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Nakamura Y, Fujishima F, Hui XG, Felizola SJ, Shibahara Y, Akahira JI, McNamara KM, Rainey WE, Sasano H. 3βHSD and CYB5A double positive adrenocortical cells during adrenal development/aging. Endocr Res 2015; 40:8-13. [PMID: 24832628 PMCID: PMC4242803 DOI: 10.3109/07435800.2014.895377] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Androstenedione is a common precursor of sex steroids produced and secreted in the human adrenal gland and produced by 3β-hydroxysteroid dehydrogenase (3βHSD), 17β-hydroxylase/17,20-lyase (CYP17) and cytochrome b5 (CYB5A). 3βHSD is expressed in the zona glomerulosa (ZG) and fasciculata (ZF), CYP17 in the ZF and zona reticularis (ZR) and CYB5A in the ZR, respectively. We previously demonstrated the presence of cortical parenchymal cells co-expressing 3βHSD and CYB5A with hybrid features of both ZF and ZR in human adrenal cortex and hypothesized that these cells may play an important role in androstenedione production in human adrenal gland. Age-related morphologic development of these hybrid cells has, however, not been studied. Therefore, in this study, 48 human adrenal specimens from various age groups were retrieved. Double-immunohistochemical analyses were used in order to study the correlation between this hybrid cell type and age. In both male and female adrenal cortex, the means of total adrenocortical area, the area positive for CYB5A and its ratio reached highest peak in the 21-40-year-old (y.o.) group. The greatest overlap between 3βHSD and CYB5A in both total and relative area was present in the 13-20 y.o. group. For all the markers mentioned above, statistically significant differences were detected among the different age groups examined (p < 0.05). These findings indicated that both area and ratio of 3βHSD and CYB5A double positive cells, which could represent the hybrid cells of ZF and ZR, are correlated with human adrenal development and could subsequently influence age-related serum androstenedione levels.
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Affiliation(s)
- Yasuhiro Nakamura
- Department of Pathology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Fumiyoshi Fujishima
- Department of Pathology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Xiao-Gang Hui
- Department of Pathology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Saulo J.A. Felizola
- Department of Pathology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Yukiko Shibahara
- Department of Pathology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Jun-ichi Akahira
- Department of Pathology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Keely M. McNamara
- Department of Pathology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - William E. Rainey
- University of Michigan, Department of Physiology and Medicine, Ann Arbor, Michigan, USA
| | - Hironobu Sasano
- Department of Pathology, Tohoku University Graduate School of Medicine, Sendai, Japan
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Phillips KA, Bales KL, Capitanio JP, Conley A, Czoty PW, ‘t Hart BA, Hopkins WD, Hu SL, Miller LA, Nader MA, Nathanielsz PW, Rogers J, Shively CA, Voytko ML. Why primate models matter. Am J Primatol 2014; 76:801-27. [PMID: 24723482 PMCID: PMC4145602 DOI: 10.1002/ajp.22281] [Citation(s) in RCA: 391] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 03/01/2014] [Accepted: 03/02/2014] [Indexed: 12/13/2022]
Abstract
Research involving nonhuman primates (NHPs) has played a vital role in many of the medical and scientific advances of the past century. NHPs are used because of their similarity to humans in physiology, neuroanatomy, reproduction, development, cognition, and social complexity-yet it is these very similarities that make the use of NHPs in biomedical research a considered decision. As primate researchers, we feel an obligation and responsibility to present the facts concerning why primates are used in various areas of biomedical research. Recent decisions in the United States, including the phasing out of chimpanzees in research by the National Institutes of Health and the pending closure of the New England Primate Research Center, illustrate to us the critical importance of conveying why continued research with primates is needed. Here, we review key areas in biomedicine where primate models have been, and continue to be, essential for advancing fundamental knowledge in biomedical and biological research.
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Affiliation(s)
- Kimberley A. Phillips
- Department of Psychology, Trinity University, San Antonio TX 78212
- Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio TX
| | - Karen L. Bales
- Department of Psychology, University of California, Davis CA 95616
- California National Primate Research Center, Davis CA 95616
| | - John P. Capitanio
- Department of Psychology, University of California, Davis CA 95616
- California National Primate Research Center, Davis CA 95616
| | - Alan Conley
- Department of Population Health & Reproduction, School of Veterinary Medicine, University of California, Davis CA 95616
| | - Paul W. Czoty
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem NC 27157
| | - Bert A. ‘t Hart
- Department of Immunobiology, Biomedical Primate Research Center, Rijswick, The Netherlands
| | - William D. Hopkins
- Neuroscience Institute and Language Research Center, Georgia State University, Atlanta GA 30302
- Division of Cognitive and Developmental Neuroscience, Yerkes National Primate Research Center, Atlanta GA 30030
| | - Shiu-Lok Hu
- Department of Pharmaceutics and Washington National Primate Research Center, University of Washington, Seattle WA
| | - Lisa A. Miller
- California National Primate Research Center, Davis CA 95616
- Department of Anatomy, Physiology and Cell Biology, University of California, Davis CA 95616
| | - Michael A. Nader
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem NC 27157
| | - Peter W. Nathanielsz
- Center for Pregnancy and Newborn Research, University of Texas Health Science Center, San Antonio TX 78229
| | - Jeffrey Rogers
- Human Genome Sequencing Center, Baylor College of Medicine, Houston TX
- Wisconsin National Primate Research Center, Madison, WI
| | - Carol A. Shively
- Department of Pathology, Section on Comparative Medicine, Wake Forest University School of Medicine, Winston-Salem NC 27157
| | - Mary Lou Voytko
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem NC 27157
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Parker CR, Grizzle WE, Blevins JK, Hawkes K. Development of adrenal cortical zonation and expression of key elements of adrenal androgen production in the chimpanzee (Pan troglodytes) from birth to adulthood. Mol Cell Endocrinol 2014; 387:35-43. [PMID: 24576611 PMCID: PMC4016767 DOI: 10.1016/j.mce.2014.02.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 02/11/2014] [Accepted: 02/18/2014] [Indexed: 11/26/2022]
Abstract
The basis for the pattern of adrenal androgen production in the chimpanzee, which resembles that of humans, is poorly defined. We characterized the developmental zonation and expression of elements of the androgen biosynthetic pathway in the chimpanzee adrenal. The newborn adrenal contained a broad fetal zone (FZ) expressing CYP17, SULT2A1, and Cytochrome B5 (CB5) but not HSD3B; the outer cortex expressed HSD3B but not SULT2A1 or CB5. During infancy, the FZ involuted and the HSD3B-expressing outer cortex broadened. By 3years of age, a thin layer of cells that expressed CB5, SULT2A1, and CYP17 adjoined the medulla and likely represented the zona reticularis; the outer cortex consisted of distinct zonae fasiculata and glomerulosa. Thereafter, the zona reticularis broadened as also occurs in the human. The adult chimpanzee adrenal displayed other human-like characteristics: intramedullary clusters of reticularis-like cells and also a cortical cuff of zona fasiculata-like cells adjoining the central vein.
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Affiliation(s)
- C R Parker
- Department of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
| | - W E Grizzle
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
| | - J K Blevins
- Department of Anthropology, 270S 140E., University of Utah, Salt Lake City, UT, United States
| | - K Hawkes
- Department of Anthropology, 270S 140E., University of Utah, Salt Lake City, UT, United States.
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Storbeck KH, Swart AC, Goosen P, Swart P. Cytochrome b5: novel roles in steroidogenesis. Mol Cell Endocrinol 2013; 371:87-99. [PMID: 23228600 DOI: 10.1016/j.mce.2012.11.020] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 11/20/2012] [Accepted: 11/20/2012] [Indexed: 11/25/2022]
Abstract
Cytochrome b(5) (cyt-b(5)) is essential for the regulation of steroidogenesis and as such has been implicated in a number of clinical conditions. It is well documented that this small hemoprotein augments the 17,20-lyase activity of cytochrome P450 17α-hydroxylase/17,20-lyase (CYP17A1). Studies have revealed that this augmentation is accomplished by cyt-b(5) enhancing the interaction between cytochrome P450 reductase (POR) and CYP17A1. In this paper we present evidence that cyt-b(5) induces a conformational change in CYP17A1, in addition to facilitating the interaction between CYP17A1 and POR. We also review the recently published finding that cyt-b(5) allosterically augments the activity of 3β-hydroxysteroid dehydrogenase/Δ(5)-Δ(4) isomerase (3βHSD), a non cytochrome P450 enzyme, by increasing the enzymes affinity for its cofactor, NAD(+). The physiological importance of this finding, in terms of understanding adrenal androstenedione production, is examined. Finally, evidence that cyt-b(5) is able to form homomeric complexes in living cells is presented and discussed.
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Affiliation(s)
- Karl-Heinz Storbeck
- Department of Biochemistry, University of Stellenbosch, Stellenbosch 7602, South Africa
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Conley AJ, Moeller BC, Nguyen AD, Stanley SD, Plant TM, Abbott DH. Defining adrenarche in the rhesus macaque (Macaca mulatta), a non-human primate model for adrenal androgen secretion. Mol Cell Endocrinol 2011; 336:110-6. [PMID: 21184803 PMCID: PMC5881168 DOI: 10.1016/j.mce.2010.12.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2010] [Revised: 12/14/2010] [Accepted: 12/14/2010] [Indexed: 11/21/2022]
Abstract
Adrenarche, defined as a prepubertal increase in adrenal androgen secretion resulting from zona reticularis (ZR) maturation, is thought to occur only in humans and some Great Apes. In the rhesus macaque, studies of circulating dehydroepiandrosterone (DHEA) or its sulpho-conjugate (DHEAS) have failed to demonstrate a prepubertal rise typical of human adrenarche, but available data are cross-sectional and include few neonatal or early infant samples. However, ZR maturation is complete in rhesus infants by 3 months of age based on morphological and biochemical analyses. Furthermore, preliminary longitudinal studies from birth through infancy of castrated males, and intact males and females, suggests for the first time that there is a transient, prepubertal elevation of adrenal androgen in rhesus macaques. Serum DHEAS concentration increased, peaking between 6 and 8 weeks of age in castrate males, and intact males and females, then declined. These longitudinal profiles add endocrinological support to the morphological and biochemical evidence that adrenarche occurs in a narrow developmental window in infant rhesus macaques. Adrenarche in any species should be defined only after careful longitudinal hormone analysis have been conducted in stages of development that are suggested by morphological and biochemical evidence of ZR maturation.
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Affiliation(s)
- A J Conley
- School of Veterinary Medicine, University of California-Davis, 1 Shields Ave, Davis, CA 95618, USA.
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Cellular localization of androgen synthesis in equine granulosa-theca cell tumors: immunohistochemical expression of 17alpha-hydroxylase/17,20-lyase cytochrome P450. Theriogenology 2010; 74:393-401. [PMID: 20416939 DOI: 10.1016/j.theriogenology.2010.02.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Revised: 02/24/2010] [Accepted: 02/24/2010] [Indexed: 11/22/2022]
Abstract
Elevated blood testosterone concentrations, often accompanied by male-typical behaviors, is a common signalment of mares with granulosa-theca cell tumors (GCTCs), but no definitive information exists regarding the cellular differentiation of tumors associated with androgen secretion. This study was conducted to localize and thereby define the cellular expression of 17alpha-hydroxylase/17,20-lyase cytochrome P450 (P450c17), the enzyme most directly responsible for androgen synthesis, in 30 GTCTs and control tissues (gonads and adrenal glands) using immuno-histochemistry (IHC). Immuno-reactivity for P450c17 was evident in approximately half of 30 specimens examined, was most consistent in the interstitial cells surrounding existing or developing cysts, and was less intense in cells within cysts in the smaller proportion of specimens where this was observed. In control tissues, the expression of P450c17 was localized primarily in theca interna of normal ovarian follicles, in theca-lutein cells of some corpora lutea, but not in granulosa-lutein cells. Testicular interstitial cells and islands of adreno-cortical cells located in the adrenal medulla of the adrenal cortex further established the specificity of the antisera used. These data provided the first substantive evidence that polyhedral cells identified previously in GTCTs by histopathology have the potential to synthesize and secrete androgens, similar to theca interna and theca lutein cells in normal equine ovaries.
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Nguyen AD, Corbin CJ, Pattison JC, Bird IM, Conley AJ. The developmental increase in adrenocortical 17,20-lyase activity (biochemical adrenarche) is driven primarily by increasing cytochrome b5 in neonatal rhesus macaques. Endocrinology 2009; 150:1748-56. [PMID: 19036885 PMCID: PMC2732332 DOI: 10.1210/en.2008-1303] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Adrenarche is thought to be experienced only by humans and some Old World primates despite observed regression of an adrenal fetal zone and establishment of a functional zona reticularis (ZR) in other species like rhesus macaques. Adrenal differentiation remains poorly defined biochemically in nonhuman primates. The present studies defined ZR development in the neonatal rhesus by examining androgen synthetic capacity and factors affecting it in rhesus and marmoset adrenals. Western immunoblots examined expression of 17alpha-hydroxylase/17,20-lyase cytochrome P450 (P450c17), cytochrome b5 (b5), and 3beta-hydroxysteroid dehydrogenase (3betaHSD), among other key enzymes. 17,20-lyase activity was quantified in adrenal microsomes, as was the contribution of b5 to 17,20-lyase activity in microsomes and cell transfection experiments with rhesus and marmoset P450c17. Expression of b5 increased from birth to 3 months, and was positively correlated with age and 17,20-lyase activity in the rhesus. Recombinant b5 addition stimulated 17,20-lyase activity to an extent inversely proportional to endogenous levels in adrenal microsomes. Although 3betaHSD expression also increased with age, P450c17, 21-hydroxylase cytochrome P450, and the redox partner, reduced nicotinamide adenine dinucleotide phosphate-cytochrome P450 oxidoreductase, did not; nor did recombinant cytochrome P450 oxidoreductase augment 17,20-lyase activity. Cotransfection with b5 induced a dose-dependent increase in dehydroepiandrosterone synthesis by both nonhuman primate P450c17 enzymes. We conclude that the increase in 17,20-lyase activity characteristic of an adrenarche in rhesus macaques is driven primarily by increased b5 expression, without the need for a decrease in 3betaHSD, as suggested from human studies. The rhesus macaque is a relevant and accessible model for human ZR development and adrenal function.
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Affiliation(s)
- Ann D Nguyen
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, California 95616, USA
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Abbott DH, Bird IM. Nonhuman primates as models for human adrenal androgen production: function and dysfunction. Rev Endocr Metab Disord 2009; 10:33-42. [PMID: 18683055 PMCID: PMC2653599 DOI: 10.1007/s11154-008-9099-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The origin of circulating DHEA and adrenal-derived androgens in humans and nonhuman primates is largely distinct from other mammalian species. In humans and many Old world primates, the fetal adrenal gland and adult zona reticularis (ZR) are known to be the source for production of DHEA (and DHEAS) in mg quantities. In spite of similarities there are also some differences. Herein, we take a comparative endocrine approach to the diversity of adrenal androgen biosynthesis and its developmental timing in three primate species to illustrate how understanding such differences may provide unique insight into mechanisms underlying adrenal androgen regulation and its pathophysiology in humans. We contrast the conventional developmental onset of adrenal DHEA biosynthesis at adrenarche in humans with (1) an earlier, peri-partutrition onset of adrenal DHEA synthesis in rhesus macaques (Old World primate) and (2) a more dynamic and reversible onset of adrenal DHEA biosynthesis in female marmosets (New World primate), and further consider these events in terms of the corresponding developmental changes in expression of CYP17, HSD3B2 and CYB5 in the ZR. We also integrate these observations with recently described biochemical characterization of CYP17 cDNA cloned from each of these nonhuman primate species and the corresponding effects of phosphorylation versus CYB5 coexpression on 17,20 lyase versus 17-hydroxylase activity in each case. In addition, female rhesus macaques exposed in utero to exogenous androgen excess, exhibit symptoms of adrenal hyperandrogenism in adult females in a manner reminiscent of that seen in the human condition of PCOS. The possible mechanisms underlying such adrenal hyperandrogenism are further considered in terms of the effects of altered relative expression of CYP17, HSD3B2 and CYB5 as well as the altered signaling responses of various kinases including protein kinase A, or the insulin sensitive PI3-kinase/AKT signaling pathway which may impact on 17,20 lyase activity. We conclude that while the triggers for the onset of ZR function in all three species show clear differences (age, stage of development, social status, gender), there are still common mechanisms driving an increase in DHEA biosynthesis in each case. A full understanding of the mechanisms that control 17,20 lyase function and dysfunction in humans may best be achieved by comparative studies of the endocrine mechanisms controlling adrenal ZR function and dysfunction in these nonhuman primate species.
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Affiliation(s)
- D H Abbott
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI 53715, USA
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Abbott DH, Zhou R, Bird IM, Dumesic DA, Conley AJ. Fetal programming of adrenal androgen excess: lessons from a nonhuman primate model of polycystic ovary syndrome. ENDOCRINE DEVELOPMENT 2008; 13:145-158. [PMID: 18493139 PMCID: PMC2531212 DOI: 10.1159/000134831] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Adrenal androgen excess is found in adult female rhesus monkeys previously exposed to androgen treatment during early gestation. In adulthood, such prenatally androgenized female monkeys exhibit elevated basal circulating levels of dehydroepiandrosterone sulfate (DHEAS), typical of polycystic ovary syndrome (PCOS) women with adrenal androgen excess. Further androgen and glucocorticoid abnormalities in PA female monkeys are revealed by acute ACTH stimulation: DHEA, androstenedione and corticosterone responses are all elevated compared to responses in controls. Pioglitazone treatment, however, diminishes circulating DHEAS responses to ACTH in both prenatally androgenized and control female monkeys, while increasing the 17-hydroxyprogesterone response and reducing the DHEA to 17-hydroxyprogesterone ratio. Since 60-min post-ACTH serum values for 17-hydroxyprogesterone correlate negatively with basal serum insulin levels (all female monkeys on pioglitazone and placebo treatment combined), while similar DHEAS values correlate positively with basal serum insulin levels, circulating insulin levels may preferentially support adrenal androgen biosynthesis in both prenatally androgenized and control female rhesus monkeys. Overall, our findings suggest that differentiation of the monkey adrenal cortex in a hyperandrogenic fetal environment may permanently upregulate adult adrenal androgen biosynthesis through specific elevation of 17,20-lyase activity in the zona fasciculata-reticularis. As adult prenatally androgenized female rhesus monkeys closely emulate PCOS-like symptoms, excess fetal androgen programming may contribute to adult adrenal androgen excess in women with PCOS.
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Affiliation(s)
- David H Abbott
- Department of Obstetrics and Gynecology, Wisconsin National Primate Research Center and Endocrinology-Reproductive Physiology Training Program, University of Wisconsin, Madison, Wisc., USA
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Zhou R, Bird IM, Dumesic DA, Abbott DH. Adrenal hyperandrogenism is induced by fetal androgen excess in a rhesus monkey model of polycystic ovary syndrome. J Clin Endocrinol Metab 2005; 90:6630-7. [PMID: 16174719 PMCID: PMC1350929 DOI: 10.1210/jc.2005-0691] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Adrenal androgen excess is found in approximately 25-60% of women with polycystic ovary syndrome (PCOS), but the mechanisms underlying PCOS-related adrenal androgen excess are unclear. OBJECTIVE The objective of this study was to determine whether adrenal androgen excess is manifest in a nonhuman primate model for PCOS. PARTICIPANTS Six prenatally androgenized (PA) and six control female rhesus monkeys of similar age, body weight, and body mass index were studied during d 2-6 of two menstrual cycles or anovulatory 30-d periods. INTERVENTIONS Predexamethasone adrenal steroid levels were assessed in the first cycle (cycle 1). In a subsequent cycle (cycle 2), occurring one to three cycles after cycle 1, adrenal steroids were determined 14.5-16.0 h after an i.m. injection of 0.5 mg/kg dexamethasone (postdexamethasone levels) and after an i.v. injection of 50 microg ACTH-(1-39). RESULTS Both before and after dexamethasone, serum levels of dehydroepiandrosterone (DHEA) in PA females exceeded those in controls. After ACTH injection, PA females exhibited higher circulating levels of DHEA, androstenedione, and corticosterone but comparable levels of 17alpha-hydroxyprogesterone, cortisol, the sulfoconjugate of DHEA, and testosterone compared with controls. CONCLUSION Enhanced basal and ACTH-stimulated adrenal androgen levels in PA female monkeys may reflect up-regulation of 17,20 lyase activity in the adrenal zona reticularis, causing adrenal androgen excess comparable with that found in PCOS women with adrenal androgen excess. These findings open the possibility that PCOS adrenal hyperandrogenism may have its origins in fetal androgen excess reprogramming of adrenocortical function.
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Affiliation(s)
- Rao Zhou
- National Primate Research Center, University of Wisconsin, Madison 53715, USA.
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Abstract
Cytochrome P450 enzymes catalyze the degradation of drugs and xenobiotics, but also catalyze a wide variety of biosynthetic processes, including most steps in steroidogenesis. The catalytic rate of a P450 enzyme is determined in large part by the rate of electron transfer from its redox partners. Type I P450 enzymes, found in mitochondria, receive electrons from reduced nicotinamide adenine dinucleotide (NADPH) via the intermediacy of two proteins-ferredoxin reductase (a flavoprotein) and ferredoxin (an iron/sulfur protein). Type I P450 enzymes include the cholesterol side-chain cleavage enzyme (P450scc), the two isozymes of 11-hydroxylase (P450c11beta and P450c11AS), and several vitamin D-metabolizing enzymes. Disorders of these enzymes, but not of the two redox partners, have been described. Type II P450 enzymes, found in the endoplasmic reticulum, receive electrons from NADPH via P450 oxidoreductase (POR), which contains two flavin moieties. Steroidogenic Type II P450 enzymes include 17alpha-hydroxylase/17,20 lyase (P450c17), 21-hydroxylase (P450c21), and aromatase (P450aro). All P450 enzymes catalyze multiple reactions, but P450c17 appears to be unique in that the ratio of its activities is regulated at a posttranslational level. Three factors can increase the degree of 17,20 lyase activity relative to the 17alpha-hydroxylase activity by increasing electron flow from POR: a high molar ratio of POR to P450c17, serine phosphorylation of P450c17, and the presence of cytochrome b(5), acting as an allosteric factor to promote the interaction of POR with P450c17. POR is required for the activity of all 50 human Type II P450 enzymes, and ablation of the Por gene in mice causes embryonic lethality. Nevertheless, mutation of the human POR gene is compatible with life, causing multiple steroidogenic defects and a skeletal dysplasia called Antley-Bixler syndrome.
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Affiliation(s)
- Walter L Miller
- Department of Pediatrics, Building MR-4, Room 209, University of California, San Francisco, San Francisco, California 94143-0978, USA
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Huang N, Dardis A, Miller WL. Regulation of cytochrome b5 gene transcription by Sp3, GATA-6, and steroidogenic factor 1 in human adrenal NCI-H295A cells. Mol Endocrinol 2005; 19:2020-34. [PMID: 15831526 DOI: 10.1210/me.2004-0411] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Sex steroid synthesis requires the 17,20 lyase activity of P450c17, which is enhanced by cytochrome b5, acting as an allosteric factor to promote association of P450c17 with its electron donor, P450 oxidoreductase. Cytochrome b5 is preferentially expressed in the fetal adrenal and postadrenarchal adrenal zona reticularis; the basis of this tissue-specific, developmentally regulated transcription of the b5 gene is unknown. We found b5 expression in all cell lines tested, including human adrenal NCI-H295A cells, where its mRNA is reduced by cAMP and phorbol ester. Multiple sites, between -83 and -122 bp upstream from the first ATG, initiate transcription. Deletional mutagenesis localized all detectable promoter activity within -327/+15, and deoxyribonuclease I footprinting identified protein binding at -72/-107 and -157/-197. DNA segments -65/-40, -114/-70 and -270/-245 fused to TK32/Luc yielded significant activity, and mutations in their Sp sites abolished that activity; electrophoretic mobility shift assay (EMSA) showed that Sp3, but not Sp1, binds to these Sp sites. Nuclear factor 1 (NF-1) and GATA-6, but not GATA-4 bind to the NF-1 and GATA sites in -157/-197. In Drosophila S2 cells, Sp3 increased -327/Luc activity 58-fold, but Sp1 and NF-1 isoforms were inactive. Mutating the three Sp sites ablated activity without or with cotransfection of Sp1/Sp3. In NCI-H295A cells, mutating the three Sp sites reduced activity to 39%; mutating the Sp, GATA, and NF-1 sites abolished activity. In JEG-3 cells, GATA-4 was inactive, GATA-6 augmented -327/Luc activity to 231% over the control, and steroidogenic factor 1 augmented activity to 655% over the control; these activities required the Sp and NF-1 sites. Transcription of cytochrome b5 shares many features with the regulation of P450c17, whose activity it enhances.
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Affiliation(s)
- Ningwu Huang
- Department of Pediatrics, University of California, San Francisco, San Francisco, California 94143-0978, USA
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Pandey AV, Miller WL. Regulation of 17,20 lyase activity by cytochrome b5 and by serine phosphorylation of P450c17. J Biol Chem 2005; 280:13265-71. [PMID: 15687493 DOI: 10.1074/jbc.m414673200] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytochrome P450c17 catalyzes the 17alpha-hydroxylase activity required for glucocorticoid synthesis and the 17,20 lyase activity required for sex steroid synthesis. Most P450 enzymes have fixed ratios of their various activities, but the ratio of these two activities of P450c17 is regulated post-translationally. We have shown that serine phosphorylation of P450c17 and the allosteric action of cytochrome b5 increase 17,20 lyase activity, but it has not been apparent whether these two post-translational mechanisms interact. Using purified enzyme systems, we now show that the actions of cytochrome b5 are independent of the state of P450c17 phosphorylation. Suppressing cytochrome b5 expression in human adrenal NCI-H295A cells by >85% with RNA interference had no effect on 17alpha-hydroxylase activity but reduced 17,20 lyase activity by 30%. Increasing P450c17 phosphorylation could compensate for this reduced activity. When expressed in bacteria, human P450c17 required either cytochrome b5 or phosphorylation for 17,20 lyase activity. The combination of cytochrome b5 and phosphorylation was not additive. Cytochrome b5 and phosphorylation enhance 17,20 lyase activity independently of each other, probably by increasing the interaction between P450c17 and NADPH-cytochrome P450 oxidoreductase.
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Affiliation(s)
- Amit V Pandey
- Department of Pediatrics and The Metabolic Research Unit, University of California San Francisco, San Francisco, California 94143-0978, USA
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Dharia S, Slane A, Jian M, Conner M, Conley AJ, Parker CR. Colocalization of P450c17 and cytochrome b5 in androgen-synthesizing tissues of the human. Biol Reprod 2004; 71:83-8. [PMID: 14985252 DOI: 10.1095/biolreprod.103.026732] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Androgens are an integral part of human physiology. The de novo production of androgens is generally limited to the adrenal cortex and the gonads. Androgen synthesis by these steroidogenic tissues requires the bifunctional enzyme cytochrome P450c17, which catalyzes both 17 hydroxylase and 17,20 lyase activities. 17,20-lyase activity is relevant to the regulation of androgen production, and is allosterically modulated through the action of an accessory protein, cytochrome b5 (CytB5). Our objective was to determine the cellular localization of P450c17 and CytB5 in androgen-synthesizing tissues of the human. Immunohistochemical analyses of P450c17 and CytB5 were performed on fetal and adult human adrenals, ovaries, and testes. In the fetal adrenal, CytB5 and P450c17 were both found in the cells of the fetal zone, but not in the neocortex. In the adult adrenal, the zona fasciculata was immunoreactive for P450c17 only, whereas the zona reticularis was immunopositive for both P450c17 and CytB5. In the adult gonads, P450c17 and CytB5 were colocalized in the Leydig cells of the testis, theca interna cells of the follicle, theca lutein cells, and isolated cell clusters in the ovarian stroma. Whereas P450c17 and CytB5 were colocalized in the Leydig cells of the fetal testes, there was no immunostaining for either in the midgestational fetal ovary. Our findings of colocalization of CytB5 and P450c17 are strongly supportive of the view that CytB5 plays an important role in the regulation of the androgen biosynthetic pathway in the fetal and adult human.
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Affiliation(s)
- Sejal Dharia
- Department of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Corbin CJ, Moran FM, Vidal JD, Ford JJ, Wise T, Mapes SM, Njar VC, Brodie AM, Conley AJ. Biochemical assessment of limits to estrogen synthesis in porcine follicles. Biol Reprod 2003; 69:390-7. [PMID: 12672661 DOI: 10.1095/biolreprod.103.015578] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Limits to estrogen production by early and late preovulatory porcine follicles were assessed by comparing enzymatic capacities for androgen (17,20-lyase) and estrogen (aromatase) synthesis in theca interna and granulosa, support of enzyme activities by the redox partner proteins NADPH-cytochrome P450 oxidoreductase (reductase) and cytochrome b5, and tissue-specific expression and regulation of these proteins. Parameters included follicular fluid (FF) estradiol and progesterone levels, theca and granulosa aromatase and reductase activities, and theca 17,20-lyase activity. Expression of proteins responsible for these activities, aromatase (P450arom) and 17 alpha-hydroxylase/17,20-lyase (P450c17) cytochromes P450, reductase, and for the first time in ovarian tissues cytochrome b5, were examined by Western immunoblot and immunocytochemistry. Theca and granulosa aromatase activities were as much as 100-fold lower than theca 17,20-lyase activity, but aromatase was correlated with only the log of FF estradiol. Granulosa reductase activity was twice that of the theca, and cytochrome b5 expression was clearly identified in both the theca and granulosa layers, as was P450arom, but was not highly correlated with either 17,20-lyase or aromatase activities. Reductase expression did not change with stage of follicular development, but cytochrome b5, P450c17, and P450arom were markedly lower in post-LH tissues. These data indicate that aromatase and not 17,20-lyase must limit porcine follicular estradiol synthesis, but this limitation is not reflected acutely in FF steroid concentrations. Neither reductase nor cytochrome b5 appear to regulate P450 activities, but the expression of cytochrome b5 in granulosa and theca suggests possible alternative roles for this protein in follicular development or function.
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Affiliation(s)
- C J Corbin
- Department of Population Health & Reproduction, School of Veterinary Medicine, University of California, Davis, California 95616, USA
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Morán FM, VandeVoort CA, Overstreet JW, Lasley BL, Conley AJ. Molecular target of endocrine disruption in human luteinizing granulosa cells by 2,3,7,8-tetrachlorodibenzo-p-dioxin: inhibition of estradiol secretion due to decreased 17alpha-hydroxylase/17,20-lyase cytochrome P450 expression. Endocrinology 2003; 144:467-73. [PMID: 12538606 DOI: 10.1210/en.2002-220813] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Estradiol (E2) production by human luteinized granulosa cells (hLGC) is inhibited by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The molecular target of TCDD toxicity has not been identified. The decrease in E2 is ameliorated by androgen substrate addition and is not associated with changes in aromatase cytochrome P450 (P450arom) activity or protein expression. An antihuman 17alpha-hydroxylase/17,20-lyase cytochrome P450 (P450c17) antisera and a direct radiometric assay of 17,20-lyase activity were used to test the hypothesis that TCDD targets P450c17, thereby decreasing substrate availability for E2 synthesis by hLGC. P450c17 expression and 17,20-lyase activity were detected in hLGC with high levels of E2 secretion. Western immunoblot analysis demonstrated that TCDD treatment of hLGC decreased the expression of P450c17 by as much 50% (P < 0.05). TCDD exposure induced a 65% decrease in 17,20-lyase activity (P < 0.05), but no changes were seen in P450arom or in nicotinamide adenine dinucleotide phosphate (reduced)-cytochrome P450 oxidoreductase (reductase). Furthermore, the decreases in P450c17 and 17,20-lyase were proportional to the inhibition of E2 secretion. We conclude that the molecular target for endocrine disruption of hLGC by TCDD is P450c17, specifically decreasing the supply of androgens for E2 synthesis, and that it does not involve either P450arom or the redox partner protein reductase.
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Affiliation(s)
- F M Morán
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, California 95616, USA
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