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)

Epinephrine, norepinephrine, and isoproterenol produced dose-dependent stimulation of ornithine decarboxylase (EC 4.1.1.17) activity in isolated porcine granulosa cells maintained under defined conditions in vitro. beta- but not alpha-receptor-blocking agents prevented enzyme stimulation by catecholamines. Application of preferential beta-1 and beta-2-receptor antagonists and agonists localized the epinephrine effect to beta-2-adrenergic mediation. Epinephrine action was enhanced by the phosphodiesterase inhibitor, 1-methyl-3-isobutyl-xanthine, but not by saturating concentrations of the cyclic AMP analogue, 8-bromocyclic AMP, of follicle-stimulating hormone, or of prostaglandin E2. However, stimulation by epinephrine was additive to that of luteinizing hormone. Follicular fluid obtained from immature Graafian follicles contained concentrations of norepinephrine and epinephrine active in vitro. Thus, catecholamines may participate in the regulation of ornithine decarboxylase activity in the ovary. Catecholamine effects may be mediated by beta-2-receptors linked to the adenylate cyclase system.
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PMID:Beta-2-Adrenergic stimulation of ornithine decarboxylase activity in porcine granulosa cells in vitro. 615 44

Granulosa cells from small (1-2 mm) follicles of porcine ovaries produced cAMP in response to follicle-stimulating hormone (FSH); they produced little cAMP in response to human chorionic gonadotropin (hCG) or to cholera toxin. Production, estimated by quantification of total cAMP (medium + cells) by radioimmunoassay, appeared to be episodic in the absence or presence of the phosphodiesterase inhibitor 1-methyl-3-isobutylxanthine (MIX) and continued for at least 20 h. Results of dual incubation experiments with thorough washing of cells between incubations indicated that cells remained responsive to FSH, to hCG, and to cholera toxin after prior exposure to homologous stimulator. Preincubation of cells for 3 h in the absence of stimulator enhanced FSH responsiveness. In experiments with heterologous stimulators in two incubations, first, preincubation with FSH enhanced subsequent hCG and cholera toxin responsiveness; and second, preincubation with hCG or cholera toxin did not affect FSH responsiveness. Desensitization of FSH-activated adenylate cyclase was never greater than 35%; the degree of attenuation was dependent on FSH concentration and duration of exposure to FSH. Cells perifused with medium containing MIX and a maximally effective concentration of FSH for 5 h released cAMP continuously. In summary, the results indicated that porcine granulosa cells do not become unresponsive to FSH after prolonged exposure to FSH in vitro.
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PMID:Porcine granulosa cell desensitization: prolonged FSH-responsive cAMP production in vitro. 618 6

Suspensions of purified rat ovarian plasma membranes were irradiated by high-intensity light in the cold. This treatment gradually reduced the ability of the membrane receptor to bind 125I-labeled human chorionic gonadotropin and the ability of adenylate cyclase (ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1) to respond to luteinizing hormone, follicle-stimulating hormone, human chorionic gonadotropin and prostaglandin E2. In contrast adenylate cyclase activity stimulated by NaF or guanosine 5'(beta, gamma-imido)triphosphate (p(NH)ppG) was significantly more resistant to irradiation. Human chorionic gonadotropin protected the binding site from light-induced damage, but not the ability of the hormone to activate adenylate cyclase. Irradiation destroyed close to 50% of unoccupied guanosine nucleotide binding sites but apparently did not induce massive covalent binding of nucleotides to membrane components. It is suggested that high-intensity light induces damage to two separate sites in the adenylate cyclase system. One affects hormone binding and is presumably associated with the hormone receptor, the second interferes with coupling but at a step proximal to regulation of adenylate cyclase by GTP binding protein.
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PMID:Photo-induced inactivation and uncoupling of gonadotropin receptors in rat ovarian plasma membrane. 624

Granulosa cells from small follicles were cultured as suspensions in spinner flasks for 10 days in the absence or presence of follicle-stimulating hormone (FSH). With or without FSH, the cultured cells ultrastructurally resembled luteinized cells to different degrees. FSH increased progesterone accumulation in the culture medium. Ovine prolactin potentiated the effect of FSH in terms of the quantity of progesterone produced and the duration of accumulation. FSH increased acute human chorionic gonadotropin (hCG)-responsive progesterone secretion in short-term incubations of cultured granulosa cells. Responsiveness of FSH-cultured cells was maximal at day 4; that of control cultured cells was maximal at day 6. Adenylate cyclase activity of homogenates of cells cultured for 4, 6, or 8 days was measured. FSH induced in cultured cells an hCG sensitivity of the adenylate cyclase enzyme. These results indicate that FSH induced hCG-responsive progesterone secretion and hCG-responsive adenylate cyclase activity that correlate with ultrastructural signs of luteinization and with the previously reported FSH induction of hCG receptors.
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PMID:Porcine granulosa cells in suspension culture. II. Luteinization and hCG responsiveness. 626 90

The effects of follicle-stimulating hormone (FSH) and testosterone on the development of the cytosolic germ cell adenylate cyclase and germ cell morphology in rats hypophysectomized at 29 days of age were studied. Following hypophysectomy, the adenylate cyclase content fell to marginal levels and germ cell development ceased at the late pachytene stage. Testosterone treatment led to a moderate increase in the cytosolic enzyme content and to progression of spermatid cell development to stages 8-12. FSH treatment with doses of 80-100 micrograms/day restored enzyme content to levels seen in control rats, as well as progression of germ cell development up to stages 15-16, i.e., to the same stages present in age-matched control (sham-operated) rats. The results indicate that in immature rats FSH is essential for spermatid cell maturation as is evidenced by its ability to stimulate the formation of cytosolic germ cell adenylate cyclase to quantitatively normal levels, as well as to stimulate the development of spermatid cells.
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PMID:FSH and testosterone effects in seminiferous tubules of immature hypophysectomized rats. 626 35

The antigonadal effects of gonadotropin-releasing hormone in ovarian granulosa cells are due to attenuation of the adenosine 3',5'-monophosphate (cyclic AMP) response to follicle-stimulating hormone. Agonists of gonadotropin-releasing hormone progressively inhibit adenylate cyclase and stimulate phosphodiesterase activities in cultured granulosa cells, indicating that blockade of gonadotropin action is attributable to the combined effects of decreased production and increased degradation of cyclic AMP.
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PMID:Gonadotropin-releasing hormone: regulation of adenosine 3',5'-monophosphate in ovarian granulosa cells. 627 16

Pseudohypoparathyroidism is an inherited disorder associated with resistance to the action of several hormones, including parathyroid hormone, thyroid-stimulating hormone, follicle-stimulating hormone, and luteinizing hormone. The disorders described under this designation are heterogeneous in regard to the underlying genetic defects, the phenotypic manifestation, and the severity of the defects in hormone action. The majority of affected individuals who also have the characteristic skeletal changes (heredity osteodystrophy) have a defect in the guanine nucleotide regulatory protein (G protein) that is essential for coupling certain cell-surface hormone receptors to the adenylate cyclase system. This defect is probably the cause for resistance to the action of multiple hormones. In the remaining patients the cause for hormone resistance has not been identified.
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PMID:Deficiency of hormone receptor-adenylate cyclase coupling protein: basis for hormone resistance in pseudohypoparathyroidism. 628 11

The induction of luteinizing hormone (LH) receptor by follicle-stimulating hormone (FSH) in granulosa cells was compared following culture in serum-free or serum-containing medium. Incubation of primary cultures of granulosa cells in serum-free defined medium with purified FSH resulted in dramatic increases in the level of functional LH receptors. This striking enhancement of LH receptor by FSH was completely abolished by concomitant incubation with serum (rat, horse, porcine, human or calf). The serum inhibition of FSH was not readily reversible and could be evoked throughout the culture period. The synthesis of cAMP by FSH was markedly suppressed by serum, suggesting that serum component(s) are inhibiting FSH action at the level of adenylate cyclase. Such an action, however, cannot be the sole mechanism because serum also blocked LH receptor induction by cyclic AMP analogs. In defined medium, addition of insulin, transferrin, dexamethasone or fibronectin alone had no effect on basal levels of LH receptor. However, following incubation with either insulin or dexamethasone, the FSH-induced increases in LH receptor were markedly suppressed. Insulin was found to markedly inhibit FSH-stimulated cyclic AMP formation; this was not the case with dexamethasone. The present results demonstrated the complete inhibition of FSH action by serum in cultured granulosa cells and suggest that the effect is caused by a combination of direct actions of common metabolic hormones which inhibit FSH action at multiple sites. These experiments clearly indicate the obligatory role of defined medium in the hormone-dependent differentiation of the granulosa cell in culture.
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PMID:Role of serum-free defined medium in regulation of LH receptor in cultured rat granulosa cells. 630 7

Although luteinizing hormone (LH) is known to down-regulate its own receptor in several gonadal cell types, the mechanisms underlying this process are poorly understood. To elucidate these mechanisms we have examined the role of cAMP and progesterone in LH-stimulated down-regulation of the LH receptor, using cultured granulosa cells as a model. LH receptors were induced by culturing the cells with follicle-stimulating hormone for 2 days, and once induced, could be down-regulated by a brief exposure to LH. Down-regulation also occurred when cells were cultured with activators of adenylate cyclase, inhibitors of phosphodiesterase, or analogues of cAMP. Cholera toxin and N6,O2'-dibutyryladenosine 3':5'-cyclic monophosphate, like LH, decreased the number of LH receptors, without affecting affinity for 125I-human chorionic gonadotropin (hCG). The extent of receptor loss after treatment with LH plus cholera toxin was no greater than that caused by LH alone. LH, hCG, and deglycosylated hCG, which binds to the LH receptor but has little bioactivity, caused down-regulation, and their relative capacity to cause down-regulation was highly correlated with their relative capacity to stimulate cAMP production. Indirect evidence suggested that maximal down-regulation requires activation of adenylate cyclase for at least 3 h. Consistent with this idea, a 3-h exposure to dibutyryl cAMP caused near-maximal down-regulation. Progesterone secretion was enhanced by all agents that caused down-regulation of the LH receptor; however, there was little correlation between progesterone secretion and down-regulation. Furthermore, maximal down-regulation occurred when progesterone secretion was inhibited greater than 99% with cyanoketone. These data indicate that cAMP, but not progesterone, plays a central role in LH receptor down-regulation in the granulosa cell and that elevation of intracellular cAMP levels for 3 h is both necessary and sufficient to trigger maximal down-regulation.
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PMID:A central role for cyclic AMP, but not progesterone, in luteinizing hormone receptor down-regulation in the granulosa cell. 631 88

The induction of luteinizing hormone (LH) receptors was studied in granulosa cells prepared from the ovaries of hypophysectomized diethylstilbestrol-treated immature rats. Incubation of granulosa cells for 48 h with increasing concentrations of follicle-stimulating hormone (FSH) or choleragen caused parallel rises in cAMP levels and LH receptors. These observations, with the finding that 8-Bromo-cAMP also induced LH receptor formation, indicate that hormonal stimulation of LH binding sites is mediated by cAMP. Peptide hormones that inhibited FSH-stimulated cAMP production, such as epidermal growth factor (EGF) and a gonadotropin-releasing hormone agonist (GnRHa), also prevented LH receptor formation. GnRHa and EGF had negligible effects on FSH-stimulated cAMP production from 0 to 24 h of culture, but reduced cAMP accumulation by 80% and 90%, respectively, from 24 to 48 h when the majority of LH receptors appeared. FSH-sensitive adenylate cyclase activity, as measured by the conversion of (3H)-ATP to (3H)-cAMP, was inhibited by GnRHa and EGF at 48 h of culture. EGF and GnRHa also reversed the inhibiton of ectophosphodiesterase activity caused by FSH in granulosa cells between 48 and 72 h of culture. Both EGF and GnRHa inhibited induction of LH receptors by 8-Bromo-cAMP, suggesting that their effects are also on cAMP action. Addition of GnRHa, but not EGF, between 36 and 48 h of culture completely prevented further increases in LH receptors induced by 8-Bromo-cAMP, indicating that the inhibitory action of GnRHa can be initiated at later times during granulosa cell differentiation, whereas full expression of EGF action requires a longer period. These results demonstrate that EGF and GnRH inhibit FSH-induced LH receptor formation in the granulosa cell by reducing hormone-dependent cAMP production and also by impairing the ability of cAMP to stimulate LH receptor formation.
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PMID:Epidermal growth factor and gonadotropin-releasing hormone inhibit cyclic AMP-dependent luteinizing hormone receptor formation in ovarian granulosa cells. 631 8


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