Expression and Localization of Secreted Frizzled-Related Protein-4 in the Rodent Ovary: Evidence for Selective Up-Regulation in Luteinized Granulosa Cells

Secreted frizzled-related protein-4 (sFRP-4) belongs to a family of soluble proteins that have a Frizzled-like cysteine-rich domain and function as modulators of Wnt-Frizzled (Fz) signals. As several Wnts and Fz are expressed at defined stages of follicular development in rodent ovaries, these studies were undertaken to evaluate the hormone-regulated expression and localization of sFRP-4. In the mouse ovary, the expression of sFRP-4 mRNA was up-regulated in granulosa cells of large antral follicles after human chorionic gonadotropin administration and was also elevated in corpora lutea, as determined by RT-PCR and in situ hybridization analyses. In hypophysectomized rat ovaries, sFRP-4 expression was similarly induced by human chorionic gonadotropin and further up-regulated by PRL. PRL also stimulated the secretion of sFRP-4 protein from luteinized rat granulosa cells in culture. Therefore, regulation of sFRP-4 by LH and PRL may be important for modulating Fz-1, which is known to be expressed in periovulatory follicles, and Wnt-4/Fz-4, which are expressed in corpora lutea.

Download Full-text

Relationship between FoxO1 protein levels and follicular development, atresia, and luteinization in the rat ovary

Journal of Endocrinology ◽

10.1677/joe.0.1790195 ◽

2003 ◽

Vol 179 (2) ◽

pp. 195-203 ◽

Cited By ~ 35

Author(s):

F Shi ◽

PS LaPolt

Keyword(s):

Chorionic Gonadotropin ◽

Granulosa Cells ◽

Cell Cycle Progression ◽

Follicular Development ◽

Immunohistochemical Analysis ◽

Female Rats ◽

Corpora Lutea ◽

Protein Levels ◽

Physiological Processes ◽

Preovulatory Follicles

FoxO1 is a transcription factor implicated in a growing number of physiological processes, including apoptosis, cell cycle progression, and insulin signaling. Recent findings indicate that FSH and growth factors influence ovarian functions in part through regulation of FoxO1. The present study utilized immunohistochemical analysis to determine the ovarian localization and regulation of FoxO1 protein levels in neonatal rats, immature rats during gonadotropin-induced follicular development, ovulation, and luteinization, and in spontaneously developing ovarian cysts of aging rats. In postnatal rats, FoxO1 immunoreactivity was very faint in ovaries of 5- and 10-day-old females. In contrast, strong immunoreactivity was observed in granulosa cells of larger developing follicles at 25 days of age. To stimulate follicle development, immature female rats received equine chorionic gonadotropin (eCG) followed 52 h later by an ovulatory dose of human chorionic gonadotropin (hCG). Prior to gonadotropin treatment, moderate FoxO1 immunoreactivity was observed in granulosa cells of small follicles. Subsequently, treatment with eCG markedly decreased FoxO1 protein levels in granulosa cells of healthy antral and preovulatory follicles. Interestingly, FoxO1 staining was observed in cumulus and antral, but not mural granulosa cells of preovulatory follicles. Induction of ovulation and luteinization with hCG further decreased ovarian FoxO1 levels, with no staining evident in corpora lutea. At all time points, the most intensive FoxO1 staining was observed in granulosa cells of atretic follicles, with predominantly nuclear localization. Similarly, while FoxO1 levels were low in granulosa cells of preovulatory follicles in proestrous rats, FoxO1 staining was intense in granulosa cells of spontaneously developing cystic follicles in aged, acyclic females. Together, these findings indicate that FoxO1 is expressed in a regulated, cell-specific manner during ovarian follicular development, atresia and luteinization, suggesting roles in these physiological processes.

Download Full-text

Molecular characterization of tumor necrosis α-induced protein 6 and its human chorionic gonadotropin-dependent induction in theca and mural granulosa cells of equine preovulatory follicles

Reproduction ◽

10.1530/rep.1.01200 ◽

2007 ◽

Vol 133 (1) ◽

pp. 135-145 ◽

Cited By ~ 12

Author(s):

Khampoune Sayasith ◽

Monique Doré ◽

Jean Sirois

Keyword(s):

Chorionic Gonadotropin ◽

Granulosa Cells ◽

Human Chorionic Gonadotropin ◽

Tumor Necrosis ◽

Stop Codon ◽

Cell Types ◽

Corpora Lutea ◽

Control Of Gene Expression ◽

Reading Frame ◽

Factor Α

The preovulatory rise in gonadotropins causes an expansion of the cumulus–oocyte complex, a process requiring the induction of several genes. The objectives of this study were to clone the equine tumor necrosis factor α-induced protein 6 (TNFAIP6), and investigate its regulation in equine follicles during human chorionic gonadotropin (hCG)-induced ovulation. The isolation of the equine TNFAIP6 cDNA revealed that it contains an open reading frame of 834 bp (including the stop codon), encoding a predicted 277 amino acid protein that is highly similar (91–93% identity) to known mammalian homologs. The regulation of TNFAIP6 mRNA was studied in equine follicles isolated during estrus between 0 and 39 h post-hCG and in corpora lutea (CL) obtained on day 8 of the estrous cycle. Results from semi-quantitative RT-PCR/Southern blot showed that levels of TNFAIP6 mRNA were low in follicles obtained at 0 h, increased at 12 h, returned to basal levels at 24 h, and increased again at 36 h post-hCG (P<0.05). Levels of TNFAIP6 transcripts were relatively moderate in CL, but low in non-ovarian tissues tested. Analyses performed with isolated preparations of theca and granulosa cells indicated that TNFAIP6 mRNA was regulated in both layers, with a maximal induction obtained 33–36 h post-hCG (P<0.05). Immunohistochemical staining of sections of equine follicles isolated at 0 and 33 h post-hCG confirmed the induction of TNFAIP6 protein in both cell types after hCG treatment. Thus, the present study describes for the first time the gonadotropin-dependent regulation of follicular TNFAIP6 during the ovulation in a monoovulatory species. The biphasic induction of TNFAIP6 in equine theca and granulosa cells differs from the pattern observed in rodents, suggesting a distinct control of gene expression in this monoovulatory species.

Download Full-text

Localization of the mRNA for the Angiotensin II Receptor Subtype 2 (AT2) in Follicular Granulosa Cells of the Rat Ovary by Nonradioactive In Situ Hybridization

Journal of Histochemistry & Cytochemistry ◽

10.1177/002215549804600801 ◽

1998 ◽

Vol 46 (8) ◽

pp. 865-870 ◽

Cited By ~ 9

Author(s):

Nicholas Obermüller ◽

Dirk Schlamp ◽

Sigrid Hoffmann ◽

Monika Gentili ◽

Tadashi Inagami ◽

...

Keyword(s):

Angiotensin Ii ◽

Mrna Expression ◽

Granulosa Cells ◽

Follicular Development ◽

Renin Angiotensin System ◽

Receptor Subtype ◽

Corpora Lutea ◽

At2 Receptor ◽

Angiotensin Ii Receptor

SUMMARY The ovary is one of the organs in which an intrinsic renin-angiotensin system (RAS) has been described. Among angiotensin II receptors, the angiotensin II receptor sub-type 2 (AT2) is believed to play an important role in mediating or modulating a variety of intraovarian processes. Previous studies were mainly based on ligand binding techniques using AT2 receptor-specific antagonists. Despite the recent cloning of the AT2 gene, no information is available about the exact intraovarian distribution of AT2 mRNA expression. Therefore, we analyzed ovaries from sexually mature, untreated rats by nonradioactive in situ hybridzation using an AT2-specific anti-sense RNA probe. Experiments were performed on perfusion-fixed ovaries obtained from different stages of the estrous cycle. As an important finding, strong AT2 mRNA expression could be demonstrated exclusively in follicular granulosa cells. Follicles containing AT2 mRNA-positve granulosa cells were mainly in the advanced tertiary stage of follicular development, already exhibiting features of atresia. In addition, individual collapsed, definitive atretic follicles also showed strong AT2 mRNA expression solely in granulosa cells. In corpora lutea and in other structures of the ovary, no message for the AT2 receptor could be detected under these conditions. These data may contribute to a better understanding of the effects exerted by an intraovarian RAS.

Download Full-text

Connective Tissue Growth Factor Expression in the Human Corpus Luteum: Paracrine Regulation by Human Chorionic Gonadotropin

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jc.2005-0014 ◽

2005 ◽

Vol 90 (9) ◽

pp. 5366-5376 ◽

Cited By ~ 32

Author(s):

W. Colin Duncan ◽

Stephen G. Hillier ◽

Eva Gay ◽

Julie Bell ◽

Hamish M. Fraser

Keyword(s):

Growth Factor ◽

Connective Tissue ◽

Chorionic Gonadotropin ◽

Granulosa Cells ◽

Human Chorionic Gonadotropin ◽

Luteal Phase ◽

Primary Cultures ◽

Tissue Growth ◽

Corpora Lutea

Abstract Context: The molecular mechanisms of luteolysis and its inhibition during maternal recognition of pregnancy remain unclear. Objective: The objective of this study was to investigate the differential regulation of connective tissue growth factor (CTGF) expression in human corpora lutea using in vivo and in vitro models. Design: Corpora lutea from different stages of the luteal phase and after luteal rescue with human chorionic gonadotropin (hCG) were studied. Primary cultures and cocultures of luteinized granulosa cells and luteal fibroblast-like cells were performed. Setting: This study was performed at the research center of a university teaching hospital. Patients: Women with regular cycles having hysterectomy for nonmalignant conditions and women undergoing oocyte collection for assisted conception were studied. Interventions: CTGF localization was determined by in situ hybridization, and expression by quantitative RT-PCR. Outcomes: The outcome measures were the effect of hCG on the expression and localization of CTGF mRNA in human corpora lutea and the effect of hCG on CTGF expression in primary cultures of luteinized granulosa cells and luteal fibroblast-like cells. Results: Luteal rescue reduced CTGF expression compared with that in the late luteal phase (P < 0.05). CTGF expression was localized to fibroblast-like cells and endothelial cells of larger blood vessels, not to steroidogenic cells. The expression of CTGF by fibroblast-like cells in vitro was not regulated by hCG. When cocultured with luteinized granulosa cells, fibroblast-like cell CTGF expression was inhibited by hCG (P < 0.001). This effect was independent of stimulated progesterone concentrations and was not blocked by follistatin or indomethacin. Both IL-1α (P < 0.05) and cAMP (P < 0.001) inhibited CTGF expression in fibroblast-like cells. Conclusions: These results provide evidence for negative regulation of CTGF by hCG during luteal rescue mediated by paracrine signals.

Download Full-text

Insulin and Human Chorionic Gonadotropin Cause a Shift in the Balance of Sterol Regulatory Element-Binding Protein (SREBP) Isoforms Toward the SREBP-1c Isoform in Cultures of Human Granulosa Cells

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jc.2004-2057 ◽

2005 ◽

Vol 90 (6) ◽

pp. 3738-3746 ◽

Cited By ~ 15

Author(s):

Malcolm C. Richardson ◽

Iain T. Cameron ◽

Chantal D. Simonis ◽

Madhab C. Das ◽

Tessa E. Hodge ◽

...

Keyword(s):

Fatty Acid ◽

Chorionic Gonadotropin ◽

Granulosa Cells ◽

Human Chorionic Gonadotropin ◽

Binding Protein ◽

Regulatory Element ◽

Human Granulosa Cells ◽

Igf Binding ◽

Sterol Regulatory Element ◽

Igf Binding Protein

The isoforms of sterol regulatory element-binding proteins (SREBP) (1a, 1c, and 2) are key transcriptional regulators of lipid biosynthesis. We examined their regulation by gonadotropin and insulin in human granulosa cells. After removal of leukocytes, granulosa cells were exposed to hormonal additions for 16 h starting on d 2 of culture. Progesterone, lactate, and IGF binding protein-1 were measured in culture medium and cellular mRNA measured by competitive RT-PCR. Addition of human chorionic gonadotropin (hCG) (100 ng/ml) stimulated progesterone production (7.0-fold, P < 0.001 vs. control), whereas lactate was increased by hCG (1.6-fold, P < 0.001) and insulin (1.4-fold, P < 0.001; 1000 ng/ml). Insulin decreased IGF binding protein-1 production by 85% (P < 0.001). There were no significant effects on the expression of SREBP-1a but significant increases in mRNA for SREBP-1c with insulin (6.3-fold), hCG (10.4-fold) and in combination (15.2-fold; P < 0.01 for all comparisons). No consistent effects on SREBP-2 were observed. The expression of mRNA for fatty acid synthase, a target gene for SREBP-1c, was increased by hCG (24-fold, P = 0.006) and insulin (19-fold, P = 0.024), which also increased the level of cellular, total fatty acid (1.34-fold; P = 0.03). Thus, hCG and insulin cause a switch toward expression of the SREBP-1c isoform with consequent effects on fatty acid synthesis. We suggest that high circulating insulin, associated with clinically defined insulin resistance, may up-regulate SREBP-1c expression in the ovary.

Download Full-text