The Role of MAPK3/1 and AKT in the Acquisition of High Meiotic and Developmental Competence of Porcine Oocytes Cultured In Vitro in FLI Medium

FGF2, LIF, and IGF-1 supplementation improves mouse oocyte in vitro maturation via increased glucose metabolism†

Chemically defined oocyte maturation media supplemented with FGF2, LIF, and IGF-1 (FLI medium) enabled significantly improved oocyte quality in multiple farm animals, yet the molecular mechanisms behind such benefits were poorly defined. Here, we first demonstrated that FLI medium enhanced mouse oocyte quality assessed by blastocyst formation after in vitro fertilization and implantation and fetal development after embryo transfer. We then analyzed the glucose concentrations in the spent media; reactive oxygen species concentrations; mitochondrial membrane potential; spindle morphology in oocytes; and the abundance of transcripts of endothelial growth factor-like factors, cumulus expansion factors, and glucose metabolism-related genes in cumulus cells. We found that FLI medium enabled increased glucose metabolism through glycolysis, pentose phosphate pathway, and hexosamine biosynthetic pathway, as well as more active endothelial growth factor-like factor expressions in cumulus cells, resulting in improved cumulus cell expansion, decreased spindle abnormality, and overall improvement in oocyte quality. In addition, the activities of MAPK1/3, PI3K/AKT, JAK/STAT3, and mTOR signaling pathways in cumulus cells were assessed by the phosphorylation of MAPK1/3, AKT, STAT3, and mTOR downstream target RPS6KB1. We demonstrated that FLI medium promoted activations of all these signaling pathways at multiple different time points during in vitro maturation.

Impact of media supplements FGF2, LIF and IGF1 on the genome activity of porcine embryos produced in vitro

In this article, we focused on the impact of precisely chemically modified FLI maturation medium enriched with fibroblast growth factor 2 (FGF2), leukemia inhibitory factor (LIF), insulin-like growth factor 1 (IGF1), and polyvinyl alcohol (PVA) and its potential to improve the efficiency of in vitro production of porcine embryos. We hypothesized that enhancing the composition of the maturation medium could result in an elevated production of embryos in vitro and can affect EGA. FLI medium resulted in a significantly higher rate of oocyte blastocyst maturation and formation compared to the control DMEM medium. In addition, immunocytochemical labelling confirmed the detection of UBF in 4-cell FLI parthenogenic embryos, suggesting similarities with natural embryo development. Through RNAseq analysis, upregulated genes present in 4-cell FLI embryos were found to play key roles in important biological processes such as cell proliferation, cell differentiation, and transcriptional regulation. Based on our findings, we demonstrated the positive influence of FLI medium in the evaluation of in vitro embryo production, EGA detection, transcriptomic and proteomic profile, which was confirmed by the positive activation of the embryonal genome in the 4-cell stage of parthenogenetically activated embryos.

Meiotic and developmental competence of growing pig oocytes derived from small antral follicles is enhanced in culture medium containing FGF2, LIF, and IGF1 (FLI medium)

BACKGROUND

Oocytes of large animal species isolated from small ovarian follicles (< 2 mm) are less competent to support early embryonic development after in vitro maturation and fertilization than their counterparts isolated from medium-sized and preovulatory follicles. This study aimed to assess the effect of a new maturation medium containing FGF2, LIF, and IGF1 (FLI medium) on the meiotic and developmental competence of pig cumulus-oocytes complexes (COCs) derived from the small and medium-sized follicles.

METHODS

The growing oocytes were isolated from 1 to 2 (small follicle; SF) and the fully-grown ones from 3 to 6 (large follicle; LF) mm follicles and matured in a control M199 medium with gonadotropins and EGF and the FLI medium enriched by the triplet of growth factors. The matured oocytes were parthenogenetically activated and cultured to the blastocyst stage. Chromatin configuration before and during the culture and MAP kinase activity were assessed in the oocytes. Finally, the expression of cumulus cell genes previously identified as markers of oocyte quality was assessed.

RESULTS

The maturation and blastocyst rates of oocytes gained from LF were significantly higher than that from SF in the control medium. In contrast, similar proportions of oocytes from LF and SF completed meiosis and developed to blastocysts when cultured in FLI. Most of the oocytes freshly isolated from SF possessed germinal vesicles with fine filaments of chromatin (GV0) or chromatin surrounding the nucleolus (GVI; 30%); the oocytes from LF were mainly in GVI (or GVII) exhibiting a few small lumps of chromatin beneath the nuclear membrane. When cultured in the FLI medium for 16 h, an acceleration of the course of maturation in oocytes both from SF and LF compared to the control medium was observed and a remarkable synchrony in the course of chromatin remodeling was noticed in oocytes from SF and LF.

CONCLUSIONS

This work demonstrates that the enrichment of culture medium by FGF2, LIF, and IGF1 can enhance the meiotic and developmental competence of not only fully-grown, but also growing pig oocytes and significantly thus expanding the number of oocytes available for various assisted reproductive technology applications.

Investigating the expression of fertility-regulating LncRNAs in multiparous and uniparous Shal ewe's ovaries

Sheep is the primary source of animal protein in Iran. Birth type is one of the significant features that determine total meat output. Little is known about how long non-coding RNAs (LncRNAs) affect litter size. The purpose of this research is to investigate the DE-LncRNAs in ovarian tissue between multiparous and uniparous Shal ewes. Through bioinformatics analyses, LncRNAs with variable expression levels between ewes were discovered. Target genes were annotated using the DAVID database, and STRING and Cytoscape software were used to evaluate their interactions. The expression levels of 148 LncRNAs were different in the multiparous and uniparous ewe groups (false discovery rate (FDR) < 0.05). Eight biological process terms, nine cellular component terms, 10 molecular function terms, and 38 KEGG pathways were significant (FDR < 0.05) in the GO analysis. One of the most significant processes impacting fertility is mitogen-activated protein kinase (MAPK) signaling pathway, followed by oocyte meiosis, gonadotropin-releasing hormone signaling pathway, progesterone-mediated oocyte maturation, oxytocin signaling pathway, and cAMP signaling pathway. ENSOARG00000025710, ENSOARG00000025667, ENSOARG00000026034, and ENSOARG00000026632 are LncRNAs that may affect litter size and fertility. The most crucial hub genes include MAPK1, BRD2, GAK, RAP1B, FGF2, RAP1B, and RAP1B. We hope that this study will encourage researchers to further investigate the effect of LncRNAs on fertility.

Mechanisms of polydatin against spinal cord ischemia-reperfusion injury based on network pharmacology, molecular docking and molecular dynamics simulation

BACKGROUND

Polydatin has shown considerable pharmacological activities in ischemia-reperfusion injuries of various organs. However, its effects and mechanisms in spinal cord ischemia-reperfusion injury have not been fully established. In this study, the mechanisms of polydatin against spinal cord ischemia-reperfusion injury were investigated via network pharmacology, molecular docking and molecular dynamics simulation.

METHODS

Spinal cord ischemia-reperfusion injury-related targets were obtained from the GeneCards database, while polydatin-related action targets were obtained from the CTD and SwissTarget databases. A protein-protein interaction network of potential targets was constructed using the String platform. After selecting the potential key targets, GO functional enrichment and KEGG pathway enrichment analyses were performed via the Metascape database, and a network map of "drug-target-pathway-disease" constructed. The relationships between polydatin and various key targets were assessed via molecular docking. Molecular dynamics simulation was conducted for optimal core protein-compound complexes obtained by molecular docking.

RESULTS

Topological analysis of the PPI network revealed 14 core targets. GO functional enrichment analysis revealed that 435 biological processes, 12 cell components and 29 molecular functions were enriched while KEGG pathway enrichment analysis revealed 91 enriched signaling pathways. Molecular docking showed that polydatin had the highest binding affinity for MAPK3, suggesting that MAPK3 is a key target of polydatin against spinal cord ischemia-reperfusion injury. Molecular dynamics simulations revealed good binding abilities between polydatin and MAPK3.

CONCLUSIONS

Polydatin exerts its effects on spinal cord ischemia-reperfusion injury through multiple targets and pathways. MAPK3 may be a key target of polydatin in spinal cord ischemia-reperfusion injury.

FGF2, LIF, and IGF1 (FLI) supplementation during human in vitro maturation enhances markers of gamete competence

STUDY QUESTION

Does a chemically defined maturation medium supplemented with FGF2, LIF, and IGF1 (FLI) improve in vitro maturation (IVM) of cumulus-oocyte complexes (COCs) obtained from children, adolescents, and young adults undergoing ovarian tissue cryopreservation (OTC)?

SUMMARY ANSWER

Although FLI supplementation did not increase the incidence of oocyte meiotic maturation during human IVM, it significantly improved quality outcomes, including increased cumulus cell expansion and mitogen-activated protein kinase (MAPK) expression as well as enhanced transzonal projection retraction.

WHAT IS KNOWN ALREADY

During OTC, COCs, and denuded oocytes from small antral follicles are released into the processing media. Recovery and IVM of these COCs is emerging as a complementary technique to maximize the fertility preservation potential of the tissue. However, the success of IVM is low, especially in the pediatric population. Supplementation of IVM medium with FLI quadruples the efficiency of pig production through improved oocyte maturation, but whether a similar benefit occurs in humans has not been investigated.

STUDY DESIGN, SIZE, DURATION

This study enrolled 75 participants between January 2018 and December 2021 undergoing clinical fertility preservation through the Fertility & Hormone Preservation & Restoration Program at the Ann & Robert H. Lurie Children's Hospital of Chicago. Participants donated OTC media, accumulated during tissue processing, for research.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Participants who underwent OTC and include a pediatric population that encompassed children, adolescents, and young adults ≤22 years old. All participant COCs and denuded oocytes were recovered from media following ovarian tissue processing. IVM was then performed in either a standard medium (oocyte maturation medium) or one supplemented with FLI (FGF2; 40 ng/ml, LIF; 20 ng/ml, and IGF1; 20 ng/ml). IVM outcomes included meiotic progression, cumulus cell expansion, transzonal projection retraction, and detection of MAPK protein expression.

MAIN RESULTS AND THE ROLE OF CHANCE

The median age of participants was 6.3 years, with 65% of them classified as prepubertal by Tanner staging. Approximately 60% of participants had been exposed to chemotherapy and/or radiation prior to OTC. On average 4.7 ± 1 COCs and/or denuded oocytes per participant were recovered from the OTC media. COCs (N = 41) and denuded oocytes (N = 29) were used for IVM (42 h) in a standard or FLI-supplemented maturation medium. The incidence of meiotic maturation was similar between cohorts (COCs: 25.0% vs 28.6% metaphase II arrested eggs in Control vs FLI; denuded oocytes: 0% vs 5.3% in Control vs FLI). However, cumulus cell expansion was 1.9-fold greater in COCs matured in FLI-containing medium relative to Controls and transzonal projection retraction was more pronounced (2.45 ± 0.50 vs 1.16 ± 0.78 projections in Control vs FLIat 16 h). Additionally, MAPK expression was significantly higher in cumulus cells obtained from COCs matured in FLI medium for 16-18 h (chemiluminescence corrected area 621,678 vs 2,019,575 a.u., P = 0.03).

LIMITATIONS, REASONS FOR CAUTION

Our samples are from human participants who exhibited heterogeneity with respect to age, diagnosis, and previous treatment history. Future studies with larger sample sizes, including adult participants, are warranted to determine the mechanism by which FLI induces MAPK expression and activation. Moreover, studies that evaluate the developmental competence of eggs derived from FLI treatment, including assessment of embryos as outcome measures, will be required prior to clinical translation.

WIDER IMPLICATIONS OF THE FINDINGS

FLI supplementation may have a conserved beneficial effect on IVM for children, adolescents, and young adults spanning the agricultural setting to clinical fertility preservation.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by Department of Obstetrics and Gynecology startup funds (F.E.D.), Department of Surgery Faculty Practice Plan Grant and the Fertility & Hormone Preservation & Restoration Program at the Ann & Robert H. Lurie Children's Hospital of Chicago (M.M.L. and E.E.R.). M.M.L. is a Gesualdo Foundation Research Scholar. Y.Y.'s research is supported by the internal research funds provided by Colorado Center of Reproductive Medicine. Y.Y., L.D.S., R.M.R., and R.S.P. have a patent pending for FLI. The remaining authors have no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

A Role of PI3K/Akt Signaling in Oocyte Maturation and Early Embryo Development

A serine/threonine-specific protein kinase B (PKB), also known as Akt, is a key factor in the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway that regulates cell survival, metabolism and proliferation. Akt phosphorylates many downstream specific substrates, which subsequently control the nuclear envelope breakdown (NEBD), centrosome maturation, spindle assembly, chromosome segregation, and cytokinesis. In vertebrates, Akt is also an important player during oogenesis and preimplantation development. In the signaling pathways regulating mRNA translation, Akt is involved in the control of mammalian target of rapamycin complex 1 (mTORC1) and thereby regulates the activity of a translational repressor, the eukaryotic initiation factor 4E (eIF4E) binding protein 1 (4E-BP1). In this review, we summarize the functions of Akt in mitosis, meiosis and early embryonic development. Additionally, the role of Akt in the regulation of mRNA translation is addressed with respect to the significance of this process during early development.

Combination of CNP, MT and FLI during IVM Significantly Improved the Quality and Development Abilities of Bovine Oocytes and IVF-Derived Embryos

Oocyte maturation is a critical step in the completion of female gametogenesis in the ovary; thus, for subsequent fertilization and embryogenesis. Vitrification of embryo also has been shown to be closely associated with oocyte maturation. To improve the quality and developmental potential of bovine oocytes derived from in vitro maturation (IVM), Pre-IVM with C-type natriuretic peptide (CNP), melatonin (MT) and in combination, IGF1, FGF2, LIF (FLI) were supplemented in the IVM medium. In this current study, we cultured bovine oocytes in Pre-IVM with CNP for 6 h before transferring them to the IVM medium supplemented with MT and FLI. The developmental potential of bovine oocytes was then investigated by measuring the reactive oxygen species (ROS), the intracellular glutathione (GSH) and ATP levels, the transzonal projections (TZP), the mitochondrial membrane potential (ΔΨm), cacline-AM, and the expression of related genes (cumulus cells (CCs), oocytes, blastocysts). The results revealed that oocytes treated with a combination of CNP, MT, and FLI had dramatically improved the percentage of oocytes developed to blastocyst, ATP content, GSH levels, TZP intensity, the ΔΨm, cacline-AM fluorescence intensity, and considerably reduced ROS levels of oocytes. Furthermore, the survival rate and the hatched rate after vitrification of the CNP+MT+FLI group were significantly higher than those other groups. Thus, we speculated that CNP+MT+FLI increases the IVM of bovine oocytes. In conclusion, our findings deepen our understanding and provide new perspectives on targeting the combination of CNP, MT and FLI to enhance the quality and developmental potential of bovine oocytes.

The combination of rolipram and cilostamide improved the developmental competence of cloned porcine embryos

In vitro maturation of porcine oocytes is characterized by asynchronous cytoplasmic and nuclear maturation, leading to less competent oocytes supporting embryo development. The purpose of this study was to evaluate the combined effect of rolipram and cilostamide as cyclic Adenine monophosphate (cAMP) modulators to find the maximum cAMP levels that temporarily arrest meiosis. We determined the optimal time to maintain functional gap junction communication during pre-in vitro maturation to be four hours. Oocyte competence was evaluated by the level of glutathione, reactive oxygen species, meiotic progression, and gene expression. We evaluated embryonic developmental competence after parthenogenetic activation and somatic cell nuclear transfer. The combined treatment group showed significantly higher glutathione and lower reactive oxygen species levels and a higher maturation rate than the control and single treatment groups. Cleavage and blastocyst formation rates in parthenogenetic activation and somatic cell nuclear transfer embryos were higher in two-phase in vitro maturation than in the other groups. The relative levels of BMP15and GDF9 expression were increased in two-phase in vitro maturation. Somatic cell nuclear transfer blastocysts from two-phase in vitro maturation oocytes showed a lower level of expression of apoptotic genes than the control, indicating better pre-implantation developmental competence. The combination of rolipram and cilostamide resulted in optimal synchrony of cytoplasmic and nuclear maturation in porcine in vitro matured oocytes and there by enhanced the developmental competence of pre-implantation embryos.

The transcription factor RUNX1 affects the maturation of porcine oocytes via the BMP15/TGF-β signaling pathway

Bone morphogenetic protein 15 (BMP15) is specifically expressed in oocytes in pigs at all stages from early stages to ovulation and has an important role in oocyte maturation. However, there are few reports on the molecular mechanisms by which BMP15 affects oocyte maturation. In this study, we identified the core promoter region of BMP15 using a dual luciferase activity assay and successfully predicted the DNA binding motif of the transcription factor RUNX1. The effect of BMP15 and RUNX1 on oocyte maturation was examined using the first polar body extrusion rate, a reactive oxygen species (ROS) assay and total glutathione (GSH) content at three time points of 12, 24 and 48 h of in vitro culture of porcine isolated oocytes. Subsequently, the effect of the transcription factor RUNX1 on the TGF-β signaling pathway (BMPR1B and ALK5) was further verified using RT-qPCR and Western blotting. We found that the overexpression of BMP15 significantly increased the first polar body extrusion rate (P < 0.01) and total glutathione content of oocytes cultured in vitro for 24 h and decreased reactive oxygen levels (P < 0.01), whereas interference with BMP15 decreased the first polar body extrusion rate (P < 0.01), increased reactive oxygen levels in oocytes cultured in vitro for 24 h (P < 0.01), and decreased glutathione content (P < 0.01). The dual luciferase activity assay and online software prediction showed that RUNX1 is a potential transcription factor binding to the core promoter region (-1203/-1423 bp) of BMP15. Overexpression of RUNX1 significantly increased the expression of BMP15 and oocyte maturation rate, while inhibition of RUNX1 decreased the expression of BMP15 and the oocyte maturation rate. Moreover, the expression of BMPR1B and ALK5 in the TGF-β signaling pathway increased significantly after overexpression of RUNX1, whereas their expression decreased after inhibition of RUNX1. Overall, our results suggest that the transcription factor RUNX1 positively regulates the expression of BMP15 and influences oocyte maturation through the TGF-β signaling pathway. This study provides a theoretical basis for further complementing the BMP15/TGF-β signaling pathway to regulate mammalian oocyte maturation.

Effect of Disulfiram on the Reproductive Capacity of Female Mice

In the process of assisted reproduction, the high-oxygen in vitro environment can easily cause oxidative damage to oocytes. Disulfiram (DSF) can play an anti-oxidant or pro-oxidant role in different cells, and the effect of DSF on oocytes remains unclear. Moreover, it remains unclear whether the use of DSF in the early stages of pregnancy has a negative impact on the fetus. In this study, we found that DSF increased serum FSH levels and increased the ovulation rate in mice. Moreover, DSF enhanced the antioxidant capacity of oocytes and contributed to the success rate of in vitro fertilization. Moreover, the use of DSF in early pregnancy in mice increased the uterine horn volume and the degree of vascularization, which contributed to a successful pregnancy. In addition, it was found that DSF regulated the mRNA expression of angiogenesis-related genes (VEGF), follicular development-related genes (C1QTNF3, mTOR and PI3K), ovulation-related genes (MAPK1, MAPK3 and p38 MAPK) and antioxidant-related genes (GPX4 and CAT). These results indicate that DSF is helpful for increasing the antioxidant capacity of oocytes and the ovulation rate. In early pregnancy in mice, DSF promotes pregnancy by increasing the degree and volume of uterine vascularization.

Supplementation of porcine in vitro maturation medium with FGF2, LIF, and IGF1 enhances cytoplasmic maturation in prepubertal gilts oocytes and improves embryo quality

In porcine in vitro production (IVP) systems, the use of oocytes derived from prepubertal gilts, whilst being commercially attractive, remains challenging due to their poor developmental competence following in vitro maturation (IVM). Follicular fluid contains important growth factors and plays a key role during oocyte maturation; therefore, it is a common supplementation for porcine IVM medium. However, follicular fluid contains many poorly characterized components, is batch variable, and its use raises biosecurity concerns. In an effort to design a defined IVM system, growth factors such as cytokines have been previously tested. These include leukaemia inhibitory factor (LIF), fibroblast growth factor 2 (FGF2), and insulin-like growth factor 1 (IGF1), the combination of which is termed 'FLI'. Here, using abattoir-derived oocytes in a well established porcine IVP system, we compared follicular fluid and FLI supplementation during both IVM and embryo culture to test the hypothesis that FLI can substitute for follicular fluid without compromising oocyte nuclear and cytoplasmic maturation. We demonstrate that in oocytes derived from prepubertal gilts, FLI supplementation enhances oocyte meiotic maturation and has a positive effect on the quality and developmental competence of embryos. Moreover, for the first time, we studied the effects of follicular fluid and FLI combined showing no synergistic effects.

Production of Pigs From Porcine Embryos Generated in vitro

Generating porcine embryos in vitro is a critical process for creating genetically modified pigs as agricultural and biomedical models; however, these embryo technologies have been scarcely applied by the swine industry. Currently, the primary issue with in vitro-produced porcine embryos is low pregnancy rate after transfer and small litter size, which may be exasperated by micromanipulation procedures. Thus, in this review, we discuss improvements that have been made to the in vitro porcine embryo production system to increase the number of live piglets per pregnancy as well as abnormalities in the embryos and piglets that may arise from in vitro culture and manipulation techniques. Furthermore, we examine areas related to embryo production and transfer where improvements are warranted that will have direct applications for increasing pregnancy rate after transfer and the number of live born piglets per litter.