I/transforming growth factor-beta, suggesting that these clones may originate from the osteoprogenitor cell pool. While most clonal cell populations were characterized as fully functional osteoblastic cells, some clones expressed merely 1, 2, or 3 osteoblastic markers, which suggests that they may represent stages of differentiation along the osteogenic pathway. In addition, other subclones displayed the capacity to synthesize osteocalcin and showed PTH and prostaglandin-E2 responsiveness, but were found to be devoid of alkaline phosphatase activity. Others expressed all osteoblastic cell markers except PTH responsiveness. The phenotypic constellation of the latter suggests that these cell clones may represent mature osteoblast-like cells, which, perhaps due to environmental circumstances present at the time of isolation, have become altered in accordance with the physiological requirements of the tissue.
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PMID:Evidence for heterogeneity of the osteoblastic phenotype determined with clonal rat bone cells established from transforming growth factor-beta-induced cell colonies grown anchorage independently in semisolid medium. 267 79

Endothelial cells express the product of the c-sis gene, which encodes the B-chain of platelet-derived growth factor (PDGF). Through local production of growth factors such as PDGF in vascular sites, endothelial cells may stimulate proliferation of adjacent cells through a paracrine mechanism. Previously, we have shown that the expression of c-sis mRNA and release of growth factor activity by human renal endothelial cells is induced by thrombin. We now show that another agent of possible importance in mediating proliferation of cells adjacent to the endothelial cell layer, transforming growth factor-beta (TGF-beta), also induced c-sis expression in these cells. In addition, we have studied the effect of agents that increase intracellular cAMP levels upon the induction of endothelial cell c-sis mRNA. The adrenergic agonists isoproterenol and norepinephrine blocked the elevation of cellular c-sis mRNA accompanying exposure to either thrombin or TGF-beta. This effect was mediated through beta-adrenergic receptors, since propranolol but not phentolamine reversed the inhibition. Forskolin, a direct activator of adenylate cyclase, also blocked induction of c-sis mRNA by thrombin and TGF-beta and inhibited the release of PDGF activity into the media of these cells. Basal, as well as stimulated c-sis mRNA levels were attenuated by these agents that increase cellular cAMP levels. These data suggest that increased cAMP production inhibits the expression of c-sis encoded mitogens by endothelial cells, and that c-sis expression is subject to bidirectional regulation in these cells.
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PMID:Agents that increase cAMP accumulation block endothelial c-sis induction by thrombin and transforming growth factor-beta. 304 Jul 21

We have developed and characterized a primary cell culture system to study the regulation of 17 alpha-hydroxylase cytochrome P450 (P45017 alpha) gene expression in bovine thecal cells. Conditions have been established for the dispersal and growth of thecal cells isolated from bovine follicles, which maintain the expression of P45017 alpha for up to 8 days. Bovine theca interna cells were grown to subconfluence and transferred into medium containing forskolin, a stimulator of adenylate cyclase. Levels of P45017 alpha transcripts reached a maximum value after 48 h of stimulation with forskolin. Added progesterone was converted to 17 alpha-hydroxyprogesterone at a rate of 214 pmol/mg protein.h in cells treated with forskolin for 72 h, whereas in control cells, the rate was 9.2 pmol/mg protein.h after 72 h. This was reflected in a 10-fold increase in endogenous androstenedione production by forskolin-stimulated cells. Studies employing various growth factors suggest that transforming growth factor-beta, but not basic fibroblast growth factor, is a potent inhibitor of forskolin-induced 17 alpha-hydroxylase activity and androstenedione production in these cells. We have also characterized this cell culture system with respect to expression of other steroidogenic enzymes. Cholesterol side-chain cleavage cytochrome P450 and 3 beta-hydroxysteroid dehydrogenase transcripts as well as endogenous progesterone accumulation were increased in response to forskolin stimulation. On the other hand, aromatase cytochrome P450 expression was undetectable. The ability to maintain bovine thecal cells, which retain 17 alpha-hydroxylase activity, in culture will provide a model system to study the regulation of expression of the P45017 alpha gene in the bovine ovary.
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PMID:Maintenance and regulation of 17 alpha-hydroxylase expression by bovine thecal cells in primary culture. 767 80

Epidermal growth factor (EGF) is a potent mitogen for sheep pituitary cells but the factors controlling the binding and expression of EGF and its receptor (EGFR) in the pituitary are poorly understood. Regulation of EGF binding and EGFR gene expression may determine cellular responsiveness to EGF and could play a role in neoplastic development. Scatchard analysis of 125I-EGF binding in cultured sheep pituitary cells revealed two receptor binding sites (high affinity class of 2.5 +/- 0.5 x 10(3) receptors/cell with a dissociation affinity constant (Kd) of 3.2 +/- 0.7 x 10(-10) M and low affinity class of 3.3 +/- 1.0 x 10(4) receptors/cell with a Kd of 7.1 +/- 1.3 x 10(-9) M). Exposure of the cultured cells to some target gland hormones of the pituitary (oestrogen, tri-iodothyronine and hydrocortisone), pituitary growth factors (EGF, basic fibroblast growth factor, transforming growth factor-beta) and a tumour-promoting phorbol ester (TPA) resulted in an increase in the binding affinity of the high affinity receptors while reducing the receptor number and also a reduction of EGFR mRNA levels, shown by Northern blot analysis. In contrast, forskolin, an activator of adenylate cyclase, showed no significant effect on EGF binding and receptor gene expression. We conclude that the EGFR in normal pituitary cels can be modulated by several hormones and other growth factors at both receptor binding and mRNA levels. Transmodulation of EGFR by hormones and growth factors in the pituitary may be one of the regulatory mechanisms controlling the balance of normal pituitary growth and function.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Modulation of epidermal growth factor binding and receptor gene expression by hormones and growth factors in sheep pituitary cells. 783 94

Seminiferous tubules prepared from adult rats cultured for 48 h in serum-free conditions produce multiple biological factors that modulate Leydig cell steroidogenic function in vitro. Using gel filtration chromatography, it was shown that seminiferous tubular culture medium (STCM) contained at least three inhibitory activities designated AI, AII, and AIII that inhibited testosterone production by purified Leydig cells. The factor that induced AIII activity, designated Leydig cell inhibitor (LCI), was further purified to apparent homogeneity by sequential HPLC using gel permeation, C8-, C18-, C2/C18-reversed-phase, and microbore anion exchange columns. When this batch of purified factor was resolved by SDS-PAGE under reducing conditions, only a single silver stained band with an apparent M(r) of 21,000 was detected. Protein sequence analysis using about 100 pmol of purified LCI revealed that its N-terminus was blocked. Incubation of this highly purified factor with Percoll gradient purified Leydig cells induced a dose-dependent inhibition of hCG-stimulated testosterone production. LCI inhibited the basal testosterone production and hCG-stimulated cAMP production by Leydig cell dose-dependently. It also inhibited the forskolin- and cholera toxin-stimulated testosterone and cAMP production but had no apparent effect on the binding of 125I-labeled hCG to LH receptors. These data suggest that this LCI exerts its inhibitory action at steps beyond the LH receptors but prior to the cAMP formation by affecting the adenylate cyclase activity directly or indirectly through inhibition of the stimulatory G-protein (Gs-protein); however, it is also possible that it decreases the coupling of the receptors to the Gs-protein. LCI also inhibited the conversion of exogenously added 22R-hydroxycholesterol, pregnenolone, progesterone, and 17 alpha-hydroxyprogesterone to testosterone. However, it had no effect on the conversion of dehydroepiandrostenedione and androstenedione to testosterone. These data strongly suggest that LCI affects the steroidogenic enzymes metabolizing cholesterol to testosterone, the cytochrome P-450 side-chain cleavage (P-450SCC), and cytochrome P-450 17 alpha-hydroxylase/17,20-lyase (P-450C17). However, it has no effect on the 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) and 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) enzyme activities. Based on the results of the present study, it is apparent that this LCI is distinct from other known potent Leydig cells inhibitors such as interleukin-1 (IL-1) and transforming growth factor-beta (TGF-beta). The LCI appears to involve in the paracrine regulation of Leydig cell function.
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PMID:Rat seminiferous tubular culture medium contains a biological factor that inhibits Leydig cell steroidogenesis: its purification and mechanism of action. 798 48

The factors that regulate growth and function of the human adrenal gland during intrauterine development and thereafter are ill defined. Whereas others have reported that adrenocorticotropic hormone (ACTH) augments the inhibitory effect of transforming growth factor-beta (TGF-beta) on growth of fetal zone (FZ) cells of the human fetal adrenal, we recently found that ACTH interferes with TGF-beta's inhibition of growth of fetal adrenal neocortex cells. In this study we sought to assess independently the effects of TGF-beta in the absence and presence of ACTH on growth of FZ cells. TGF-beta, in a time- and dose-dependent manner, inhibited growth (i.e., [3H]thymidine incorporation) of FZ cells. ACTH (Cortrosyn), at 90 pM to 90 nM, was found to interfere with the TGF-beta inhibition of FZ growth. ACTH 1-24 and human ACTH 1-39, both from Sigma Chemical, also were found to blunt the response of FZ cells to TGF-beta. Growth inhibition due to TGF-beta action and the reversal by ACTH of TGF-beta effects on FZ cell growth were confirmed by the results of immunohistochemical analyses of 5'-bromo-2'-deoxyuridine incorporation into nuclei of FZ cells and by indirect evaluations of cell numbers. Both forskolin (10 microM) and dibutyryl adenosine 3',5'-cyclic monophosphate (1 mM), but not phorbol 12-myristate 13-acetate (1 or 100 mM), were able to mimic ACTH actions in blunting the inhibitory effects of TGF-beta on DNA synthesis. We conclude that ACTH, possibly via activation of adenylate cyclase, interferes with, rather than augments, the growth-inhibitory effect of TGF-beta on FZ cell growth.
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PMID:Interactions between TGF-beta and adrenocorticotropin in growth regulation of human adrenal fetal zone cells. 816 71

In a recent communication, we demonstrated that prostaglandin E2 (PGE2) lowers basal while it ablates interleukin-1beta((IL-1beta) and transforming growth factor-beta (TGFbeta) upregulated lysyl oxidase (LO) mRNA levels. Correspondingly, PGE2 increases cyclooxygenase-1 (COX1) mRNA in diploid, human embryo lung fibroblasts (IMR90) [Roy et al., 19961. We now report that these actions by PGE2 are routed through cAMP via the PGE2, EP2 receptor. Among the PGE2 receptor types, the IMR90 predominantly express the EP2 mRNA. These cells also express EP3 and EP4 mRNA at comparatively low levels. Northern blot analyses show that 11-deoxy PGE1, an EP2/EP4 agonist, emulates the action of PGE2. In a similar manner to PGE2, 11-deoxy PGE1 decreases basal and TGF-beta induced type I collagen alpha1 (COL) mRNA, basal and IL-1beta induced LO mRNA while it increases COX1 mRNA. Sulprostone, an EP3/EP1 agonist, has no effect on the expression of these three genes. Forskolin, an adenylate cyclase activator, acts in a very similar manner to PGE2 or 11-deoxy PGE1. It suppresses both basal and TGF-beta induced COL mRNA levels. Both PGE2 and 11-deoxy PGE1 increase cAMP to a level comparable with forskolin. The role of the EP2 receptor in controlling collagen production is further underscored in the immortalized Rat-1 fibroblasts, derived from Fischer rat embryos, which do not express detectable EP2 mRNA. In these cells, PGE2 has little effect on COL mRNA level, whereas forskolin increases it. Furthermore, forskolin increases cAMP level in Rat-1 cells, whereas PGE2 does not. Overall, these results illustrate that much of the PGE2 action on the expression of COL, LO, and COX1 genes is mediated through the EP2 receptor and a subsequent increase in intracellular cAMP.
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PMID:Role of EP2 receptors and cAMP in prostaglandin E2 regulated expression of type I collagen alpha1, lysyl oxidase, and cyclooxygenase-1 genes in human embryo lung fibroblasts. 977 23


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