Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Luteinizing hormone is the major regulator of Leydig cell differentiation and steroidogenic function. A number of hormones produced by the Leydig cell (e.g. estrogen, angiotensin, CRF, vasopressin) and the tubular compartment (inhibin, TGF beta), can influence both acute and long-term actions of LH. Conversely, hormones produced in the Leydig cells modulate tubular function (e.g. androgen, beta-endorphin, oxytocin). The LH stimulatory event can be negatively influenced by the action of angiotensin II through the guanyl nucleotide inhibitory unit of adenylate cyclase. We have recently discovered an action of corticotrophin releasing hormone through specific high-affinity low-capacity receptors in the Leydig cells which involves a pertussis toxin insensitive guanyl nucleotide regulatory unit with interaction between signalling pathways and resulting inhibition of LH induced cAMP generation and consequently of steroidogenesis. In contrast to other tissues the CRF receptor in the Leydig cells did not couple to Gs. CRF action is exerted through direct or indirect action of protein kinase C, at the level of the catalytic subunit of adenylate cyclase. Physiological increases in endogenous LH cause positive regulation of membrane receptors and steroidogenesis, while major elevations in circulating gonadotropin can induce down-regulation of LH receptors and desensitization of steroid responses in the adult cell. Gonadotropin-induced desensitization in adult rat tests include an estrogen mediated steroidogenic lesion of the microsomal enzymes 17 alpha-hydroxylase/17,20-desmolase. For further understanding of the regulation of this key enzyme of the androgen pathway the rat P450(17) alpha cDNA was cloned and sequenced. This cDNA expressed in COS-1 cells 17 alpha-hydroxylase/17,20-desmolase activities. From the deduced amino acid sequence, two transmembrane regions were identified, a signal peptide for insertion in the ER, and a 2nd transmembrane region separated from the first by 122 amino acids. The carboxy terminal non-transmembrane region possesses 4 hydrophobic clefts, of which cleft II would contain the putative steroid binding site for both hydroxylase and lyase activities. The rat cDNA was employed to evaluate the hormonal regulation of mRNA levels in adult and fetal Leydig cells. Low dose hCG treatment caused an early increase in mRNA levels followed by a return to control values at later times, while with higher desensitizing doses the initial increase in mRNA was followed by a marked reduction in mRNA at 24 h and a small recovery at 48 h. Fetal rat Leydig cells treated with E2 showed a 70% decrease in P450 mRNA levels, and testosterone production closely followed the changes in mRNA.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:LH action in the Leydig cell: modulation by angiotensin II and corticotropin releasing hormone, and regulation of P450(17) alpha mRNA. 269 45

Ketoconazole is an antifungal agent that, in high doses, inhibits testicular and adrenal steroid synthesis. The ability of ketoconazole to block steroid synthesis has prompted us to use it in the treatment of advanced prostatic carcinoma. This study was designed to determine the site of steroid synthetic blockade that was induced by ketoconazole. Twelve patients with metastatic prostate carcinoma on long term high dose ketoconazole therapy were compared with 12 control volunteers. Values of serum progesterone, 17-hydroxyprogesterone, androstenedione, dehydroepiandrosterone sulphate, testosterone, and cortisol were measured in a baseline state and after Cosyntropin and human chorionic gonadotropin stimulation. Baseline data showed that serum levels of testosterone, androstenedione, and dehydroepiandrosterone sulphate were lower and that plasma progesterone, luteinizing hormone, and adrenocorticotropin were higher in the ketoconazole group. With Cosyntropin, plasma cortisol, androstenedione, and dehydroepiandrosterone sulphate increased only in the control group. With human chorionic gonadotropin, testosterone increased only in the control group. Basal 17-hydroxyprogesterone and progesterone rose after Cosyntropin only in the ketoconazole group. Following human chorionic gonadotropin, progesterone rose in the ketoconazole group but not in the control group. These results suggest that ketoconazole is a potent inhibitor of steroid synthesis. The major site of action appears to be in the inhibition of 17-20 desmolase. A moderate blockade of 17-hydroxylase may be present. There is a marked inhibition of 21- and/or 11-hydroxylase. The ability of ketoconazole to inhibit steroid synthesis should have therapeutic potential in the treatment of steroid dependent disease. Frequent high dose ketoconazole therapy can inhibit adrenal steroid synthesis, which can be important for patients undergoing stressful situations.
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PMID:Steroid synthesis inhibition by ketoconazole: sites of action. 296 91

The effect of spironolactone on adrenal androgen and cortisol production was studied in six hirsute women. Hirsute women were evaluated before and 1 month after receiving 200 mg of spironolactone daily. Basal levels of serum androgens, 17-hydroxyprogesterone (17-OHP), cortisol (F), corticosteroid-binding globulin, and plasma adrenocorticotropic hormone (ACTH) were normal and did not change with therapy. The delta maximum (delta max) responses after dexamethasone suppression and ACTH administration of dehydroepiandrosterone (DHEA), androstenedione (delta 4A), 17-hydroxypregnenolone, and 17-OHP were similar in hirsute women and ovulatory control subjects. After spironolactone administration, the delta max DHEA response was unchanged, whereas the delta max delta 4A response was decreased (P less than 0.05). The delta max ratios of DHEA/delta 4A and 17-OHP/delta 4A were significantly increased after spironolactone in hirsute women, which suggested inhibitions of 3 beta-ol-dehydrogenase-isomerase and delta 4 17,20 desmolase activities. A significant reduction in delta max F occurred after spironolactone administration (P less than 0.05). Although baseline 11-desoxycortisol (S) and the plasma S/ACTH ratio were unaltered, the delta max S/F ratio increased after treatment (P less than 0.01), suggesting an inhibition of 11 beta-hydroxylase activity. Inhibition of adrenal androgen production occurs with spironolactone, but only serum levels of delta 4A are decreased, whereas DHEA and its sulfate (DHEA-S) levels remain unchanged.
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PMID:The effects of spironolactone on adrenal steroidogenesis in hirsute women. 299 51

Insulin-like growth factors (IGFs) are single-chain polypeptides important for cell proliferation and growth. IGFs are produced in several tissues, suggesting that they function in a paracrine or autocrine fashion as well as functioning as endocrine hormones. We studied the hormonal regulation of IGF-I and IGF-II mRNA in human steroidogenic tissues. In cultured human ovarian granulosa cells, follicle-stimulating hormone, human chorionic gonadotropin, and dibutyryl cAMP increased IGF-II mRNA, but corticotropin [adrenocorticotropic hormone (ACTH)], chorionic somatomammotropin, growth hormone, prolactin, dexamethasone, estradiol, and progesterone had no effect. In cultured human fetal adrenal cells, ACTH and dibutyryl cAMP increased IGF-II mRNA accumulation, but human chorionic gonadotropin and angiotensin II did not. The same five size species of IGF-II mRNA were detected in transfer blots of RNA from granulosa cells and fetal adrenal cells, and all of these increased after hormonal stimuli. Dibutyryl cAMP also increased IGF-II mRNA accumulation in cultured human placental cells. Accumulation of mRNA for the cholesterol side-chain-cleavage monooxygenase [P450scc [corrected]; cholesterol, reduced-adrenal-ferredoxin:oxygen oxidoreductase (side-chain-cleaving), EC 1.14.15.6] was regulated in parallel with IGF-II mRNA in all these steroidogenic tissues. IGF-I mRNA was not detected in transfer blots of these RNAs, and the minimal amounts detected in dot blots showed no detectable change after any of the hormonal stimuli studied. The data indicate that the IGF-II gene is expressed in human steroidogenic tissues and is regulated by cAMP. These data suggest that IGF-II may act in an autocrine or paracrine fashion to stimulate the adrenal and gonadal growth stimulated by ACTH and gonadotropins, respectively.
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PMID:Coordinate tropic hormone regulation of mRNAs for insulin-like growth factor II and the cholesterol side-chain-cleavage enzyme, P450scc [corrected], in human steroidogenic tissues. 303 44

The orphan nuclear receptor steroidogenic factor 1 (SF-1) is expressed in the adrenal cortex and gonads and regulates the expression of several P450 steroid hydroxylases in vitro. We examined the role of SF-1 in the adrenal glands and gonads in vivo by a targeted disruption of the mouse SF-1 gene. All SF-1-deficient mice died shortly after delivery. Their adrenal glands and gonads were absent, and persistent Mullerian structures were found in all genotypic males. While serum levels of corticosterone in SF-1-deficient mice were diminished, levels of adrenocorticotropic hormone (ACTH) were elevated, consistent with intact pituitary corticotrophs. Intrauterine survival of SF-1-deficient mice appeared normal, and they had normal serum level of corticosterone and ACTH, probably reflecting transplacental passage of maternal steroids. We tested whether SF-1 is required for P450 side-chain-cleavage enzyme (P450scc) expression in the placenta, which expresses both SF-1 and P450scc, and found that in contrast to its strong activation of the P450scc gene promoter in vitro, the absence of SF-1 had no effect on P450scc mRNA levels in vivo. Although the region targeted by our disruption is shared by SF-1 and by embryonal long terminal repeat-binding protein (ELP), a hypothesized alternatively spliced product, we believe that the observed phenotype reflects absent SF-1 alone, as PCR analysis failed to detect ELP transcripts in any mouse tissue, and sequences corresponding to ELP are not conserved across species. These results confirm that SF-1 is an important regulator of adrenal and gonadal development, but its regulation of steroid hydroxylase expression in vivo remains to be established.
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PMID:Mice deficient in the orphan receptor steroidogenic factor 1 lack adrenal glands and gonads but express P450 side-chain-cleavage enzyme in the placenta and have normal embryonic serum levels of corticosteroids. 747 14

Adrenal hyperandrogenism is a common feature of patients with polycystic ovary syndrome (PCO). This may be due to enhanced adrenal sensitivity to ACTH. Because enhanced ovarian androgen secretion does not appear to explain this phenomenon, we explored the role of estrogen in inducing enhanced adrenal sensitivity, in that a state of relative hyperestrogenism exists in PCO. Eight patients with PCO and seven matched controls received ovine corticotropin-releasing hormone (oCRH; 0.1 micrograms/kg) iv before and after hypoestrogenism was induced by leuprolide acetate (LA; 1 mg, sc, each day). In patients with PCO, a third oCRH test was repeated after transdermal estradiol (E2; 0.1 mg) had been applied for a week, during which time LA was continued. At baseline, patients with PCO had increased responses of 11 beta-hydroxyandrostenedione and dehydroepiandrosterone (P < 0.03 and P < 0.02) and increased delta maximal ratios of androstenedione (A4)/ACTH and dehydroepiandrosterone/ACTH (P < 0.01) after oCRH treatment. After LA administration to patients with PCO, these ratios were significantly suppressed (P < 0.01) and returned to baseline after E2 was added. There were no changes in controls. Steroid ratio responses to oCRH suggested that 17,20-desmolase activity (delta maximum change in the ratio of A4/17-hydroxyprogesterone) was lowered with estrogen suppression and increased again after transdermal E2 administration. There was a significant positive correlation between changes in E2 levels and delta maximum change in the ratios of A4/17-OHP after oCRH treatment, signifying 17,20-desmolase activity (r = 0.58, P < 0.02). In conclusion, these data provide evidence that estrogen is at least one factor that influences adrenal androgen sensitivity in PCO and may help explain the frequent finding of adrenal hyperandrogenism in this syndrome.
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PMID:The impact of estrogen on adrenal androgen sensitivity and secretion in polycystic ovary syndrome. 785 27

Using cultured human fetal adrenal cells, we have investigated the basal secretion of cortisol and dehydroepiandrosterone sulfate (DHAS) and the effect of corticotropin (ACTH), angiotensin-II (A-II) and transforming growth factor beta 1 (TGF beta 1) on the secretion of these steroids and on the mRNA levels of ACTH receptor (ACTHR), cytochrome P-450scc (cholesterol side-chain cleavage), P450 17 alpha (17 alpha-hydroxylase/17-20 lyase) and 3 beta-HSD (3 beta-hydroxysteroid dehydrogenase). The basal DHAS/cortisol ratio declined progressively between 12.5 and 21 weeks. ACTH treatment enhanced the secretion of cortisol and to a lesser extent that of DHAS, and increased the steroidogenic response to an acute stimulation with ACTH. These changes were associated with increased mRNA levels of ACTHR and of the steroidogenic enzymes. A-II treatment also increased the secretion of both DHAS and cortisol, but less than ACTH, enhanced the responsiveness to ACTH and increased ACTHR, P450scc and P450 17 alpha mRNA levels. In contrast, TGF beta 1 alone or together with ACTH decreased DHAS secretion, but not cortisol secretion. Moreover, TGF beta 1 had no effect on ACTHR and P450scc mRNA levels, decreased by about 50% the mRNA levels of P450 17 alpha both in the absence or presence of ACTH, but enhanced the stimulatory effects of ACTH on 3 beta-HSD mRNA. These results, along with those previously reported, suggest that both A-II and TGF beta may play a role in fetal adrenal function. In addition, they show that the effects of both peptides are qualitatively different from, even sometimes opposite to, those previously reported in bovine and ovine adrenal cells.
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PMID:Regulation of corticotropin and steroidogenic enzyme mRNAs in human fetal adrenal cells by corticotropin, angiotensin-II and transforming growth factor beta 1. 789 1

RU486, a synthetic steroid receptor antagonist, has strong antiprogesterone and antiglucocorticoid properties. Chronic RU486 administration in two patients with ectopic secretion of adrenocorticotropin (ACTH) has been associated with decreasing plasma cortisol concentrations. One explanation of this finding is that RU486 may directly inhibit adrenal steroidogenesis. To test this hypothesis, we measured the effect of RU486 on specific steroidogenic enzymatic steps using an in vivo rat and an in vitro monkey model. Hypophysectomized-castrated-ACTH-replaced Sprague-Dawley rats were given RU486 i.p. at daily doses of 0, 0.0005, 0.005, 0.05, 0.5 and 5 mg/kg body weight per day for 7 days. The animals were sacrificed, and blood and adrenal glands collected. Adrenal cortical mitochondria and microsomes were purified from the rats and from two untreated Cynomolgus macaque monkeys. Specific steroidogenic enzyme activities were measured in the rat by the incorporation of 14C-labeled steroid substrates into products. A similar protocol was used to assay the steroidogenesis in the monkey adrenal fractions in the presence and absence of added RU486. Although rat adrenal weights decreased significantly at the highest RU486 dose, plasma levels of corticosterone were similar in control and treated rats. Rat adrenal 3 beta-hydroxysteroid dehydrogenase/isomerase (3-HSD), 21-hydroxylase (21-OH) and 11-hydroxylase (11-OH) activities decreased with increasing RU486 doses, with 21-OH and 11-OH being most severely affected. Monkey adrenal 3-HSD, 21-OH, 11-OH, 17-hydroxylase and 17,20-desmolase similarly decreased in the presence of increasing in vitro concentrations of RU486.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of the antiglucocorticoid RU486 on adrenal steroidogenic enzyme activity and steroidogenesis. 813 Aug 96

The major regulator of mineralocorticoid production in the adrenal is angiotensin II produced by the action of renal renin. The discovery that the rodent adrenal also synthesizes renin and angiotensinogen suggests there is autocrine regulation of mineralocorticoid synthesis. The transgenic rat [TGR(mREN2)27] expresses the Ren-2d gene predominantly in the adrenal. Despite suppressed kidney and plasma renin, these animals develop fulminant hypertension between 5 and 15 weeks of age. Corticosteroid concentrations are significantly elevated during hypertension development. We assessed steroidogenesis in TGR(mREN2)27 rats by analyzing the expression of the mRNAs for three steroidogenic enzymes: P450scc, the rate-limiting step of steroidogenesis; P450c11 beta, which converts deoxycorticosterone to corticosterone in the zona fasciculata/reticularis; and P450c11AS, which converts deoxycorticosterone to aldosterone in the zona glomerulosa. P450c11AS mRNA, but neither P450c11 beta nor P450scc mRNA, was overexpressed in the adrenal gland of TGR(mREN2)27 rats. In situ hybridization with specific probes for P450c11 beta and P450c11AS mRNA localized the former exclusively to the zona fasciculata and the latter to the zona glomerulosa. In TGR(mREN2)27 rats, the size of the adrenal and number of P450c11AS-expressing zona glomerulosa cells were about twice those of a normal Sprague-Dawley rat. Both animals respond to corticotropin similarly; corticotropin had no effect on the expression of P450scc and P45011 beta mRNAs, rendered P450c11AS mRNA undetectable, and simultaneously altered the morphology of the adrenal cortex, resulting in a lack of zona glomerulosa-like cells. Thus, the local renin-angiotensin system has a major effect on the basal expression of P450c11AS mRNA, but little effect on the corticotropin-regulated expression of P450scc, P450c11 beta, and P450c11AS mRNAs.
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PMID:Role of adrenal renin in the regulation of adrenal steroidogenesis by corticotropin. 827 56

Steroid hormones are synthesized from cholesterol in the adrenals, gonads, and placenta by a complex series of reactions. The human genes encoding each of these biosynthetic enzymes have been cloned, permitting study of their regulation. Tropic hormones, such as corticotropin and the gonadotropins, exert their chronic effects on steroidogenesis by increasing the amounts of steroidogenic enzymes; this in turn occurs primarily through increased gene transcription. Our studies have emphasized the cholesterol side-chain cleavage enzyme P450scc, which catalyzes the first and rate-limiting step in steroidogenesis, and P450c17, which determines what class of steroids is synthesized. By fusing the promoters of the genes for these enzymes to readily assayed reporter genes and transiently transfecting cultured cells with these constructions, we have identified the regions of each promoter that confer basal expression, induction by cAMP, and repression by activators of protein kinase C. Different segments of the P450scc promoter are used for each of these purposes in different cell types, indicating that the regulation of this gene is very complex. Transcription is not the only level at which steroidogenesis is regulated. The abundance of mRNA for adrenodoxin reductase, a flavoprotein needed for P450scc activity, is post-transcriptionally regulated by cAMP.
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PMID:Transcriptional regulation of human genes for steroidogenic enzymes. 843 24


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