Ovarian aging in squirrel monkeys (Saimiri sciureus)

In female squirrel monkeys (Saimiri sciureus), the reproductive period normally extends from ∼2.5 years to the mid-teens. In the present study, we examined the age-associated cytological changes in the ovaries of 24 squirrel monkeys ranging in age from newborn to ∼20 years. We found a significant, age-related decline in the number of primordial follicles, with the most pronounced loss occurring between birth and 5 years. After ∼8 years of age, relatively few primordial follicles were evident in the ovarian sections examined. An unusual feature of the aging squirrel monkey ovary is the emergence of highly differentiated, encapsulated clusters of granulosa cells that increase in size and number, particularly after the age of 8 years. Many of these cells express anti-Müllerian hormone, and, histologically, the clusters resemble granulosa cell tumors in humans. However, granulosa cell clusters (GCCs) are present in both ovaries of all older squirrel monkeys, and they display no obvious signs of malignancy, suggesting that they are a normal feature of ovarian aging in this species. Our findings indicate that reproductive senescence in female squirrel monkeys, as in other primates, involves the inexorable depletion of ovarian follicles. In addition, the consistent appearance of abundant, well-differentiated clusters of granulosa cells in older squirrel monkeys, prior to the cessation of reproduction, suggests that these structures may influence the later stages of reproductive potential in this species. Analysis of GCCs in older squirrel monkeys also could yield insights into the pathophysiology of granulosa cell tumors in humans.

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Sirtuin 1 and Sirtuin 3 in Granulosa Cell Tumors

International Journal of Molecular Sciences ◽

10.3390/ijms22042047 ◽

2021 ◽

Vol 22 (4) ◽

pp. 2047

Author(s):

Nina Schmid ◽

Kim-Gwendolyn Dietrich ◽

Ignasi Forne ◽

Alexander Burges ◽

Magdalena Szymanska ◽

...

Keyword(s):

Cell Proliferation ◽

Granulosa Cell ◽

Granulosa Cells ◽

Drug Targets ◽

Growth Regulation ◽

Sirtuin 1 ◽

Ki 67 ◽

Granulosa Cell Tumors ◽

Novel Drug

Sirtuins (SIRTs) are NAD+-dependent deacetylases that regulate proliferation and cell death. In the human ovary, granulosa cells express sirtuin 1 (SIRT1), which has also been detected in human tumors derived from granulosa cells, i.e., granulosa cell tumors (GCTs), and in KGN cells. KGN cells are an established cellular model for the majority of GCTs and were used to explore the role of SIRT1. The SIRT1 activator SRT2104 increased cell proliferation. By contrast, the inhibitor EX527 reduced cell numbers, without inducing apoptosis. These results were supported by the outcome of siRNA-mediated silencing studies. A tissue microarray containing 92 GCTs revealed nuclear and/or cytoplasmic SIRT1 staining in the majority of the samples, and also, SIRT2-7 were detected in most samples. The expression of SIRT1–7 was not correlated with the survival of the patients; however, SIRT3 and SIRT7 expression was significantly correlated with the proliferation marker Ki-67, implying roles in tumor cell proliferation. SIRT3 was identified by a proteomic analysis as the most abundant SIRT in KGN. The results of the siRNA-silencing experiments indicate involvement of SIRT3 in proliferation. Thus, several SIRTs are expressed by GCTs, and SIRT1 and SIRT3 are involved in the growth regulation of KGN. If transferable to GCTs, these SIRTs may represent novel drug targets.

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GATA-4 Regulates Bcl-2 Expression in Ovarian Granulosa Cell Tumors

Endocrinology ◽

10.1210/en.2008-0148 ◽

2008 ◽

Vol 149 (11) ◽

pp. 5635-5642 ◽

Cited By ~ 43

Author(s):

Antti Kyrönlahti ◽

Maarit Rämö ◽

Maija Tamminen ◽

Leila Unkila-Kallio ◽

Ralf Butzow ◽

...

Keyword(s):

Cell Fate ◽

Granulosa Cell ◽

Granulosa Cells ◽

Dominant Negative ◽

Rt Pcr ◽

Cyclin D2 ◽

Granulosa Cell Tumors ◽

Ovarian Granulosa Cell ◽

Cell Cycle Regulator Cyclin

Excessive cell proliferation and decreased apoptosis have been implicated in the pathogenesis of ovarian granulosa cell tumors (GCTs). We hypothesized that transcription factor GATA-4 controls expression of the antiapoptotic factor Bcl-2 and the cell cycle regulator cyclin D2 in normal and neoplastic granulosa cells. To test this hypothesis, a tissue microarray based on 80 GCTs was subjected to immunohistochemistry for GATA-4, Bcl-2, and cyclin D2, and the data were correlated to clinical and histopathological parameters. In addition, quantitative RT-PCR for GATA-4, Bcl-2, and cyclin D2 was performed on 21 human GCTs. A mouse GCT model was used to complement these studies. The role of GATA-4 in the regulation of Bcl2 and ccdn2 (coding for cyclin D2) was studied by transactivation assays, and by disrupting GATA-4 function with dominant negative approaches in mouse and human GCT cell lines. We found that GATA-4 expression correlated with Bcl-2 and cyclin D2 expression in human and murine GCTs. Moreover, GATA-4 enhanced Bcl-2 and cyclin D2 promoter activity in murine GCT cells. Whereas GATA-4 overexpression up-regulated and dominant negative GATA-4 suppressed Bcl-2 expression in human GCT cells, the effects on cyclin D2 were negligible. Our results reveal a previously unknown relationship between GATA-4 and Bcl-2 in mammalian granulosa cells and GCTs, and suggest that GATA-4 influences granulosa cell fate by transactivating Bcl-2.

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The m6A mRNA demethylase FTO in granulosa cells retards FOS-dependent ovarian aging

Cell Death and Disease ◽

10.1038/s41419-021-04016-9 ◽

2021 ◽

Vol 12 (8) ◽

Author(s):

Zhong-xin Jiang ◽

Yi-ning Wang ◽

Zi-yuan Li ◽

Zhi-hui Dai ◽

Yi He ◽

...

Keyword(s):

Granulosa Cells ◽

Therapeutic Target ◽

Rna Sequence ◽

Ovarian Aging ◽

Age Related ◽

Fos Expression

AbstractMultifunctional N6-methyladenosine (m6A) has been revealed to be an important epigenetic component in various physiological and pathological processes, but its role in female ovarian aging remains unclear. Thus, we demonstrated m6A demethylase FTO downregulation and the ensuing increased m6A in granulosa cells (GCs) of human aged ovaries, while FTO-knockdown GCs showed faster aging-related phenotypes mediated. Using the m6A-RNA-sequence technique (m6A-seq), increased m6A was found in the FOS-mRNA-3′UTR, which is suggested to be an erasing target of FTO that slows the degradation of FOS-mRNA to upregulate FOS expression in GCs, eventually resulting in GC-mediated ovarian aging. FTO acts as a senescence-retarding protein via m6A, and FOS knockdown significantly alleviates the aging of FTO-knockdown GCs. Altogether, the abovementioned results indicate that FTO in GCs retards FOS-dependent ovarian aging, which is a potential diagnostic and therapeutic target against ovarian aging and age-related reproductive diseases.

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Minireview: Physiological and Pathological Actions of RAS in the Ovary

Molecular Endocrinology ◽

10.1210/me.2009-0251 ◽

2010 ◽

Vol 24 (2) ◽

pp. 286-298 ◽

Cited By ~ 29

Author(s):

Heng-Yu Fan ◽

JoAnne S. Richards

Keyword(s):

Granulosa Cell ◽

Granulosa Cells ◽

Ras Genes ◽

Granulosa Cell Tumors ◽

Ovarian Surface ◽

Ovarian Cells ◽

Conditional Expression ◽

Wide Range ◽

Ovarian Surface Epithelial ◽

Complete Disruption

Abstract The small G proteins of the RAS superfamily act as molecular switches in the transduction of cellular signals critical for a wide range of normal developmental events as well as pathological processes. However, the functions of Ras genes in ovarian cells have only started to be unveiled. RAS, most likely KRAS that is highly expressed in granulosa cells of growing follicles, appears crucial for mediating the gonadotropin-induced events associated with the unique physiological process of ovulation. By contrast, conditional expression of a constitutively active KrasG12D mutant in granulosa cells results in ovulation defects due to the complete disruption of normal follicular growth, cessation of granulosa cell proliferation, and blockage of granulosa cell apoptosis and differentiation. When the tumor suppressor Pten is disrupted conditionally in the KrasG12D-expressing granulosa cells, granulosa cell tumors fail to develop. However, ovarian surface epithelial cells expressing the same Pten;KrasG12D mutations rapidly become ovarian surface epithelial serous cystadenocarcinomas. In this minireview, we summarize some of the physiological as well as pathological functions of RAS in the rodent ovary, discuss the implications of the KrasG12D mutant mouse models for understanding human diseases such as premature ovarian failure and ovarian cancers, and highlight new questions raised by the results of recent studies.

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VOCAL DEVELOPMENT IN SQUIRREL MONKEYS

Behaviour ◽

10.1163/156853901753287190 ◽

2001 ◽

Vol 138 (9) ◽

pp. 1179-1204 ◽

Cited By ~ 56

Author(s):

Kurt Hammerschmidt ◽

Uwe Jürgens ◽

Tamara Freudenstein

Keyword(s):

Acoustic Analysis ◽

Acoustic Parameter ◽

Squirrel Monkeys ◽

High Variability ◽

Saimiri Sciureus ◽

Vocal Development ◽

Ontogenetic Changes ◽

Age Related ◽

Species Specific ◽

Over Time

AbstractSix squirrel monkeys (Saimiri sciureus) were studied for their vocal development over the first 20 months of life, using a multi-parametric acoustic analysis. Four of the animals were normally raised, one animal ('Kaspar Hauser') was deprived of adult species-specific calls, one animal was congenitally deaf. The study showed that in all 12 call types under investigation, age-related changes in one or the other acoustic parameter occurred. The degree to which vocal structures changed, was call type-specific, with some calls showing dramatic changes and others showing only minor changes. Most changes occurred within the first four months; some lasted up to 10 months. All call types showed a high variability throughout the 20 months study period. Only five of the 12 call types showed a reduction in variability over time. Both acoustically deprived animals remained within the variability range of the normally raised animals, suggesting that the ontogenetic changes found were mainly maturational.

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Expression Status and Mutational Analysis of the PTEN and P13K Subunit Genes in Ovarian Granulosa Cell Tumors

International Journal of Gynecological Cancer ◽

10.1111/igc.0b013e3181a1cdfd ◽

2009 ◽

Vol 19 (3) ◽

pp. 339-342 ◽

Cited By ~ 15

Author(s):

Sophie Bittinger ◽

Maria Alexiadis ◽

Peter J. Fuller

Keyword(s):

Sequence Analysis ◽

Granulosa Cell ◽

Granulosa Cells ◽

Mutational Analysis ◽

Regulatory Subunit ◽

Missense Mutations ◽

Altered Expression ◽

Granulosa Cell Tumors ◽

Ovarian Granulosa Cell ◽

Pathway Activation

Granulosa cell tumors (GCT) are a unique subset of ovarian tumors which have a molecular phenotype resembling that of follicle stimulating hormone (FSH)-stimulated pre-ovulatory granulosa cells. FSH acts via its receptor to stimulate signaling pathways including the phosphatidylinositol 3-kinase (PI3K)-AKT pathway. Activation of this pathway occurs in solid tumors, including ovarian epithelial tumors, through mutation of the PI3K subunit genes or inactivation of the tumor suppressor, PTEN. Activation of this pathway would be predicted to be tumorigenic in granulosa cells.Expression of the 2 PI3K subunit genes, PIK3CA, which encodes the catalytic subunit, and PIK3R1, which encodes the regulatory subunit, together with the PTEN gene was determined in a panel of GCT, 2 human GCT-derived cell lines, COV434 and KGN, and normal ovary. Direct sequence analysis was used to screen for mutations. Expression of all 3genes was observed in the GCT without evidence of overexpression for the PI3K subunit genes or loss of expression for PTEN. Sequence analysis of amplicons spanning exons 9and 20, in which greater than 75% of mutations occur in the PIK3CA gene did not identify any missense mutations. Similarly, the previously reported deletions in exons 12 and 13 of the PIK3R1 were not found in the GCT. Three amplicons spanning the entire coding sequence of the PTEN gene were sequenced; neither deletions nor mutations were identified.These findings suggest that activation of PI3K signaling through PI3K/PTEN mutation or altered expression, in contrast to many other types of solid tumor, is not associated with GCT.

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Lack of effect of short-term DHEA supplementation on the perimenopausal ovary†

Biology of Reproduction ◽

10.1093/biolre/ioaa160 ◽

2020 ◽

Vol 103 (6) ◽

pp. 1209-1216

Author(s):

Selva L Luna ◽

Donald I Brown ◽

Steven G Kohama ◽

Henryk F Urbanski

Keyword(s):

Ovarian Function ◽

Rhesus Macaques ◽

Reproductive Potential ◽

Oocyte Quality ◽

Short Term ◽

Primordial Follicles ◽

Start Date ◽

Age Related ◽

The Mean ◽

The Impact

Abstract Dehydroepiandrosterone (DHEA) hormonal supplementation can improve oocyte quality in women with diminished ovarian function. However, it is unclear whether DHEA supplementation can also enhance ovarian function during the perimenopause (i.e., when the number of follicles in the ovary has undergone a marked reduction). To address this question, we examined the impact of 2.5-months of daily 5-mg oral DHEA supplementation on the number of ovarian follicles and the concentration of anti-Müllerian hormone (AMH) in perimenopausal rhesus macaques. Like women, these long-lived nonhuman primates have ~ 28-day menstrual cycles and eventually undergo menopause. They also show similar age-related neuroendocrine changes, including a marked decrease in circulating concentrations of DHEA and DHEA sulfate (DHEAS). Our experimental design involved the following three groups of animals (N = 6 per group): Young adult (mean age = 11.6 years), Old control (mean age = 23.1 years), and Old DHEA-treated (mean age = 23.5 years). Histological examination of the ovaries revealed a significant age-related decrease in the mean number of primordial follicles despite DHEA supplementation. Moreover, AMH concentrations within the ovaries and circulation, assessed by Western analysis and ELISA, respectively, showed significant age-related decreases that were not attenuated by DHEA supplementation. Taken together, these results fail to show a clear effect of short-term physiological DHEA supplementation on the perimenopausal ovary. However, they do not exclude the possibility that alternative DHEA supplementation paradigms (e.g., involving an earlier start date, longer duration and using pharmacological doses) may extend reproductive potential during aging.

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Insulin-like growth factor, insulin-like growth factor–binding protein-4, and pregnancy-associated plasma protein-A gene expression in human granulosa cell tumors

International Journal of Gynecological Cancer ◽

10.1111/j.1525-1438.2006.00724.x ◽

2006 ◽

Vol 16 (6) ◽

pp. 1973-1979 ◽

Cited By ~ 11

Author(s):

M. Alexiadis ◽

P. Mamers ◽

S. Chu ◽

P. J. Fuller

Keyword(s):

Gene Expression ◽

Growth Factor ◽

Granulosa Cell ◽

Plasma Protein ◽

Granulosa Cells ◽

Protein A ◽

Insulin Like Growth Factor ◽

Granulosa Cell Tumors ◽

Igf System ◽

Igf I

The insulin-like growth factor (IGF) system plays an important role in folliculogenesis. It is also thought to contribute to the pathogenesis of many cancers, including those of the ovarian epithelium. In the human follicle, the predominant IGF is IGF-II and its actions are modulated by insulin-like growth factor–binding protein-4 (IGFBP-4), the IGFBP-4 protease, and the pregnancy-associated plasma protein-A (PAPP-A). These peptide components are synthesized by the granulosa cells of the developing follicle. The aim of this study was to characterize the expression of these components of the IGF system in granulosa cell tumors (GCT) of the ovary. IGF-I, IGF-II, IGFBP-4, and PAPP-A gene expression was determined in a panel of GCT and compared to the levels in normal ovary and in epithelial ovarian tumors. Although both the IGF-I and IGF-II genes were expressed in the GCT, the levels were lower than in the other tissue groups. IGFBP-4 expression was also low in the GCT, whereas PAPP-A gene expression was highest in the GCT. These findings were unexpected given the prominent role this signaling system plays in normal granulosa cells. In conclusion, these observations suggest that the IGF system may have a limited role in the pathogenesis of GCT with PAPP-A subserving a function other than IGFBP-4 proteolysis.

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