Monoclonal antibody c262 counteracts the stimulatory effect of progesterone on sperm-oocyte fusion

Assessment of progesterone synthesis and its regulation role on dihydrotestosterone secretion in sheep epididymis

Progesterone (P4) is an anti-androgen compound whose role in sperm maturation and functionality remains unclear in sheep. Here, we aimed to investigate the regulation mechanism of P4 on the epididymal secretion of dihydrotestosterone (DHT). To this end, we performed enzyme-linked immunosorbent assays, immunohistochemical staining, western blotting, and quantitative real-time polymerase chain reaction to detect P4 concentration as well as StAR, P450scc, and 3β-HSD expression in sheep epididymis. Besides, cauda epithelial cells were cultured at different concentrations of P4 (10^-9-10^-5 g ml^-1) as well as with or without the P4 receptor (PGR) inhibitor RU486 (10^-7 M) or the PI3K-AKT inhibitor LY294006 (10^-7 M) to explore the effect of P4 on DHT secretion and the underlying regulatory mechanism. The results showed that the caput, corpus, and cauda of sheep epididymis could synthesize P4 but had different synthesis ability. The PGR expression levels were the highest in the cauda, followed by the corpus. In vitro cell culture showed that P4 inhibition of DHT secretion and 5α-reductase 1 and 2 expression in epididymal epithelial cells could be moderately mitigated by RU486 but not by LY294002. Our results indicated that the paracrine and autocrine P4 could affect the secretion of DHT in epididymal cells through PGR. Overall, this study provides new data regarding the involvement of P4 in sperm maturation and functionality in sheep.

Ovulatory signals alter granulosa cell behavior through YAP1 signaling

BACKGROUND

The Hippo pathway plays critical roles in regulating cell proliferation, differentiation and survival among species. Hippo pathway proteins are expressed in the ovary and are involved in ovarian function. Deletion of Lats1 causes germ cell loss, ovarian stromal tumors and reduced fertility. Ovarian fragmentation induces nuclear YAP1 accumulation and increased follicular development. At ovulation, follicular cells stop proliferating and terminally differentiate, but the mechanisms controlling this transition are not completely known. Here we explore the role of Hippo signaling in mouse granulosa cells before and during ovulation.

METHODS

To assess the effect of oocytes on Hippo transcripts in cumulus cells, cumulus granulosa cells were cultured with oocytes and cumulus oocyte complexes (COCs) were cultured with a pSMAD2/3 inhibitor. Secondly, to evaluate the criticality of YAP1 on granulosa cell proliferation, mural granulosa cells were cultured with oocytes, YAP1-TEAD inhibitor verteporfin or both, followed by cell viability assay. Next, COCs were cultured with verteporfin to reveal its role during cumulus expansion. Media progesterone levels were measured using ELISA assay and Hippo transcripts and expansion signatures from COCs were assessed. Lastly, the effects of ovulatory signals (EGF in vitro and hCG in vivo) on Hippo protein levels and phosphorylation were examined. Throughout, transcripts were quantified by qRT-PCR and proteins were quantified by immunoblotting. Data were analyzed by student's t-test or one-way ANOVA followed by Tukey's post-hoc test or Dunnett's post-hoc test.

RESULTS

Our data show that before ovulation oocytes inhibit expression of Hippo transcripts and promote granulosa cell survival likely through YAP1. Moreover, the YAP1 inhibitor verteporfin, triggers premature differentiation as indicated by upregulation of expansion transcripts and increased progesterone production from COCs in vitro. In vivo, ovulatory signals cause an increase in abundance of Hippo transcripts and stimulate Hippo pathway activity as indicated by increased phosphorylation of the Hippo targets YAP1 and WWTR1 in the ovary. In vitro, EGF causes a transient increase in YAP1 phosphorylation followed by decreased YAP1 protein with only modest effects on WWTR1 in COCs.

CONCLUSIONS

Our results support a YAP1-mediated mechanism that controls cell survival and differentiation of granulosa cells during ovulation.

Eurycoma longifolia: Medicinal Plant in the Prevention and Treatment of Male Osteoporosis due to Androgen Deficiency

Osteoporosis in elderly men is now becoming an alarming health issue due to its relation with a higher mortality rate compared to osteoporosis in women. Androgen deficiency (hypogonadism) is one of the major factors of male osteoporosis and it can be treated with testosterone replacement therapy (TRT). However, one medicinal plant, Eurycoma longifolia Jack (EL), can be used as an alternative treatment to prevent and treat male osteoporosis without causing the side effects associated with TRT. EL exerts proandrogenic effects that enhance testosterone level, as well as stimulate osteoblast proliferation and osteoclast apoptosis. This will maintain bone remodelling activity and reduce bone loss. Phytochemical components of EL may also prevent osteoporosis via its antioxidative property. Hence, EL has the potential as a complementary treatment for male osteoporosis.

Modulation of ATP-induced calcium signaling by progesterone in T47D-Y breast cancer cells

Extracellular ATP activates purinergic (P(2)) receptors with an increase in intracellular calcium and phosphorylation of MAPK. In this study we have investigated the effect of progesterone/progestin on ATP-induced calcium mobilization and phosphorylation of the kinase ERK in the T47D-Y breast cancer cell line that exhibits no detectable nuclear progesterone receptor expression. Brief pretreatment with progesterone/progestin results in a dose dependent inhibition of ATP-induced intracellular calcium mobilization, and inhibition of ERK phosphorylation. Response to a cell impermeable ligand and inhibition of the response by an inactivating antibody suggests a mechanism of action at the plasma membrane. These results in T47D-Y cells strongly suggest that progesterone can act in a rapid non-nuclear manner to inhibit extracellular ATP effects on intracellular calcium mobilization and ERK activation. This research provides an example of progesterone action in a breast cancer cell line lacking expression of the classical nuclear progesterone receptors.

Eurycoma longifolia Jack in managing idiopathic male infertility

This study investigated the effect of treatment with the proprietary standardized, water-soluble extract of the root of the Malaysian plant, Eurycoma longifolia Jack, which is thought to enhance male fertility with regard to higher semen volumes, sperm concentrations, the percentage of normal sperm morphology and sperm motility in male partners of sub-fertile couples with idiopathic infertility. A total of 350 patients were given 200 mg of the extract daily and follow-up semen analyses were performed every 3 months for 9 months. Of these 350 patients, 75 patients completed one full cycle of 3 months. Follow-up semen analyses in these patients showed significant improvement in all semen parameters. The proprietary extract of Eurycoma longifolia Jack significantly improved the sperm quality in these patients, allowing for 11 (14.7%) spontaneous pregnancies.

N-terminal region of progesterone receptor B isoform in human spermatozoa

Progesterone is known to act on human spermatozoa by an unidentified membrane receptor. Previous studies have demonstrated the existence of transcripts of conventional progesterone receptor (PR) in sperm RNA; antibodies directed against the C-terminal region of the conventional PR recognize a protein in sperm extracts. The present study aimed at characterizing the sperm PR using probes unique to the N-terminal region of the PR-B isoform. PR-B transcripts that were homologous to the conventional PR were detected in sperm RNA and localized in the midpiece region. Using specific antibody against the N-terminal region of PR-B, strong immunoreactivity was observed on the acrosomal region of digitonin-treated spermatozoa; Western blot analysis revealed a single band of approximately 55 kDa. Immunogold labelling studies using the same antibody localized the protein at the inner acrosomal membrane of testicular spermatids. This antibody blocked the binding of fluorescent-tagged progesterone to digitonin-treated spermatozoa and inhibited the progesterone-mediated kinase activation. The results of the present study gives an insight to speculate that the sperm membrane PR may have homology at the N-terminal region of the conventional PR-B isoform, or the membrane PR protein may share structural motifs that allows progesterone binding and interactions with the antibodies against the conventional PR.