Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The most common enzymatic defect of steroid synthesis is adrenal steroid 21-hydroxylase deficiency. Inhibited formation of cortisol causes increased pituitary release of ACTH, driving the adrenal cortex to overproduce androgens, whose synthesis does not involve the 21-hydroxylase enzyme. This hormonal setting is established in the embryonic period and affects development of genetic females, misdirecting differentiation of the external genitalia toward male type. At birth, the genitalia are visibly ambiguous (enlarged clitoris, fused labia) or in some cases even male in appearance (phallus with urethral opening, rugated scrotal sac), leading to wrong sex assignment. Adrenal steroid 21-hydroxylase deficiency is the most common basis of female pseudohermaphroditism. These females, however, have normal fertility and potential for gestation (gonads are functional and the internal duct-derived structures are well-formed), thus the sex of rearing should always be female. Management is by life-long hormonal (glucocorticoid) replacement, with surgical correction of the genital ambiguity. Prenatal diagnosis of 21-hydroxylase deficiency, first possible by steroid assay of the amniotic fluid, has utilized HLA typing for identification of loci (antigens B and DR) in close linkage with the 21-hydroxylase gene, and now increasingly relies on DNA analysis for linked HLA or C4 genes or for mutant 21-hydroxylase alleles directly by molecular genetic techniques. The most recent clinical advance is a program of combined prenatal diagnosis with karyotyping and suppression of fetal androgen production in genetic females by steroid administration to the mother. This is the first instance of an inborn metabolic error to be prenatally treated. A series of 85 managed pregnancies is reported on, including accuracy of diagnosis, response of the mother to steroid treatment, and outcome for treated and untreated male and female fetuses (of 77 born by 6/91). Prenatal diagnosis by current techniques is accurate. Normal growth and development patterns postnatally suggest that dexamethasone treatment is safe.
J Steroid Biochem Mol Biol 1992 Mar
PMID:Prenatal diagnosis/treatment in families at risk for infants with steroid 21-hydroxylase deficiency (congenital adrenal hyperplasia). 156 17

The 5' end of the steroid 21-hydroxylase B gene encompassing putative control regions and the first 3 exons, has been selectively amplified in vitro from a number of patients with congenital adrenal hyperplasia caused by a deficiency of this enzyme. Sequence analysis has revealed a number of isolated instances of gene conversion to the 21-hydroxylase A sequence. One mutation, a C to G transversion at the 3' end of the second intron, thought to lead to incorrect splicing of the mRNA, was found in 11 subjects all with the classical form of the disease.
J Steroid Biochem Mol Biol 1992 Mar
PMID:Genetic analysis of the steroid 21-hydroxylase gene following in vitro amplification of genomic DNA. 156 57

The long-term effects of angiotensin-II (A-II) and corticotropin (ACTH) on bovine adrenal fasciculata cells (BAC) were studied. Cells were pretreated for 3 days with either A-II or ACTH followed by an examination of the acute steroidogenic response to both hormones as well as the ability to convert several steroid precursors to cortisol and corticosterone. ACTH pretreatment caused a marked increase in cortisol output associated with a decrease in corticosterone secretion in response to both hormones leading to a 50-fold decrease in the corticosterone/cortisol ratio compared to control cells. After incubation with saturating concentrations (5 X 10(-5) M) of 22 R-hydroxycholesterol, pregnenolone or progesterone, ACTH-pretreated cells produced more cortisol than corticosterone whereas the contrary was observed in control cells. However, the conversion of 17 alpha-hydroxyprogesterone and 11-deoxycortisol to cortisol by ACTH-pretreated cells was lower than by control cells. Thus, the main effects of ACTH were a marked increase of 17 alpha-hydroxylase and a small but significant decrease of 21-hydroxylase and 11 beta-hydroxylase activities. A-II pretreatment produced, in a concentration-dependent manner, a down-regulation of its own receptors and homologous and heterologous steroidogenic desensitization. At maximal concentrations (10(-6) M) A-II reduced by 70% its own receptors while the steroidogenic response to A-II and ACTH was reduced by 95% and 75%, respectively. However, the coupling of A-II receptors to phosphoinositide pathway and to Ca2+ influx, as well as its potentiation effect on ACTH-induced cAMP production were similar in control and A-II pretreated cells. Moreover, the conversion of several steroid precursors to corticosterone was similar in control cells and A-II-pretreated cells, whereas the conversion to cortisol was reduced by approximately 30% due mainly to a decrease of 17 alpha-hydroxylase activity. Thus, the marked steroidogenic desensitization induced by A-II is most likely related to some alteration located beyond the activation of the two branches of the phosphoinositide pathway and before the first steps of steroidogenesis.
Mol Cell Endocrinol 1991 Oct
PMID:Opposite effects of angiotensin-II and corticotropin on bovine adrenocortical cell steroidogenic responsiveness. 166 31

The Y1 mouse adrenocortical tumor cell line retains the ability to synthesize and secrete steroids, but does not express steroid 21-hydroxylase (C21) and, therefore, does not produce 21-hydroxylated steroids. In this investigation the mechanisms underlying the loss of C21 activity in the Y1 cell line were explored. A 9-kilobase BglII fragment containing the C21 gene was cloned from the Y1 genome. This genomic clone directed the synthesis of C21 transcripts and 21-hydroxylated steroid products when transfected back into the Y1 cell line. As determined by restriction endonuclease digestions with MspI and HpaII, enzymes that distinguish between unmethylated and methylated CCGG sites, the endogenous C21 gene was extensively methylated in Y1 adrenal cells and in cells from other mouse tissues that do not normally express this gene. In contrast, the C21 gene was hypomethylated in primary cultures of mouse adrenal cells which normally synthesize large amounts of C21. The cloned C21 gene transfected into Y1 cells initially was unmethylated, but became extensively methylated with prolonged culture of the cells; prolonged culture of these transfectants also resulted in a loss of C21 expression. Loss of C21 expression in Y1 transfectants, however, temporally preceded the extensive methylation of the transfected C21 gene. Furthermore, treatment of Y1 cells with 5-azacytidine caused a demethylation of the endogenous C21 gene, but did not result in the recovery of C21 expression. These results indicate that Y1 cells contain a functional C21 gene that has been silenced by a reversible cis-modification event.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Endocrinol 1990 Aug
PMID:cis modification of the steroid 21-hydroxylase gene prevents its expression in the Y1 mouse adrenocortical tumor cell line. 170 55

We present an unusual case with bilateral testicular Leydig cell tumors displaying extraadrenal expression of steroid 21-hydroxylase and 11 beta-hydroxylase. Histological examination of a 38-yr-old man infertile due to azoospermia showed him to have bilateral testicular Leydig cell tumors. The in vitro steroidogenic potential of the tumors and their adjacent testicular tissue was evaluated using organ culture. Tumor tissue was found to secrete deoxycorticosterone (DOC), corticosterone (B) and cortisol, which are not produced in normal adult testis, into the medium, while testicular tissue adjacent to the tumors secreted a small amount of DOC and B. Northern blot analysis with cytochrome P-450C21 complementary DNA (cDNA) and P-45011 beta cDNA as probes revealed that the tumor contained a considerable amount of mRNA for P-450C21 and P-45011 beta, while the MRNAs were not detected in the testicular tissues adjacent to the tumors. It is suggested that the high local levels of estrogen and/or progesterone within the Leydig cell tumors and their adjacent testicular tissues induced extraadrenal expression of steroid 21-hydroxylase and 11 beta-hydroxylase by the tumors and their adjacent testicular tissues.
J Steroid Biochem Mol Biol 1991 Dec
PMID:Extraadrenal expression of steroid 21-hydroxylase and 11 beta-hydroxylase by a benign testicular Leydig cell tumor. 175 89

The adrenal cortex of the mouse coordinately expresses three cytochrome P450 enzymes that are required for the biosynthesis of corticosteroids: cholesterol side-chain cleavage enzyme (SCC), steroid 21-hydroxylase (21-OHase), and steroid 11 beta-hydroxylase (11 beta-OHase). Within their 5'-flanking regions, we previously identified six elements containing variations of an AGGTC motif that regulated expression in mouse Y1 adrenocortical cells: 21-OHase elements at -210, -140, and -65; SCC elements at -70 and -40; and an 11 beta-OHase element at -310. We demonstrate here that all six elements interact with the same, or closely related, DNA-binding protein(s). First, these elements all formed complexes of similar mobility in gel shift assays, suggesting that they interacted with protein(s) of similar size. Additional larger complexes were seen with those probes containing exact AGGTCA sequences. Second, competition experiments confirmed that the factor(s) interacting with different elements had closely related or identical recognition specificities. Finally, indistinguishable profiles of shift activities were seen upon fractionation of nuclear proteins over sequential chromatographic columns. Collectively, these results suggest that related elements interact with a shared protein to regulate three essential steroidogenic enzymes. An AGGTCA sequence motif comprises the response element for several members of the nuclear hormone receptor family. Oligonucleotide competitions and specific effects of antisera in gel shift assays implicated chicken ovalbumin upstream promoter-transcription factor in the formation of the larger complexes seen with the elements containing exact AGGTCA sequences. Therefore, this member of the nuclear hormone receptor family also may regulate the expression of the adrenal steroidogenic enzymes.
Mol Endocrinol 1991 Oct
PMID:A shared promoter element regulates the expression of three steroidogenic enzymes. 177 36

Studies were done to determine the mechanism(s) of action of spironolactone (SL) and of its deacetylated metabolite, 7 alpha-thio-SL, to inhibit cortisol secretion by guinea pig adrenocortical cells in vitro. Preincubation of cells at 37 degrees C with SL or with 7 alpha-thio-SL caused a time-dependent decline in subsequent ACTH-stimulated cortisol secretion. In the absence of a preincubation, neither compound affected cortisol production, indicating the need for production of an active metabolite. When the 17 alpha-hydroxylase inhibitor, SU-10'603, was included during the preincubation period, neither SL nor 7 alpha-thio-SL decreased cortisol secretion, indicating the involvement of the 17 alpha-hydroxylase in the activation of both compounds. By contrast, neither the 11 beta-hydroxylase inhibitor, metyrapone, nor the cholesterol sidechain cleavage inhibitor, aminoglutethimide, diminished the effects of SL or of 7 alpha-thio-SL on cortisol secretion. Preincubation of cells with SL or 7 alpha-thio-SL also decreased the conversion of exogenous progesterone to cortisol, but did not affect cortisol production from the 17 alpha-hydroxylated substrates, 17 alpha-hydroxyprogesterone and 11-deoxycortisol, suggesting that only 17 alpha-hydroxylation was impaired. In addition, there was a decline in 17 alpha-hydroxylase activity in microsomes isolated from cells preincubated with SL or with 7 alpha-thio-SL, but no change in microsomal 21-hydroxylase or in mitochondrial 11 beta-hydroxylase and cholesterol sidechain cleavage activities. The results indicate that the direct effects of SL and of 7 alpha-thio-SL on the adrenal cortex to decrease cortisol production result from the selective inhibition of 17 alpha-hydroxylation. Since 17 alpha-hydroxylase activity is apparently required for the activation of both compounds, suicide inhibition of the enzyme may be the mechanism of action.
Mol Cell Endocrinol 1991 Oct
PMID:Mechanism of action of spironolactone on cortisol production by guinea pig adrenocortical cells. 179 82

We studied the contents of aldosterone and cortisol (F) and the expression of mRNA of cytochrome P-450 for side-chain cleavage (P-450scc), 17 alpha-hydroxylase (P-450c17), 21-hydroxylase (P-450c21) and 11 beta-hydroxylase (P-450c11) in adrenocortical adenomas from three patients with primary aldosteronism. The aldosterone content was significantly higher in adrenocortical adenomas than in normal adrenal glands, while F content in adenomas was similar to the level in normal adrenal glands. The aldosterone-producing adenomas showed a markedly higher level of P-450c11 mRNA, a slightly but not significantly increased level of P-450c21 mRNA and a significantly decreased level of P-450c17 mRNA, compared with those in normal adrenal glands. The expression of P-450scc mRNA in adenomas was similar to the level in normal adrenal glands. These results suggested that the renin-independent overproduction of aldosterone in adrenocortical adenomas from the patients with primary aldosteronism results from increasing expression of the mRNA for P-450c11 and decreasing expression of the mRNA for P-450c17.
Mol Cell Endocrinol 1991 Apr
PMID:Expression of cytochrome P-450 mRNAs in steroidogenesis of adrenocortical adenomas from patients with primary aldosteronism. 182 Sep 78

Previous investigations have established that spironolactone (SL) is converted to a reactive metabolite by adrenal microsomal enzymes, resulting in the degradation of cytochrome P-450 (P-450). Deacetylation of SL to 7 alpha-thiospironolactone (7 alpha-thio-SL) is the first step in the activation pathway, but further NADPH-dependent metabolism of 7 alpha-thio-SL is required for P-450 destruction. Studies were done to evaluate the role of the steroid 17 alpha-hydroxylase in the activation of 7 alpha-thio-SL by adrenal microsomes. Incubation of guinea pig adrenal microsomes with 7 alpha-thio-SL in the presence of NADPH effected greater than 50% declines in P-450 content and in 17 alpha-hydroxylase activity but no change in the rate of 21-hydroxylation. Preincubation of the microsomes with antisera to the 17 alpha-hydroxylase P-450 isozyme (P-450(17 alpha,lyase)) decreased 17 alpha-hydroxylase but not 21-hydroxylase activity and prevented the degradation of P-450 by 7 alpha-thio-SL. Control IgG had no effect on 17 alpha-hydroxylase activity or on the 7 alpha-thio-SL-mediated destruction of P-450. When added to a purified P-450(17 alpha,lyase) preparation, 7 alpha-thio-SL and the endogenous substrate progesterone caused typical type I spectral changes, but SL did not. Incubation of a purified and reconstituted 17 alpha-hydroxylase system, consisting of P-450(17 alpha,lyase), NADPH-P-450 reductase, cytochrome b5, and dilauroylphosphatidylcholine, with 7 alpha-thio-SL plus NADPH effected the complete degradation of the P-450(17 alpha,lyase). Neither progesterone nor SL caused P-450 destruction with the reconstituted enzyme preparation. The results provide direct evidence for the activation of 7 alpha-thio-SL by the 17 alpha-hydroxylase and support the hypothesis that a mechanism-based inhibition of the enzyme occurs. The data also provide additional evidence that 7 alpha-thio-SL is an obligatory intermediate in the degradation of P-450 by SL.
Mol Pharmacol 1991 Aug
PMID:Role of the steroid 17 alpha-hydroxylase in spironolactone-mediated destruction of adrenal cytochrome P-450. 187 14

The gene encoding steroid 21-hydroxylase activity, P450c21B, is located in the major histocompatibility complex (MHC) class III region, in close proximity to a highly homologous pseudogene, P450c21A. Recombinations between P450c21B and P450c21A have been shown to result in deficiency of 21-hydroxylase activity, the usual cause of congenital adrenal hyperplasia (CAH). A mutant P450c21 gene from a patient with simple virilizing CAH was identified and shown to be consistent with a recombination between P450c21A and P450c21B. Sequence analysis of the mutant gene showed the recombination site to be located between the first exon and the second intron. The mutant gene encodes a leucine instead of the normal proline at codon 31. This mutation resides on a chromosome bearing the HLA-B44 serotype. A comparison of mutations associated with HLA-B44 and that normally found with the HLA-Bw47 serotype suggests that the HLA-B44 mutations are of more ancient origin. The patient's homologous chromosome has a deletion of P450c21B. Endocrinological testing therefore allows for testing of the mutant gene in genetic isolation. Such testing demonstrated that the patient was capable of producing aldosterone and retaining sodium in response to a low-sodium diet, indicating that the mutant gene encodes an enzyme with partial 21-hydroxylase activity.
J Steroid Biochem Mol Biol 1991 Jun
PMID:Molecular and endocrine characterization of a mutation involving a recombination between the steroid 21-hydroxylase functional gene and pseudogene. 190 48


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>