scholarly journals Altered germline cyst and oocyte differentiation in Tex14 mutant mice reveal a new mechanism underlying female reproductive life-span

2019 ◽  
Author(s):  
Nafisa Nuzhat ◽  
Kanako Ikami ◽  
Haley Abbott ◽  
Heather Tanner ◽  
Allan C. Spradling ◽  
...  
Keyword(s):  
Germ Cells ◽  
Ovarian Function ◽  
Primordial Follicle ◽  
Wild Type ◽  
Developmental Potential ◽  
Primordial Follicles ◽  
Intercellular Bridges ◽  
Reproductive Life ◽  
Reproductive Life Span ◽  
Oocyte Differentiation

AbstractIn adult mammalian females, primordial follicles that form in the fetal/neonatal ovary are the only source to sustain adult ovarian function. Our previous studies revealed that during oocyte differentiation and primordial follicle formation in mouse fetal ovaries, primary oocytes form via gaining cytoplasm and organelles from sister germ cells that are connected to them by intercellular bridges within germline cysts. To better understand the role of intercellular bridges in oocyte differentiation, we analyzed mutant females lacking testis-expressed 14 (Tex14), a gene involved in cytokinesis and bridge formation. In Tex14-/- fetal ovaries, germ cells divide to form a reduced number of cysts in which sister germ cells are still connected via syncytia or fragmented cell membranes, rather than normal intercellular bridges. Compared with wildtype cysts, Tex14-/- cysts fragment at a higher frequency and produce a greatly reduced number of primary oocytes with highly precocious cytoplasmic enrichment and enlarged volume. By contrast, Tex14+/- germline cysts are less fragmented and generate primary oocytes that are smaller than wild type. Interestingly, enlarged Tex14-/- primary oocytes are much more stable than wild type oocytes and more efficiently sustain folliculogenesis, whereas undersized Tex14+/- primary oocytes turn over at an accelerated rate. Our observations directly link the nature of fetal germ cell connectivity to cytoplasmic enrichment during oocyte differentiation and to oocyte developmental potential in the adult ovary. Our results imply that the duration of adult ovarian function is strongly influenced by the number of primary oocytes acquiring highly enriched cytoplasm during oocyte differentiation in fetal ovaries, rather than just by the size of the primordial follicle pool.

scholarly journals Reproductive Longevity and Aging: Geroscience Approaches to Maintain Long-Term Ovarian Fitness

2020 ◽  
Author(s):  
Natalia Llarena ◽  
Christopher Hine
Keyword(s):  
Ovarian Reserve ◽  
Ovarian Function ◽  
Reproductive Function ◽  
Primordial Follicle ◽  
Oocyte Quality ◽  
Nutrient Sensing ◽  
Primordial Follicles ◽  
Age Related ◽  
Reproductive Life ◽  
Reproductive Life Span

Abstract Increases in delayed childbearing worldwide have elicited the need for a better understanding of the biological underpinnings and implications of age-related infertility. In women 35 years and older the incidences of infertility, aneuploidy, and birth defects dramatically increase. These outcomes are a result of age-related declines in both ovarian reserve and oocyte quality. In addition to waning reproductive function, the decline in estrogen secretion at menopause contributes to multisystem aging and the initiation of frailty. Both reproductive and hormonal ovarian function are limited by the primordial follicle pool, which is established in utero and declines irreversibly until menopause. Because ovarian function is dependent on the primordial follicle pool, an understanding of the mechanisms that regulate follicular growth and maintenance of the primordial follicle pool is critical for the development of interventions to prolong the reproductive life span. Multiple pathways related to aging and nutrient-sensing converge in the mammalian ovary to regulate quiescence or activation of primordial follicles. The PI3K/PTEN/AKT/FOXO3 and associated TSC/mTOR pathways are central to the regulation of the primordial follicle pool; however, aging-associated systems such as the insulin-like growth factor-1/growth hormone pathway, and transsulfuration/hydrogen sulfide pathways may also play a role. Additionally, sirtuins aid in maintaining developmental metabolic competence and chromosomal integrity of the oocyte. Here we review the pathways that regulate ovarian reserve and oocyte quality, and discuss geroscience interventions that leverage our understanding of these pathways to promote reproductive longevity.

scholarly journals Follistatin Regulates Germ Cell Nest Breakdown and Primordial Follicle Formation

Endocrinology ◽  
2010 ◽  
Vol 152 (2) ◽  
pp. 697-706 ◽  
Author(s):  
Fuminori Kimura ◽  
Lara M. Bonomi ◽  
Alan L. Schneyer
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Ovarian Function ◽  
Primordial Follicle ◽  
Biochemical Properties ◽  
The Body ◽  
Protein Isoforms ◽  
Primordial Follicles ◽  
Reduced Rate ◽  
Regulatory Functions

Abstract Follistatin (FST) is an antagonist of activin and related TGFβ superfamily members that has important reproductive actions as well as critical regulatory functions in other tissues and systems. FST is produced as three protein isoforms that differ in their biochemical properties and in their localization within the body. We created FST288-only mice that only express the short FST288 isoform and previously reported that females are subfertile, but have an excess of primordial follicles on postnatal day (PND) 8.5 that undergo accelerated demise in adults. We have now examined germ cell nest breakdown and primordial follicle formation in the critical PND 0.5–8.5 period to test the hypothesis that the excess primordial follicles derive from increased proliferation and decreased apoptosis during germ cell nest breakdown. Using double immunofluorescence microscopy we found that there is virtually no germ cell proliferation after birth in wild-type or FST288-only females. However, the entire process of germ cell nest breakdown was extended in time (through at least PND 8.5) and apoptosis was significantly reduced in FST288-only females. In addition, FST288-only females are born with more germ cells within the nests. Thus, the excess primordial follicles in FST288-only mice derive from a greater number of germ cells at birth as well as a reduced rate of apoptosis during nest breakdown. These results also demonstrate that FST is critical for normal regulation of germ cell nest breakdown and that loss of the FST303 and/or FST315 isoforms leads to excess primordial follicles with accelerated demise, resulting in premature cessation of ovarian function.

scholarly journals Altered germline cyst formation and oogenesis in Tex14 mutant mice

Biology Open ◽  
2021 ◽  
Vol 10 (6) ◽  
Author(s):  
Kanako Ikami ◽  
Nafisa Nuzhat ◽  
Haley Abbott ◽  
Ronald Pandoy ◽  
Lauren Haky ◽  
...  
Keyword(s):  
Germ Cells ◽  
Cyst Formation ◽  
Intercellular Bridge ◽  
Wild Type ◽  
Intercellular Bridges ◽  
Mutant Female ◽  
Homozygous Mutant ◽  
Germline Cyst ◽  
Oocyte Differentiation

ABSTRACT During oocyte differentiation in mouse fetal ovaries, sister germ cells are connected by intercellular bridges, forming germline cysts. Within the cyst, primary oocytes form via gaining cytoplasm and organelles from sister germ cells through germ cell connectivity. To uncover the role of intercellular bridges in oocyte differentiation, we analyzed mutant female mice lacking testis-expressed 14 (TEX14), a protein involved in intercellular bridge formation and stabilization. In Tex14 homozygous mutant fetal ovaries, germ cells divide to form a reduced number of cysts in which germ cells remained connected via syncytia or fragmented cell membranes, rather than normal intercellular bridges. Compared with wild-type cysts, homozygous mutant cysts fragmented at a higher frequency and produced a greatly reduced number of primary oocytes with precocious cytoplasmic enrichment and enlarged volume. By contrast, Tex14 heterozygous mutant germline cysts were less fragmented and generate primary oocytes at a reduced size. Moreover, enlarged primary oocytes in homozygous mutants were used more efficiently to sustain folliculogenesis than undersized heterozygous mutant primary oocytes. Our observations directly link the nature of fetal germline cysts to oocyte differentiation and development.

scholarly journals miR-378-3p maintains the size of mouse primordial follicle pool by regulating cell autophagy and apoptosis

2020 ◽  
Vol 11 (9) ◽  
Author(s):  
Xiaowen Sun ◽  
Francesca Gioia Klinger ◽  
Jing Liu ◽  
Massimo De Felici ◽  
Wei Shen ◽  
...  
Keyword(s):  
Post Partum ◽  
Expression System ◽  
Primordial Follicle ◽  
Underlying Mechanism ◽  
Newborn Mice ◽  
Primordial Follicles ◽  
Reproductive Life ◽  
Reproductive Life Span

Abstract Primordial follicle pool provides all available oocytes throughout the whole reproductive life span. Abnormal regulation in primordial follicle assembly leads to abnormal size of primordial follicle pool, even causes infertility. Here, miR-378-3p was proved to regulate mouse primordial follicle assembly both in vivo and in vitro. The expression of miR-378-3p significantly increased in mice ovaries from 17.5 dpc (days post coitum) up to 3 dpp (day post partum) compared with the expression of 16.5 dpc ovaries, which suggested that miR-378-3p was involved in primordial follicle assembly. To uncover the underlying mechanism, newborn mice ovaries were cultured in vitro in the presence of rapamycin and 3-methyladenine, which showed that the expression of miR-378-3p changed together with the percentage of primordial follicle. Moreover, during the normal process of primordial follicle assembly between 17.6 dpc and 3 dpp, autophagy is activated, while, apoptosis is inhibited. The in vivo results showed that newborn mice starved for 1.5 days showing the increased miR-378-3p, activated autophagy and inhibited apoptosis in the ovaries, had more percentage of primordial follicles. Over-expression of miR-378-3p using miR-378-3p agomir caused increased percentage of primordial follicle, increased level of autophagy, and decreased level of apoptosis. Knockdown of miR-378-3p by miR-378-3p antiagomir had the opposite results. Using pmirGLO Dual-Luciferase miRNA Target Expression system, we confirmed both PDK1 and Caspase9 were targets of miR-378-3p, which suggested that miR-378-3p activated autophagy by targeting PDK1 and inhibited apoptosis by targeting Caspase9. MiR-378-3p could be used as a biomarker of diseases caused by abnormal size of primordial follicle pool for diagnosis, prevention, or therapy.

scholarly journals Gap junctions are essential for murine primordial follicle assembly immediately before birth

Reproduction ◽  
2016 ◽  
Vol 151 (2) ◽  
pp. 105-115 ◽  
Author(s):  
Zhen Teng ◽  
Chao Wang ◽  
Yijing Wang ◽  
Kun Huang ◽  
Xi Xiang ◽  
...  
Keyword(s):  
Gap Junction ◽  
Granulosa Cells ◽  
Primordial Follicle ◽  
Underlying Mechanism ◽  
Temporal Window ◽  
Primordial Follicles ◽  
Reproductive Ability ◽  
Ovarian Cells ◽  
Gap Junction Communication ◽  
Reproductive Life

The reserve of primordial follicles determines the reproductive ability of the female mammal over its reproductive life. The primordial follicle is composed of two types of cells: oocytes and surrounding pre-granulosa cells. However, the underlying mechanism regulating primordial follicle assembly is largely undefined. In this study, we found that gap junction communication (GJC) established between the ovarian cells in the perinatal mouse ovary may be involved in the process. First, gap junction structures between the oocyte and surrounding pre-granulosa cells appear at about 19.0 dpc (days post coitum). As many as 12 gap junction-related genes are upregulated at birth, implying that a complex communication may exist between ovarian cells, because specifically silencing the genes of individual gap junction proteins, such as Gja1, Gja4 or both, has no influence on primordial follicle assembly. On the other hand, non-specific blockers of GJC, such as carbenoxolone (CBX) and 18α-glycyrrhetinic acid (AGA), significantly inhibit mouse primordial follicle assembly. We proved that the temporal window for establishment of GJC in the fetal ovary is from 19.5 dpc to 1 dpp (days postpartum). In addition, the expression of ovarian somatic cell (OSC)-specific genes, such as Notch2, Foxl2 and Irx3, was negatively affected by GJC blockers, whereas oocyte-related genes, such as Ybx2, Nobox and Sohlh1, were hardly affected, implying that the establishment of GJC during this period may be more important to OSCs than to oocytes. In summary, our results indicated that GJC involves in the mouse primordial follicle assembly process at a specific temporal window that needs Notch signaling cross-talking.

scholarly journals Bridge Integrator 2, a New Specific Target for Improving Reproductive Life Span through RPS6 and NNT

2021 ◽  
Author(s):  
Feng-Yu Zhu ◽  
Li-Li Wang ◽  
Tie-Gang Meng ◽  
Zhi-Xia Yang ◽  
Ruo-Lei Wang ◽  
...  
Keyword(s):  
Free Radical ◽  
Side Effects ◽  
Life Span ◽  
Quantitative Proteomics ◽  
Primordial Follicle ◽  
Oocyte Quality ◽  
Specific Target ◽  
Reproductive Life ◽  
Reproductive Life Span ◽  
Female Ovary

Abstract Female ovary is the earliest degenerated organ and it faces distinct medical disadvantages that impair primordial follicle reserve and oocyte quality. Herein, we found that bridge integrator 2 (Bin2) was predominant within mouse ovaries and oocytes, and global-knockout of Bin2 improved both female fertility and oocyte quality with healthy physiology in mice. Ovarian quantitative proteomics and phosphomics showed that Bin2 knockout specifically decreased only p-RPS6 of mTOR pathway; meanwhile, it increased nicotinamide nucleotide transhydrogenase (NNT), the free-radical detoxifier, over 6-fold. Mechanically, phosphorylation at Thr423 & Ser424 translocated membrane Bin2 into cytoplasm to phosphorylate RPS6, while p-RPS6 bound 42-95 bp NNT UTR to inhibit NNT translation. We then synthesized a peptide (BPP) to mimic Bin2 inhibition, and found that 3-week BPP injection improved primordial follicle reserve and oocyte quality in aging or chemotherapeutics-treated mice. In all, Bin2 inhibition improve both primordial follicle reserve and oocyte quality without discernible side effects.

scholarly journals 207 OOCYTE SURVIVAL AND FOLLICULAR DEVELOPMENT IN Fas-KNOCKOUT AND KIT-DEFICIENT DOUBLE MUTANT MICE

2005 ◽  
Vol 17 (2) ◽  
pp. 254
Author(s):  
M. Moniruzzaman ◽  
K.O. Sakamaki ◽  
Y. Akazawa ◽  
T. Miyano
Keyword(s):  
Germ Cells ◽  
Double Mutant ◽  
Death Receptor ◽  
Follicular Development ◽  
The Other ◽  
Wild Type ◽  
Severe Combined Immune Deficiency ◽  
Growth And Survival ◽  
Primordial Follicles ◽  
Student’S T

Growth factors and cytokines regulate survival and growth of mammalian oocytes via their cognate receptors. Among those receptors, KIT, a receptor tyrosine kinase, has been thought of as an essential molecule for growth and survival of oocytes and for follicular development. The defect of KIT-mediated signals leads to the loss of oocytes and impairment of follicular development. Fas is a member of the death receptor family inducing apoptosis; it expresses in the ovary. In a previous study (Sakata et al. 2003 Cell Death Differ. 10, 676–86), we generated KIT-deficient and Fas-knockout double mutant (Wv/Wv:Fas−/−) mice to study the relation between Fas and KIT signaling in germ cell apoptosis. To further understand the role of KIT in oocyte survival and follicular development, we examined the ovaries of Wv/Wv and Wv/Wv:Fas−/− in comparison to those of C57BL/6 (wild type) mice. We also examined the possibility of overcoming the deleterious effects of KIT deficiency by ovarian allotransplantation. One ovary of each mouse was fixed for immediate histological examination and the other was transplanted under the kidney capsule of a female SCID (severe combined immune deficiency) mouse. Ovaries and recovered grafts were fixed, embedded, serially sectioned at 5 μm, stained with hematoxylin and eosin, and examined under a microscope. Oocytes were counted in every section where the nucleus was seen, avoiding double counting in adjacent sections. Mean (with standard deviation) numbers of oocytes per graft or ovary were compared using Student's t-test. At 13 days post-coitum (dpc), ovaries of Wv/Wv fetuses contained 1104.3 ± 118.8 (n = 4) germ cells which was significantly (P < 0.05) lower than those of wild-type mice. However, at 16 dpc (n = 6) and 2-days old (n = 6), ovaries did not contain any germ cells/oocytes. After allotransplantation of the ovaries (n = 6) from Wv/Wv fetuses (13 dpc) for 2 weeks, all of the germ cells disappeared. When the ovaries from 2-day-old Wv/Wv mice (n = 6) were allotransplanted for 12 days, no oocytes appeared. On the other hand, transplanted ovaries from C57BL/6 fetuses (13 dpc) contained 2162.0 ± 97.3 (n = 6) oocytes after 2 weeks. In those ovaries, 4.7 ± 1.6% follicles developed to secondary follicles which contained growing oocytes. Importantly, ovaries of 2-day-old Wv/Wv:Fas−/− mice (n = 4) contained 1936.0 ± 245.0 oocytes (64.0 ± 10.0% of wild-type mice), and 14-day-old mice (n = 4) still contained 911.3 ± 106.3 follicles in which 28.6 ± 6.0% and 11.4 ± 3.2% follicles developed to primary and secondary follicles, respectively. These results indicate that oocyte death due to KIT-deficiency can not be rescued by ovarian transplantation in SCID mice, and that the Fas-knockout condition partially prevents the death of oocytes induced by KIT-deficiency, and primordial follicles develop in this condition.

scholarly journals Anti-Müllerian hormone overexpression restricts preantral ovarian follicle survival

2018 ◽  
Vol 237 (2) ◽  
pp. 153-163 ◽  
Author(s):  
Michael W Pankhurst ◽  
Rebecca L Kelley ◽  
Rachel L Sanders ◽  
Savana R Woodcock ◽  
Dorothy E Oorschot ◽  
...  
Keyword(s):  
Reproductive Output ◽  
Ovarian Follicle ◽  
Follicle Stimulating Hormone ◽  
Primordial Follicle ◽  
Slight Reduction ◽  
Wild Type ◽  
Primordial Follicles ◽  
Antral Follicles ◽  
Primordial Follicle Activation ◽  
Ovarian Folliculogenesis

Anti-Müllerian hormone (AMH) is an ovarian regulator that affects folliculogenesis. AMH inhibits the developmental activation of the dormant primordial follicles and the oocyte within. In more mature follicles, AMH reduces granulosa cell sensitivity to follicle-stimulating hormone (FSH). We examined the effects of AMH overexpression on the stages of ovarian folliculogenesis, and the development of embryos, with a transgenic mouse that overexpresses human AMH in central nervous system neurons under the control of the mouse Thy1.2 promoter (Thy1.2-AMH Tg mice). These mice are severely sub-fertile, despite relatively normal ovulation rates. The embryos of Thy1.2-AMHTg females exhibited delayed preimplantation development and extensive mid-gestation fetal resorption. Young Thy1.2-AMHTg mouse ovaries exhibited only a slight reduction in the rate of primordial follicle activation but large declines in the number of developing follicles surviving past the primary stage. It was expected that Thy1.2-AMHTg mice would retain more primordial follicles as they aged, but at 5 months, their number was significantly reduced relative to wild-type females. These data indicate that moderate elevations in AMH levels can severely restrict reproductive output and the number of developing follicles in the ovary. This evidence suggests that early antral follicles are a target for AMH signaling, which may regulate early follicle survival.

scholarly journals microRNA 376a regulates follicle assembly by targeting Pcna in fetal and neonatal mouse ovaries

Reproduction ◽  
2014 ◽  
Vol 148 (1) ◽  
pp. 43-54 ◽  
Author(s):  
Huan Zhang ◽  
Xiaohua Jiang ◽  
Yuanwei Zhang ◽  
Bo Xu ◽  
Juan Hua ◽  
...  
Keyword(s):  
Proliferating Cell Nuclear Antigen ◽  
Primordial Follicle ◽  
Neonatal Mouse ◽  
Nuclear Antigen ◽  
Mrna Levels ◽  
Microrna Target ◽  
Ovarian Insufficiency ◽  
Primordial Follicles ◽  
Reproductive Life ◽  
Proliferating Cell

In mammals, the primordial follicle pool, providing all oocytes available to a female throughout her reproductive life, is established perinatally. Dysregulation of primordial follicle assembly results in female reproductive diseases, such as premature ovarian insufficiency and infertility. Female mice lackingDicer1(Dicer), a gene required for biogenesis of microRNAs, show abnormal morphology of follicles and infertility. However, the contribution of individual microRNAs to primordial follicle assembly remains largely unknown. Here, we report that microRNA 376a (miR-376a) regulates primordial follicle assembly by modulating the expression of proliferating cell nuclear antigen (Pcna), a gene we previously reported to regulate primordial follicle assembly by regulating oocyte apoptosis in mouse ovaries. miR-376a was shown to be negatively correlated withPcnamRNA expression in fetal and neonatal mouse ovaries and to directly bind toPcnamRNA 3′ untranslated region. Cultured 18.5 days postcoitum mouse ovaries transfected with miR-376a exhibited decreasedPcnaexpression both in protein and mRNA levels. Moreover, miR-376a overexpression significantly increased primordial follicles and reduced apoptosis of oocytes, which was very similar to those in ovaries co-transfected with miR-376a and siRNAs targetingPcna. Taken together, our results demonstrate that miR-376a regulates primordial follicle assembly by modulating the expression ofPcna. To our knowledge, this is the first microRNA–target mRNA pair that has been reported to regulate mammalian primordial follicle assembly and further our understanding of the regulation of primordial follicle assembly.

scholarly journals Metformin: a novel promising option for fertility preservation during cyclophosphamide-based chemotherapy

2021 ◽  
Author(s):  
Chu-Chun Huang ◽  
Chia-Hung Chou ◽  
Yu-Shih Yang ◽  
Hong-Nerng Ho ◽  
Chia-Tung Shun ◽  
...  
Keyword(s):  
Ovarian Function ◽  
Primordial Follicle ◽  
Inhibitory Effect ◽  
Metformin Treatment ◽  
High Power Field ◽  
Primordial Follicles ◽  
Apoptotic Effect ◽  
Apoptotic Effects

Abstract Cyclophosphamide (CP) could cause severe gonadotoxicity via imbalanced activation of primordial follicles through PI3K/AKT/mTOR activation. Whether metformin, a widely prescribed anti-diabetes agent with mTOR inhibitory effect, could preserve ovarian function against CP toxicity is unknown. Female C57BL/6 mice were randomized into seven groups (n = 11), including control, CP-alone, CP+metformin, CP+sirolimus or everolimus, metformin-alone and sirolimus-alone groups. The duration of pharmaceutical treatment was four weeks. CP treatment significantly impaired ovarian function and fertility in mice. CP+metformin treatment significantly attenuated the gonadotoxicity comparing to CP-alone treatment (Primordial follicle count: 17.6 ± 4.2 versus 10.3 ± 2.7 follicles/high-power field; p = 0.027). CP+metformin treatment also tended to increase antral follicular count (5.4 ± 1.1 versus 2.5 ± 1.6 follicles/section), serum AMH levels (4.6 ± 1.2 versus 2.0 ± 0.8 ng/ml) and the litter size (4.2 ± 1.3 versus 1.5 ± 1.0 mice per pregnancy), compared with CP-alone group. Expression of phospho-mTOR and the number of TUNEL-positive granulosa cells increased after CP treatment and decreased in the CP+metformin groups, suggesting the mTOR inhibitory and anti-apoptotic effects of metformin. In in vitro granulosa cell experiments, the anti-apoptotic effect of metformin was blocked after inhibiting p53 or p21 function, and the expression of p53 mRNA was blocked with AMPK inhibitor, suggesting that the anti-apoptotic effect was AMPK/p53/p21-mediated. In conclusion, concurrent metformin treatment during CP therapy could significantly preserve ovarian function and fertility and could be a promising novel fertility preserving agent during chemotherapy. The relatively acceptable cost and well-established long-term safety profiles of this old drug might prompt its further clinical application at a faster pace.

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