Beclin-1 deficiency in the murine ovary results in the reduction of progesterone production to promote preterm labor

Rubicon, a Key Molecule for Oxidative Stress-Mediated DNA Damage, in Ovarian Granulosa Cells

Aging drives excessive ovarian oxidative stress (OS), impairing fertility and affecting granulosa cells (GCs), which are involved in folliculogenesis. This study aims to clarify the relationship between OS and autophagy in GCs and to identify compounds that enhance OS resistance. We identified Rubicon, an autophagy suppressor, as a key mediator of DNA damage in GCs under OS. Hydrogen peroxide (H2O2) compromised cell viability via DNA damage in the human GC cell line, HGrC1, without affecting autophagic activity. However, autophagy activation increased OS resistance in HGrC1 cells, and vice versa. Among clinically safe materials, trehalose, a disaccharide, protected cells as an autophagy activator against H2O2-induced cytotoxicity. Trehalose significantly increased autophagic activity, accompanied by reduced Rubicon expression, compared to other carbohydrates. It also reduced the expression of DNA damage-responsive proteins and the production of reactive oxygen species. Rubicon knockdown mitigated OS-induced DNA damage, while Rubicon overexpression enhanced DNA damage and decreased HGrC1 cell viability. Trehalose enhanced OS resistance by activating autophagy and suppressing Rubicon in a bidirectional manner. As Rubicon expression increases in aged human ovaries, trehalose may improve ovarian function in patients with infertility and other OS-related diseases.

The autophagy protein ATG14 safeguards against unscheduled pyroptosis activation to enable embryo transport during early pregnancy

Recurrent pregnancy loss, characterized by two or more failed clinical pregnancies, poses a significant challenge to reproductive health. In addition to embryo quality and endometrial function, proper oviduct function is also essential for successful pregnancy establishment. Therefore, structural abnormalities or inflammation resulting from infection in the oviduct may impede the transport of embryos to the endometrium, thereby increasing the risk of miscarriage. However, our understanding of the biological processes that preserve the oviductal cellular structure and functional integrity is limited. Here, we report that autophagy-related protein ATG14 plays a crucial role in maintaining the cellular integrity of the oviduct by controlling inflammatory responses, thereby supporting efficient embryo transport. Specifically, the conditional depletion of the autophagy-related gene Atg14 in the oviduct causes severe structural abnormalities compromising its cellular integrity, leading to the abnormal retention of embryos. Interestingly, the selective loss of Atg14 in oviduct ciliary epithelial cells did not impact female fertility, highlighting the specificity of ATG14 function in distinct cell types within the oviduct. Mechanistically, loss of Atg14 triggered unscheduled pyroptosis via altering the mitochondrial integrity, leading to inappropriate embryo retention and impeded embryo transport in the oviduct. Finally, pharmacological activation of pyroptosis in pregnant mice phenocopied the genetically induced defect and caused impairment in embryo transport. Together, we found that ATG14 safeguards against unscheduled pyroptosis activation to enable embryo transport from the oviduct to uterus for the successful implantation. Of clinical significance, these findings provide possible insights into the underlying mechanism(s) of early pregnancy loss and might aid in developing novel prevention strategies using autophagy modulators.

Visualizing bulk autophagy in vivo by tagging endogenous LC3B

Macroautophagy/autophagy plays a crucial role in maintaining cellular and organismal health, making the measurement of autophagy flux in vivo essential for its study. Current tools often depend on the overexpression of autophagy probes. In this study, we developed a knock-in mouse model, termed tfLC3-KI, by inserting a tandem fluorescent tag coding sequence into the native Map1lc3b gene locus. We found that tfLC3-KI mice exhibit optimal expression of mRFP-eGFP-LC3B, allowing for convenient measurement of autophagic structures and flux at single-cell resolution, both in vivo and in primary cell cultures. Additionally, we compared autophagy in neurons and glial cells across various brain regions between tfLC3-KI mice and CAG-tfLC3 mice, the latter overexpressing the probe under the strong CMV promoter. Finally, we used tfLC3-KI mice to map the spatial and temporal dynamics of basal autophagy activity in the reproductive system. Our findings highlight the value of the tfLC3-KI mouse model for investigating autophagy flux in vivo and demonstrate the feasibility of tagging endogenous proteins to visualize autophagic structures and flux in both bulk and selective autophagy research in vivo.Abbreviation: BafA1: bafilomycin A1; CQ: chloroquine; EBSS: Earle's balanced salt solution; Es: elongating spermatids; HPF: hippocampalformation; HY: hypothalamus; LCs: leydig cells; OLF: olfactory areas; PepA: pepstatin A; Rs: round spermatids; SCs: sertoli cells; Spc: spermatocytes; Spg: spermatogonia; tfLC3: tandem fluorescently tagged mRFP-eGFP-LC3; TH: thalamus.

Real-Time Visualization of Cholesterol Trafficking in Human Granulosa Cells Using Confocal Live Cell Microscopy as a Tool to Study the Novel Role of Autophagy in Sex Steroid Synthesis

Autophagy is an evolutionarily conserved process that aims to maintain the energy homeostasis of the cell by recycling long-lived proteins and organelles. We have very recently demonstrated that lipophagy, a special form of autophagy, mediates the association of the lipid droplets (LDs) with lysosomes to deliver the lipid cargo within the LDs to lysosomes for degradation in order to release free cholesterol required for steroid synthesis in human ovary and testis. In this chapter, we describe live cell confocal microscopy technique that allows us to monitor real-time cholesterol trafficking and the association of cholesterol-laden LDs with lysosome (lipophagy) in human granulosa cells.

Autophagy in reproduction and pregnancy-associated diseases

As advantageous as sexual reproduction is during progeny generation, it is also an expensive and treacherous reproductive strategy. The viviparous eukaryote has evolved to survive stress before, during, and after pregnancy. An important and conserved intracellular pathway for the control of metabolic stress is autophagy. The autophagy process occurs in multiple stages through the coordinated action of autophagy-related genes. This review summarizes the evidence that autophagy is an integral component of reproduction. Additionally, we discuss emerging in vitro techniques that will enable cellular and molecular studies of autophagy and its associated pathways in reproduction. Finally, we discuss the role of autophagy in the pathogenesis and progression of several pregnancy-related disorders such as preterm birth, preeclampsia, and intra-uterine growth restriction, and its potential as a therapeutic target.

RAB37-mediated autophagy guards ovarian homeostasis and function

Loss of ovarian homeostasis is associated with ovary dysfunction and female diseases; however, the underlying mechanisms responsible for the establishment of homeostasis and its function in the ovary have not been fully elucidated. Here, we showed that conditional knockout of Rab37 in oocytes impaired macroautophagy/autophagy proficiency in the ovary and interfered with follicular homeostasis and ovary development in mice. Flunarizine treatment upregulated autophagy, thus rescuing the impairment of follicular homeostasis and ovarian dysfunction in rab37 knockout mice by reprogramming of homeostasis. Notably, both the E2F1 and EGR2 transcription factors synergistically activated Rab37 transcription and promoted autophagy. Thus, RAB37-mediated autophagy ensures ovary function by maintaining ovarian homeostasis.Abbreviations: AMH: anti-Mullerian hormone; ATG: autophagy related; BECN1: beclin 1; cKO: conditional knockout; Cre: cyclization recombination enzyme; dpp: days postpartum; E2: estradiol; E2F1: E2F transcription factor 1; EBF1: EBF transcription factor 1; EGR2: early growth response 2; FSH: follicle stimulating hormone; LH: luteinizing hormone; mpp: months postpartum; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; RAB37: RAB37, member RAS oncogene family; SQSTM1: sequestosome 1; TFEB: transcription factor EB; Zp3: zona pellucida glycoprotein 3.

The autophagy protein, ATG14 safeguards against unscheduled pyroptosis activation to enable embryo transport during early pregnancy

Recurrent pregnancy loss (RPL), characterized by two or more failed clinical pregnancies, poses a significant challenge to reproductive health. In addition to embryo quality and endometrial function, proper oviduct function is also essential for successful pregnancy establishment. Therefore, structural abnormalities or inflammation resulting from infection in the oviduct may impede the transport of embryos to the endometrium, thereby increasing the risk of miscarriage. However, our understanding of the biological processes that preserve the oviductal cellular structure and functional integrity is limited. Here, we report that autophagy-related protein ATG14 plays a crucial role in maintaining the cellular integrity of the oviduct by controlling inflammatory responses, thereby supporting efficient embryo transport. Specifically, the conditional depletion of the autophagy-related gene, Atg14 in the oviduct causes severe structural abnormalities compromising its cellular integrity leading to the abnormal retention of embryos. Interestingly, the selective loss of Atg14 in oviduct ciliary epithelial cells did not impact female fertility, highlighting the specificity of ATG14 function in distinct cell types within the oviduct. Mechanistically, loss of Atg14 triggered unscheduled pyroptosis via altering the mitochondrial integrity leading to inappropriate embryo retention and impeded embryo transport in the oviduct. Finally, pharmacological activation of pyroptosis in pregnant mice phenocopied the genetically induced defect and caused impairment in embryo transport. Together, we found that ATG14 safeguards against unscheduled pyroptosis activation to enable embryo transport from the oviduct to uterus for the successful implantation. Of clinical significance, these findings provide possible insights into the underlying mechanism(s) of early pregnancy loss and might aid in developing novel prevention strategies using autophagy modulators.

Autophagy in the corpus luteum correlates with tissue growth in pregnant rats

The developmental activation of the corpus luteum (CL) structurally and functionally is critical for the temporally regulated establishment, maintenance, and termination of pregnancy in rats. In this study, we have investigated the possible involvement of autophagy in the regulation of the CL during pregnancy in rats. The expression ratio of microtubule-associated protein light chain 3 (LC3)-II/-I, a widely used indicator of autophagic activity, in the CL remained relatively stable until day 15 of pregnancy. Subsequently, it progressively increased until day 21, and then declined until day 3 postpartum. This fluctuation was closely associated with the tissue weight of the CL rather than progesterone (P4) production activity. Light and electron microscopy revealed the presence of immunoreactive LC3 aggregates and irregularly shaped autolysosome-like microstructures in the cytoplasm of luteal cells during late pregnancy. Notably, a bolus intrabursal injection of the autophagy inhibitor bafilomycin A1 on day 15 of pregnancy resulted in a significant reduction in luteal cell size and disrupted the normal alteration of circulating P4 levels. Consequently, treatment with this inhibitor increased the likelihood of the varied timing (both advanced and delayed) of delivery and led to reduced body weight in neonates when compared with the vehicle-treated control group. Our findings suggest that autophagy in the rat CL contributes to luteal tissue growth, influences P4 production, and thereby fine-tunes the regulation of gestation length in rats.

Regulatory Mechanism of Autophagy in Premature Ovarian Failure

Premature ovarian failure (POF) is intricately linked to cellular fates such as senescence, apoptosis, and impaired granulosa cell (GC) differentiation, each of which contributes to ovarian dysfunction and follicular depletion. Autophagy is essential in preventing POF by maintaining cellular homeostasis through the degradation and recycling of damaged organelles and proteins, thereby preserving ovarian function and preventing follicular depletion. Recent studies have revealed that the targeted regulation and disruption of autophagy through various molecular mechanisms ultimately lead to the pathogenesis of POF. In this review, we provide a comprehensive analysis of the disruption in regulatory mechanisms of autophagy contributing to POF. Specifically, we elucidate the molecular mechanisms that can be targeted to restore autophagy homeostasis, offering therapeutic potential for the treatment of POF.

Targeting a mTOR/autophagy axis: a double-edged sword of rapamycin in spontaneous miscarriage

Immune dysfunction is a primary culprit behind spontaneous miscarriage (SM). To address this, immunosuppressive agents have emerged as a novel class of tocolytic drugs, modulating the maternal immune system's tolerance towards the embryo. Rapamycin (PubChem CID:5284616), a dual-purpose compound, functions as an immunosuppressive agent and triggers autophagy by targeting the mTOR pathway. Its efficacy in treating SM has garnered significant research interest in recent times. Autophagy, the cellular process of self-degradation and recycling, plays a pivotal role in numerous health conditions. Research indicates that autophagy is integral to endometrial decidualization, trophoblast invasion, and the proper functioning of decidual immune cells during a healthy pregnancy. Yet, in cases of SM, there is a dysregulation of the mTOR/autophagy axis in decidual stromal cells or immune cells at the maternal-fetal interface. Both in vitro and in vivo studies have highlighted the potential benefits of low-dose rapamycin in managing SM. However, given mTOR's critical role in energy metabolism, inhibiting it could potentially harm the pregnancy. Moreover, while low-dose rapamycin has been deemed safe for treating recurrent implant failure, its potential teratogenic effects remain uncertain due to insufficient data. In summary, rapamycin represents a double-edged sword in the treatment of SM, balancing its impact on autophagy and immune regulation. Further investigation is warranted to fully understand its implications.

Roles of lipid droplets and related proteins in metabolic diseases

Lipid droplets (LDs), which are active organelles, derive from the monolayer membrane of the endoplasmic reticulum and encapsulate neutral lipids internally. LD-associated proteins like RAB, those in the PLIN family, and those in the CIDE family participate in LD formation and development, and they are active players in various diseases, organelles, and metabolic processes (i.e., obesity, non-alcoholic fatty liver disease, and autophagy). Our synthesis on existing research includes insights from the formation of LDs to their mechanisms of action, to provide an overview needed for advancing research into metabolic diseases and lipid metabolism.

A review on the nexus of autophagy genes from the perspective of polycystic ovary syndrome

Polycystic ovary syndrome or PCOS is an endocrine disorder in women of reproductive age. It is a diversified multi factorial disorder and diagnosis is very complicated because of its overlapping symptoms some of which are irregular menstrual cycle, acne in face, excess level of androgen (AE), insulin resistance, obesity, cardiovascular disease, mood disorder and type 2 diabetes (T2DM). PCOS may be caused by hormonal imbalance, genetic and epigenetic vulnerability, hypothalamic and ovarian troubles. PCOS is essentially hyperandrogenimia with oligo-anovulation. This review explains the abnormal regulation of autophagy related genes and proteins in different cells at various stages which leads to the genesis of PCOS. During nutrient starvation cells face stress condition, which it tries to overcome by activating its macroautophagy mechanism and by degrading the cytoplasmic material. This provides energy to the cell facilitating its survival. Downregulation of autophagy related genes in endometria has been observed in PCOS women. PCOS can be managed by maintaining proper lifestyle and medical treatment. Healthy meals and regular exercise can prevent the excessive weight and also reduce the PCOS complications. Medicines such as metformin, clomiphene, and the oral contraceptive pill can also balance the hormonal level. The imbalance in regulation of autophagy genes has been discussed with correlation to PCOS. The different management strategies for PCOS have also been summarized.

VD3/VDR attenuates bisphenol A-induced impairment in mouse Leydig cells via regulation of autophagy

Bisphenol A (BPA) is an endocrine disruptor with reproductive toxicity. Further, 1,25-dihydroxyvitamin D3 (VD3) plays an important role in male reproduction by binding vitamin D receptor (VDR) and mediating the pleiotropic biological actions that include spermatogenesis. However, whether VD3/VDR regulates the effect of BPA on Leydig cells (LCs) injury remains unknown. This study aimed to explore the effects of VD on BPA-induced cytotoxicity in mouse LCs. Hereby, LCs treated with BPA, VD3, or both were subjected to the assays of cell apoptosis, proliferation, autophagy, and levels of target proteins. This study unveiled that cell viability was dose-dependently reduced after exposure to BPA. BPA treatment significantly inhibited LC proliferation, induced apoptosis, and also downregulated VDR expression. By jointly analyzing transcriptome data and Comparative Toxicogenomics Database (CTD) data, autophagy signaling pathways related to testicular development and male reproduction were screened out. Therefore, the autophagy phenomenon of cells was further detected. The results showed that BPA treatment could activate cell autophagy, Vdr-/- inhibits cell autophagy, and active VD3 does not have a significant effect on the autophagy of normal LCs. After VD3 and BPA were used in combination, the autophagy of cells was further enhanced, and VD3 could alleviate BPA-induced damage of LCs. In conclusion, this study found that supplementing VD3 could eliminate the inhibition of BPA on VDR expression, further enhance LCs autophagy effect, and alleviate the inhibition of LCs proliferation and induction of apoptosis by BPA, playing a protective role in cells. The research results will provide valuable strategies to alleviate BPA-induced reproductive toxicity.

Functional role of autophagy in testicular and ovarian steroidogenesis

Autophagy is an evolutionarily conserved cellular recycling process that maintains cellular homeostasis. Despite extensive research in endocrine contexts, the role of autophagy in ovarian and testicular steroidogenesis remains elusive. The significant role of autophagy in testosterone production suggests potential treatments for conditions like oligospermia and azoospermia. Further, influence of autophagy in folliculogenesis, ovulation, and luteal development emphasizes its importance for improved fertility and reproductive health. Thus, investigating autophagy in gonadal cells is clinically significant. Understanding these processes could transform treatments for endocrine disorders, enhancing reproductive health and longevity. Herein, we provide the functional role of autophagy in testicular and ovarian steroidogenesis to date, highlighting its modulation in testicular steroidogenesis and its impact on hormone synthesis, follicle development, and fertility therapies.

Lipid droplets synthesized during luteinization are degraded after pregnancy

After pregnancy, the corpus luteum (CL) functions as a transient endocrine gland that produces progesterone, which is necessary to maintain pregnancy. To maintain constant progesterone production, CLs are enriched in lipids as its precursors. Lipid droplets (LDs) are organelles that originate from the endoplasmic reticulum and store neutral lipids such as triacylglycerols and cholesteryl esters. The size and number of LDs in a cell are regulated by LD-associated proteins that coat their surface. LD degradation is regulated by either neutral lipid hydrolases (lipolysis), selective autophagic mechanism (lipophagy), or both. Mammalian CLs are long known to be enriched in LDs, but LDs are rapidly depleted after pregnancy and reappear near the time of delivery. In this present study, we hypothesized that LDs synthesized by luteinization are massively degraded after pregnancy. Using mCherry-HPos mice, in which LD synthesis can be visualized in vivo, we found that LD synthesis, which was activated during luteal development, was suppressed after implantation. In CLs, LD synthesis remained low during pregnancy, but was reactivated before and after delivery. These changes in LDs were confirmed using electron microscopy and immunostaining. Furthermore, LD degradation was mediated by lipolysis rather than lipophagy. In summary, our findings indicate that luteinization-induced LD synthesis is suppressed after pregnancy onset and that CLs are lipid-poor during pregnancy because LDs stored during luteal development are extensively degraded by lipolysis.

CIRBP Increases the synthesis and secretion of steroid hormones by in yak granulaso cells

As a regulatory protein that upregulates transcription in response to various stresses, cold-induced RNA-binding protein (CIRBP) is involved in a variety of physiological pathological processes in cells. However, little is known about the role of CIRBP in regulating autophagy and the synthesis and secretion of ovarian steroid hormones (estradiol E2 and progesterone P4). This study aimed to explore whether the synthetic secretion of ovarian steroid hormones is related to CIRBP-regulated autophagy. We detected the differential expression of CIRBP, LC3, E2 and P4 in YGCs cultured at mild low temperature (32 °C) for 6 and 12 h. CIRBP, LC3, E2 and P4 expression was increased in response to low temperature in YGCs. In order to illustrate that the changes in secretion of E2/P4 and autophagy might be caused by CIRBP induced by low temperature, we overexpressed CIRBP in YGCs cultured in vitro to detect its effects on autophagy and steroid hormone synthesis and secretion. We found that overexpression of CIRBP can induce autophagy of YGCs and enhance the synthesis and secretion of E2 and P4, suggesting that mild hypothermia may activate autophagy by inducing the expression of CIRBP and enhance the synthesis and secretion of E2 and P4. To further explore the relationship between CIRBP regulated autophagy and steroid hormone synthesis and secretion, we verified it by regulating autophagy. The results showed that Inhibition of autophagy significantly reversed CIRBP overexpression-enhanced autophagy and synthetic secretion of E2, P4 in YGCs, while activated autophagy showed similar results to overexpression of CIRBP. In conclusion, our data suggest that autophagy is involved in the synthesis and secretion of YGCs E2 and P4 and is associated with overexpression of CIRBP.

Autophagy core protein BECN1 is vital for spermatogenesis and male fertility in mice†

Mammalian spermatogenesis is a highly complex multi-step biological process, and autophagy has been demonstrated to be involved in the process of spermatogenesis. Beclin-1/BECN1, a core autophagy factor, plays a critical role in many biological processes and diseases. However, its function in spermatogenesis remains largely unclear. In the present study, germ cell-specific Beclin 1 (Becn1) knockout mice were generated and were conducted to determine the role of Becn1 in spermatogenesis and fertility of mice. Results indicate that Becn1 deficiency leads to reduced sperm motility and quantity, partial failure of spermiation, actin network disruption, excessive residual cytoplasm, acrosome malformation, and aberrant mitochondrial accumulation of sperm, ultimately resulting in reduced fertility in male mice. Furthermore, inhibition of autophagy was observed in the testes of germ cell-specific Becn1 knockout mice, which may contribute to impaired spermiogenesis and reduced fertility. Collectively, our results reveal that Becn1 is essential for fertility and spermiogenesis in mice.

Cisplatin Nephrotoxicity Is Critically Mediated by the Availability of BECLIN1

Cisplatin nephrotoxicity is a critical limitation of solid cancer treatment. Until now, the complex interplay of various pathophysiological mechanisms leading to proximal tubular cell apoptosis after cisplatin exposure has not been fully understood. In our study, we assessed the role of the autophagy-related protein BECLIN1 (ATG6) in cisplatin-induced acute renal injury (AKI)-a candidate protein involved in autophagy and with putative impact on apoptosis by harboring a B-cell lymphoma 2 (BCL2) interaction site of unknown significance. By using mice with heterozygous deletion of Becn1, we demonstrate that reduced intracellular content of BECLIN1 does not impact renal function or autophagy within 12 months. However, these mice were significantly sensitized towards cisplatin-induced AKI, and by using Becn1+/-;Sglt2-Cre;Tomato/EGFP mice with subsequent primary cell analysis, we confirmed that nephrotoxicity depends on proximal tubular BECLIN1 content. Mechanistically, BECLIN1 did not impact autophagy or primarily the apoptotic pathway. In fact, a lack of BECLIN1 sensitized mice towards cisplatin-induced ER stress. Accordingly, the ER stress inhibitor tauroursodeoxycholic acid (TUDCA) blunted cisplatin-induced cell death in Becn1 heterozygosity. In conclusion, our data first highlight a novel role of BECLIN1 in protecting against cellular ER stress independent from autophagy. These novel findings open new therapeutic avenues to intervene in this important intracellular stress response pathway with a promising impact on future AKI management.

Resveratrol-βcd inhibited premature ovarian insufficiency progression by regulating granulosa cell autophagy

BACKGROUND

The ovarian environment of premature ovarian insufficiency (POI) patients exhibits immune dysregulation, which leads to excessive secretion of numerous proinflammatory cytokines that affect ovarian function. An abnormal level of macrophage polarization directly or indirectly inhibits the differentiation of ovarian granulosa cells and steroid hormone production, ultimately leading to POI. Resveratrol, as a health supplement, has been widely recognized for its safety. There is a substantial amount of evidence indicating that resveratrol and its analogs possess significant immune-regulatory functions. It has also been reported that resveratrol can effectively inhibit the progression of POI. However, the underlying immunological and molecular mechanisms through which resveratrol inhibits the progression of POI are still unclear.

RESULTS

Our preliminary reports have shown that resveratrol-βcd, the beta-cyclodextrin complex of resveratrol, significantly enhances the stability of resveratrol. Resveratrol-βcd could regulate the dysfunctional immune status of macrophages and T cells in the tumor microenvironment. In this study, we treated busulfan and cyclophosphamide (B/C)-treated mice, which were used as a POI model, with resveratrol-βcd. After resveratrol-βcd treatment, the levels of IL-6 in the ovaries were significantly increased, and the progression of POI was suppressed. IL-6 activated granulosa cells (GCs) through soluble IL-6R (sIL-6R), promoting autophagy in GCs. Resveratrol-βcd and IL-6 had a synergistic effect on enhancing autophagy in GCs and promoting E2 secretion.

CONCLUSIONS

We partially elucidated the immune mechanism by which resveratrol inhibits the progression of POI and the autophagy-regulating function of GCs. This provides a theoretical basis for using resveratrol to prevent POI in future studies and clinical guidance.

Increased IGFBP2 Levels by Placenta-Derived Mesenchymal Stem Cells Enhance Glucose Metabolism in a TAA-Injured Rat Model via AMPK Signaling Pathway

The insulin resistance caused by impaired glucose metabolism induces ovarian dysfunction due to the central importance of glucose as a source of energy. However, the research on glucose metabolism in the ovaries is still lacking. The objectives of this study were to analyze the effect of PD-MSCs on glucose metabolism through IGFBP2-AMPK signaling and to investigate the correlation between glucose metabolism and ovarian function. Thioacetamide (TAA) was used to construct a rat injury model. PD-MSCs were transplanted into the tail vein (2 × 106) 8 weeks after the experiment started. The expression of the IGFBP2 gene and glucose metabolism factors (e.g., AMPK, GLUT4) was significantly increased in the PD-MSC group compared to the nontransplantation (NTx) group (* p < 0.05). The levels of follicular development markers and the sex hormones AMH, FSH, and E2 were also higher than those in the TAA group. Using ex vivo cocultivation, the mRNA and protein expression of IGFBP2, AMPK, and GLUT4 were significantly increased in the cocultivation with the PD-MSCs group and the recombinant protein-treated group (* p < 0.05). These findings suggest that the increased IGFBP2 levels by PD-MSCs play an important role in glucose metabolism and ovarian function through the IGFBP2-AMPK signaling pathway.

Activation of Atg5-dependent placental lipophagy ameliorates cadmium-induced fetal growth restriction

Cadmium (Cd), an environmental contaminant, can result in placental non-selective autophagy activation and fetal growth restriction (FGR). However, the role of placental lipophagy, a selective autophagy, in Cd-induced FGR is unclear. This work uses case-control study, animal experiments and cultures of primary human placental trophoblast cells to explore the role of placental lipophagy in Cd-induced FGR. We found association of placental lipophagy and all-cause FGR. Meanwhile, pregnancy Cd exposure induced FGR and placental lipophgay. Inhibition of placental lipophagy by pharmacological and genetic means (Atg5^-/- mice) exacerbated Cd-caused FGR. Inversely, activating of placental lipophagy relieved Cd-stimulated FGR. Subsequently, we found that activation of Atg5-dependent lipophagy degrades lipid droplets to produce free cholesterol, and promotes placental progesterone (P4) synthesis. Gestational P4 supplementation significantly reversed Cd-induced FGR. Altogether, activation of Atg5-dependent placental lipophagy ameliorates Cd-induced FGR.

Autophagy regulates sex steroid hormone synthesis through lysosomal degradation of lipid droplets in human ovary and testis

Autophagy is an evolutionarily conserved process that aims to maintain the energy homeostasis of the cell by recycling long-lived proteins and organelles. Previous studies documented the role of autophagy in sex steroid hormone biosynthesis in different animal models and human testis. Here we demonstrate in this study that sex steroid hormones estrogen and progesterone are produced through the same autophagy-mediated mechanism in the human ovary in addition to the human testis. In brief, pharmacological inhibition and genetic interruption of autophagy through silencing of autophagy genes (Beclin1 and ATG5) via siRNA and shRNA technologies significantly reduced basal and gonadotropin-stimulated estradiol (E₂), progesterone (P₄) and testosterone (T) production in the ex vivo explant tissue culture of ovary and testis and primary and immortalized granulosa cells. Consistent with the findings of the previous works, we observed that lipophagy, a special form of autophagy, mediates the association of the lipid droplets (LD)s with lysosome to deliver the lipid cargo within the LDs to lysosomes for degradation in order to release free cholesterol required for steroid synthesis. Gonadotropin hormones are likely to augment the production of sex steroid hormones by upregulating the expression of autophagy genes, accelerating autophagic flux and promoting the association of LDs with autophagosome and lysosome. Moreover, we detected some aberrations at different steps of lipophagy-mediated P₄ production in the luteinized GCs of women with defective ovarian luteal function. The progression of autophagy and the fusion of the LDs with lysosome are markedly defective, along with reduced P₄ production in these patients. Our data, together with the findings of the previous works, may have significant clinical implications by opening a new avenue in understanding and treatment of a wide range of diseases, from reproductive disorders to sex steroid-producing neoplasms, sex steroid-dependent malignancies (breast, endometrium, prostate) and benign disorders (endometriosis).

Beclin-1-dependent autophagy, but not apoptosis, is critical for stem-cell-mediated endometrial programming and the establishment of pregnancy

The human endometrium shows a remarkable regenerative capacity that enables cyclical regeneration and remodeling throughout a woman's reproductive life. Although early postnatal uterine developmental cues direct this regeneration, the vital factors that govern early endometrial programming are largely unknown. We report that Beclin-1, an essential autophagy-associated protein, plays an integral role in uterine morphogenesis during the early postnatal period. We show that conditional depletion of Beclin-1 in the uterus triggers apoptosis and causes progressive loss of Lgr5+/Aldh1a1+ endometrial progenitor stem cells, with concomitant loss of Wnt signaling, which is crucial for stem cell renewal and epithelial gland development. Beclin-1 knockin (Becn1 KI) mice with disabled apoptosis exhibit normal uterine development. Importantly, the restoration of Beclin-1-driven autophagy, but not apoptosis, promotes normal uterine adenogenesis and morphogenesis. Together, the data suggest that Beclin-1-mediated autophagy acts as a molecular switch that governs the early uterine morphogenetic program by maintaining the endometrial progenitor stem cells.

Role of Macroautophagy in Mammalian Male Reproductive Physiology

Physiologically, autophagy is an evolutionarily conserved and self-degradative process in cells. Autophagy carries out normal physiological roles throughout mammalian life. Accumulating evidence shows autophagy as a mechanism for cellular growth, development, differentiation, survival, and homeostasis. In male reproductive systems, normal spermatogenesis and steroidogenesis need a balance between degradation and energy supply to preserve cellular metabolic homeostasis. The main process of autophagy includes the formation and maturation of the phagophore, autophagosome, and autolysosome. Autophagy is controlled by a group of autophagy-related genes that form the core machinery of autophagy. Three types of autophagy mechanisms have been discovered in mammalian cells: macroautophagy, microautophagy, and chaperone-mediated autophagy. Autophagy is classified as non-selective or selective. Non-selective macroautophagy randomly engulfs the cytoplasmic components in autophagosomes that are degraded by lysosomal enzymes. While selective macroautophagy precisely identifies and degrades a specific element, current findings have shown the novel functional roles of autophagy in male reproduction. It has been recognized that dysfunction in the autophagy process can be associated with male infertility. Overall, this review provides an overview of the cellular and molecular basics of autophagy and summarizes the latest findings on the key role of autophagy in mammalian male reproductive physiology.

The Role of Autophagy in the Female Reproduction System: For Beginners to Experts in This Field

Autophagy is a fundamental process involved in regulating cellular homeostasis. Autophagy has been classically discovered as a cellular process that degrades cytoplasmic components non-selectively to produce energy. Over the past few decades, this process has been shown to work in energy production, as well as in the reduction of excessive proteins, damaged organelles, and membrane trafficking. It contributes to many human diseases, such as neurodegenerative diseases, carcinogenesis, diabetes mellitus, development, longevity, and reproduction. In this review, we provide important information for interpreting results related to autophagic experiments and present the role of autophagy in this field.

1α,25(OH)2D3 Promotes the Autophagy of Porcine Ovarian Granulosa Cells as a Protective Mechanism against ROS through the BNIP3/PINK1 Pathway

Vitamin D (VD) is one of the important nutrients required by livestock; however, VD deficiency is reported to be widespread. Earlier studies have suggested a potential role for VD in reproduction. Studies on the correlation between VD and sow reproduction are limited. The aim of the current study was aimed to determine the role of 1,25-dihydroxy vitamin D₃ (1α,25(OH)₂D₃) on porcine ovarian granulosa cells (PGCs) in vitro to provide a theoretical basis for improving the reproductive efficiency of sows. We used chloroquine (autophagy inhibitor) and reactive oxygen species (ROS) scavenger N-acetylcysteine in conjunction with 1α,25(OH)₂D₃ to explore the effect on PGCs. The results showed that 10 nM of 1α,25(OH)₂D₃ increased PGC viability and ROS content. In addition, 1α,25(OH)₂D₃ induces PGC autophagy according to the gene transcription and protein expression levels of LC3, ATG7, BECN1, and SQSTM1 and promotes the generation of autophagosomes. 1α,25(OH)₂D₃-induced autophagy affects the synthesis of E₂ and P₄ in PGCs. We investigated the relationship between ROS and autophagy, and the results showed that 1α,25(OH)₂D₃-induced ROS promoted PGC autophagy. The ROS-BNIP3-PINK1 pathway was involved in PGC autophagy induced by 1α,25(OH)₂D₃. In conclusion, this study suggests that 1α,25(OH)₂D₃ promotes PGC autophagy as a protective mechanism against ROS via the BNIP3/PINK1 pathway.

Epg5 deficiency leads to primary ovarian insufficiency due to WT1 accumulation in mouse granulosa cells

Primary ovarian insufficiency (POI), also known as premature ovarian failure, is an ovarian defect in humans characterized by the premature depletion of ovarian follicles before the age of 40. However, the mechanisms underlying POI remain largely unknown. Here, we show that knockout of Epg5 (ectopic P-granules autophagy protein 5 homolog (C. elegans)) results in subfertility in female mice, which exhibit a POI-like phenotype. Single-cell RNA sequencing analysis revealed that the knockout of Epg5 affected the differentiation of granulosa cells (GCs). Further investigation demonstrated that knockout of Epg5 blocks macroautophagic/autophagic flux, resulting in the accumulation of WT1 (WT1 transcription factor), an essential transcription factor for GCs, suggesting WT1 needs to be selectively degraded by the autophagy pathway. We found that the insufficient degradation of WT1 in the antral follicular stage contributes to reduced expression of steroidogenesis-related genes, thereby disrupting GC differentiation. Collectively, our studies show that EPG5 promotes WT1 degradation in GCs, indicating that the dysregulation of Epg5 in GCs can trigger POI pathogenesis.Abbreviations: 3-MA, 3-methyladenine; CHX, cycloheximide; CQ, chloroquine; EPG5, ectopic P-granules autophagy protein 5 homolog (C. elegans); GC, granulosa cell; MAP1LC3/LC3, microtubule-associated protein 1 light chain 3; MII, metaphase II; POI, primary ovarian insufficiency; PB1, polar body 1; SQSTM1/p62, sequestosome 1; WT1, WT1 transcription factor.

Selective autophagic degradation of ACLY (ATP citrate lyase) maintains citrate homeostasis and promotes oocyte maturation

Macroautophagy/autophagy is a cellular and energy homeostatic mechanism that contributes to maintain the number of primordial follicles, germ cell survival, and anti-ovarian aging. However, it remains unknown whether autophagy in granulosa cells affects oocyte maturation. Here, we show a clear tendency of reduced autophagy level in human granulosa cells from women of advanced maternal age, implying a potential negative correlation between autophagy levels and oocyte quality. We therefore established a co-culture system and show that either pharmacological inhibition or genetic ablation of autophagy in granulosa cells negatively affect oocyte quality and fertilization ability. Moreover, our metabolomics analysis indicates that the adverse impact of autophagy impairment on oocyte quality is mediated by downregulated citrate levels, while exogenous supplementation of citrate can significantly restore the oocyte maturation. Mechanistically, we found that ACLY (ATP citrate lyase), which is a crucial enzyme catalyzing the cleavage of citrate, was preferentially associated with K63-linked ubiquitin chains and recognized by the autophagy receptor protein SQSTM1/p62 for selective autophagic degradation. In human follicles, the autophagy level in granulosa cells was downregulated with maternal aging, accompanied by decreased citrate in the follicular fluid, implying a potential correlation between citrate metabolism and oocyte quality. We also show that elevated citrate levels in porcine follicular fluid promote oocyte maturation. Collectively, our data reveal that autophagy in granulosa cells is a beneficial mechanism to maintain a certain degree of citrate by selectively targeting ACLY during oocyte maturation.Abbreviations: 3-MA: 3-methyladenine; ACLY: ATP citrate lyase; AMA: advanced maternal age; CG: cortical granule; CHX: cycloheximide; CQ: chloroquine; CS: citrate synthase; COCs: cumulus-oocyte-complexes; GCM: granulosa cell monolayer; GV: germinal vesicle; MII: metaphase II stage of meiosis; PB1: first polar body; ROS: reactive oxygen species; shRNA: small hairpin RNA; SQSTM1/p62: sequestosome 1; TCA: tricarboxylic acid; TOMM20/TOM20: translocase of outer mitochondrial membrane 20; UBA: ubiquitin-associated domain; Ub: ubiquitin; WT: wild-type.

Genes linked with early menopause and the pathogenesis of its associated diseases: a systematic review

Background

Menopause is a biological process when a woman’s reproductive capability is no longer functional. A naturally or artificially caused premenopausal is known as early menopause occurs between the ages 40–45, which substantially impacts fertility and disease influenced by genetic plus environmental factors and their interactions. Women in early menopause are at greater risk of cardiovascular disease, general mortality, neurological disorders, osteoporosis, mental illness, and other problems.

Main body

A PubMed search of the electronic literature database yielded articles on early menopause and disease etiology. Several unique genes were identified, such as ESR1, ESR2, CYP1B1, BRSK1, HK3, andTMEM150B are associated with early menopause, and research focused on case-control, cohort, and cross-sectional studies are finding novel predisposition loci for early menopause.

Conclusion

The current study’s focus is to understand better the genetic aspects of early menopause. This knowledge will help researchers enhance EM etiology and identify biomarkers that may detect early development of the disease, allowing women at risk to begin family planning earlier.

Apoptosis, autophagic cell death, and necroptosis: different types of programmed cell death in bovine corpus luteum regression

In mammals, the corpus luteum (CL) is a transient organ that secretes progesterone (P4). In the absence of pregnancy, the CL undergoes regression (luteolysis), which is a crucial preparation step for the next estrous cycle. Luteolysis, initiated by uterine prostaglandin F_2α (PGF) in cattle, is usually divided into two phases, namely functional luteolysis characterized by a decline in P4 concentration and structural luteolysis characterized by the elimination of luteal tissues from the ovary. Programmed cell death (PCD) of luteal cells, including luteal steroidogenic cells (LSCs) and luteal endothelial cells (LECs), plays a crucial role in structural luteolysis. The main types of PCD are caspase-dependent apoptosis (type 1), autophagic cell death (ACD) via the autophagy-related gene (ATG) family (type 2), and receptor-interacting protein kinase (RIPK)-dependent programmed necrosis (necroptosis, type 3). However, these PCD signaling pathways are not completely independent and interact with each other. Over the past several decades, most studies on luteolysis have focused on apoptosis as the principal mode of bovine luteal cell death. Recently, ATG family members were reported to be expressed in bovine CL, and their levels increased during luteolysis. Furthermore, the expression of RIPKs, which are crucial mediators of necroptosis, is reported to increase in bovine CL during luteolysis and is upregulated by pro-inflammatory cytokines in bovine LSCs and LECs. Therefore, apoptosis, ACD, and necroptosis may contribute to bovine CL regression. In this article, we present the recent findings regarding the mechanisms of the three main types of PCD and the contribution of these mechanisms to luteolysis.

High Fat-High Fructose Diet Elicits Hypogonadotropism Culminating in Autophagy-Mediated Defective Differentiation of Ovarian Follicles

Pituitary gonadotropins directly govern ovarian functions, which are in turn regulated by the ovarian steroid hormones. The precise interplay of gonadotropins and steroid hormones is critical for follicle growth and differentiation. Furthermore, autophagy regulates ovarian follicle differentiation. However, how the high-fat-high fructose (HFD-HF) diet regulates gonadotropins and facilitates autophagy-mediated follicular differentiation in the ovary is obscure. We fed prepubertal rats (PND 25) an HFD-HF diet until PND 90. The results showed diminished adenohypophyseal GnRHR, PR, and aromatase expression, whereas AR, ERα, PRLR, and inhibin were augmented, resulting in gonadotropins decline. Interestingly, autophagy biomarkers, Beclin-1, ATG5, ATG12, LC3-II, and LAMP1 were reduced but SQSTM1/p62 was augmented in the ovaries of HFD-HF-fed rats, causing autolysosome to aggregation. The diet altered T, E2, P4, PRL, and their receptors status in the ovary, disturbed estrous cyclicity, and delayed vaginal opening. Ovarian histomorphology exhibited numerous cystic and atretic follicles, along with disturbed follicular maturation and ovulation. Moreover, the reduction of FSHR; steroidogenic proteins; receptor proteins AR, ERβ, PR; and signaling proteins Wnt2 and β-catenin was also noticed in the ovary, whereas PRLR, inhibin, and pGSK3β were augmented. In conclusion, exposure to a prepubertal HFD-HF diet leads to hypogonadotropism and the autophagy-mediated defective differentiation of ovarian follicles, abating fertility in adult rats.

Effect of rapamycin treatment on oocyte in vitro maturation and embryonic development after parthenogenesis in yaks

Autophagy plays an important role in mammalian oocyte maturation and early embryonic development and rapamycin is well known for inducing autophagy. Although previous studies have reported the effects of rapamycin on oocytes in vitro maturation (IVM) in different species, few studies have been reported on the role of rapamycin in yak oocytes IVM and embryonic development. Therefore, the objective of this study was to examine the effect of rapamycin treatment on yak oocytes IVM and early embryonic development. Specifically, immature yak oocytes during IVM or parthenogenetic (PA) embryos were treated with different rapamycin concentrations to select an optimal dose. Then evaluated its effect on maturation rates, cleavage, and blastocyst formation rates, mitochondrial membrane potential, ROS levels. Related genes and proteins expression in matured oocytes and blastocysts were also evaluated. The results show that 10 nM rapamycin treatment during IVM significantly improved oocyte maturation rates of oocytes and blastocyst formation rates. Treatment with 10 nM rapamycin reduced ROS level but increased mitochondrial membrane potential. Correspondingly, mRNA and protein expressions of LC3, Beclin-1, and Bcl-2 up-regulated while Bax down-regulated in matured yak COCs. When parthenogenetic embryos were treated with different rapamycin concentrations, 10 nM rapamycin treatment showed higher 8-cell and blastocyst formation rates. Also, CDX2, POU5F1, SOX2, and Nanog levels in blastocysts were upregulated. In summary, our findings demonstrate that rapamycin treatment improves oocytes maturation probably by increasing mitochondrial membrane potential, reducing ROS levels, and regulating the apoptosis in mature yak oocytes. Rapamycin treatment also improves embryonic developmental competence in the yak.

The intracellular cholesterol pool in steroidogenic cells plays a role in basal steroidogenesis

The framework of steroidogenesis across steroidogenic cells is constructed around cholesterol - the precursor substrate molecule for all steroid hormones - including its cellular uptake, storage in intracellular lipid droplets, mobilization upon steroidogenic stimulation, and finally, its transport to the mitochondria, where steroidogenesis begins. Thus, cholesterol and the mitochondria are highly interconnected in steroidogenic cells. Moreover, accruing evidence suggests that autophagy and mitochondrial dynamics are important cellular events in the regulation of trophic hormone-induced cholesterol homeostasis and steroidogenesis. However, a potential role of cholesterol in itself in the regulation of steroidogenic factors and events remain largely unexplored. We tested the hypothesis that cholesterol plays a role in the regulation of cell-intrinsic factors and events involving steroidogenesis. Here, we show that depleting the intracellular cholesterol pool in steroidogenic cells induces autophagy, affects mitochondrial dynamics, and upregulates steroidogenic factors and basal steroidogenesis in three different steroidogenic cell types producing different steroid hormones. Notably, the cholesterol insufficiency-induced changes in different steroidogenic cell types occur independent of pertinent hormone stimulation and work in a dynamic and temporal manner with or without hormonal stimulation. Such effects of cholesterol deprivation on autophagy and mitochondrial dynamics were not observed in the non-steroidogenic cells, indicating that cholesterol insufficiency-induced changes in steroidogenic cells are specific to steroidogenesis. Thus, our data suggests a role of cholesterol in steroidogenesis beyond being a mere substrate for steroid hormones. The implications of our findings are broad and offer new insights into trophic hormone-dependent and hormone-independent steroidogenesis during development, as well as in health and disease.

Autophagy participates in germline cyst breakdown and follicular formation by modulating glycolysis switch via Akt signaling in newly-hatched chicken ovaries

In females, the establishment of the primordial follicle pool is accompanied by a remarkable programmed oocyte loss for unclear reasons. In this study, the role of autophagy was investigated to serve as a protective mechanism for oocyte survival during chicken folliculogenesis. Inhibition of autophagy by 3-methyladenine (3-MA) led to a remarkable delay in germ cell cyst breakdown that resulted in fewer primordial follicles and retarded sequent follicular development either in vivo or in the ovarian organ culture. Furthermore, the glycolysis level was downregulated in ovaries treated with 3-MA, while Recilisib (a specific activator of Akt) reversed this inhibiting effect of 3-MA on primordial folliculogenesis. Collectively, these data indicate that autophagy functions to maintain germ cell cyst breakdown and primordial follicle assembly by regulating ovarian glycolysis involving Akt signaling in the ovaries of newly-hatched chickens.

Beclin1-mediated interplay between autophagy and apoptosis: New understanding

The definition for autophagy holds a 'single' meaning as a conserved cellular process that constitutes a recycling pathway for damaged organelles and long-lived proteins to maintain nutrient homeostasis and mediate quality control within the cell. But this process of autophagy may behave ambiguously depending on the physiological stress as the stress progresses in the cellular microenvironment; the 'single' meaning of the autophagy changes from the 'cytoplasmic turnover process' to 'tumor suppressive' and a farther extent, 'tumor promoter' process. In a tumorigenic state, the chemotherapy-mediated resistance and intolerance due to upregulated autophagy in cancer cells have become a significant concern. This concern has provided insight to the scientific community to enter into the arena of cross-talk between autophagy and apoptosis. Recent findings and ongoing research have provided insights on some of the key regulators of this cross-talk; one of them is Beclin1 and their involvement in the physiological and the pathophysiological processes; however, reconciliation of these two forms of death remains an arena to be explored extensively. This review sheds light on the interplay between autophagy and apoptosis, emphasizing one of the key players, Beclin1, and its importance in health and diseases.

BECLIN1 Is Essential for Podocyte Secretory Pathways Mediating VEGF Secretion and Podocyte-Endothelial Crosstalk

Vascular endothelial growth factor A (VEGFA) secretion from podocytes is crucial for maintaining endothelial integrity within the glomerular filtration barrier. However, until now, the molecular mechanisms underlying podocyte secretory function remained unclear. Through podocyte-specific deletion of BECLIN1 (ATG6 or Becn1), a key protein in autophagy initiation, we identified a major role for this molecule in anterograde Golgi trafficking. The Becn1-deficient podocytes displayed aberrant vesicle formation in the trans-Golgi network (TGN), leading to dramatic vesicle accumulation and complex disrupted patterns of intracellular vesicle trafficking and membrane dynamics. Phenotypically, podocyte-specific deletion of Becn1 resulted in early-onset glomerulosclerosis, which rapidly progressed and dramatically reduced mouse life span. Further, in vivo and in vitro studies clearly showed that VEGFA secretion, and thereby endothelial integrity, greatly depended on BECLIN1 availability and function. Being the first to demonstrate the importance of a secretory pathway for podocyte integrity and function, we identified BECLIN1 as a key component in this complex cellular process. Functionally, by promoting VEGFA secretion, a specific secretory pathway emerged as an essential component for the podocyte-endothelial crosstalk that maintains the glomerular filtration barrier.

Exposure to benzo(a)pyrene suppresses mitophagy via ANT1-PINK1-Parkin pathway in ovarian corpus luteum during early pregnancy

Exposure to benzo (a)pyrene (BaP) has been confirmed to interfere with embryo implantation. As the primary organ of progesterone synthesis during early pregnancy, the ovarian corpus luteum (CL) is essential for embryo implantation and pregnancy maintenance. We previously demonstrated that BaP impaired luteal function, but the molecular mechanism remains unclear. In CL cells, mitochondria are the main sites of progesterone synthesis. Mitophagy, a particular type of autophagy, regulates mitochondrial quality by degrading damaged mitochondria and ensuring the homeostasis of cell physiology. Therefore, the present study investigated the effects and the potential molecular mechanisms of BaP on ovarian mitophagy during early pregnancy. We found that BaP and its metabolite, BPDE, inhibited autophagy and PINK1/Parkin-mediated mitophagy in the pregnant ovaries and luteinized granulosa cell, KGN. Notably, adenine nucleotide translocator 1 (ANT1), a crucial mediator of PINK1-dependent mitophagy, was suppressed by BaP and BPDE both in vivo and in vitro. The inhibition of ANT1 leads to the decrease in the PINK1 bound to the outer membrane of mitochondria and consequently reduces recruitment of Parkin to the mitochondria, which is required for the subsequent clearance of mitochondria. Meanwhile, exposure to BPDE also damaged mitochondrial function, causing the reduction in mitochondrial potential and ATP production. Overexpression of ANT1 in KGN cells partially relieved the inhibition of mitophagy caused by BPDE, restored mitochondrial function and expression of hormone synthesis-associated genes. Collectively, our study firstly clarified that BaP and BPDE suppress mitophagy of CL cells via the ANT1-PINK1-Parkin pathway, which provides a new insight to explore the detailed mechanism of the BaP-induced ovarian toxicity.

Autophagy regulates differentiation of ovarian granulosa cells through degradation of WT1

Ovarian granulosa cells (GCs) proliferate and differentiate along with follicular growth, and this is indispensable for oocyte development and female fertility. Although the role of macroautophagy/autophagy in ovarian function has been reported, its contribution to the regulation of GC characteristics remains elusive. The siRNA-mediated knockdown of two key autophagy-related genes ATG5 and BECN1 and the autophagy inhibitor chloroquine were used to interfere with autophagy in GCs. Inhibition of autophagy both genetically and pharmacologically resulted in decreased expression of genes associated with GC differentiation, including CYP19A1/Aromatase and FSHR, as well as in reduced estradiol synthesis. Mechanistically, when autophagy was disrupted, the transcription factor WT1 accumulated in GCs due to its insufficient degradation by the autophagic pathway, and this inhibited GC differentiation. Finally, decreased expression of several autophagy-related genes, as well as reduced LC3-II:LC3-I and elevated SQSTM1/p62 protein levels, which are indications of decreased autophagy, were detected in GCs from biochemical premature ovarian insufficiency patients. In summary, our study reveals that autophagy regulates the differentiation of ovarian GCs by degrading WT1 and that insufficient autophagy might be involved in ovarian dysfunction.

Autophagy: a multifaceted player in the fate of sperm

BACKGROUND

Autophagy is an intracellular catabolic process of degrading and recycling proteins and organelles to modulate various physiological and pathological events, including cell differentiation and development. Emerging data indicate that autophagy is closely associated with male reproduction, especially the biosynthetic and catabolic processes of sperm. Throughout the fate of sperm, a series of highly specialized cellular events occur, involving pre-testicular, testicular and post-testicular events. Nonetheless, the most fundamental question of whether autophagy plays a protective or harmful role in male reproduction, especially in sperm, remains unclear.

OBJECTIVE AND RATIONALE

We summarize the functional roles of autophagy in the pre-testicular (hypothalamic–pituitary–testis (HPG) axis), testicular (spermatocytogenesis, spermatidogenesis, spermiogenesis, spermiation) and post-testicular (sperm maturation and fertilization) processes according to the timeline of sperm fate. Additionally, critical mechanisms of the action and clinical impacts of autophagy on sperm are identified, laying the foundation for the treatment of male infertility.

SEARCH METHODS

In this narrative review, the PubMed database was used to search peer-reviewed publications for summarizing the functional roles of autophagy in the fate of sperm using the following terms: ‘autophagy’, ‘sperm’, ‘hypothalamic–pituitary–testis axis’, ‘spermatogenesis’, ‘spermatocytogenesis’, ‘spermatidogenesis’, ‘spermiogenesis’, ‘spermiation’, ‘sperm maturation’, ‘fertilization’, ‘capacitation’ and ‘acrosome’ in combination with autophagy-related proteins. We also performed a bibliographic search for the clinical impact of the autophagy process using the keywords of autophagy inhibitors such as ‘bafilomycin A1’, ‘chloroquine’, ‘hydroxychloroquine’, ‘3-Methyl Adenine (3-MA)’, ‘lucanthone’, ‘wortmannin’ and autophagy activators such as ‘rapamycin’, ‘perifosine’, ‘metformin’ in combination with ‘disease’, ‘treatment’, ‘therapy’, ‘male infertility’ and equivalent terms. In addition, reference lists of primary and review articles were reviewed for additional relevant publications. All relevant publications until August 2021 were critically evaluated and discussed on the basis of relevance, quality and timelines.

OUTCOMES

(i) In pre-testicular processes, autophagy-related genes are involved in the regulation of the HPG axis; and (ii) in testicular processes, mTORC1, the main gate to autophagy, is crucial for spermatogonia stem cell (SCCs) proliferation, differentiation, meiotic progression, inactivation of sex chromosomes and spermiogenesis. During spermatidogenesis, autophagy maintains haploid round spermatid chromatoid body homeostasis for differentiation. During spermiogenesis, autophagy participates in acrosome biogenesis, flagella assembly, head shaping and the removal of cytoplasm from elongating spermatid. After spermatogenesis, through PDLIM1, autophagy orchestrates apical ectoplasmic specialization and basal ectoplasmic specialization to handle cytoskeleton assembly, governing spermatid movement and release during spermiation. In post-testicular processes, there is no direct evidence that autophagy participates in the process of capacitation. However, autophagy modulates the acrosome reaction, paternal mitochondria elimination and clearance of membranous organelles during fertilization.

WIDER IMPLICATIONS

Deciphering the roles of autophagy in the entire fate of sperm will provide valuable insights into therapies for diseases, especially male infertility.

Autophagy in ovary and polycystic ovary syndrome: role, dispute and future perspective

Polycystic ovary syndrome (PCOS) is a unification of endocrine and metabolic disorders and has become immensely prevalent among women of fertile age. The prime organ affected in PCOS is the ovary and its distressed functioning elicits disturbed reproductive outcomes. In the ovary, macroautophagy/autophagy performs a pivotal role in directing the chain of events starting from oocytes origin until its fertilization. Recent discoveries demonstrate a significant role of autophagy in the pathogenesis of PCOS. Defective autophagy in the follicular cells during different stages of follicles is observed in the PCOS ovary. Exploring different autophagy pathways provides a platform for predicting the possible cause of altered ovarian physiology in PCOS. In this review, we have emphasized autophagy's role in governing follicular development under normal circumstances and in PCOS, including significant abnormalities associated with PCOS such as anovulation, hyperandrogenemia, metabolic disturbances, and related abnormality. So far, few studies have linked autophagy and PCOS and propose its essential role in PCOS progression. However, detailed knowledge in this area is lacking. Here we have summarized the latest knowledge related to autophagy associated with PCOS. This review's main objective is to provide a background of autophagy in the ovary, its possible connection with PCOS and suggested a novel proposal for future studies to aid a better understanding of PCOS pathogenesis.Abbreviations: AE: androgen excess; AF: antral follicle; AKT/PKB: AKT serine/threonine kinase; AMH: anti-Mullerian hormone; AMPK: AMP-activated protein kinase; ATG: autophagy-related; BCL2: BCL2 apoptosis regulator; BECN1: beclin 1; BMP: bone morphogenetic protein; CASP3: caspase 3; CL: corpus luteum; CYP17A1/P450C17: cytochrome P450 family 17 subfamily A member 1; CYP19A1: cytochrome P450 family 19 subfamily A member 1; DHEA: dehydroepiandrosterone; EH: endometrial hyperplasia; FF: follicular fluid; FOXO: forkhead box O; FSH: follicle stimulating hormone; GC: granulosa cell; GDF: growth differentiation factor; HA: hyperandrogenemia; HMGB1: high mobility group box 1; IGF1: insulin like growth factor 1; INS: insulin; IR: insulin resistance; LHCGR/LHR: luteinizing hormone/choriogonadotropin receptor; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MAPK/ERK: mitogen-activated protein kinase; MAPK8/JNK: mitogen-activated protein kinase 8; MTOR: mechanistic target of rapamycin kinase; MTORC: mechanistic target of rapamycin complex; NAFLD: nonalcoholic fatty liver disease; NFKB: nuclear factor kappa B; OLR1/LOX-1: oxidized low density lipoprotein receptor 1; oxLDL: oxidized low-density lipoproteins; PA: palmitic acid; PCOS: polycystic ovary syndrome; PF: primary follicle; PGC: primordial germ cell; PI3K: phosphoinositide 3-kinase; PMF: primordial follicle; ROS: reactive oxygen species; RP: resting pool; SIRT1: sirtuin 1; SQSTM1/p62: sequestosome 1; T2DM: type 2 diabetes mellitus; TC: theca cell; TUG1: taurine up-regulated 1.

Integrated Analysis of Transcriptome and Histone Modifications in Granulosa Cells During Ovulation in Female Mice

The ovulatory luteinizing hormone (LH) surge induces rapid changes of gene expression and cellular functions in granulosa cells (GCs) undergoing luteinization. However, it remains unclear how the changes in genome-wide gene expression are regulated. H3K4me3 histone modifications are involved in the rapid alteration of gene expression. In this study, we investigated genome-wide changes of transcriptome and H3K4me3 status in mouse GCs undergoing luteinization. GCs were obtained from mice treated with equine chorionic gonadotropin (hCG) before, 4 hours, and 12 hours after human chorionic gonadotropin injection. RNA-sequencing identified a number of upregulated and downregulated genes, which could be classified into 8 patterns according to the time-course changes of gene expression. Many genes were transiently upregulated or downregulated at 4 hours after hCG stimulation. Gene Ontology terms associated with these genes included steroidogenesis, ovulation, cumulus-oocyte complex (COC) expansion, angiogenesis, immune system, reactive oxygen species (ROS) metabolism, inflammatory response, metabolism, and autophagy. The cellular functions of DNA repair and cell growth were newly identified as being activated during ovulation. Chromatin immunoprecipitation-sequencing revealed a genome-wide and rapid change in H3K4me3 during ovulation. Integration of transcriptome and H3K4me3 data identified many H3K4me3-associated genes that are involved in steroidogenesis, ovulation, COC expansion, angiogenesis, inflammatory response, immune system, ROS metabolism, lipid and glucose metabolism, autophagy, and regulation of cell size. The present results suggest that genome-wide changes in H3K4me3 after the LH surge are associated with rapid changes in gene expression in GCs, which enables GCs to acquire a lot of cellular functions within a short time that are required for ovulation and luteinization.

Prostaglandin E2 Receptor 4 (EP4) Affects Trophoblast Functions via Activating the cAMP-PKA-pCREB Signaling Pathway at the Maternal-Fetal Interface in Unexplained Recurrent Miscarriage

Implantation consists of a complex process based on coordinated crosstalk between the endometrium and trophoblast. Furthermore, it is known that the microenvironment of this fetal–maternal interface plays an important role in the development of extravillous trophoblast cells. This is mainly due to the fact that tissues mediate embryonic signaling biologicals, among other molecules, prostaglandins. Prostaglandins influence tissue through several cell processes including differentiation, proliferation, and promotion of maternal immune tolerance. The aim of this study is to investigate the potential pathological mechanism of the prostaglandin E2 receptor 4 (EP4) in modulating extravillous trophoblast cells (EVTs) in unexplained recurrent marriage (uRM). Our results indicated that the expression of EP4 in EVTs was decreased in women experiencing uRM. Furthermore, silencing of EP4 showed an inhibition of the proliferation and induced apoptosis in vitro. In addition, our results demonstrated reductions in β- human chorionic gonadotropin (hCG), progesterone, and interleukin (IL)-6, which is likely a result from the activation of the cyclic adenosine monophosphate (cAMP)- cAMP-dependent protein kinase A (PKA)-phosphorylating CREB (pCREB) pathway. Our data might provide insight into the mechanisms of EP4 linked to trophoblast function. These findings help build a more comprehensive understanding of the effects of EP4 on the trophoblast at the fetal–maternal interface in the first trimester of pregnancy.

Curcumin mediates autophagy and apoptosis in granulosa cells: a study of integrated network pharmacology and molecular docking to elucidate toxicological mechanisms

Curcumin (Cur) is a flavonoid derived from Curcuma longa L. that has been shown to have a variety of biological activities, but some previous studies have described its non-negligible negative effects on female reproduction and embryo development. To further explore the toxic stress effect, this study investigated apoptosis and autophagy of healthy buffalo (Bubalus bubalis) derived granulosa cells (GCs) exposed to Cur and/or autophagy inhibitors. Results showed that Cur declined viability of GCs in a concentration-dependent manner. Apoptosis was observed in Cur-treated GCs from 3 h. Meanwhile, under Cur stress, autophagosomes accumulated in cells, and the expression levels of autophagy key proteins LC3 and Beclin 1 were up-regulated, suggesting that Cur could induce autophagy in GCs. Early autophagy inhibitor 3-methyladenine (3-MA) increased the apoptosis rate of Cur exposed GCs, but the autophagosome degradation inhibitor chloroquine (CQ) had no effect on the apoptosis rate. The network pharmacological and molecular docking analysis indicated that the perturbation of IKK/NF-κB might be the cause of Cur toxicity toward GCs. This study unveiled another side of Cur pharmacological effects that programmed cell death can be induced by Cur in GCs, suggesting that it should be prudent to use Cur as a clinical drug for its side effects on the female reproductive system.

The Expanding Role of Mitochondria, Autophagy and Lipophagy in Steroidogenesis

The fundamental framework of steroidogenesis is similar across steroidogenic cells, especially in initial mitochondrial steps. For instance, the START domain containing protein-mediated cholesterol transport to the mitochondria, and its conversion to pregnenolone by the enzyme P450scc, is conserved across steroidogenic cells. The enzyme P450scc localizes to the inner mitochondrial membrane, which makes the mitochondria essential for steroidogenesis. Despite this commonality, mitochondrial structure, number, and dynamics vary substantially between different steroidogenic cell types, indicating implications beyond pregnenolone biosynthesis. This review aims to focus on the growing roles of mitochondria, autophagy and lipophagy in cholesterol uptake, trafficking and homeostasis in steroidogenic cells and consequently in steroidogenesis. We will focus on these aspects in the context of the physiological need for different steroid hormones and cell-intrinsic inherent features in different steroidogenic cell types beyond mitochondria as a mere site for the beginning of steroidogenesis. The overall goal is to provide an authentic and comprehensive review on the expanding role of steroidogenic cell-intrinsic processes in cholesterol homeostasis and steroidogenesis, and to bring attention to the scientific community working in this field on these promising advancements. Moreover, we will discuss a novel mitochondrial player, prohibitin, and its potential role in steroidogenic mitochondria and cells, and consequently, in steroidogenesis.

Guizhi Fuling Wan reduces autophagy of granulosa cell in rats with polycystic ovary syndrome via restoring the PI3K/AKT/mTOR signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Guizhi Fuling Wan (GFW) is a traditional Chinese medicine used to remove blood stasis and dissipate phlegm for treating gynecological diseases that was invented by Zhang Zhongjing in the Eastern Han dynasty. In recent years, GFW has been widely used to treat patients with polycystic ovary syndrome (PCOS). Clinical and animal studies have shown that it is effective in the treatment of PCOS, but its mechanism is unknown. Generally, it works by regulating autophagy via the PI3K/AKT/mTOR signaling pathway.

AIM OF THE STUDY

This study investigated the effects and mechanism of GFW in PCOS rats with insulin resistance (IR) in order to provide better understanding of its observed clinical effects and a theoretical basis for the study of traditional Chinese medicine.

MATERIALS AND METHODS

Eighty-four female Sprague-Dawley rats were randomly divided into seven groups (n = 12 per group): 1) control, 2) PCOS model, 3) low-dose GFW, 4) medium-dose GFW, 5) high-dose GFW, 6) metformin, and 7) medium-dose GFW plus LY294002. In all non-control groups, we induced PCOS through daily letrozole combined with intragastric high-fat emulsion for 21 days. After treatment, rats were sacrificed and serum follicle-stimulating hormone (FSH), testosterone (T), progesterone, luteinizing hormone (LH), 17β-estradiol, fasting insulin (FINS), and fasting plasma glucose levels were measured by enzyme-linked immunosorbent assay (ELISA). The LH/FSH ratios and HOMA-IR values were calculated. Ovarian morphology was observed by hematoxylin and eosin staining, and all follicles were counted under a microscope. MDC-positive vesicles were used as markers to detect autophagy, and the expression levels of p62, Beclin1, and LC3-II were examined by immunostaining. Western blotting was used to measure PI3K/AKT/mTOR pathway activation, granulosa cell apoptosis, and autophagy.

RESULTS

Compared with the PCOS model group, GFW-treated rats had less atretic and cystic follicles, and more mature follicles and corpus lutea. The GFW-treated rats had lower serum T, LH, and FINS levels than the PCOS model group, as well as lower LH/FSH ratios and HOMA-IR values. GFW treatment resulted in significantly reduced levels of cleaved-Caspase-3, cleaved-Caspase-9, BAX, Beclin1, Atg5, and LC3-II. Phosphorylation of PI3K, AKT, and mTOR was significantly higher in GFW-treated rats compared with the PCOS model group. The phosphorylation of PI3K, AKT, and mTOR was decreased with the use of a PI3K antagonist.

CONCLUSIONS

Our results indicate that GFW inhibited granulosa cell autophagy and promoted follicular development to attenuate ovulation disorder in PCOS-IR rats. This was associated with activation of the PI3K/AKT/mTOR signaling pathway.

Tet1 Deficiency Leads to Premature Ovarian Failure

Tet enzymes participate in DNA demethylation and play critical roles in stem cell pluripotency and differentiation. DNA methylation alters with age. We find that Tet1 deficiency reduces fertility and leads to accelerated reproductive failure with age. Noticeably, Tet1-deficient mice at young age exhibit dramatically reduced follicle reserve and the follicle reserve further decreases with age, phenomenon consistent with premature ovarian failure (POF) syndrome. Consequently, Tet1-deficient mice become infertile by reproductive middle age, while age matched wild-type mice still robustly reproduce. Moreover, by single cell transcriptome analysis of oocytes, Tet1 deficiency elevates organelle fission, associated with defects in ubiquitination and declined autophagy, and also upregulates signaling pathways for Alzheimer's diseases, but down-regulates X-chromosome linked genes, such as Fmr1, which is known to be implicated in POF. Additionally, Line1 is aberrantly upregulated and endogenous retroviruses also are altered in Tet1-deficient oocytes. These molecular changes are consistent with oocyte senescence and follicle atresia and depletion found in premature ovarian failure or insufficiency. Our data suggest that Tet1 enzyme plays roles in maintaining oocyte quality as well as oocyte number and follicle reserve and its deficiency can lead to POF.

FSH Promotes Progesterone Synthesis by Enhancing Autophagy to Accelerate Lipid Droplet Degradation in Porcine Granulosa Cells

Little is known about the molecular relationships among follicle stimulating hormone (FSH), lipid droplet (LD) degradation, and autophagy. In this study, we aimed to investigate the pathway by which FSH regulates autophagy and the potential role of autophagy in progesterone production. Our results revealed that FSH stimulated progesterone production in mammalian follicular granulosa cells (GCs) through a non-canonical pathway. In porcine secondary follicles cultured in vitro, FSH treatment increased the level of the autophagic marker, LC3-II, as well as increased the number of autophagic vacuoles in GCs. The underlying molecular mechanism and biological functions were then investigated in porcine GCs. Our results demonstrated that FSH could upregulate Beclin1 levels in porcine GCs; however, this effect was blocked by LY294002 (a PI3K/AKT inhibitor) and SP600125 (SAPK/JNK inhibitor). Further research confirmed that the transcriptional factor, c-Jun, was phosphorylated by FSH, then translocated into the nucleus from the cytoplasm and bound to the BECLIN1 promoter region, and that LY294002, SP600125, or c-Jun knockdown prevented the increase in Beclin1 levels induced by FSH. Interestingly, inhibition of autophagy using chloroquine or SP600125 decreased progesterone production in porcine GCs treated with FSH, although the expression of StAR and P450scc was not disturbed. Moreover, FSH treatment reduced the average number and size of LDs in porcine GCs, but these effects were eliminated by knocking down the key autophagy genes, ATG5 and BECLIN1; in addition, the effect of FSH on promoting progesterone secretion by the cells was also reduced significantly. Based on the above results, we concluded that FSH promoted progesterone production by enhancing autophagy through upregulation of Beclin1 via the PI3K/JNK/c-Jun pathway to accelerate LD degradation in porcine GCs, independent of the classical steroidogenic pathway.

Induction of autophagy by Beclin-1 in granulosa cells contributes to follicular progesterone elevation in ovarian endometriosis

Endometriosis is a common gynecological disease in which ovarian dysfunction can be an important cause of infertility. Elevated progesterone (P4) levels during the follicular phase is possibly associated with impaired oocyte quality and pregnancy outcome in endometriosis. Beclin-1 (BECN1), an essential mediator of autophagy, has been shown to be related to the development and progression of endometriosis. This study aimed to investigate the autophagic activity in ovarian granulosa cells (GCs) of patients with endometriosis and to clarify the role of BECN1 in preovulatory P4 elevation. Our results demonstrated that serum P4/estradiol (E2) ratio and P4-to-follicle index (the average P4 secretion per follicle) on the day of human chorionic gonadotropin administration were elevated in women with ovarian endometriosis. Increased expression of BECN1 and enhanced autophagy were observed in GCs of patients with ovarian endometriomas. In cultured GCs, BECN1 knockdown reduced P4 secretion and the expression of key steroidogenic enzymes; whereas overexpression of BECN1 resulted in induced P4 production with activated biosynthesis pathway. Moreover, inhibition of autophagy by BECN1 knockdown significantly attenuated low-density lipoprotein (LDL)-induced P4 synthesis. These findings provide new insights into the role of BECN1 in late follicular P4 elevation in patients with endometriosis by promoting the degradation pathway of LDL for P4 biosynthesis via lysosome activation in GCs, and have potential therapeutic implications for the improvement of oocyte quality in women affected by endometriosis.

Follicle inhibition at the primordial stage without increasing apoptosis, with a combination of everolimus, verapamil

The aim of the present study was to test whether inhibition of ovarian primordial follicles and subsequent activation can be achieved by transient mTOR inhibition. In this preclinical investigation, forty-five female immature Wistar rats were randomized in 5 groups. The control group received subcutaneous saline injections. The other groups received Everolimus, Everolimus plus Verapamil, Everolimus plus Fisetin, and Fisetin alone. Primary and secondary outcomes were measured in the left ovary after a treatment period of 8 weeks. Ten days later, animals received 35 IU FSH for 4 days and 35 IU of hCG on the 5th day. The same parameters were examined in the right ovary. AMH, estradiol, and progesterone levels were assessed at the end of both interventions. Significantly, more primordial and less atretic follicles were observed in the Everolimus plus Verapamil group. AMH and progesterone levels were substantially lower in the Everolimus group. Interestingly, after ovarian stimulation higher levels of AMH and progesterone were observed in the Everolimus plus Verapamil group. Immunoblot analysis of ovarian extracts revealed that the administration of Everolimus led to a significant reduction in the mTORC1-mediated phosphorylation of the 70-kDa ribosomal protein S6 kinase 1. This decrease was reversed in the presence of FSH after stopping drug administration. The expression of the anti-apoptotic molecule Bcl2 as well as of LC3-II and ATG12 was increased after removal of the Everolimus plus Verapamil combination, indicating reduced apoptosis and increased autophagy, whereas the levels of the proliferation marker PCNA in the granulosa cells were elevated, consistent with initiation of follicular growth.Thus, the combination of Everolimus plus Verapamil is capable of increasing the number of competent primordial follicles while reducing atresia.

Progesterone Receptor Membrane Components: Key Regulators of Fetal Membrane Integrity†

Pro-pregnancy hormone progesterone (P4) helps to maintain a quiescent status of uterine tissues during gestation. However, P4's functional role in maintaining fetal membrane (amniochorion) integrity remains unclear. P4 functions through its membrane receptors (PGRMCs) as fetal membrane cells lack nuclear receptors. This study screened the differential expression of PGRMCs in the fetal membranes and tested P4-PGRMC interactions under normal and oxidative stress (OS) conditions expected that can disrupt P4-PGRMC interactions impacting fetal membrane stability resulting in parturition. Human fetal membranes were collected from term and preterm deliveries (N = 5). Immunohistochemistry and western blot localized and determined differential expression of P4 receptors. Primary amnion epithelial (AEC), mesenchymal (AMCs), and chorion cell were treated with P4 alone or cotreat (P4 + OS induced by cigarette smoke extract [CSE]). Proximity ligation assay (PLA) documented P4-receptor binding, while P4 ELISA documented culture supernatant levels. Immunohistology confirmed lack of nuclear PRs; however, confirmed expressions of PGRMC 1 and 2. Term labor (P = 0.01) and preterm rupture (P = 0.01) are associated with significant downregulation of PGRMC2. OS induced differential downregulation of PGRMCs in both amnion and chorion cells (all P < 0.05) and downregulates P4 release (AMCs; P = 0.01). The PLA showed preferential receptor-ligand binding in amnion and chorion cells. Co-treatment of P4 + CSE did not reverse CSE-induced effects. In conclusion, P4-PGRMCs interaction maintains fetal membranes' functional integrity throughout pregnancy. Increased OS reduces endogenous P4 production and cell type-dependent downregulation of PGRMCs. These changes can lead to fetal membrane-specific 'functional progesterone withdrawal', contributing to the dysfunctional fetal membrane status seen at term and preterm conditions.