Gold E.,University of Otago |
Marino F.E.,University of Otago |
Harrison C.,Prince Henrys Institute |
Makanji Y.,Prince Henrys Institute |
Risbridger G.,Monash University
Journal of Pathology | Year: 2013
Activins are involved in the regulation of a diverse range of physiological processes including development, reproduction, and fertility, and have been implicated in the progression of cancers. Bioactivity is regulated by the inhibin α-subunit and by an activin-binding protein, follistatin. The activin-βC subunit was not considered functionally significant in this regard due to an absence of phenotype in knockout mice. However, activin-βC forms heterodimers with activin-βA and activin-C antagonizes activin-A in vitro. Thus, it is proposed that overexpression, rather than loss of activin-βC, regulates activin-A bioactivity. In order to prove biological efficacy, inhibin α-subunit knockout mice (α-KO) were crossed with mice overexpressing activin-βC (ActC++). Deletion of inhibin leads to Sertoli and granulosa cell tumours, increased activin-A, and cancer-associated cachexia. Therefore, cachexia and reproductive tumour development should be modulated in α-KO/ActC++ mice, where excessive activin-A is the underlying cause. Accordingly, a reduction in activin-A, no significant weight loss, and reduced incidence of reproductive tumours were evident in α-KO/ActC++ mice. Overexpression of activin-βC antagonized the activin signalling cascade; thus, the tumourigenic effects of activin-A were abrogated. This study provides proof of the biological relevance of activin-βC. Being a regulator of activin-A, it is able to abolish cachexia and modulate reproductive tumour development in α-KO mice. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Evans J.,Prince Henrys Institute |
Evans J.,Monash University |
Salamonsen L.A.,Prince Henrys Institute |
Salamonsen L.A.,Monash University
Human Reproduction | Year: 2013
STUDY QUESTION Does prolonged exposure of the endometrium to hCG, as experienced after ovulation induction in an assisted reproduction technology (ART) cycle, affect functional measures of endometrial receptivity? SUMMARY ANSWER Prolonged endometrial hCG exposure detrimentally affects the manner in which the endometrium can respond to hCG secreted by the blastocyst. WHAT IS KNOWN ALREADY Prolonged hCG exposure down-regulates endometrial LH-CG receptor (LHCGR) expression in a baboon model. HCG exposure during the proliferative phase of oocyte-donation cycles and frozen embryo transfer cycles is associated with a lower pregnancy rate. STUDY DESIGN, SIZE, DURATION LHCGR was examined in endometria of women undergoing ART cycles (GnRH agonist/antagonist) and across the menstrual cycle in normally cycling fertile women. To determine whether prolonged hCG exposure affects the subsequent endometrial response to hCG, endometrial epithelial cells (HES cell line and primary cultures of human endometrial epithelial cells) were exposed to a low dose of hCG (0.5-5 IU) for up to 5 days, to mimic the chronic exposure during an ART cycle, and subsequently exposed to an acute 'blastocyst mimic' dose of hCG (20 IU).PARTICIPANTS/ MATERIALS, SETTING, METHODS Endometrial tissues were collected at hCG + 2 (n = 37) from women undergoing ART between August 2006 and August 2008, and across the cycle from women with known fertility (n = 40). LHCGR localization and staining intensity were determined by immunohistochemistry and semi-quantitative scoring. HES cells were treated with hCG as above and analyzed for LHCGR localization (immunocytochemistry), phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 (western immunoblotting), adhesion to trophoblast-like matrices (adhesion assays) and tight junction integrity (trans-epithelial resistance assessment). MAIN RESULTS AND THE ROLE OF CHANCE Endometrial epithelial LHCGR staining was significantly lower in women stimulated with a GnRH agonist protocol who did not become pregnant in that cycle versus the natural menstrual cycle (P < 0.05). Chronic low-dose hCG exposure in vitro mediated a down-regulation and internalization of the LHCGR in endometrial epithelial cells. Prolonged exposure to chronic low-dose hCG (3-5 days) abrogated ERK 1/2 phosphorylation, adhesion to extracellular matrices and changes in tight junction integrity in response to a subsequent acute high dose (20 IU) of hCG. LIMITATIONS, REASONS FOR CAUTION Studies using cell lines and primary cultures of cells in vitro are not fully representative of the complex endometrial milieu in vivo. WIDER IMPLICATIONS OF THE FINDINGS These data reinforce the clinical observations that precocious or prolonged hCG exposure may detrimentally affect endometrial receptivity and provide a mechanistic basis for these clinical findings. The data appear to support the notion that in women for whom ART has not succeeded, a different, minimally stimulated approach without exposure to exogenous hCG may improve outcomes. STUDY FUNDING/COMPETING INTEREST(S) The authors have no competing interests. © 2013 The Author. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved.
Funder J.W.,Prince Henrys Institute
Current Hypertension Reports | Year: 2012
Primary aldosteronism is commonly regarded as largely sporadic, but both germline and somatic mutations are increasingly recognized as underlying the condition. Three germline mutations causing familial hyperaldosteronism have been described, dubbed FH I (due to a CYP11B1/CYP11B2 chimera), FH II (localized to chromosome 7p22, exact location of mutation[s] unknown to date), and FH III (reflecting a T158A mutation in the potassium channel subunit KCNJ5). Major contributions (FH I, FH III) have been by Lifton and his associates; more recently they have also described somatic mutations (G151R, L168R) in KCNJ5 in over a third of aldosterone-producing adenomas, with results confirmed, refined, and extended in amuch larger study fromEurope. These findings have sparked considerable interest, and over the next 12 months a number of additional reports can be confidently expected to throw light on both normal and abnormal adrenocortical zonation and the genesis of primary aldosteronism. © Springer Science+Business Media, LLC 2012.
Funder J.W.,Prince Henrys Institute |
Reincke M.,Ludwig Maximilians University of Munich
Biochimica et Biophysica Acta - Molecular Basis of Disease | Year: 2010
The hormone aldosterone has a well-recognized physiological role in epithelial fluid and electrolyte homeostasis, and more recently defined pathophysiological roles in the cardiovascular system. The term "risk factor" implies an active role in pathophysiology, with levels lower (e.g. HDL) or higher (e.g. LDL, BP) than normal contributing to an increased likelihood of morbidity and/or mortality. In this regard, primary aldosteronism represents a classic illustration of aldosterone as a cardiovascular risk factor. In this syndrome of (relatively) autonomous aldosterone secretion, the effects of elevated hormone levels are on a range of organs and tissues-the heart, blood vessels and brain, inter alia. In other cardiovascular disorders (e.g. CCF, EH) while an elevation of aldosterone levels is often regarded as a risk factor, it is more correctly a response to the severity of disease (or to treatment intervention), rather than necessarily a risk factor with a primary role in disease progression. An enduring enigma relevant to any discussion of aldosterone as a risk factor is that very high levels of aldosterone in response to chronic sodium deficiency have homeostatic (and protective of cardiovascular) functions, while the considerably lower levels commonly seen in primary aldosteronism are incontrovertibly damaging. A final section of the paper will thus propose a mechanism which might solve this enigma, based on the commonalities-and a single crucial difference-in the factors stimulating the secretion of aldosterone and endogenous ouabain from the zona glomerulosa of the adrenal gland. © 2010 Elsevier B.V.
Sarraj M.A.,Prince Henrys Institute |
Drummond A.E.,Prince Henrys Institute
Reproduction | Year: 2012
The development of a normal ovary during foetal life is essential for the production and ovulation of a high-quality oocyte in adult life. Early in embryogenesis, the primordial germ cells (PGCs) migrate to and colonise the genital ridges. Once the PGCs reach the bipotential gonad, the absence of the sex-determining region on the Y chromosome (SRY) gene and the presence of female-specific genes ensure that the indifferent gonad takes the female pathway and an ovary forms. PGCs enter into meiosis, transform into oogonia and ultimately give rise to oocytes that are later surrounded by granulosa cells to form primordial follicles. Various genes and signals are implicated in germ and somatic cell development, leading to successful follicle formation and normal ovarian development. This review focuses on the differentiation events, cellular processes and molecular mechanisms essential for foetal ovarian development in the mice and humans. A better understanding of these early cellular and morphological events will facilitate further study into the regulation of oocyte development, manifestation of ovarian disease and basis of female infertility. © 2012 Society for Reproduction and Fertility.
Czajka-Oraniec I.,Bielanski Hospital |
Simpson E.R.,Prince Henrys Institute
Endokrynologia Polska | Year: 2010
Aromatase is a member of the cytochrome P450 superfamily that catalyzes the conversion of androgens (C19), namely testosterone and androstenedione, into oestrogens (C18), oestradiol, and oestrone, respectively. The enzyme is active in various tissues in both females and males, thus oestrogens are produced not only in gonads but also in extra-gonadal localizations such as brain, adipose tissue, breast, skin, and bone. Aromatase gene CYP19A1 located on chromosome 15 comprises nine coding exons and a number of alternative non-coding first exons that regulate tissue-specific expression. Studies on local regulation of aromatase expression and activity are important for understanding processes such as growth of oestrogen-dependent breast cancer. Rare clinical conditions of aromatase deficiency and excess have revealed some new and unexpected oestrogen functions in metabolism and bone health in both women and men. They were further studied using transgenic animal models such as aromatase knockout mice (ArKO) or (AROM+) mice overexpressing human aromatase. Research on aromatase was important for its practical outcome as it contributed to the development of aromatase inhibitors (Als), an effective and safe group of drugs for the first-line endocrine therapy of breast cancer. Further studies are needed to establish Als application in other oestrogen-dependent conditions, to overcome the resistance in breast cancer patients, and to develop tissue-specific selective inhibitors.
Funder J.W.,Prince Henrys Institute
Molecular and Cellular Endocrinology | Year: 2012
Since the isolation and characterization of aldosterone in 1953, subsequent developments in the field can be neatly considered over three time spans, each of two decades. In the first aldosterone itself was the primary focus; from 1973, for two decades the mineralocorticoid receptor (MR) was the front runner; since 1993 the focus has been on both, with aldosterone being discovered by cardiologists, and distinguished within their panoply of neurohumoral factors. © 2011 Elsevier Ireland Ltd.
Chand A.L.,Prince Henrys Institute |
Legge M.,University of Otago
Human Reproduction | Year: 2011
Background Little is known about metabolic processes in the developing ovarian follicle. Using mouse ovarian follicles, we investigated uptake of L-leucine by follicles at varying stages of maturity in the presence of insulin-like growth factor (IGF)-1. Methods Mouse ovarian follicles were cultured in vitro for 5 days in increasing concentrations of IGF-1, and follicle diameter and atresia measured as endpoints for growth. Uptake of 3H-leucine was measured in follicles at different stages of development. In optimal IGF-1-mediated growth conditions, competitive inhibition of 3H-leucine uptake by 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (BCH), a non-metabolizable substrate analogue of L-leucine, was performed to demonstrate specificity of influx, via system L transporters. To test whether uptake rates were dependent on intracellular amino acid availability, follicles from in vitro cultures were pre-treated with L-phenylalanine prior to 3H-leucine uptake. Results Follicle development (P< 0.001) and survival (P< 0.001) increased with IGF-1 treatment. As pre-antral follicles progressed to late antral stage, we observed an increase in L-leucine uptake, which was reduced in pre-ovulatory follicles. BCH decreased L-leucine uptake rates in early antral (P< 0.05), antral (P< 0.001) and pre-ovulatory follicles (P< 0.01). L-leucine influx increased in follicles preloaded with phenylalanine (trans-stimulation). In follicles lacking free intracellular amino acids (zero-trans suppression), uptake rate was reduced (P< 0.05). Conclusions These results demonstrate, for the first time, evidence of specific system L amino acid transport in intact, mouse ovarian follicles and profile L-leucine uptake during folliculogenesis. A better understanding of ovarian follicle metabolic pathways is necessary for improved in vitro maturation as well as determining the impact of altered metabolism on fertility. © 2011 The Author.
Bilandzic M.,Prince Henrys Institute |
Stenvers K.L.,Prince Henrys Institute
Molecular and Cellular Endocrinology | Year: 2011
Betaglycan is a co-receptor for the TGFβ superfamily, particularly important in establishing the potency of its ligands on their target cells. In recent years, new insights have been gained into the structure and function of betaglycan, expanding its role from that of a simple co-receptor to include additional ligand-dependent and ligand-independent roles. This review focuses on recent advances in the betaglycan field, with a particular emphasis on its newly discovered actions in mediating the trafficking of TGFβ superfamily receptors and as a determinant of the functional output of TGFβ superfamily signalling. In addition, this review encompasses a discussion of the emerging roles of the betaglycan/inhibin pathway in reproductive cancers and disease. © 2011 Elsevier Ireland Ltd.
Funder J.W.,Prince Henrys Institute
Integrated Blood Pressure Control | Year: 2013
Spironolactone was first developed over 50 years ago as a potent mineralocorticoid receptor (MR) antagonist with undesirable side effects; it was followed a decade ago by eplerenone, which is less potent but much more MR-specific. From a marginal role as a potassium- sparing diuretic, spironolactone was shown to be an extraordinarily effective adjunctive agent in the treatment of progressive heart failure, as was eplerenone in subsequent heart failure trials. Neither acts as an aldosterone antagonist in the heart as the cardiac MR are occupied by cortisol, which becomes an aldosterone mimic in conditions of tissue damage. The accepted term "MR antagonist", (as opposed to "aldosterone antagonist" or, worse, " aldosterone blocker"), should be retained, despite the demonstration that they act not to deny agonist access but as inverse agonists. The prevalence of primary aldosteronism is now recognized as accounting for about 10% of hypertension, with recent evidence suggesting that this figure may be considerably higher: in over two thirds of cases of primary aldosteronism therapy including MR antagonists is standard of care. MR antagonists are safe and vasoprotective in uncomplicated essential hypertension, even in diabetics, and at low doses they also specifically lower blood pressure in patients with so-called resistant hypertension. Nowhere are more than 1% of patients with primary aldosteronism ever diagnosed and specifically treated. Given the higher risk profile in patients with primary aldosteronism than that of age, sex, and blood pressure matched essential hypertension, on public health grounds alone the guidelines for first-line treatment of all hypertension should mandate inclusion of a low-dose MR antagonist. © 2013 Funder, publisher and licensee Dove Medical Press Ltd.