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Wang Q.,University of Ottawa | Wang Q.,Ottawa Hospital Research Institute | Leader A.,University of Ottawa | Leader A.,Ottawa Hospital Research Institute | And 4 more authors.
Endocrinology | Year: 2013

Follicular differentiation is a tightly regulated process involving various endocrine, autocrine, and paracrine factors. The biosynthesis of progesterone and estradiol in response to FSH involves the regulation of multiple steroidogenic enzymes, such asp450 cholesterol side-chain cleavage enzyme and aromatase. Here we demonstrated that prohibitin (PHB), a multifunctional protein, inhibits FSH-induced progesterone and estradiol secretion in rat granulosa cells. The mRNA abundances of cyp11a (coding p450 cholesterol side-chain cleavage enzyme) and cyp19 (coding aromatase) were also suppressed by PHB in a time-dependent manner. It is known that a novel adipokine chemerin suppresses FSH-induced steroidogenesis in granulosa cells. Chemerin up-regulates the content of PHB, and PHB knockdown attenuates the suppressive role of chemerin on steroidogenesis. In addition, inhibition of phosphatidylinositol 3-kinase/Akt pathway enhances the suppressive action of PHB, whereas expression of constitutively active Akt attenuates this response. These findings suggest that PHB is a novel negative regulator of FSH-induced steroidogenesis, and its action with chemerin may contribute to the dysregulation of steroidogenesis in the pathogenesis of polycystic ovarian syndrome. Copyright © 2013 by The Endocrine Society.

Kim J.Y.,Ottawa Hospital Research Institute | Kim J.Y.,Seoul National University | Xue K.,Ottawa Hospital Research Institute | Xue K.,Nanjing Medical University | And 8 more authors.
Endocrinology | Year: 2013

In the present study, we have investigated the cellular mechanisms of androgen-induced antral follicular growth arrest and the possible involvement of chemerin and its receptor chemokine-like receptor 1 (CMKLR1) in this process, using a chronically androgenized rat model. We hypothesize that hyperandrogenism induces antral follicle growth arrest via the action of chemerin and ovarian structural changes, resulting from granulosa cell and oocyte apoptosis and theca cell survival. Dihydrotestosterone (DHT) treatment resulted in increased expression of chemerinandCMKLR1in antral follicles, absence of corpus luteum, and increased atypical follicles. Addition of chemerin to follicle cultures induced granulosa cell apoptosis and suppressed basal, FSH- and growth differentiation factor-9- stimulated follicular growth. DHT down-regulated aromatase expression and increased active caspase-3 contentandDNAfragmentation in granulosa cells in vivo. These changeswereaccompanied by higher phosphatase and tensin homolog and lower phospho-Akt (Ser473) content in antral follicles and higher calpain expression and down-regulation of cytoskeletal proteins in atypical follicles, which were constituted predominantly of theca cells. DHT also activated granulosa cell caspase-3, decreased X-linked inhibitor of apoptosis protein, poly(ADP-ribose) polymerase, and phospho-Akt contents and induced apoptosis in vitro, responses readily attenuated by forced X-linked inhibitor of apoptosis protein expression. These findings are consistent with our hypothesis that antral follicular growth arrest in DHT-treated rats results from increased chemerin expression and action, as well as changes in follicular cell fate and structure, which are a consequence of dysregulated interactions of pro-survival and pro-apoptotic modulators in a cell-specific manner. Our observations suggest that this chronically androgenized rat model may be useful for studies on the long-term effects of androgens on folliculogenesis and may have implications for the female reproductive disorders associated with hyperandrogenism. © 2013 by The Endocrine Society.

Sylvestre E.-L.,Laval University | Robert C.,Laval University | Pennetier S.,Laval University | Labrecque R.,Laval University | And 4 more authors.
Molecular Human Reproduction | Year: 2013

Cross-phylum and cross-species comparative transcriptomic analyses provide an evolutionary perspective on how specific tissues use genomic information. A significant mRNA subset present in the oocytes of most vertebrates is stabilized or stored for post- LH surge use. Since transcription is arrested in the oocyte before ovulation, this RNA is important for completing maturation and sustaining embryo development until zygotic genome activation. We compared the human oocyte transcriptome with an oocyte-enriched subset of mouse, bovine and frog (Xenopus laevis) genes in order to evaluate similarities between species. Graded temperature stringency hybridization on a multi-species oocyte cDNA array was used to measure the similarity of preferentially expressed sequences to the human oocyte library. Identity analysis of 679 human orthologs compared with each identified official gene symbol found in the subtractive (somatic-oocyte) libraries comprising our array revealed that bovine/human similarity was greater than mouse/human or frog/human similarity. However, based on protein sequence, mouse/human similarity was greater than bovine/human similarity. Among the genes over-expressed in oocytes relative to somatic tissue in Xenopus, Mus and Bos, a high level of conservation was found relative to humans, especially for genes involved in early embryonic development. © The Author 2013.

Wang Q.,University of Ottawa | Wang Q.,Ottawa Hospital Research Institute | Kim J.Y.,University of Ottawa | Kim J.Y.,Ottawa Hospital Research Institute | And 9 more authors.
Endocrinology | Year: 2012

Polycystic ovarian syndrome (PCOS) is a heterogeneous syndrome associated with follicle growth arrest, minimal granulosa cell proliferation, dysregulated sex hormone profile, hyperthecosis, and insulin resistance. Using a 5α-dihydrotestosterone (DHT)-induced rat model that recapitulates the reproductive and metabolic phenotypes of human PCOS, we have examined the steroidogenic capability of granulosa cells from DHT-treated rats. Gene expression of several key steroidogenic enzymes including p450 side-chain cleavage enzyme (p450scc), aromatase, steroidogenic acute regulatory protein, hydroxysteroid dehydrogenase-17β, and hydroxysteroid dehydrogenase-3β were markedly lower in DHT-treated rats than the controls, although the responsiveness of their granulosa cells to FSH was higher. Expression of the adipokine chemerin and its receptor, chemokine receptor-like 1, was evident in control and DHT-treated rats, with significantly higher ovarian mRNA abundances and protein contents of chemerin and its receptor. Recombinant chemerin decreases basal estradiol secretion in granulosa cells from DHT-treated rats. When the inhibitory role of chemerin on steroidogenesis was further examined in vitro, chemerin suppressed FSH-induced progesterone and estradiol secretion in cultured preantral follicles and granulosa cells. Chemerin also inhibits FSH-induced aromatase and p450scc expression in granulosa cells. Overexpression of nuclear receptors NR5a1 and NR5a2 promotes p450scc and aromatase expression, respectively, which is suppressed by chemerin. These findings suggest that chemerin is a novel negative regulator of FSH-induced follicular steroidogenesis and may contribute to the pathogenesis of PCOS. Copyright © 2012 by The Endocrine Society.

Wen S.W.,University of Ottawa | Wen S.W.,Ottawa Hospital Research Institute | Leader A.,Ottawa Fertility Center | White R.R.,University of Ottawa | And 8 more authors.
European Journal of Obstetrics Gynecology and Reproductive Biology | Year: 2010

Objective: To assess the association between in vitro fertilization (IVF) with or without intracytoplasmic sperm injection (ICSI) and adverse birth outcomes. Study design: Retrospective cohort study involved IVF/ICSI patients who were treated in the Ottawa Fertility Centre from 1996 to 2005 with a viable pregnancy (>20 weeks of gestation) and mothers who conceived naturally. Results: Eleven of the 1044 infants conceived with IVF/ICSI (1.1%) and 7 of the 1910 naturally conceived infants (0.4%) had congenital heart defects (P < 0.01). Five of the 138 infants (3.6%) born to mothers with a body mass index > 30 and conceived by IVF/ICSI had congenital heart defects, compared with none in the 240 infants born to mothers with a body mass index > 30 and conceived naturally (P < 0.01). Conclusion: Infants conceived with use of IVF/ICSI have three times as high a risk of a congenital heart defect as naturally conceived infants. © 2010 Elsevier Ireland Ltd. All rights reserved.

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