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McCarty KD, Liu L, Tateishi Y, Wapshott-Stehli HL, Guengerich FP. The multistep oxidation of cholesterol to pregnenolone by human cytochrome P450 11A1 is highly processive. J Biol Chem 2024; 300:105495. [PMID: 38006947 PMCID: PMC10716780 DOI: 10.1016/j.jbc.2023.105495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 11/17/2023] [Accepted: 11/20/2023] [Indexed: 11/27/2023] Open
Abstract
Cytochrome P450 (P450, CYP) 11A1 is the classical cholesterol side chain cleavage enzyme (P450scc) that removes six carbons of the side chain, the first and rate-limiting step in the synthesis of all mammalian steroids. The reaction is a 3-step, 6-electron oxidation that proceeds via formation of 22R-hydroxy (OH) and 20R,22R-(OH)2 cholesterol, yielding pregnenolone. We expressed human P450 11A1 in bacteria, purified the enzyme in the absence of nonionic detergents, and assayed pregnenolone formation by HPLC-mass spectrometry of the dansyl hydrazone. The reaction was inhibited by the nonionic detergent Tween 20, and several lipids did not enhance enzymatic activity. The 22R-OH and 20R,22R-(OH)2 cholesterol intermediates were bound to P450 11A1 relatively tightly, as judged by steady-state optical titrations and koff rates. The electron donor adrenodoxin had little effect on binding; the substrate cholesterol showed a ∼5-fold stimulatory effect on the binding of adrenodoxin to P450 11A1. Presteady-state single-turnover kinetic analysis was consistent with a highly processive reaction with rates of intermediate oxidation steps far exceeding dissociation rates for products and substrates. The presteady-state kinetic analysis revealed a second di-OH cholesterol product, separable by HPLC, in addition to 20R,22R-(OH)2 cholesterol, which we characterized as a rotamer that was also converted to pregnenolone at a similar rate. The first oxidation step (at C-22) is the slowest, limiting the overall rate of cleavage. d3-Cholesterol showed no kinetic deuterium isotope effect on C-22, indicating that C-H bond cleavage is not rate-limiting in the first hydroxylation step.
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Affiliation(s)
- Kevin D McCarty
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Lu Liu
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Yasuhiro Tateishi
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | | | - F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
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Meyer T, Wirtz PH. Mechanisms of Mitochondrial Redox Signaling in Psychosocial Stress-Responsive Systems: New Insights into an Old Story. Antioxid Redox Signal 2018; 28:760-772. [PMID: 28558479 DOI: 10.1089/ars.2017.7186] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
SIGNIFICANCE Psychosocial stress is associated with alterations in serum glucocorticoids and cytokines, such as interleukin-6 (IL-6) and IL-1β, which functionally interact. However, the molecular mechanisms and physiological relationship between the two systems within the context of stress exposure are not well characterized. Recent Advances: Extracellular IL-6, which stimulates the release of cortisol from the zona fasciculata of the adrenal cortex, mediates its intracellular effects by tyrosine phosphorylation of the transcription factor signal transducer and activator of transcription 3 (STAT3). Mitochondrial electron transfer reactions are involved in both STAT3-driven ATP production in oxidative respiration and adrenocortical steroid biosynthesis. CRITICAL ISSUES The role of STAT3 in oxidative respiration and steroidogenesis suggests that it integrates both nuclear and mitochondrial actions, thereby preserving main steps of glucocorticoid biosynthesis in the adrenal gland under psychosocial stress. This review discusses the notion that these two pathways are together simultaneously involved in protection against chronic stressors. FUTURE DIRECTIONS Linking the function of cytokines and main components of the hypothalamic-pituitary-adrenal (HPA) axis to molecular mechanisms of mitochondrial redox signaling will be essential for a better understanding of the relevant stress-responsive systems engaged in stress vulnerability. Antioxid. Redox Signal. 28, 760-772.
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Affiliation(s)
- Thomas Meyer
- 1 Department of Psychosomatic Medicine and Psychotherapy, University of Göttingen , Göttingen, Germany
| | - Petra H Wirtz
- 2 Biological Work and Health Psychology, Department of Psychology, University of Konstanz , Konstanz, Germany
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Narasimhulu S. Differential behavior of the sub-sites of cytochrome 450 active site in binding of substrates, and products (implications for coupling/uncoupling). Biochim Biophys Acta Gen Subj 2006; 1770:360-75. [PMID: 17134838 DOI: 10.1016/j.bbagen.2006.09.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2006] [Revised: 08/31/2006] [Accepted: 09/22/2006] [Indexed: 10/24/2022]
Abstract
The cytochrome P450 catalyzes hydroxylation of many substrates in the presence of O(2) and specific electron transport system. The ternary complex S-Fe(+)O(2) with substrate and O(2) bound to their respective sites on the reduced enzyme is an important intermediate in the formation of the hydroxylating species. Then the active site may be considered as having two sub-sites geared for entirely different types of functionally relevant interactions. The two sites are the substrate binding site, the specific protein residues (Site I), and the L(6) position of the iron (Site II) to which O(2) binds upon reduction. In the ferric enzyme, when substrate binds to Site I, the low spin six-coordinated P450 is converted to the readily reducible high spin five coordinated state. Certain amines and OH compounds, such as products of P450-catalyzed reactions, can bind to Site II resulting in six coordinated inhibited complexes. Then the substrate and product interactions with the two sub-sites can regulate the functional state of the enzyme during catalysis. Product interactions have received very little attention. CYP101 is the only P450 in which X-ray and spectroscopic data on all three structures, the substrate-free, camphor-bound and the 5-exo-OHcamphor-bound are available. The substrate-free CYP101 is low spin and six-coordinated with a water molecule ligated at the L(6) position of the iron. The substrate camphor binds to Site I, and releases the L(6) water despite its inability to bind to this site, indicating that Site I binding can inhibit Site II ligation. The product 5-exo-OHcamphor in addition to binding to Site I, binds to Site II through its -OH group forming Fe-O bond, resulting in the low spin six-coordinated complex. New temperature-jump relaxation kinetic data indicating that Site II ligation inhibits Site I binding are presented. It appears that the Site I and Site II function as interacting sub-sites. The inhibitory allosteric interactions between the two sub-sites are also reflected in the data on binding of the substrate camphor (S) in the presence of the product 5-exo-OH camphor (P) to CYP101 (E). The data are in accordance with the two-site model involving the ternary complex ESP. The affinity of the substrate to the product-bound enzyme as well as the affinity of the product to the substrate-bound enzyme decreased with increase in product concentration, which is consistent with mixed inhibition indicative of inhibitory allosteric interactions between the two sub-sites. Implications of these observations for coupling/uncoupling mechanisms are discussed in the light of the published findings consistent with the two-site behavior of the P450 active site. In addition, kinetic data indicating that the transient high spin intermediate may have to be taken into account for understanding how some P450s have been able to express appreciable hydroxylation activities in the absence of substrate-induced low to high spin transition, observable by the traditional static spectroscopy, are presented.
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Affiliation(s)
- Shakunthala Narasimhulu
- Harrison Department For Surgical Research, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Narasimhulu S, Willcox JK. Temperature-Jump Relaxation Kinetics of Substrate-Induced Spin-State Transition in Cytochrome P450 (Comparison of the Wild-Type and C334A Mutant P450CAM and P4502B4). Arch Biochem Biophys 2001; 388:198-206. [PMID: 11368155 DOI: 10.1006/abbi.2001.2287] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The kinetics of binding of the substrate camphor to the cytochrome P450(CAM) and the C334A mutant as well as the kinetics of binding of benzphetamine to the wild-type P450(2B4) have been studied by the temperature-jump relaxation technique in order to distinguish between the two models for substrate-induced spin-state transition. These models are the bimolecular model in which spin-state transition occurs in parallel with substrate binding, and the two-step spin-equilibrium model in which substrate binding is a separate step preceding the spin-state transition. With all three P450s, the relaxation rate versus concentration data were linear as predicted by the bimolecular model and inconsistent with the spin-equilibrium model, which predicts a curve reaching saturation. With all three P450s, the relaxation rate versus concentration data exhibited maxima. These results are considered to resolve the controversy in favor of the bimolecular model for substrate-induced spin-state transition. In addition, the results suggest that the bimolecular model may be applicable to other P450s as well.
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Affiliation(s)
- S Narasimhulu
- Harrison Department for Surgical Research, School of Medicine, University of Pennsylvania, Philadelphia 19104, USA
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5
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Hormone-stimulated steroidogenesis is coupled to mitochondrial benzodiazepine receptors. Tropic hormone action on steroid biosynthesis is inhibited by flunitrazepam. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(19)67848-8] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Krueger K, Papadopoulos V. Peripheral-type benzodiazepine receptors mediate translocation of cholesterol from outer to inner mitochondrial membranes in adrenocortical cells. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)77217-7] [Citation(s) in RCA: 255] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Olakanmi O, Seybert DW. Modified acetylenic steroids as potent mechanism-based inhibitors of cytochrome P-450SCC. JOURNAL OF STEROID BIOCHEMISTRY 1990; 36:273-80. [PMID: 2391956 DOI: 10.1016/0022-4731(90)90217-g] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Synthesized 20-(4-tetrahydropyranyl-1-butynyloxy)-5-pregnen-3 alpha,20 beta- diol [steroid I] and 20-(3-tetrahydropyranyl-1-propargyloxy)-5-pregnen- 3 alpha,20 beta-diol [steroid III] have been found to inactivate purified adrenocortical cytochrome P-450SCC. When incubated with the enzyme under turnover conditions, steroid I inactivated cytochrome P-450SCC by about 85% in 40 min. This is in contrast to the free triol analog, steroid II which inactivated the enzyme by only 45% within the same incubation period. A comparison of steroid III with its free triol analog, steroid IV, also showed that the diol is a more effective inactivator of the enzyme than the triol. The partition ratio was calculated by two different methods. Each of the steroids I-IV bound to the enzyme with spectrophotometric dissociation constant (Ks) in the micromolar range, producing Type II low spin spectra changes during titration of the enzyme. In addition, it was found that the binding of each of the compounds to the enzyme occurred without inactivation of the enzyme and that the inactivation under turnover condition, is not as a result of conversion to the denatured P-420 species. This demonstrated that steroids I and III could correctly be designated as mechanism-based (suicide) inhibitors. The kinetic studies demonstrated that steroids with the tetrahydropyranyl substituent are more potent inhibitors of cytochrome P-450SCC as shown by an initial turnover rate of 0.06 min-1, an inactivation rate constant of 0.05 min-1, and a partition ratio of about 1.0 for steroid I. Based on our finding, possible mechanisms of inactivation of cytochrome P-450SCC by these acetylenic steroids are proposed.
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Affiliation(s)
- O Olakanmi
- Department of Chemistry, Duquesne University, Pittsburgh, PA 15282
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8
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McNamara BC, Jefcoate CR. Synergistic stimulation of pregnenolone synthesis in rat adrenal mitochondria by n-hexane and cardiolipin. Arch Biochem Biophys 1988; 260:780-8. [PMID: 2829741 DOI: 10.1016/0003-9861(88)90508-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
n-Hexane and cardiolipin each stimulate pregnenolone production by isolated rat adrenal mitochondria. Following corticotropin (ACTH) stimulation, mitochondrial cholesterol metabolism exhibits a fast phase lasting 2 min, followed by a 10-fold slower metabolism. ACTH suppression by dexamethazone or cycloheximide (CX) treatment removes this fast phase. n-Hexane, at concentrations approaching 80% of the aqueous solubility limit (approximately 0.08 mM), selectively stimulates the slow phase of metabolism, while cardiolipin (100 microM) stimulates only the fast phase. Other alkanes and ethers are effective. The effect of n-hexane is dependent on mitochondrial integrity, as evidenced by decreased effects in hypoosmotically shocked mitochondria (outer membrane disrupted) and ineffectiveness in sonicated mitochondria (both membranes disrupted). n-Hexane apparently enhances the transfer of outer membrane cholesterol to inner membrane P-450scc. Stimulation by cardiolipin is retained by disrupted mitochondria and may involve enhanced availability of P-450scc to inner membrane cholesterol. When added together, these agents produce more than additive effects on cholesterol metabolism. Preincubation with n-hexane did not increase reactive cholesterol, suggesting that enhanced cholesterol transport occurs only in concert with metabolism of inner membrane cholesterol. Uptake of alkanes into mitochondrial membranes may effect structural changes that facilitate outer to inner membrane cholesterol transfer, but major changes are excluded by the effectiveness of isocitrate as a reductant for P-450scc. In combination, n-hexane and cardiolipin reproduce the effect of the ACTH-sensitive sterol regulatory peptide on mitochondria [R. C. Pedersen and A. C. Brownie (1983) Proc. Natl. Acad. Sci. USA 80, 1882-1886], suggesting that peptide action on adrenal mitochondria may resolve into two analogous components.
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Affiliation(s)
- B C McNamara
- Department of Pharmacology, University of Wisconsin Medical School, Madison 53706
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9
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Md. Sadeque AJ, Shimizu T, Hatano M. Interaction of fluoroaniline with Cytochrome P−450scc and myoglobin: Temperature and pH dependence studies. Inorganica Chim Acta 1988. [DOI: 10.1016/s0020-1693(00)83483-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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10
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Privalle CT, McNamara BC, Dhariwal MS, Jefcoate CR. ACTH control of cholesterol side-chain cleavage at adrenal mitochondrial cytochrome P-450scc. Regulation of intramitochondrial cholesterol transfer. Mol Cell Endocrinol 1987; 53:87-101. [PMID: 2822509 DOI: 10.1016/0303-7207(87)90195-x] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Rat adrenal mitochondria exhibit a linear 2-fold accumulation of cholesterol for 20 min following either in vivo ether stress or ACTH administration, providing cholesterol metabolism is inhibited by aminoglutethimide (AMG). Additional cycloheximide (CX) pretreatment only slightly decreases this increase, but the location of accumulation shifts from the inner membrane to the outer membrane, implying a decreased cholesterol transfer from outer to inner membrane. Although the capacity of outer mitochondrial membranes was saturated after a 10-min treatment with CX, a 20-min treatment resulted in further retention of cholesterol in intact mitochondria that was not recovered in the isolated membranes. An additional pool of loosely bound cholesterol is proposed for CX mitochondria. These studies provide evidence that the CX-sensitive step of adrenal steroidogenesis attributed to loss of a labile ACTH regulatory protein (Pedersen, R.C. and Brownie, A.C. (1983) Proc. Natl. Acad. Sci. U.S.A. 80, 1882-1886) involves cholesterol transfer from the outer to the inner mitochondrial membrane. ACTH also enhances the PI and PE content of the outer membranes by a CX-sensitive mechanism that may contribute to intramitochondrial cholesterol transport. CX treatment does not affect cholesterol uptake by the inner membrane from phospholipid vesicles. The initial rate of endogenous metabolism in isolated inner membranes is insensitive to pretreatment (2 nmol/nmol P-450/min). The duration of this linear rate was increased 4-fold by AMG treatment while this increase was prevented by CX treatment. The kinetics indicate differences in inner membrane reactive cholesterol levels. Inner membranes also contained a fraction of unreactive cholesterol that is insensitive to pretreatment. Cholesterol-P-450scc complex formation for all pretreatments fits a single hyperbolic function of the reactive cholesterol content of the inner mitochondrial membrane (Kd = 0.025 mol cholesterol/mol phospholipid), and is activated over 5-fold upon mitochondrial disruption. All changes in inner membranes caused by CX can, therefore, be attributed solely to the restricted cholesterol access in vivo.
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Affiliation(s)
- C T Privalle
- Department of Pharmacology, University of Wisconsin Medical School, Madison 53706
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11
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DiBartolomeis MJ, Moore RW, Peterson RE, Christian BJ, Jefcoate CR. Altered regulation of adrenal steroidogenesis in 2,3,7,8-tetrachlorodibenzo-p-dioxin-treated rats. Biochem Pharmacol 1987; 36:59-67. [PMID: 3026405 DOI: 10.1016/0006-2952(87)90382-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A single treatment of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (50 micrograms/kg) produced two distinct effects on adrenal steroidogenesis in rats 13 days post-treatment. In unstressed rats, the very low corticosterone levels early in the light phase (AM) increased 4-fold relative to ad libitum-fed control (ALC) rats, but the peak level of corticosterone that is seen late in the light phase (PM) decreased up to 40% relative to ALC rats. The AM stimulation was also observed in rats pair-fed to compensate for the diminished feed intake of TCDD-treated animals, indicating that the change results from nutritional deprivation. The PM suppression, however, was not observed in pair-fed rats. In rats given a lower dose of TCDD (15 micrograms/kg), there was no AM stimulation, whereas the suppression of the PM diurnal peak of corticosterone was retained. Plasma adrenocorticotropin (ACTH) levels and adrenal size were not changed by these treatments, indicating that TCDD affects adrenal responsiveness. TCDD did not, however, have a significant effect on corticosterone secretion in rats receiving high doses of ACTH. In control animals, the availability of cholesterol to cytochrome P-450scc limits the rate of steroidogenesis. While the specific content of the cytochrome was unaffected by TCDD, cholesterol turnover by this enzyme appeared to be affected following TCDD treatment, as evidenced by small increases in the mitochondrial levels of free cholesterol, reactive cholesterol, and in the proportion of P-450scc complexed with cholesterol relative to both ad libitum- and pair-fed controls. This accumulation of mitochondrial cholesterol following TCDD treatment is consistent with an inhibition of cholesterol metabolism at cytochrome P-450scc in vivo that is removed upon isolation of the mitochondria. These TCDD-induced increases were enhanced substantially in ACTH-stimulated rats, probably because ACTH enhances cholesterol influx into the mitochondria. Normally, substrate availability is rate limiting in cholesterol side-chain cleavage, and the AM stimulation of steroidogenesis by TCDD may result from such increased cholesterol transfer. The inhibition of cholesterol side-chain cleavage resulting from TCDD treatment may, however, only become rate limiting for corticosterone synthesis when cholesterol transfer is more substantially activated, as for peak PM secretion.
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12
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DiBartolomeis MJ, Moore RW, Peterson RE, Jefcoate CR. Hypercholesterolemia and the regulation of adrenal steroidogenesis in 2,3,7,8-tetrachlorodibenzo-p-dioxin-treated rats. Toxicol Appl Pharmacol 1986; 85:313-23. [PMID: 3764917 DOI: 10.1016/0041-008x(86)90338-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Plasma and adrenal cholesterol disposition have been examined to gain further insight into the mechanisms by which 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) treatment decreases the diurnal peak in plasma corticosterone concentrations. TCDD induces an increase in plasma cholesterol concentration that is nearly complete on Day 2, at least 2 days before the most pronounced increase in adrenal cholesterol concentration (Days 4-6). This adrenal increase involves both free cholesterol and cholesterol esters, in contrast to the response to dietary hypercholesterolemia where only cholesterol esters increase. Although adrenocorticotropin (ACTH) does not increase adrenal mitochondrial cholesterol in normal rats (cholesterol turnover is faster than cholesterol uptake), this response changes between Days 6 and 9 after TCDD treatment such that ACTH then stimulates accumulation of mitochondrial cholesterol. This additional cholesterol is fully available to cytochrome P-450SCC, as judged both by active cholesterol metabolism in isolated mitochondria and by increased cholesterol-P-450SCC complex formation. The accompanying in vivo suppression of the peak plasma corticosterone concentration suggests a TCDD-induced inhibition of cholesterol side-chain cleavage (SCC). Consistent with this hypothesis, similar effects on adrenal mitochondrial cholesterol were produced by in vivo administration of the cholesterol side-chain cleavage inhibitor, aminoglutethimide, to ACTH-stimulated rats. Although the putative TCDD-induced inhibitory factor is apparently readily lost from mitochondria during preparation, inhibition may be retained in isolated cells. TCDD, therefore, affects adrenal cholesterol regulation by at least two mechanisms. Adrenal cholesterol content increases in part as a consequence of elevated plasma cholesterol, and cholesterol side-chain cleavage becomes partially inhibited in vivo.
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13
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Anderson CM, Mendelson CR. Regulation of the synthesis of cholesterol side-chain cleavage cytochrome P-450 and adrenodoxin in rat Leydig cells in culture. Ann N Y Acad Sci 1984; 438:259-68. [PMID: 6100016 DOI: 10.1111/j.1749-6632.1984.tb38291.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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15
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Kramer RE, Rainey WE, Funkenstein B, Dee A, Simpson ER, Waterman MR. Induction of synthesis of mitochondrial steroidogenic enzymes of bovine adrenocortical cells by analogs of cyclic AMP. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(17)43515-0] [Citation(s) in RCA: 68] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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16
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Induction of synthesis of cholesterol side chain cleavage cytochrome P-450 by adrenocorticotropin in cultured bovine adrenocortical cells. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)69090-3] [Citation(s) in RCA: 91] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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17
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Gould P, Gelb M, Sligar S. Interaction of 5-bromocamphor with cytochrome P-450 cam. Production of 5-ketocamphor from a mixed spin state hemoprotein. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)69046-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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18
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Greenfield N, Gerolimatos B, Szwergold B, Wolfson A, Prasad V, Lieberman S. Effects of phospholipid and detergent on the substrate specificity of adrenal cytochrome P-450scc. Substrate binding and kinetics of cholesterol side chain oxidation. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)69449-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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19
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Nimrod A. On the synergistic action of androgen and FSH on progestin secretion of cultured rat granulosa cells. Cellular and mitochondrial cholesterol metabolism. Mol Cell Endocrinol 1981; 21:51-62. [PMID: 6781951 DOI: 10.1016/0303-7207(81)90030-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The effect of FSH and androgen on the conversion of cholesterol into progesterone by cultured rat granulosa cells (GC) was studied in intact cells or mitochondrial preparations. Culture of GC for immature hypophysectomized diethylstilbestrol-treated rats for 48 h in the presence of ovine FSH (5 microgram/ml) alone, or FSH + testosterone (Te; 0.5 microgram/ml) caused a slight increase in the activity of the mitochondrial marker enzyme succinic dehydrogenase, while Te had no effect. Culture with the hormones for 48 h had no significant effect on the levels of free and esterified cellular cholesterol. GC monolayers after 48 h with or without FSH and Te converted [3H]cholesterol into 4 major metabolites, 3 of which were secreted into the medium and, in thin-layer chromatographic behavior, resembled pregnenolone, progesterone and 20 alpha-dihydroprogesterone. The total amount of the 3 C-21 steroids was higher (p less than 0.01) in FSH- or Te-treated than in control cells, and combined treatment had a synergistic effect. The uptake of labeled cholesterol (4--10%) was significantly higher (p less than 0.01) in cells pretreated with FSH or Te, whereas a combined FSH and Te treatment had an additive effect. Mitochondria isolated from GC monolayers took up cholesterol in a temperature-dependent fashion, but this uptake was not affected by hormonal pretreatment. In the presence of cyanoketone, the mitochondrial fractions activity converted cholesterol into pregnenolone. This activity was enhanced by FSH or Te (p less than 0.01), and further enhancement was observed with FSH + Te; the combined effect appeared to be more than additive (p = 0.05). The results suggest that both FSH and Te enhance the activity of cholesterol side-chain cleavage, but do not affect the transport of cholesterol into the mitochondria. A possible hormonal effect on a pre-mitochondrial step is discussed.
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20
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Intracellular movement of cholesterol in rat adrenal cells. Kinetics and effects of inhibitors. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(19)70620-6] [Citation(s) in RCA: 159] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Alsema GJ, Degenhart HJ, Hoogerbrugge J. Side chain cleavage of hydroxylated sterols by bovine adrenal cortex mitochondria: observation of 25-hydroxylase activity during incubation at pH 7.80. JOURNAL OF STEROID BIOCHEMISTRY 1980; 13:539-43. [PMID: 7392630 DOI: 10.1016/0022-4731(80)90210-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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22
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Crivello JF, Jefcoate CR. The effects of cytochalasin B and vinblastine on movement of cholesterol in rat adrenal glands. Biochem Biophys Res Commun 1979; 89:1127-34. [PMID: 496943 DOI: 10.1016/0006-291x(79)92125-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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23
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Orme-Johnson N, Light D, White-Stevens R, Orme-Johnson W. Steroid binding properties of beef adrenal cortical cytochrome P-450 which catalyzes the conversion of cholesterol into pregnenolone. J Biol Chem 1979. [DOI: 10.1016/s0021-9258(17)37772-4] [Citation(s) in RCA: 71] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Dufau ML, Catt KJ. Gonadotropin receptors and regulation of steroidogenesis in the testis and ovary. VITAMINS AND HORMONES 1979; 36:461-592. [PMID: 217174 DOI: 10.1016/s0083-6729(08)60989-9] [Citation(s) in RCA: 119] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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25
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Jefcoate C. Cytochrome P-450 of adrenal mitochondria. Steroid binding sites on two distinguishable forms of rat adrenal mitochondrial cytochrome P-450sec. J Biol Chem 1977. [DOI: 10.1016/s0021-9258(17)38311-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Falke HE, Huijmans JG, Degenhart HJ. Different effects of cycloheximide and chloramphenicol on corticosterone production by isolated rat adrenal cells. Mol Cell Endocrinol 1976; 4:331-9. [PMID: 181283 DOI: 10.1016/0303-7207(76)90049-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cycloheximide and chloramphenicol both inhibit the stimulating effect of adenocorticotropic hormone (ACTH) on adrenal steroid production. To test whether these inhibitors had andy effect on adrenal steroid production, independent fromthe mechanism of action of ACTH we investigated their effect on the conversion of 25-hydroxycholesterol into corticosterone in isolated rat adrenal cells. Cycloheximide, both in the absence and in the presence of ACTH, had no effect on this conversion. Chloramphenicol inhibited the conversion of 25-hydroxycholesterol into corticosterone whether ACTH has no direct efeect on the cholesterol side-chain cleaving system. The inhibition by chloramphenicol of the ACTH-stimulated steroid production is at least partly due to inhibition of one or more of the processes involved in the conversion of 25-hydroxycholesterol into corticosterone.
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