RESUMO
PIWI-interacting small RNAs (piRNAs) maintain genome stability in animal germ cells, with a predominant role in silencing transposable elements. Mutations in the piRNA pathway in the mouse uniformly lead to failed spermatogenesis and male sterility. By contrast, mutant females are fertile. In keeping with this paradigm, we previously reported male sterility and female fertility associated with loss of the enzyme HENMT1, which is responsible for stabilising piRNAs through the catalysation of 3'-terminal 2'-O-methylation. However, the Henmt1 mutant females were poor breeders, suggesting they could be subfertile. Therefore, we investigated oogenesis and female fertility in these mice in greater detail. Here, we show that mutant females indeed have a 3- to 4-fold reduction in follicle number and reduced litter sizes. In addition, meiosis-II mutant oocytes display various spindle abnormalities and have a dramatically altered transcriptome which includes a down-regulation of transcripts required for microtubule function. This down-regulation could explain the spindle defects observed with consequent reductions in litter size. We suggest these various effects on oogenesis could be exacerbated by asynapsis, an apparently universal feature of piRNA mutants of both sexes. Our findings reveal that loss of the piRNA pathway in females has significant functional consequences.
Assuntos
Fertilidade , Infertilidade Feminina/enzimologia , Meiose , Metiltransferases/metabolismo , Oócitos/enzimologia , Oogênese , RNA Interferente Pequeno/metabolismo , Animais , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Infertilidade Feminina/genética , Infertilidade Feminina/fisiopatologia , Metiltransferases/genética , Camundongos , RNA Interferente Pequeno/genética , TranscriptomaRESUMO
Primordial follicle oocytes are extremely vulnerable to DNA damage caused by exogenous agents, such as those commonly used to treat cancer. Consequently, female cancer patients often have diminished ovarian reserve, which if severe enough, can cause premature ovarian failure and early menopause. Advances in cancer therapies have resulted in significantly improved cancer survival rates; therefore, it is becoming increasingly important to devise strategies to protect the ovarian reserve from cancer treatments, to avoid loss of fertility and endocrine dysfunction. In this study, we aimed to determine whether supplementation with nicotinamide mononucleotide (NMN) could preserve the ovarian reserve following exposure to DNA-damaging cancer treatments. Adult female mice (n = 5-6/group) received saline or NMN (500 mg/kg/day) for 8 days. Mice were left untreated or exposed to γ-irradiation (0.1 Gy) or cyclophosphamide (150 mg/kg) on day 7 and ovaries and serum collected for analysis on day 12. We report that γ-irradiation treatment significantly reduced the number of primordial follicles, but supplementation with NMN did not prevent the observed follicle loss. Similarly, cyclophosphamide treatment significantly reduced primordial follicle numbers, but these losses were not prevented by NMN supplementation. In conclusion, depletion of the ovarian reserve following γ-irradiation or cyclophosphamide was not protected by NMN supplementation under the conditions employed in this study.
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Prenatal alcohol exposure (PAE) has been associated with reproductive dysfunction in offspring. However, studies in females, particularly examining long-term infertility or impacts on ovarian reserve, are lacking. The current study utilised a moderate, episodic exposure model in rats to mimic 'special occasion' drinking, which is reported to be common during pregnancy. Our objective was to examine the consequences of this prenatal alcohol exposure on reproductive parameters in female offspring. Pregnant Sprague-Dawley rats were treated with either an ethanol gavage (1 g EtOH/kg body weight), or an equivalent volume of saline, on embryonic days 13.5 and 14.5 of pregnancy, resulting in a peak blood alcohol concentration of ~0.04%. Neonatal female offspring were examined for molecular markers regulating early follicle numbers in the ovary, and unbiased stereology was used to quantify primordial and early growing follicle numbers. Puberty onset (age at vaginal opening and first estrous) was measured post-weaning, and estrous cycles, reproductive hormones (progesterone and estradiol) and pregnancy success was measured in adults (5-6 months of age). We found no evidence that any of these reproductive parameters were significantly altered by PAE in this model. This animal study provides some reassurance for women who may have consumed a small amount of alcohol during their pregnancy. However, previously published effects on offspring metabolism using this model reinforce avoidance of alcohol during pregnancy.
Assuntos
Ciclo Estral/efeitos dos fármacos , Etanol/administração & dosagem , Fertilidade/efeitos dos fármacos , Efeitos Tardios da Exposição Pré-Natal/fisiopatologia , Animais , Feminino , Fertilidade/fisiologia , Ovário/efeitos dos fármacos , Ovário/metabolismo , Gravidez , Efeitos Tardios da Exposição Pré-Natal/metabolismo , Ratos , Ratos Sprague-Dawley , Maturidade Sexual/efeitos dos fármacosRESUMO
Trp63, a transcription factor related to the tumor suppressor p53, is activated by diverse stimuli and can initiate a range of cellular responses. TAp63 is the predominant Trp53 family member in primordial follicle oocyte nuclei and is essential for their apoptosis triggered by DNA damage in vivo. After γ-irradiation, induction of the proapoptotic BH3-only members Puma and Noxa was observed in primordial follicle oocytes from WT and Trp53(-/-) mice but not in those from TAp63-deficient mice. Primordial follicle oocytes from mice lacking Puma or both Puma and Noxa were protected from γ-irradiation-induced apoptosis and, remarkably, could produce healthy offspring. Hence, PUMA and NOXA are critical for DNA damage-induced, TAp63-mediated primordial follicle oocyte apoptosis. Thus, blockade of PUMA may protect fertility during cancer therapy and prevent premature menopause, improving women's health.
Assuntos
Proteínas Reguladoras de Apoptose/genética , Apoptose/genética , Dano ao DNA , Fertilidade/genética , Oócitos/metabolismo , Proteínas Supressoras de Tumor/genética , Animais , Apoptose/efeitos da radiação , Proteínas Reguladoras de Apoptose/metabolismo , Feminino , Raios gama , Expressão Gênica/efeitos da radiação , Imuno-Histoquímica , Hibridização In Situ , Masculino , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Knockout , Oócitos/citologia , Oócitos/efeitos da radiação , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Transativadores/genética , Transativadores/metabolismo , Proteína Supressora de Tumor p53/deficiência , Proteína Supressora de Tumor p53/genética , Proteínas Supressoras de Tumor/metabolismoRESUMO
Female fertility and offspring health are critically dependent on the maintenance of an adequate supply of high-quality oocytes. Like somatic cells, oocytes are subject to a variety of different types of DNA damage arising from endogenous cellular processes and exposure to exogenous genotoxic stressors. While the repair of intentionally induced DNA double strand breaks in gametes during meiotic recombination is well characterised, less is known about the ability of oocytes to repair pathological DNA damage and the relative contribution of DNA repair to oocyte quality is not well defined. This review will discuss emerging data suggesting that oocytes are in fact capable of efficient DNA repair and that DNA repair may be an important mechanism for ensuring female fertility, as well as the transmission of high-quality genetic material to subsequent generations.
Assuntos
Dano ao DNA , Reparo do DNA , Perfilação da Expressão Gênica , Oócitos/metabolismo , Animais , Feminino , Fertilidade/genética , Humanos , Folículo Ovariano/citologia , Folículo Ovariano/metabolismoRESUMO
The HLH transcriptional regulator Id4 exerts important roles in different organs, including the neural compartment, where Id4 loss usually results in early lethality. To explore the role of this basally restricted transcription factor in the mammary gland, we generated a cre-inducible mouse model. MMTV- or K14-cre-mediated deletion of Id4 led to a delay in ductal morphogenesis, consistent with previous findings using a germ-line knockout mouse model. A striking increase in the expression of ERα (Esr1), PR and FoxA1 was observed in both the basal and luminal cellular subsets of Id4-deficient mammary glands. Together with chromatin immunoprecipitation of Id4 on the Esr1 and Foxa1 promoter regions, these data imply that Id4 is a negative regulator of the ERα signaling axis. Unexpectedly, examination of the ovaries of targeted mice revealed significantly increased numbers of secondary and antral follicles, and reduced Id4 expression in the granulosa cells. Moreover, expression of the cascade of enzymes that are crucial for estrogen biosynthesis in the ovary was decreased in Id4-deficient females and uterine weights were considerably lower, indicating impaired estrogen production. Thus, compromised ovarian function and decreased circulating estrogen likely contribute to the mammary ductal defects evident in Id4-deficient mice. Collectively, these data identify Id4 as a novel regulator of estrogen signaling, where Id4 restrains ERα expression in the basal and luminal cellular compartments of the mammary gland and regulates estrogen biosynthesis in the ovary.
Assuntos
Estrogênios/metabolismo , Proteínas Inibidoras de Diferenciação/genética , Proteínas Inibidoras de Diferenciação/fisiologia , Glândulas Mamárias Animais/fisiologia , Ovário/fisiologia , Animais , Sequência de Bases , Receptor alfa de Estrogênio/metabolismo , Feminino , Deleção de Genes , Regulação da Expressão Gênica , Células da Granulosa/citologia , Fator 3-alfa Nuclear de Hepatócito/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Dados de Sequência Molecular , Regiões Promotoras Genéticas , Receptores de Progesterona/metabolismo , Transdução de Sinais , Útero/fisiologiaRESUMO
Apoptosis plays a prominent role during ovarian development by eliminating large numbers of germ cells from the female germ line. However, the precise mechanisms and regulatory proteins involved in germ cell death are yet to be determined. In this study, we characterised the role of the pro-apoptotic BH3-only protein, BCL2-modifying factor (BMF), in germ cell apoptosis in embryonic and neonatal mouse ovaries. BMF protein was immunohistochemically localised to germ cells at embryonic days 15.5 (E15.5) and E17.5 and postnatal day 1 (PN1), coincident with entry into the meiotic prophase, but was undetectable at E13.5, and only present at low levels at PN3 and PN5. Consistent with this expression pattern, loss of BMF in female mice was associated with a decrease in apoptosis at E15.5 and E17.5. Furthermore, increased numbers of germ cells were found in ovaries from Bmf(-/-) mice compared with WT animals at E15.5 and PN1. However, germ cell numbers were comparable between Bmf(-/-) and WT ovaries at PN3, PN5 and PN10. Collectively, these data indicate that BMF mediates foetal oocyte loss and its action limits the maximal number of germ cells attained in the developing ovary, but does not influence the number of primordial follicles initially established in ovarian reserve.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/fisiologia , Apoptose , Embrião de Mamíferos/patologia , Células Germinativas/patologia , Oócitos/patologia , Oogênese/fisiologia , Ovário/patologia , Animais , Western Blotting , Células Cultivadas , Embrião de Mamíferos/metabolismo , Feminino , Imunofluorescência , Células Germinativas/metabolismo , Técnicas Imunoenzimáticas , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Oócitos/metabolismo , Ovário/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2RESUMO
Precisely how the length of the female fertile lifespan is regulated is poorly understood and it is likely to involve complex factors, one of which is follicle number. Indeed, the duration of female fertility appears to be intimately linked to the number of available oocytes, which are stored in the ovary as primordial follicles. There is mounting evidence implicating the intrinsic apoptosis pathway, which is controlled by members of the B-cell lymphoma-2 (BCL-2) family, as a key regulator of the number of primordial follicles established in the ovary at birth and maintained throughout reproductive life. Consequently, the pro- and anti-apoptotic BCL-2 family proteins are emerging as key determinants of the length of the female fertile lifespan. This review discusses the relationship between the intrinsic apoptosis pathway, follicle number and length of the female fertile lifespan.
Assuntos
Apoptose , Fertilidade , Folículo Ovariano/fisiologia , Proteínas Proto-Oncogênicas c-bcl-2/fisiologia , Animais , Feminino , Humanos , Camundongos , Oócitos , OvárioRESUMO
The duration of the female fertile life span is influenced by the number of oocytes stored in the ovary as primordial follicles. Cell death, both during ovarian development in the embryo and in the postnatal ovary, plays a critical role in determining how many primordial follicles are established and maintained within the ovary. However, the roles of individual apoptotic regulators in mediating cell death within the ovary have not yet been characterized. In this study, gene targeted mice were used to investigate the role of BCL-2-modifying factor (BMF), a proapoptotic protein belonging to the BH3-only subgroup of the BCL-2 family, in determining the number of primordial follicles maintained in the adult ovary and the length of the fertile life span. Stereological analysis of ovaries showed that Bmf(-/-) mice had significantly more primordial follicles than wild-type (WT) control animals at Postnatal Days 100, 200, 300, and 400 but not at Day 20. No differences were observed between WT and Bmf(-/-) mice in the number of ova shed following ovulatory stimulation with exogenous gonadotropins. Bmf(-/-) females were fertile and produced the same number pups/litter as WT females, but Bmf(-/-) females produced litters more frequently and consequently more offspring than WT females over a 6-mo period. Furthermore, the fertile life span of Bmf(-/-) females was significantly extended compared to WT females. Our findings support an important role for BMF in determining the number of primordial follicles maintained in the ovary throughout adult reproductive life and thus indicate that the length of female fertility may be extended by increasing the number of primordial follicles maintained within the ovary through inhibition of BMF.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Envelhecimento/fisiologia , Apoptose/fisiologia , Fertilidade/fisiologia , Folículo Ovariano/fisiologia , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Proteínas Reguladoras de Apoptose/genética , Proteínas Reguladoras de Apoptose/metabolismo , Feminino , Atresia Folicular/fisiologia , Células da Granulosa/citologia , Células da Granulosa/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Folículo Ovariano/citologia , Ovulação/fisiologia , Proteínas Proto-Oncogênicas c-bcl-2/metabolismoRESUMO
The number of primordial follicles initially established within the ovary is influenced by the extent of germ cell death during foetal ovarian development, but the mechanisms that mediate this death have not been fully uncovered. In this study, we identified BBC3 (PUMA) (p53 upregulated modulator of apoptosis, also known as BCL2-binding component 3), a pro-apoptotic BH3-only protein belonging to the BCL2 family, as a critical determinant of the number of germ cells during ovarian development. Targeted disruption of the Bbc3 gene revealed a significant increase in the number of germ cells as early as embryonic day 13.5. The number of germ cells remained elevated in Bbc3(-/-) female mice compared with WT female mice throughout the remainder of embryonic and early postnatal life, resulting in a 1.9-fold increase in the number of primordial follicles in the ovary on postnatal day 10. The increase in the number of germ cells observed in the ovaries of Bbc3(-/-) mice could not be attributed to the altered proliferative activity of germ cells within the ovaries. Furthermore, BBC3 was found to be not required for the massive germ cell loss that occurs during germ cell nest breakdown. Our data indicate that BBC3 is a critical regulator of germ cell death that acts during the migratory phase of oogenesis or very soon after the arrival of germ cells in the gonad and that BBC3-mediated cell death limits the number of primordial follicles established in the initial ovarian reserve.
Assuntos
Proteínas Reguladoras de Apoptose/fisiologia , Apoptose , Embrião de Mamíferos/citologia , Células Germinativas/patologia , Folículo Ovariano/patologia , Proteínas Supressoras de Tumor/fisiologia , Animais , Western Blotting , Células Cultivadas , Embrião de Mamíferos/metabolismo , Feminino , Citometria de Fluxo , Imunofluorescência , Células Germinativas/metabolismo , Técnicas Imunoenzimáticas , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Folículo Ovariano/metabolismoRESUMO
Loss of fertility is a major concern for female reproductive-age cancer survivors, since a common side-effect of conventional cytotoxic cancer therapies is permanent damage to the ovary. While immunotherapies are increasingly becoming a standard of care for many cancers-including in the curative setting-their impacts on ovarian function and fertility are unknown. We evaluated the effect of immune checkpoint inhibitors blocking programmed cell death protein ligand 1 and cytotoxic T lymphocyte-associated antigen 4 on the ovary using tumor-bearing and tumor-free mouse models. We find that immune checkpoint inhibition increases immune cell infiltration and tumor necrosis factor-α expression within the ovary, diminishes the ovarian follicular reserve and impairs the ability of oocytes to mature and ovulate. These data demonstrate that immune checkpoint inhibitors have the potential to impair both immediate and future fertility, and studies in women should be prioritized. Additionally, fertility preservation should be strongly considered for women receiving these immunotherapies, and preventative strategies should be investigated in future studies.
Assuntos
Preservação da Fertilidade , Neoplasias , Animais , Feminino , Humanos , Inibidores de Checkpoint Imunológico , Imunoterapia/efeitos adversos , Camundongos , Oócitos/patologiaRESUMO
Reproductive ageing in females is defined by a progressive decline in follicle number and oocyte quality. This is a natural process that leads to the loss of fertility and ovarian function, cycle irregularity and eventually menopause or reproductive senescence. The factors that underlie the natural depletion of follicles throughout reproductive life are poorly characterised. It has been proposed that inflammatory processes and fibrosis might contribute to ovarian ageing. To further investigate this possibility, we evaluated key markers of inflammation and immune cell populations in the ovaries of 2, 6, 12 and 18-month-old C57BL/6 female mice. We report that the decrease in follicle numbers over the reproductive lifespan was associated with an increase in the intra-ovarian percentage of CD4 + T cells, B cells and macrophages. Serum concentration and intra-ovarian mRNA levels of several pro-inflammatory cytokines, including IL-1α/ß, TNF-α, IL-6, and inflammasome genes ASC and NLRP3, were significantly increased with age. Fibrosis levels, as determined by picrosirius red staining for collagen I and III, were unchanged up to 18 months of age. Collectively, these data suggest that inflammation could be one of the mechanisms responsible for the age-related regulation of follicle number, but the role of fibrosis is unclear. Further studies are now required to determine if there is a causative relationship between inflammation and follicle depletion as females age.
Assuntos
Envelhecimento , Folículo Ovariano/fisiologia , Animais , Feminino , Fertilidade , Inflamação/patologia , Inflamação/fisiopatologia , Camundongos , Camundongos Endogâmicos C57BL , Folículo Ovariano/patologiaRESUMO
Ovarian aging is a natural process characterized by follicular depletion and a reduction in oocyte quality, resulting in loss of ovarian function, cycle irregularity and eventually infertility and menopause. The factors that contribute to ovarian aging have not been fully characterized. Activation of the NLRP3 inflammasome has been implicated in age-associated inflammation and diminished function in several organs. In this study, we used Asc -/- and Nlrp3 -/- mice to investigate the possibility that chronic low-grade systemic inflammation mediated by the inflammasome contributes to diminished ovarian reserves as females age. Pro-inflammatory cytokines, IL-6, IL-18, and TNF-α, were decreased in the serum of aging Asc -/- mice compared to WT. Within the ovary of reproductively aged Asc -/- mice, mRNA levels of major pro-inflammatory genes Tnfa, Il1a, and Il1b were decreased, and macrophage infiltration was reduced compared to age-matched WT controls. Notably, suppression of the inflammatory phenotype in Asc -/- mice was associated with retention of follicular reserves during reproductive aging. Similarly, the expression of intra-ovarian pro-inflammatory cytokines was reduced, and follicle numbers were significantly elevated, in aging Nlrp3 -/- mice compared to WT controls. These data suggest that inflammasome-dependent inflammation contributes to the age-associated depletion of follicles and raises the possibility that ovarian aging could be delayed, and fertile window prolonged, by suppressing inflammatory processes in the ovary.
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Dacarbazine is commonly administered for the treatment of cancers prevalent in reproductive age females. However, investigations of off-target effects of dacarbazine on the ovary are limited. We assessed the impact of dacarbazine on the ovarian reserve of primordial follicles, essential for fertility. Eight week and 6 month old C57BL/6 J mice were administered with dacarbazine or saline on day (d)0 and d7, then sacrificed after 12 hours (h), or 14d (n = 4-5/group). Follicle numbers, follicle density, serum AMH and corpora lutea were quantified and estrous cyclicity monitored. In reproductively young mice, dacarbazine did not affect primordial follicle numbers at 12 h, but resulted in a 36% reduction at 14d (p < 0.05). Dacarbazine-mediated primordial follicle depletion was accelerated with age, with a 24% (p < 0.05) and 36% (p < 0.01) reduction at 12 h and 14d. Follicle density remained unchanged between treatment groups at either age. Dacarbazine depleted antral follicles at 14d (p < 0.05), at both ages. Despite partial reduction of antral follicles, serum AMH, estrous cyclicity and corpora lutea (indicative of ovulation) remained unchanged between treatment groups, at both ages. Importantly, diminished ovarian reserve can result in premature ovarian insufficiency and infertility, thus, fertility preservation options should be considered for young female patients prior to dacarbazine treatment.
Assuntos
Corpo Lúteo/efeitos dos fármacos , Dacarbazina/farmacologia , Folículo Ovariano/efeitos dos fármacos , Reserva Ovariana/efeitos dos fármacos , Animais , Ciclo Estral/efeitos dos fármacos , Feminino , Fertilidade/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Ovulação/efeitos dos fármacos , Insuficiência Ovariana Primária/tratamento farmacológico , Reprodução/efeitos dos fármacosRESUMO
BACKGROUND: Within the ovary, oocytes are stored in long-lived structures called primordial follicles, each comprising a meiotically arrested oocyte, surrounded by somatic granulosa cells. It is essential that their genetic integrity is maintained throughout life to ensure that high quality oocytes are available for ovulation. Of all the possible types of DNA damage, DNA double-strand breaks (DSBs) are considered to be the most severe. Recent studies have shown that DNA DSBs can accumulate in oocytes in primordial follicles during reproductive ageing, and are readily induced by exogenous factors such as γ-irradiation, chemotherapy and environmental toxicants. DSBs can induce oocyte death or, alternatively, activate a program of DNA repair in order to restore genetic integrity and promote survival. The repair of DSBs has been intensively studied in the context of meiotic recombination, and in recent years more detail is becoming available regarding the repair capabilities of primordial follicle oocytes. OBJECTIVE AND RATIONALE: This review discusses the induction and repair of DNA DSBs in primordial follicle oocytes. SEARCH METHODS: PubMed (Medline) and Google Scholar searches were performed using the key words: primordial follicle oocyte, DNA repair, double-strand break, DNA damage, chemotherapy, radiotherapy, ageing, environmental toxicant. The literature was restricted to papers in the English language and limited to reports in animals and humans dated from 1964 until 2017. The references within these articles were also manually searched. OUTCOMES: Recent experiments in animal models and humans have provided compelling evidence that primordial follicle oocytes can efficiently repair DNA DSBs arising from diverse origins, but this capacity may decline with increasing age. WIDER IMPLICATIONS: Primordial follicle oocytes are vulnerable to DNA DSBs emanating from endogenous and exogenous sources. The ability to repair this damage is essential for female fertility. In the long term, augmenting DNA repair in primordial follicle oocytes has implications for the development of novel fertility preservation agents for female cancer patients and for the management of maternal ageing. However, further work is required to fully characterize the specific proteins involved and to develop strategies to bolster their activity.
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With increasing improvements in cancer survival rates, it is critical to reduce the significant long-term side effects that afflict patients following treatment. For women, consequences of chemotherapy-induced damage to the reproductive system include infertility and premature menopause, which adversely effects cognition, mood, cardiovascular, bone, and sexual health, and increases the risk of early mortality. These long-term effects impact patient's life quality and highlight a significant and on-going burden on the health system after treatment. However, the precise mechanisms through which chemotherapeutic agents induce ovarian damage and primordial follicle depletion remain to be characterized. Hence, preventing the development of effective pharmacological methods to preserve fertility and improve quality of life after treatment. The chemotherapeutic agent 5-Fluorouracil (5FU) is not deemed cytotoxic to the ovary, however, risks to long-term fertility after multiple doses are not known. Therefore, we sought to evaluate the impact of 3, weekly doses of 5FU treatment on the ovary. Using a mouse model enabled accurate histomorphometric analysis of follicle numbers and ovarian structure and function, to accurately assess cumulative impact of 5FU on the ovary. This study clearly demonstrated that multidose 5FU treatment resulted in dramatic and progressive atresia of growing follicles and a profound decrease in ovarian volume due to reduced corpus luteum counts. However, primordial follicle numbers were unaffected. Thus, 5FU is unlikely to cause permanent infertility when administered to women of pre or reproductive age. Furthermore, this study suggests that depletion of the growing follicle population is insufficient to stimulate follicle activation and primordial follicle depletion.
Assuntos
Antimetabólitos Antineoplásicos/toxicidade , Apoptose/efeitos dos fármacos , Dano ao DNA , Fluoruracila/toxicidade , Atresia Folicular/efeitos dos fármacos , Folículo Ovariano/efeitos dos fármacos , Animais , Antimetabólitos Antineoplásicos/administração & dosagem , Apoptose/genética , Corpo Lúteo/efeitos dos fármacos , Corpo Lúteo/crescimento & desenvolvimento , Corpo Lúteo/patologia , Relação Dose-Resposta a Droga , Esquema de Medicação , Feminino , Fluoruracila/administração & dosagem , Atresia Folicular/genética , Injeções Intraperitoneais , Camundongos Endogâmicos C57BL , Folículo Ovariano/crescimento & desenvolvimento , Folículo Ovariano/patologiaRESUMO
Female gametes are stored in the ovary in structures called primordial follicles, the supply of which is non-renewable. It is well established that DNA-damaging cancer treatments can deplete the ovarian reserve of primordial follicles, causing premature ovarian failure and infertility. The precise mechanisms underlying this chemotherapy-driven follicle loss are unclear, and this has limited the development of targeted ovarian-protective agents. To address this fundamental knowledge gap, we used gene deletion mouse models to examine the role of the DNA damage-induced pro-apoptotic protein, PUMA, and its transcriptional activator TAp63, in primordial follicle depletion caused by treatment with cyclophosphamide or cisplatin. Cyclophosphamide caused almost complete destruction of the primordial follicle pool in adult wild-type (WT) mice, and a significant destructive effect was also observed for cisplatin. In striking contrast, Puma-/- mice retained 100% of their primordial follicles following either genotoxic treatment. Furthermore, elimination of PUMA alone completely preserved fertility in cyclophosphamide-treated mice, indicating that oocytes rescued from DNA damage-induced death can repair themselves sufficiently to support reproductive function and offspring health. Primordial follicles were also protected in TAp63-/- mice following cisplatin treatment, but not cyclophosphamide, suggesting mechanistic differences in the induction of apoptosis and depletion of the ovarian reserve in response to these different chemotherapies. These studies identify PUMA as a crucial effector of apoptosis responsible for depletion of primordial follicles following exposure to cyclophosphamide or cisplatin, and this indicates that inhibition of PUMA may be an effective ovarian-protective strategy during cancer treatment in women.
Assuntos
Antineoplásicos/efeitos adversos , Proteínas Reguladoras de Apoptose/deficiência , Dano ao DNA , Fertilidade , Reserva Ovariana/fisiologia , Proteínas Supressoras de Tumor/deficiência , Animais , Apoptose/efeitos dos fármacos , Proteínas Reguladoras de Apoptose/metabolismo , Cisplatino/efeitos adversos , Ciclofosfamida/efeitos adversos , Feminino , Atresia Folicular/efeitos dos fármacos , Masculino , Camundongos Endogâmicos C57BL , Oócitos/efeitos dos fármacos , Oócitos/metabolismo , Folículo Ovariano/efeitos dos fármacos , Folículo Ovariano/patologia , Reserva Ovariana/efeitos dos fármacos , Fosfoproteínas/deficiência , Fosfoproteínas/metabolismo , Transativadores/deficiência , Transativadores/metabolismo , Proteínas Supressoras de Tumor/metabolismoRESUMO
Male fertility is inhibited by inflammatory disease, but the mechanisms responsible are poorly defined. The effects of acute systemic inflammation induced by a single IP injection of lipopolysaccharide (LPS) on spermatogenic function in adult male rats were investigated using detailed stereological analysis. The earliest effect observed was a significant maturational delay of meiosis during the leptotene/zygotene phase (at stages IX-XIII) within 24 hours. This was followed within 6 days by an increase in premature release of these cells and the adjacent, more luminally located generation of round spermatids from the seminiferous epithelium. An increase in germ cell apoptosis within stages IX-XIII also occurred at this time. These data indicate that the initial effects of acute inflammation on the seminiferous epithelium are most pronounced on stages IX-XIII. The effects were not consistent with a loss of hormonal regulation, suggesting that a direct effect of inflammation on the function of the Sertoli cell during this critical stage of meiosis is involved. In the longer term, however, the consequences of this acute inflammatory episode were relatively minor: within 28 days there had been a compensatory increase in the efficiency of the seminiferous epithelium, restoring the spermatogenic capacity of the testis towards preinflammation levels.
Assuntos
Inflamação/fisiopatologia , Espermatogênese , Animais , Apoptose , Contagem de Células , Hormônios Esteroides Gonadais/metabolismo , Inflamação/induzido quimicamente , Lipopolissacarídeos , Masculino , Ratos , Ratos Sprague-Dawley , Testículo/patologiaRESUMO
In females, germ cells are maintained in ovarian structures called primordial follicles. The number of primordial follicles in the ovarian reserve is a critical determinant of the length of the fertile lifespan. Despite this significance, knowledge of the precise physiological mechanisms that regulate primordial follicle number is lacking. In this study we show that a wave of primordial follicle depletion occurs during the transition to adulthood in mice. We demonstrate that this sudden and dramatic loss of primordial follicles is hormonally triggered and identify the pro-apoptotic BH3-only protein, BCL-2 modifying factor (BMF), as essential for this process, implicating the intrinsic apoptotic pathway as a key mechanism. The elimination of primordial follicles during puberty is not only a striking developmental event, it is also physiologically important because it ultimately reduces the availability of primordial follicles and determines the duration of fertility. Collectively, these findings show that puberty is a critical developmental window for the regulation of the size of ovarian reserve, impacting on female fertility and reproductive longevity.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Fertilidade/fisiologia , Folículo Ovariano/metabolismo , Maturidade Sexual/fisiologia , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Feminino , Camundongos , Camundongos KnockoutRESUMO
Drugs that target the Renin-Angiotensin System (RAS) have recently come into focus for their potential utility as cancer treatments. The use of Angiotensin Receptor Blockers (ARBs) and Angiotensin-Converting Enzyme (ACE) Inhibitors (ACEIs) to manage hypertension in cancer patients is correlated with improved survival outcomes for renal, prostate, breast and small cell lung cancer. Previous studies demonstrate that the Angiotensin Receptor Type I (AT1R) is linked to breast cancer pathogenesis, with unbiased analysis of gene-expression studies identifying significant up-regulation of AGTR1, the gene encoding AT1R in ER+ve/HER2-ve tumors correlating with poor prognosis. However, there is no evidence, so far, of the functional contribution of AT1R to breast tumorigenesis. We explored the potential therapeutic benefit of ARB in a carcinogen-induced mouse model of breast cancer and clarified the mechanisms associated with its success.Mammary tumors were induced with 7,12-dimethylbenz[α]antracene (DMBA) and medroxyprogesterone acetate (MPA) in female wild type mice and the effects of the ARB, Losartan treatment assessed in a preventative setting (n = 15 per group). Tumor histopathology was characterised by immunohistochemistry, real-time qPCR to detect gene expression signatures, and tumor cytokine levels measured with quantitative bioplex assays. AT1R was detected with radiolabelled ligand binding assays in fresh frozen tumor samples.We showed that therapeutic inhibition of AT1R, with Losartan, resulted in a significant reduction in tumor burden; and no mammary tumor incidence in 20% of animals. We observed a significant reduction in tumor progression from DCIS to invasive cancer with Losartan treatment. This was associated with reduced tumor cell proliferation and a significant reduction in IL-6, pSTAT3 and TNFα levels. Analysis of tumor immune cell infiltrates, however, demonstrated no significant differences in the recruitment of lymphocytes or tumour-associated macrophages in Losartan or vehicle-treated mammary tumors.Analysis of AT1R expression with radiolabelled ligand binding assays in human breast cancer biopsies showed high AT1R levels in 30% of invasive ductal carcinomas analysed. Furthermore, analysis of the TCGA database identified that high AT1R expression to be associated with luminal breast cancer subtype.Our in vivo data and analysis of human invasive ductal carcinoma samples identify the AT1R is a potential therapeutic target in breast cancer, with the availability of a range of well-tolerated inhibitors currently used in clinics. We describe a novel signalling pathway critical in breast tumorigenesis, that may provide new therapeutic avenues to complement current treatments.