The localization and expression of epidermal growth factor and epidermal growth factor receptor in bovine ovary during oestrous cycle

EGFR-ERK1/2 signaling and mitochondrial dynamics in seasonal ovarian steroidogenesis of the muskrats (Ondatra zibethicus)

The dynamic systems of mitochondria, including mitochondrial fusion and fission, are essential for ovarian endocrine and follicular development. Meanwhile, ERK1/2 signaling is an important mechanism mediating altered mitochondrial dynamics and steroidogenesis. The purpose of this study was to investigate the seasonal changes in ovarian steroidogenesis concerning EGFR-ERK1/2 signaling and mitochondrial dynamics of the muskrats (Ondatra zibethicus). The results showed that follicular development in the muskrats remained in the tertiary follicular stage during the non-breeding season, accompanied by a significant decrease in serum and ovarian concentrations of 17β-estradiol and progesterone from the breeding season to the non-breeding season. EGF, EGFR, ERK1/2, p-ERK1/2, and mitochondrial dynamics regulators were mainly localized in granulosa cells and theca cells of muskrats during the breeding and non-breeding seasons. The mRNA levels of Egfr, Erk1/2, Mfn1/2, Opa1, Drp1, and steroidogenic enzymes in the ovaries were remarkably higher during the breeding season. The 17β-estradiol concentrations in the serum and ovaries as well as the relative levels of Mfn1/2, Opa1, and Drp1 were positively associated with each other. Furthermore, transcriptomic analysis of the ovaries revealed that differentially expressed genes might be linked to steroid biosynthesis, estrogen signaling pathway, and mitochondrial membrane-related pathways. In conclusion, these results suggest that the up-regulation of mitochondrial dynamics regulators during the breeding season is closely associated with enhanced ovarian steroidogenesis in the muskrats, which may be regulated by upstream EGFR-ERK1/2 signaling.

Influence of Long Non-Coding RNAs on Human Oocyte Development

Recent research findings have highlighted the pivotal roles played by lncRNAs in both normal human development and disease pathogenesis. LncRNAs are expressed in oocytes and early embryos, and their expression levels change dynamically once the embryonic genome is activated during early human embryonic development. Abnormal expression of lncRNAs was found in follicular fluid, granulosa cells and oocytes of patients, and these lncRNAs were related to cell proliferation and apoptosis, nuclear maturation and follicle development. The expression levels of some lncRNAs in cumulus cells demonstrate correlations with the quality of oocytes and early embryos. This paper aims to present a comprehensive overview of the influence of LncRNAs on the developmental process of human oocytes as well as their involvement in certain infertility-related diseases.

The Effect of Prolactin on Gene Expression and the Secretion of Reproductive Hormones in Ewes during the Estrus Cycle

Prolactin (PRL) plays an important role in animal follicle development and ovulation. However, its regulatory effects on the different stages of the estrus cycle in ewes are unclear. In this study, bromocriptine (BCR, PRL inhibitor) was used to study the effect of PRL on the secretion of reproductive hormones and gene expressions in order to explore its regulatory effects on the sexual cycle of ewes. Eighty healthy ewes with the same parity and similar weights were randomly assigned to the control group (C, n = 40) and the treatment group (T, n = 40, fed bromocriptine). After estrus synchronization, thirty-one ewes with overt signs of estrus were selected from each group. Six blood samples were randomly obtained by jugular venipuncture to measure the concentration of PRL, estrogen (E2), progesterone (P4), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and gonadotropin-releasing hormone (GnRH) in the proestrus, estrus, metestrus, and diestrus. At the same time, we collected the ovaries of the six ewes in vivo after anesthesia in order to detect follicle and corpus luteum (CL) counts and measure the expression of hormone-receptor and apoptosis-related genes. The results show that PRL inhibition had no significant effects on the length of the estrus cycle (p > 0.05). In proestrus, the number of large and small follicles, the levels of E2, FSH, and GnRH, and the expressions of ER, FSHR, and the apoptotic gene Caspase-3 were increased (p < 0.05); and the number of middle follicles and the expression of anti-apoptotic gene Bcl-2 were decreased (p < 0.05) in the T group. In estrus, the number of large follicles, the levels of E2 and GnRH, and the expressions of the StAR, CYP19A1, and Bcl-2 genes were increased (p < 0.05), and the number of middle follicles was decreased (p < 0.05) in the T group. In metestrus, the number of small follicles and the expression of LHR (p < 0.05) and the pro-apoptotic gene Bax were increased (p < 0.05); the number of middle follicles was decreased (p < 0.05) in the T group. In diestrus, the number of large follicles, middle follicles, and CL, the level of P4, and the expressions of PR, 3β-HSD, StAR, Caspase-3, and Bax were increased (p < 0.05); the number of small follicles and the expression of Bcl-2 were decreased (p < 0.05) in the T group. In summary, PRL inhibition can affect the secretion of reproductive hormones, the follicle count, and the gene expression during the estrus cycle. These results provide a basis for understanding the mechanisms underlying the regulation of the ewe estrus cycle by PRL.

Growth factors and female reproduction in vertebrates

Female reproductive efficiency is influenced by the outcomes of various processes, including folliculogenesis, apoptosis, response to gonadotropin signaling, oocyte maturation, and ovulation. The role of hormones in regulating these processes and other reproductive activities has been well established. It is becoming increasingly evident that in addition to well-characterized hormones, growth factors play vital roles in regulating some of these reproductive activities. Growth factors and their receptors are widely distributed in vertebrate ovaries at different stages of ovarian development, indicating their involvement in intraovarian reproductive functions. In the ovary, cell surface receptors allow growth factors to regulate intraovarian reproductive activities. Understanding these actions in the reproductive axis would provide a tool to target growth factors and/or their receptors to yield desirable reproductive outcomes. These include enrichment of in vitro maturation and fertilization culture media, and management of infertility. This review discusses some widely characterized growth factors belonging to the TGF, EGF, IGF, FGF, and BDNF family of peptides and their role in female reproduction in vertebrates, with a focus on mammals.

Impact of epidermal growth factor and/or β-mercaptoethanol supplementations on the in vitro produced buffaloes' embryos

The present study investigated the effects of epidermal growth factors (EGF) and/or β-Mercaptoethanol (βME) supplementations to oocyte maturation, fertilization, and culture media on the buffalo in vitro embryo production. The ovaries were collected and transferred within 2 h to the laboratory. The cumulus oocytes complexes were aspirated from 3 to 8 mm diameter follicles. Firstly, EGF; 0, 10, 20, or 50 ng/mL or βME; 0, 25, 50, 100, or 200 μM were supplemented to the in vitro maturation (TCM-199), fertilization (IVF-TALP), or culture (IVC: SOF) media. Our results revealed that supplementing EGF (20 ng/mL) to the TCM-199, IVF-TALP, or SOF media could efficiently improve the growth rates and development of buffalos' embryos, while EGF (50 ng/mL) could stimulate the embryo production only after treatment of the IVF-TALP /or SOF media, but not the IVM medium. However, βME was less efficient than EGF; it stimulated the growth rates of buffalo embryos when supplemented with the maturation and fertilization (IVF-TALP) media in a 50 μM concentration. Secondly, combined EGF (20 ng/mL) and βME (50 μM) were supplemented to the maturation media as effective concentration. The combined treatment of EGF (20 ng/mL) and βME (50 μM) showed no significant enhancing effect on the buffalo embryos compared to each alone. For future perspectives, further study is required to examine the effects of combined EGF and βME on the maturation and fertilization of buffalo oocytes at different categories of age and seasonal localities.

Genetic Architecture and Signatures of Selection in the Caqueteño Creole (Colombian Native Cattle)

Evolutionary mechanisms have shaped the genomic architecture of Colombian Creole cattle breeds. The mating and selection processes have impacted several traits, promoting differences within and between populations. Studies of population structure and selection signatures in Colombian Creole breeds are scarce, and need more attention to better understand genetic differentiation, gene flow, and genetic distance. This study aimed to analyze the population structure and identify selection imprints in the Criollo Caqueteño (CAQ) population. It used 127 CAQ animals genotyped with Chip HD 777,000 SNPs. The population structure analyses used discriminant principal component analysis (DAPC), integrated haplotype scoring (iHS), and index-fixing (Fst) methodologies to detect selection signals. We can highlight SNP regions on the genes TMPRSS15, PGAM2, and EGFR, identified by the Fst method. Additionally, the iHS regions for cluster 1 identified candidate genes on BTA 3 (CMPK1 and FOXD2), BTA 11 (RCAN1), and BTA 22 (ARPP21). In group 2, we can highlight the genes on BTA 4 (SLC13A4, BRAF), BTA 9 (ULBP), BTA 14 (CSMD3) and BTA 19 (KRTAP9-2). These candidate genes have been associated with fertility traits, precocity, growth, and environmental and disease resistance, indicating a genetic potential in CAQ animals. All this promotes a better understanding of the diversity and genetic structure in the CAQ population. Based on that, our study can significantly assist the sustainable development and conservation of the breed in the Colombian Amazon.

Seasonal expressions of ERα, ERβ, EGF, EGFR, PI3K and Akt in the scent glands of the muskrats (Ondatra zibethicus)

Epidermal growth factor (EGF) is an important autocrine and/or paracrine mediator of steroid hormones to stimulate growth and differentiation in mammals. The aim of this study is to investigate seasonal expressions of estrogen receptor α (ERα), estrogen receptor β (ERβ), EGF, epidermal growth factor receptor (EGFR), phosphatidylinositol 3-kinase (PI3K) and protein kinase B (Akt) in the scent glands of the muskrats during the breeding and non-breeding seasons. Histologically, three types of cells including the glandular cells, interstitial cells and epithelial cells were identified in the scent glands in both seasons. Immunohistochemical results showed that ERα, ERβ, EGF, EGFR, PI3K and Akt were presented in the different types of cells of the scent glands during the breeding and non-breeding seasons. Transcriptome data of the scent glandular tissues from muskrats in the breeding and non-breeding seasons showed that differential seasonal changes might be related to the estrogen-EGFR signaling pathway. The gene expression levels of ERα, ERβ, EGF, EGFR, PI3K were increased, while the gene expression level of Akt were decreased in the breeding season than those in the non-breeding season. Besides, the concentrations of 17β-estradiol (E₂) in the serum and the scent glandular tissues were remarkably higher in the breeding season than those of the non-breeding season. Taken together, our results suggested that EGFR signaling pathway may coordinate with ERs signaling to regulate the seasonal changes of the scent glandular functions.

Transcriptomic analysis of ovarian signaling at the emergence of the embryo from obligate diapause in the American mink (Neovison vison)

Mink embryonic diapause occurs when embryos, at the blastocyst stage, enter a state of a reversible arrest in development and metabolism. Some ovarian factors are required because ovariectomy leads to prevention of implantation in mink. Mechanisms regulating this process, however, remain largely unknown. To explore ovarian modifications associated with emergence of embryonic diapause in mink, there was comparison of transcriptomes after embryonic activation to when there was embryonic diapause using RNA-sequencing. A library of 655 differentially expressed genes (DEGs) of all assembled 33,656 genes was generated. Among these, 558 genes were annotated with 106 genes being expressed to a greater extent in ovaries during embryonic diapause, whereas 452 genes were more abundantly expressed in ovaries after embryonic activation. The major categories of genes with differential transcript abundances include metabolic pathways, metabolism of tryptophan, tyrosine and vitamin B6, oxidoreductase activity, calcium signaling pathway, steroid biosynthesis and lysosome. The APOE and APOA1 hub genes identified through the protein-protein interaction (PPI) analysis have important functions in cholesterol transport and steroidogenesis. Transcript abundances associated with 39 genes were investigated using RT-qPCR procedures to confirm RNA-sequencing data. Of 29 mRNA transcripts, 26 were validated using RNA-sequencing, whereas three of ten indistinguishable genes determined using RNA-sequencing were confirmed. Most of these verified DEGs are involved in the prolactin signaling pathway, formation of functional corpora lutea, and steroid synthesis, suggesting these biological processes are implicated in embryonic reactivation. Overall, results provide new insights into ovarian signaling at the time of emergence of the blastocyst from diapause in mink.

Gefitinib reduces oocyte quality by disturbing meiotic progression

Gefitinib is a first-line anti-cancer drug for the treatment of advanced non-small cell lung cancer (NSCLC). It has been reported that gefitinib can generate several drug-related adverse effects, including nausea, peripheral edema, decreased appetite and rash. However, the reproductive toxicity of gefitinib has not been clearly defined until now. Here we assessed the effects of gefitinib on oocyte quality by examining the critical events and molecular changes of oocyte maturation. Gefitinib at 1, 2, 5 or 10 μM concentration was added to culture medium (M2). We found that gefitinib at its median peak concentration of 1 μM did not affect oocyte maturation, but 5 μM gefitinib severely blocked oocyte meiotic progression as indicated by decreased rates of germinal vesicle breakdown (GVBD) and polar body extrusion (PBE). We further showed that gefitinib treatment increased phosphorylation of CDK1 at the site of Try15, inhibited cyclin B1 entry into the nucleus, and disrupted normal spindle assembly, chromosome alignment and mitochondria dynamics, finally leading to the generation of aneuploidy and early apoptosis of oocytes. Our study reported here provides valuable evidence for reproductive toxicity of gefitinib administration employed for the treatment of cancer patients.