Prokineticin signaling in heart-brain developmental axis: Therapeutic options for heart and brain injuries.

Heart and brain development occur simultaneously during the embryogenesis, and both organ development and injuries are interconnected. Early neuronal and cardiac injuries share mutual cellular events, such as angiogenesis and plasticity that could either delay disease progression or, in the long run, result in detrimental health effects. For this reason, the common mechanisms provide a new and previously undervalued window of opportunity for intervention. Because angiogenesis, cardiogenesis and neurogenesis are essential for the development and regeneration of the heart and brain, we discuss therein the role of prokineticin as an angiogenic neuropeptide in heart-brain development and injuries. We focus on the role of prokineticin signaling and the effect of drugs targeting prokineticin receptors in neuroprotection and cardioprotection, with a special emphasis on heart failure, neurodegenerativParkinson's disease and ischemic heart and brain injuries. Indeed, prokineticin triggers common pro-survival signaling pathway in heart and brain. Our review aims at stimulating researchers and clinicians in neurocardiology to focus on the role of prokineticin signaling in the reciprocal interaction between heart and brain. We hope to facilitate the discovery of new treatment strategies, acting in both heart and brain degenerative diseases.

The role of prokineticins in recurrent implantation failure.

The aim of the present study was to investigate the expression patterns of prokineticins (PROK) and prokineticin receptors (PROKR) in the endometrium of women with recurrent implantation failure (RIF). Fifteen (15) women with RIF and 15 fertile controls were enrolled in this study. Endometrial samples were taken from study participants with an endometrial biopsy cannula during the implantation window. Real time polymerase chain reaction and immunohistochemistry were used to determine PROK/PROKR mRNA expression and protein localization, respectively. PROK1 mRNA levels were 6.09 times higher compared to endometrial samples obtained from women with RIF than in samples obtained from fertile controls, whereas PROKR1 mRNA levels were 2.46 times lower in endometrial samples obtained from women with RIF than in samples from fertile controls. In addition, decreased PROKR1 was supported by immunohistochemistry analysis at protein level. There was no statistically significant difference between women with RIF and fertile controls regarding PROK2 and PROKR2 levels. Altered expression of the PROK1/PROKR1 system could be one of the numerous abnormalities in the endometrium of women with RIF.

Prokineticin 1-prokineticin receptor 1 signaling promotes angiogenesis in the porcine endometrium during pregnancy†.

Pregnancy establishment in mammals, including pigs, requires proper communication between embryos and the maternal reproductive tract. Prokineticin 1 (PROK1) has been described as a secretory protein with pleiotropic functions and as a novel tissue-specific angiogenic factor. However, despite the studies performed mainly on human cell lines and in mice, the function of PROK1 in the endometrium during early pregnancy is still not fully elucidated. We hypothesized that PROK1 contributes to pregnancy establishment in pigs. The present study is the first to report that the expression of PROK1 and its receptor (PROKR1) is elevated in the porcine endometrium during the implantation and early placentation period. PROK1 protein was detected mainly in luminal epithelial cells, glandular epithelial cells, and blood vessels in the endometrium. Using the porcine in vivo model of unilateral pregnancy, we revealed that conceptuses induced the endometrial expression of PROK1 and PROKR1. Moreover, the embryonic signal, estradiol-17ß, as well as progesterone, stimulated the endometrial expression of PROK1 and PROKR1. We also evidenced that PROK1-PROKR1 signaling supports endometrial angiogenesis in pigs. The PROK1-stimulated proliferation of primary porcine endometrial endothelial (PEE) cells involved PI3K/AKT/mTOR, MAPK, cAMP, and NFKB signaling pathways. Furthermore, PROK1 via PROKR1 promoted the formation of capillary-like structures by PEE cells. PROK1 also stimulated VEGFA and PGF2α secretion, which in turn may indirectly support angiogenic changes within endometrial tissue. In summary, our study suggests that PROK1 acts as an embryonic signal mediator that regulates endometrial angiogenesis and secretory function during the implantation and early placentation period in pigs.

Prokineticin1 and pregnancy.

Prokineticin 1 (PROK1), also called EG-VEGF, is a peptide of 86 amino acids with multiple biological functions. PROK1 acts via two G-protein coupled receptors: PROKR1 PROKR2. PROK1 is highly expressed in the placenta. This article reports the expression and the role of PROK1 during normal and pathological pregnancies: (i) during early pregnancy, PROK1 exhibits a peak of placental expression shortly before the establishment of the feto-maternal circulation; (ii) its receptors, PROKR1 PROKR2 are highly expressed in human placenta; (iii) its expression is increased by hypoxia; (iv) PROK1 inhibits extravillous trophoblasts migration and invasion and increases their proliferation and survival; (v) PROK1 is also a pro-angiogenic placental factor that increases microvascular placental endothelial cells proliferation, migration, invasion, and permeability. Circulating PROK1 levels are five times higher in pregnant women during the first trimester compared to the second and third trimesters. Also, its serum levels are higher in patients with preeclampsia (PE) and in patients with isolated intra-uterine growth restriction (IUGR). In mice, maintaining high level of PROK1 beyond its normal period of production (>10.5dpc) reproduces symptoms of PE. To date, our results demonstrated that PROK1 is a central factor of human placentation with direct roles both in the control of trophoblast invasion and villous growth. Thus, a failure in the expression of PROK1 and/or its receptor during pregnancy may contribute to the development of PE and/or IUGR. Besides theses original findings, we also report a direct role of this factor in parturition.

Association between polymorphisms of prokineticin receptor (PKR1 rs4627609 and PKR2 rs6053283) and recurrent pregnancy loss.

Recurrent pregnancy loss (RPL) is a condition with complex etiologies, to which both genetic and environmental factors may contribute. During the last decade, studies indicated that the expression patterns of the prokineticin receptor (PKR1 and PKR2) are closely related to early pregnancy. However, there are few studies on the role of PKR1 and PKR2 in RPL. In this study, we purpose to investigate the association between polymorphisms of the prokineticin receptor (PKR1 rs4627609 and PKR2 rs6053283) and RPL on a group of 93 RPL cases and 169 healthy controls. Genotyping of the single nucleotide polymorphisms (SNPs) was performed using a Sequenom MassARRAY iPLEX system. The results revealed a significant association between PKR2 rs6053283 polymorphism and RPL (P=0.003), whereas no association was observed between PKR1 rs4627609 polymorphism and RPL (P=0.929) in the Chinese Han population.

Prokineticin signaling is required for the maintenance of a de novo population of c-KIT⁺ cells to sustain neuroblastoma progression.

High cellular heterogeneity within neuroblastomas (NBs) may account for the non-uniform response to treatment. c-KIT(+) cells are frequently detected in NB, but how they influence NB behavior still remains elusive. Here, we used NB tumor-initiating cells to reconstitute NB development and demonstrated that c-KIT(+) cells are de novo generated and dynamically maintained within the tumors to sustain tumor progression. c-KIT(+) NB cells express higher levels of neural crest and stem cell markers (SLUG, SOX2 and NANOG) and are endowed with high clonogenic capacity, differentiation plasticity and are refractory to drugs. With serial transplantation assays, we found that c-KIT expression is not required for tumor formation, but c-KIT(+) cells are more aggressive and can induce tumors ninefold more efficiently than c-KIT(-/low) cells. Intriguingly, c-KIT(+) cells exhibited a long-term in vivo self-renewal capacity to sustain the formation of secondary and tertiary tumors in mice. In addition, we showed that Prokineticin signaling and mitogen-activated protein kinase pathways are crucial for the maintenance of c-KIT(+) cells in tumor to promote NB progression. Our results highlight the importance of this de novo population of NB cells in sustainable growth of NB and reveal specific signaling pathways that may provide targets leading to more effective NB therapies.

[Prokineticins: new regulatory peptides in human reproduction]. / Prokinéticines - De nouveaux peptides régulateurs de la reproduction humaine.

During the last decade, there has been growing evidence for the involvement of prokineticins and their receptors (PROK/PROKR) in human reproduction, with multiple roles in the female and male reproductive systems. The PROK/PROKR signalling complex has been reported as a new actor in ovary, uterus, placenta, and testis physiology, with marked dysfunction in various pathological conditions such as polycystic ovary syndrome, recurrent pregnancy loss, preeclampsia, and ectopic pregnancy. Altogether, the results strongly suggest the involvement of prokineticins in spermatogenesis, oocyte competence, embryo implantation, pregnancy, and delivery, and argue for the clinical relevance of these cytokines and their receptors as diagnostic markers for several reproductive diseases.

[PROK1, prognostic marker of embryo implantation?]. / PROK1, biomarqueur de l'implantation embryonnaire ?

In spite of improvements in assisted reproductive technology (ART) during the last 30 years, the rate of pregnancy remains constrained, as only about 25 % of embryo transfer lead to successful pregnancies, even with an average of two embryos replaced. Embryo selection is currently based on the establishment of morphokinetic scores, a method that obviously exhibits limitations. Therefore, the assessment of embryo development potency by criteria of higher predictive value is mandatory in order to increase the rates of pregnancy. Nowadays, there is increasing evidence that angiogenic factors might contribute to the success of the implantation and to the pregnancy outcome. Among these factors, prokineticin 1 (PROK1) and its receptors (PROKRs) constitute new targets that showed over the last ten years strong biological features directly linked to ovarian physiology, endometrial receptivity, embryo implantation and thus successful pregnancies. In ART, the rates of circulating PROK1 were reported in 2012 as significantly linked to the quality of embryonic cohort, as well as to the rates of pregnancy. Our preliminary data suggest a high potential of this cytokine in the success of implantation and pregnancy, and strongly overtones the emergency to investigate the value of its measurement in conditioned media of oocytes and embryo cultures in ART.

[Potential role of the angiogenic factor "EG-VEGF" in gestational trophoblastic diseases]. / Rôle potentiel du facteur angiogénique «EG-VEGF¼ dans les maladies gestationnelles trophoblastiques.

Gestational trophoblastic disease (MGT) includes a wide spectrum of pathologies of the placenta, ranging from benign precancerous lesions, with gestational trophoblastic tumors. Metastases are the leading causes of death as a result of this tumor. They represent a major problem for obstetrics and for the public health system. To date, there is no predictor of the progression of molar pregnancies to gestational trophoblastic tumor (GTT). Only an unfavorable plasma hCG monitoring after evacuation of hydatidiform mole is used to diagnose a TTG. The causes of the development of this cancer are still poorly understood. Increasing data in the literature suggests a close association between the development of this tumor and poor placental vascularization during the first trimester of pregnancy. The development of the human placenta depends on a coordination between the trophoblast and endothelial cells. A disruption in the expression of angiogenic factors could contribute to uterine or extra-uterine tissue invasion by extravillous trophoblast, contributing to the development of TTG. This review sheds lights on the phenomenon of angiogenesis during normal and abnormal placentation, especially during the MGT and reports preliminary finding concerning, the variability of expression of "Endocrine Gland-Derived Vascular Endothelial Growth Factor" (EG-VEGF), a specific placental angiogenic factor, in normal and molar placentas, and the potential role of differentiated expressions of the main placental angiogenic factors in the scalability of hydatidiform moles towards a recovery or towards the development of gestational trophoblastic tumor. Deciphering the mechanisms by which the angiogenic factor influences these processes will help understand the pathophysiology of MGT and to create opportunities for early diagnosis and treatment of the latter.

Prokineticin 1 induces inflammatory response in human myometrium: a potential role in initiating term and preterm parturition.

The infiltration of human myometrium and cervix with leukocytes and the formation of a pro-inflammatory environment within the uterus have been associated with the initiation of both term and preterm parturition. The mechanism regulating the onset of this pro-inflammatory cascade is not fully elucidated. We demonstrate that prokineticin 1 (PROK1) is up-regulated in human myometrium and placenta during labor. The expression of PROK1 receptor remains unchanged during labor and is abundantly expressed in the myometrium. Gene array analysis identified 65 genes up-regulated by PROK1 in human myometrium, mainly cytokines and chemokines, including IL-1ß, chemokine C-C motif ligand 3, and colony-stimulating factor 3. In addition, we demonstrate that PROK1 increases the expression of chemokine C-C motif ligand 20, IL-6, IL-8, prostaglandin synthase 2, and prostaglandin E(2) and F(2α) secretion. The treatment of myometrial explants with 100 ng/mL of lipopolysaccharide up-regulates the expression of PROK1, PROK1 receptor, and inflammatory mediators. The infection of myometrial explants with lentiviral microRNA targeting PROK1, preceding treatment with lipopolysaccharide, reduces the expression of inflammatory genes. We propose that PROK1 is a novel inflammatory mediator that can contribute to the onset of human parturition at term and partially mediate premature onset of inflammatory pathways during bacterial infection.

Crustacean hematopoiesis and the astakine cytokines.

Major contributions to research in hematopoiesis in invertebrate animals have come from studies in the fruit fly, Drosophila melanogaster, and the freshwater crayfish, Pacifastacus leniusculus. These animals lack oxygen-carrying erythrocytes and blood cells of the lymphoid lineage, which participate in adaptive immune defense, thus making them suitable model animals to study the regulation of blood cells of the innate immune system. This review presents an overview of crustacean blood cell formation, the role of these cells in innate immunity, and how their synthesis is regulated by the astakine cytokines. Astakines are among the first invertebrate cytokines shown to be involved in hematopoiesis, and they can stimulate the proliferation, differentiation, and survival of hematopoietic tissue cells. The astakines and their vertebrate homologues, prokineticins, share similar functions in hematopoiesis; thus, studies of astakine-induced hematopoiesis in crustaceans may not only advance our understanding of the regulation of invertebrate hematopoiesis but may also provide new evolutionary perspectives about this process.

Invertebrate hematopoiesis: an astakine-dependent novel hematopoietic factor.

A novel factor, named crustacean hematopoietic factor (CHF), was identified from a library of suppression subtractive hybridization with the aim to find downstream genes of an invertebrate cytokine, astakine 1, in the freshwater crayfish Pacifastacus leniusculus. CHF is a small cysteine-rich protein (∼9 kDa) with high similarity to the N-terminal region of vertebrate CRIM1 in containing an insulin growth factor binding protein variant motif with unknown function. CHF was found to be induced in primary cell cultures of crayfish hematopoietic tissue (Hpt) cells (precursors of crayfish blood cells) after treatment with astakine 1. Silencing of CHF did not affect the renewal of Hpt cells in vitro, but induced apoptosis of Hpt cells. CHF is exclusively expressed in the blood cell lineage of crayfish (Hpt cells and blood cells), and in vivo RNA interference experiments show that knockdown of this gene results in severe loss of blood cells and a higher apoptotic rate in Hpt. Our data further suggest that crayfish CHF is critical for the survival of hemocytes and Hpt cells by preventing their apoptosis, thus it plays an important role in hemocyte homeostasis in crayfish. Our study of CHF may also shed light on the function of this untypical insulin growth factor binding protein motif located in the N-terminal of vertebrate CRIM1.

CTGF expression is up-regulated by PROK1 in early pregnancy and influences HTR-8/Svneo cell adhesion and network formation.

BACKGROUND: Prokineticin-1 (PROK1) and connective tissue growth factor (CTGF) are expressed in human endometrium and first-trimester decidua and have individually been proposed to have roles in implantation and placentation. We have recently demonstrated that CTGF may be a target gene for PROK1 in gene array analysis of a prokineticin receptor-1 stably transfected Ishikawa endometrial epithelial cell line (PROKR1-Ishikawa). The first aim of the study was to determine the effect of PROK1 on CTGF expression in PROKR1-Ishikawa cells and first-trimester decidua samples. Secondly, the effect of CTGF on trophoblast-derived HTR-8/SVneo cell adhesion and network formation was investigated. METHODS AND RESULTS: Real-time qPCR showed that CTGF expression is elevated in first-trimester decidua compared with non-pregnant endometrium. In decidua, CTGF co-localized with PROKR1 to the glandular epithelium and a subset of stromal cells. PROK1 increased CTGF mRNA and protein expression in PROKR1-Ishikawa cells and first-trimester human decidua (8-12 weeks gestation). Knock down of endogenous PROK1 using micro RNA constructs targeted at PROK1, resulted in decreased expression of CTGF mRNA and protein in decidua. Inhibitors of specific cell signalling molecules demonstrated that PROK1 regulates CTGF expression via the Gq, phospholipase C (PLC), cSrc, epidermal growth factor receptor (EGFR), mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) kinase pathway activation. Treatment of trophoblast-derived HTR-8/Svneo cells with 1 µg/ml CTGF significantly increased adhesion to collagen IV, and differentiation of the cells into tube-like structures in matrigel. CONCLUSIONS: CTGF expression in early pregnancy decidua is regulated by PROK1, via activation of the Gq, PLC, cSrc, EGFR, MAPK/ERK kinase pathway. CTGF in turn may contribute to the regulation of trophoblast conversion of maternal spiral arteries.

Prokineticins in angiogenesis and cancer.

This review will examine the roles of prokineticins in the different neoplasms that have been investigated and will discuss how and why the prokineticin family presents such interesting prospects in the research against cancer. Prokineticins belong to a family of highly conserved small peptides (8kDa) discovered a decade ago in frog skin secretions and snake venom. The mammalian orthologs consist of two prokineticin peptides, prokineticin 1 (PROK1) and prokineticin 2 (PROK2) that signal through two G-protein coupled receptors: prokineticin receptor 1 (PROKR1) and prokineticin receptor 2 (PROKR2). Over the last decade of research, the PROK/PROKR system has been associated with a considerable number of physiological and pathological functions. Due to this wide spectrum of functions, notably potent angiogenic and immunoregulatory activities, numerous investigators have researched the PROK/PROKR system's role in cancer development in a variety of tissues.

Prokineticin-1 (PROK1) modulates interleukin (IL)-11 expression via prokineticin receptor 1 (PROKR1) and the calcineurin/NFAT signalling pathway.

Prokineticin-1 (PROK1) is a multifunctional secreted protein which signals via the G-protein coupled receptor, PROKR1. Previous data from our laboratory using a human genome survey microarray showed that PROK1-prokineticin receptor 1 (PROKR1) signalling regulates numerous genes important for establishment of early pregnancy, including the cytokine interleukin (IL)-11. Here, we have shown that PROK1-PROKR1 induces the expression of IL-11 in PROKR1 Ishikawa cells and first trimester decidua via the calcium-calcineurin signalling pathway in a guanine nucleotide-binding protein (G(q/11)), extracellular signal-regulated kinases, Ca(2+) and calcineurin-nuclear factor of activated T cells dependent manner. Conversely, treatment of human decidua with a lentiviral miRNA to abolish endogenous PROK1 expression results in a significant reduction in IL-11 expression and secretion. Importantly, we have also shown a regulatory role for the regulator of calcineurin 1 isoform 4 (RCAN1-4). Overexpression of RCAN1-4 in PROKR1 Ishikawa cells using an adenovirus leads to a reduction in PROK1 induced IL-11 indicating that RCAN1-4 is a negative regulator in the calcineurin-mediated signalling to IL-11. Finally, we have shown the potential for both autocrine and paracrine signalling in the human endometrium by co-localizing IL-11, IL-11Ralpha and PROKR1 within the stromal and glandular epithelial cells of non-pregnant endometrium and first trimester decidua. Overall we have identified and characterized the signalling components of a novel PROK1-PROKR1 signalling pathway regulating IL-11.

A long form of shrimp astakine transcript: molecular cloning, characterization and functional elucidation in promoting hematopoiesis.

Hemocytes play important roles in crustacean immune responses. Generation of new hemocytes (hematopoiesis) is thus necessary to maintain homeostasis which is vital to crustaceans. In vertebrates, certain cytokines have been demonstrated to regulate hematopoiesis and immune responses. In invertebrates, however, little is known about cytokines related to hematopoiesis. In the present study, we cloned an astakine molecule from hemocytic cDNA of tiger shrimp (Penaeus monodon) which was 1509 bp in length with a 5'-UTR of 143 bp, a coding region of 375 bp and a 3'-UTR of 991 bp. The present clone (GenBank accession no. EU980444) showed to be a longer form of astakine transcript with an extra insert of 671 bp in the 3'-UTR than the NCBI-recorded shrimp astakine cDNA sequence (GenBank accession no. AY787657). The deduced protein had 124 amino acid residues, including a signal peptide and one prokineticin domain. The calculated molecular weight (MW) of the mature peptide was 11,295 Da and pI was 5.2. Phylogenetically, this molecule is most similar to astakine-related molecules of arthropod including tiger shrimp astakine, crayfish astakines 1, 2a and 2b, aphid astakine-like molecule and parasitic wasp astakine-like molecule. Nested RT-PCR showed that astakine mRNA is expressed in many tissues and organs of the shrimp such as eyestalk, subcuticular epithelium, gills, heart, hepatopancreas, lymphoid organ, intestine, muscle, nerve and hemocytes. Real-time PCR further revealed that astakine mRNA is expressed mainly in the hemocytes. The astakine transcript is not inducible in the hemocytes until 24 h post LPS injection of shrimp. The recombinant protein of shrimp astakine (rPmAst) was synthesized using insect cell-baculovirus expression system. The authenticity of rPmAst protein was examined by MALDI-MS/MS spectrometry. Using ESI-MS it was determined that the MW of C-terminally histidine-tagged recombinant protein is 12,107 Da. It is 10 Da less than the computer-predicted MW (12,117 Da), allowing the formation of five pairs of disulfide bonds. Using BrdU incorporation assay it was demonstrated that the injection of rPmAst to the shrimp promoted cell proliferation in hematopoietic tissues. Therefore, we conclude that shrimp astakine functions as a cytokine that influences cell proliferation in the hematopoietic tissues.

Role of EG-VEGF in human placentation: Physiological and pathological implications.

Pre-eclampsia (PE), the major cause of maternal morbidity and mortality, is thought to be caused by shallow invasion of the maternal decidua by extravillous trophoblasts (EVT). Data suggest that a fine balance between the expressions of pro- and anti-invasive factors might regulate EVT invasiveness. Recently, we showed that the expression of the new growth factor endocrine gland-derived vascular endothelial growth factor (EG-VEGF) is high in early pregnancy but falls after 11 weeks, suggesting an essential role for this factor in early pregnancy. Using human villous explants and HTR-8/SVneo, a first trimester extravillous trophoblast cell line, we showed differential expression of EG-VEGF receptors, PKR1 and PKR2, in the placenta and demonstrated that EG-VEGF inhibits EVT migration, invasion and tube-like organisation. EG-VEGF inhibitory effect on invasion was supported by a decrease in matrix metalloproteinase (MMP)-2 and MMP-9 production. Interference with PKR2 expression, using specific siRNAs, reversed the EG-VEGF-induced inhibitory effects. Furthermore, we determined EG-VEGF circulating levels in normal and PE patients. Our results showed that EG-VEGF levels were highest during the first trimester of pregnancy and decreased thereafter to non-pregnant levels. More important, EG-VEGF levels were significantly elevated in PE patients compared with age-matched controls. These findings identify EG-VEGF as a novel paracrine regulator of trophoblast invasion. We speculate that a failure to correctly down-regulate placental expression of EG-VEGF at the end of the first trimester of pregnancy might lead to PE.

Bv8/Prokineticins and their Receptors A New Pronociceptive System.

Bv8 is a small protein secreted by frog skin. Mammalian homologues of Bv8, the prokineticins PK1 and PK2, and their G-protein coupled receptors prokineticin receptor 1 (PKR1) and prokineticin receptor 2 (PKR2) have been identified and linked to several biological effects as gut motility, neurogenesis, angiogenesis, circadian rhythms, hematopoiesis, and nociception. Emerging evidences indicated that prokineticins are also associated with pathologies of the reproductive and nervous system, myocardial infarction, and tumorigenesis. Bv8 elicits a dose-dependent reduction in nociceptive threshold to thermal, mechanical, and chemical stimuli. The prokineticin receptors are present in a fraction of C- and Adelta-fiber neurons also expressing the vanilloid receptors, TRPV1 and TRPA1. Mice lacking PKR genes exhibit impaired Bv8-induced hyperalgesia, develop deficient responses to noxious heat, capsaicin, and protons and show reduced thermal and mechanical hypersensitivity to paw inflammation, indicating a requirement for PKR signaling in activation and sensitization of primary afferent fibers. Bv8/PK2 is highly expressed by neutrophils and other inflammatory cells and must be considered as new pronociceptive mediators in inflamed tissues. Bv8-like hyperalgesic activity was demonstrated in extracts of rat inflammatory granulocytes. Bv8 stimulates macrophage and T lymphocyte to differentiate towards an inflammatory and Th1 profile indicating that Bv8/PK2 plays a role in immunoinflammatory responses. Blockade of PKRs may represent a novel therapeutic strategy in acute and inflammatory pain conditions.

Prokineticin 1 mediates fetal-maternal dialogue regulating endometrial leukemia inhibitory factor.

Implantation requires communication between a receptive endometrium and a healthy blastocyst. This maternal-embryonic crosstalk involves local mediators within the uterine microenvironment. We demonstrate that a secreted protein, prokineticin 1 (PROK1), is expressed in the receptive endometrium and during early pregnancy. PROK1 induces expression of leukemia inhibitory factor (LIF) in endometrial epithelial cells and first trimester decidua via a Gq-Ca(2+)-cSrc-mitogen-activated protein kinase kinase-mediated pathway. We show that human embryonic chorionic gonadotropin (hCG) induces sequential mRNA expression of PROK1 and LIF in an in vivo baboon model, in human endometrial epithelial cells, and in first-trimester decidua. We have used micro RNA constructs targeted to PROK1 to demonstrate that hCG-mediated LIF expression in the endometrium is dependent on prior induction of PROK1. Dual immunohistochemical analysis colocalized expression of the luteinizing hormone/chorionic gonadotropin receptor, PROK1, PROKR1, and LIF to the glandular epithelial cells of the first trimester decidual tissue. PROK1 enhances adhesion of trophoblast cells to fibronectin and laminin matrices, which are mediated predominantly via LIF induction. These data describe a novel signaling pathway mediating maternal-embryonic crosstalk, in which embryonic hCG via endometrial PROK1 may play a pivotal role in enhancing receptivity and maintaining early pregnancy.

Endocrine gland-derived vascular endothelial growth factor stimulates proliferation and tube formation in human uterine microvascular endothelial cell through the mitogen-activated protein kinase but not through the Akt pathway.

OBJECTIVE: To study the angiogenic functions of endocrine gland-derived vascular endothelial growth factor (EG-VEGF) on a normal myometrial uterine microvascular endothelial cell line (UtMVEC-Myo) and the signaling pathways elicited by EG-VEGF in UtMVEC-Myo. DESIGN: Experimental laboratory study. SETTING: University gynecology unit. PATIENT(S): Infertile women undergoing diagnostic laparoscopy for assessment of tubal patency. INTERVENTION(S): Real-time polymerase chain reaction (PCR) analysis of mRNA of EG-VEGF and its receptors, PKR1 and PKR2, in UtMVEC-Myo and endometrial samples. The effects of EG-VEGF on the cell proliferation, tube formation, and cell signaling pathways of UtMVEC-Myo were studied. MAIN OUTCOME MEASURE(S): Cell proliferation, tube formation, and molecules of cell-signaling pathways in the treated UtMVEC-Myo. RESULT(S): UtMVEC-Myo cells had PKR1 and PKR2 but not EG-VEGF mRNA. EG-VEGF significantly stimulated cell proliferation and tube formation in UtMVEC-Myo cells. EG-VEGF activated p44/42 mitogen-activated protein kinase (MAPK) but not Akt signaling pathway. The effects of EG-VEGF on p44/42 MAPK phosphorylation and cell proliferation were nullified by the specific MAPK inhibitor, PD98059. CONCLUSION(S): EG-VEGF has a direct angiogenic effect on UtMVEC-Myo that expresses EG-VEGF receptors (PKR1 and PKR2) and modulates cell proliferation and sprouting of the endothelial cells. It is suggested that EG-VEGF enhanced cell proliferation through the activation of MAPK pathway but not through the Akt pathway.