Non-identical distribution pattern of epidermal growth factor and platelet-derived growth factor in the mouse uterus during the oestrous cycle and early pregnancy

Molecules and Prostaglandins Related to Embryo Tolerance

It is generally understood that the entry of semen into the female reproductive tract provokes molecular and cellular changes facilitating conception and pregnancy. We show a broader picture of the participation of prostaglandins in the fertilization, implantation and maintenance of the embryo. A large number of cells and molecules are related to signaling networks, which regulate tolerance to implantation and maintenance of the embryo and fetus. In this work, many of those cells and molecules are analyzed. We focus on platelets, polymorphonuclear leukocytes, and group 2 innate lymphoid cells involved in embryo tolerance in order to have a wider view of how prostaglandins participate. The combination of platelets and neutrophil extracellular traps (Nets), uterine innate lymphoid cells (uILC), Treg cells, NK cells, and sex hormones have an important function in immunological tolerance. In both animals and humans, the functions of these cells can be regulated by prostaglandins and soluble factors in seminal plasma to achieve an immunological balance, which maintains fetal-maternal tolerance. Prostaglandins, such as PGI2 and PGE2, play an important role in the suppression of the previously mentioned cells. PGI2 inhibits platelet aggregation, in addition to IL-5 and IL-13 expression in ILC2, and PGE2 inhibits some neutrophil functions, such as chemotaxis and migration processes, leukotriene B4 (LTB4) biosynthesis, ROS production, and the formation of extracellular traps, which could help prevent trophoblast injury and fetal loss. The implications are related to fertility in female when seminal fluid is deposited in the vagina or uterus.

The embryonic stress response to in vitro culture: insight from genomic analysis

Recent genomic studies have shed light on the impact of in vitro culture (IVC) on embryonic homeostasis and the differential gene expression profiles associated with lower developmental competence. Consistently, the embryonic stress responses to IVC conditions correlate with transcriptomic changes in pathways related to energetic metabolism, extracellular matrix remodelling and inflammatory signalling. These changes appear to result from a developmental adaptation that enhances a Warburg-like effect known to occur naturally during blastulation. First discovered in cancer cells, the Warburg effect (increased glycolysis under aerobic conditions) is thought to result from mitochondrial dysfunction. In the case of IVC embryos, culture conditions may interfere with mitochondrial maturation and oxidative phosphorylation, forcing cells to rely on glycolysis in order to maintain energetic homeostasis. While beneficial in the short term, such adaptations may lead to epigenetic changes with potential long-term effects on implantation, foetal growth and post-natal health. We conclude that lessening the detrimental effects of IVC on mitochondrial activity would lead to significantly improved embryo quality.

Proprotein convertase 5/6 cleaves platelet-derived growth factor A in the human endometrium in preparation for embryo implantation

Establishment of endometrial receptivity is vital for successful embryo implantation. Proprotein convertase 5/6 (referred to as PC6) is up-regulated in the human endometrium specifically at the time of epithelial receptivity. PC6, a serine protease of the proprotein convertase family, plays an important role in converting precursor proteins into their active forms through specific proteolysis. The proform of platelet-derived growth factor A (pro-PDGFA) requires PC cleavage to convert to the active-PDGFA. We investigated the PC6-mediated activation of PDGFA in the human endometrium during the establishment of receptivity. Proteomic analysis identified that the pro-PDGFA was increased in the conditioned medium of HEC1A cells in which PC6 was stably knocked down by small interfering RNA (PC6-siRNA). Western blot analysis demonstrated an accumulation of the pro-PDGFA but a reduction in the active-PDGFA in PC6-siRNA cell lysates and medium compared with control. PC6 cleavage of pro-PDGFA was further confirmed in vitro by incubation of recombinant pro-PDGFA with PC6. Immunohistochemistry revealed cycle-stage-specific localization of the active-PDGFA in the human endometrium. During the non-receptive phase, the active-PDGFA was barely detectable. In contrast, it was localized specifically to the apical surface of the luminal and glandular epithelium in the receptive phase. Furthermore, the active-PDGFA was detected in uterine lavage with levels being significantly higher in the receptive than the non-receptive phase. We thus identified that the secreted PDGFA may serve as a biomarker for endometrial receptivity. This is also the first study demonstrating that the active-PDGFA localizes to the apical surface of the endometrium during receptivity.

Expression of epidermal growth factor, fibroblast growth factor-2, and platelet-derived growth factor-A in the eutopic endometrium of women with endometriosis

AIM

The objective of the present study was to compare the levels of expression of epidermal growth factor (EGF), fibroblast growth factor-2 (FGF-2), and platelet-derived growth factor-A (PDGF-A) mRNA in the eutopic endometrium of women with and without endometriosis.

METHODS

Thirty-five women with advanced stage endometriosis and 31 control women were recruited. Following isolation of total RNA from endometrial tissue and reverse transcription, cDNA samples were amplified to quantify the level of expression of EGF, FGF-2, PDGF-A.

RESULTS

While the levels of mRNA of EGF and FGF-2 were not different between the two groups, the PDGF-A mRNA level was significantly lower in the endometriosis group than in the control group during the secretory phase (6.12 +/- 0.51 vs 12.50 +/- 0.99, mean +/- SEM, P < 0.05).

CONCLUSION

The expression level of PDGF-A, but not EGF and FGF-2, might be decreased during the secretory phase in the eutopic endometrium of women with advanced stage endometriosis.

Aberrant expression of PDGF ligands and receptors in the tumor prone ovary of follitropin receptor knockout (FORKO) mouse

Although PDGF family members play a vital role in cell proliferation, motility and chemotaxis via activation of structurally similar alpha- and beta-receptors, little is known of their function in ovarian regulation and induction of tumorigenesis. Microarray analyses of ovaries from young follitropin receptor knockout (FORKO) mice that are prone to late ovarian tumors upon aging have revealed significant imbalances in PDGF ligands and receptors. We hypothesized that FSH/FSH-R signaling may exert effects partly by regulation of PDGF the family. To further understand their implications for ovarian tumorigenesis, we studied FORKO ovaries and hormonal regulation of the PDGF family members in normal mice, by using RT-PCR, Q-PCR, immunohistochemistry and western blotting. While PDGF-C and PDGFR-alpha increased, PDGFR-beta mRNA and protein decreased significantly in absence of FSH-R signaling. In the normal ovary, PDGFR-alpha was not affected by gonadotropin (eCG) stimulation but PDGF-C and PDGFR-beta decreased. Administration of estradiol decreased PDGF and their receptors. To further probe the differential regulation of PDGF family members by eCG and estradiol, we co-administered eCG with estrogen antagonist, ICI 182780. Increase in PDGFR-alpha in the absence of estradiol suggests direct effects of FSH signaling. During the estrous cycle in mice PDGF-C, PDGF-D and PDGFR-alpha mRNA levels were higher at the proestrous. By IHC, we report for the first time the localization of PDGF-C, PDGFR-alpha and PDGFR-beta protein in mouse ovarian compartments including the surface epithelium that is also altered in mutants. Immunostaining of PDGFRs increased as the follicle developed to preantral stage and declined thereafter. Thus, FSH modulates PDGF family members, partly via E2, suggesting that loss of FSH-R signaling causes an imbalance of PDGF family members predisposing the abnormal ovarian follicular environment for inducing tumorigenesis in aging FORKO mice.

Differential expression and distribution of alternatively spliced transcripts of PDGF-A and of PDGF receptor-alpha in mouse reproductive tissues

Platelet-derived growth factor-A (PDGF-A) affects cellular activities such as proliferation, differentiation, and development by way of paracrine or autocrine interaction with PDGF-A receptor alpha (PDGFR-alpha). Two forms of alternatively spliced PDGF-A mRNA, a long and a short isoform, have been found in several mammalian species. Expression of PDGF-A and its cognate receptor PDGFR-alpha has been well studied in various tissues. However, these investigations did not distinguish between the individual isoforms of PDGF-A. In the present investigation, we identified the differential cellular expression patterns of the two isoforms of PDGF-A and of PDGFR-alpha in mouse reproductive tissues by using laser capture microdissection coupled with reverse transcriptase polymerase chain reaction. The long PDGF-A mRNA isoform was primarily detected in the epithelium, while the short isoform was ubiquitously distributed in epithelium, stroma, and muscle cells, although it was still more prominent in epithelium. PDGFR-alpha was mainly detected in stromal and muscle cells. Also, it was found in the epididymal epithelium, mucosal folds of the seminal vesicle, and ovarian granulosa cells. Thus, the complete PDGF-A/PDGFR-alpha signaling system is present in murine reproductive tissues, but the distribution of the long and short isoforms of PDFG-A differs.

Expression Patterns of the Implantation-associated Genes in the Uterus during the Estrous Cycle in Mice

The mRNA expression patterns of EGF, HB-EGF, Amphiregulin, EGF receptor, IGF-1, CSF-1, IL-1 alpha, IL-1 beta, IL-1 receptor type 1, IL-1 receptor antagonist, LIF, COX-1, COX-2, Mucin-1, calcitonin, and rat USAG-1 mouse homologue, all of which are involved in the process of conceptus implantation to the endometrium, were examined during the estrous cycle by means of real-time quantitative PCR. COX-2, HB-EGF, LIF, Mucin-1, CSF-1, IL-1 alpha, IL-1 beta, and IL-1 receptor antagonist were temporally regulated during the estrous cycle and highly expressed during the estrous stage. In the case of COX-1, EGF, IGF-1, and EGF receptor, the highest mRNA expression was during the diestrous stage. In contrast, the rat USAG-1 mouse homologue mRNA expression did not change during the estrous cycle. These results indicate that rat USAG-1 mouse homologue expression at implantation might be specifically regulated by embryonic factors rather than the maternal environment.