The human endothelins represent a gene family comprised of endothelin-1 (131240), endothelin-2, and endothelin-3 (131242). Based on the deduced amino acid sequences of the cloned ET2 and ET3 genes, corresponding proteins have been chemically synthesized and their vasoconstrictor activities studied. Of the 3 isopeptides, ET-2 has the most potent vasoconstrictor activity.
NCBI Summary:
This gene encodes a member of the endothelin protein family of secretory vasoconstrictive peptides. The preproprotein is processed to a short mature form which functions as a ligand for the endothelin receptors that initiate intracellular signaling events. This gene product is involved in a wide range of biological processes, such as hypertension and ovulation. Altered expression of this gene is implicated in tumorigenesis. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Oct 2014]
General function
Ligand, Hormone
Comment
Cellular localization
Secreted
Comment
Reduced Endothelin-2 and Hypoxic Signaling Pathways in Granulosa-Lutein Cells of PCOS Women. Szymanska M et al. (2021) Granulosa-lutein cells (GLCs) from PCOS women display reduced HIF-1α and EDN2 levels, suggesting their role in PCOS etiology. Here, we investigated the mechanisms involved in aberrant EDN2 expression in PCOS, and its association with HIF-1α. Various HIF-1α-dependent factors were studied in GLCs from PCOS and compared to normally ovulating women. MicroRNA-210 (miR-210), its target genes (SDHD and GPD1L), and HIF-1α-responsive genes (EDN2 and VEGFA) differed in GLCs from PCOS, compared with those of healthy women. Levels of miR-210-designated hypoxiamiR-and EDN2 were reduced in the PCOS GLCs; concomitantly, GPD1L and SDHD levels were elevated. Cultured GLCs retained low EDN2 expression and had low HIF-1α levels, providing evidence for a disrupted hypoxic response in the PCOS GLCs. However, VEGFA expression was elevated in these cells. Next, miR-210 levels were manipulated. miR-210-mimic stimulated EDN2 twice as much as the miR-NC-transfected cells, whereas miR-210-inhibitor diminished EDN2, emphasizing the importance of hypoxiamiR for EDN2 induction. Intriguingly, VEGFA transcripts were reduced by both miR-210-mimic and -inhibitor, demonstrating that EDN2 and VEGFA are distinctly regulated. Disrupted hypoxic response in the GLCs of periovulatory follicles in PCOS women may play a role in ovulation failure, and in the reduced fertility prevalent in this syndrome.//////////////////
Ovarian function
Ovulation, Follicle rupture, Luteinization
Comment
High-Fat Diet Induces an Ovulatory Defect Associated with Dysregulated Endothelin-2 in Mice. Hohos NM et al. (2021) High-fat diet (HFD) consumption in female rodents causes impaired estrous cyclicity, fewer pups per litter, and dysregulation of key ovulatory genes suggesting that HFD-induced subfertility may be due to ovulatory dysfunction. To test this hypothesis female mice were fed chow or HFD for 10 weeks at which point ovulation and ovarian gene expression of endothelin-2 (Edn2), a gene critical for ovulation, were assessed. After 10 weeks of HFD, both mice that remained lean and those that became obese had fewer ovulated oocytes than chow controls (p= .041, p=0.0030, respectively). In chow controls, Edn2 was expressed as expected with basal levels during diestrus and proestrus, increased 11.6-fold during estrus, and decreased to basal levels during metestrus. In HFD mice, Edn2 was dysregulated across the entire estrous cycle as were other Edn2 system components (endothelin converting enzyme 1 (Ece-1), and the endothelin receptors (Ednra, Ednrb)). Interestingly, we found dysregulation of key ovarian steroidogenic genes after HFD. We also found that estradiol treatment in prepubertal mice increased Edn2 expression in the ovary (p=0.030), suggesting that impaired steroidogenesis may be involved in the HFD-induced dysregulation of ovarian Edn2. In conclusion, HFD leads to ovulatory dysfunction regardless of the development of obesity, which appears to be mediated through dysregulation of ovarian Edn2 expression.//////////////////In vivo imaging reveals an essential role of vasoconstriction in rupture of the ovarian follicle at ovulation. Migone FF et al. (2016) Rupture of the ovarian follicle releases the oocyte at ovulation, a timed event that is critical for fertilization. It is not understood how the protease activity required for rupture is directed with precise timing and localization to the outer surface, or apex, of the follicle. We hypothesized that vasoconstriction at the apex is essential for rupture. The diameter and blood flow of individual vessels and the thickness of the apical follicle wall were examined over time to expected ovulation using intravital multiphoton microscopy. Vasoconstriction of apical vessels occurred within hours preceding follicle rupture in wild-type mice, but vasoconstriction and rupture were absent in Amhr2(cre/+)SmoM2 mice in which follicle vessels lack the normal association with vascular smooth muscle. Vasoconstriction is not simply a response to reduced thickness of the follicle wall; vasoconstriction persisted in wild-type mice when thinning of the follicle wall was prevented by infusion of protease inhibitors into the ovarian bursa. Ovulation was inhibited by preventing the periovulatory rise in the expression of the vasoconstrictor endothelin 2 by follicle cells of wild-type mice. In these mice, infusion of vasoconstrictors (either endothelin 2 or angiotensin 2) into the bursa restored the vasoconstriction of apical vessels and ovulation. Additionally, infusion of endothelin receptor antagonists into the bursa of wild-type mice prevented vasoconstriction and follicle rupture. Processing tissue to allow imaging at increased depth through the follicle and transabdominal ultrasonography in vivo showed that decreased blood flow is restricted to the apex. These results demonstrate that vasoconstriction at the apex of the follicle is essential for ovulation.//////////////////
HIF1A-dependent increase in endothelin 2 levels in granulosa cells: role of hypoxia, LH/cAMP, and reactive oxygen species. Yalu R et al. (2014) Hypoxia-inducible factor 1 alpha (HIF1A) and endothelin 2 (EDN2) are transiently expressed during the same time window in the developing corpus luteum (CL). In this study, we sought to investigate the involvement of LH/cAMP, reactive oxygen species (ROS), and a hypoxia-mimetic compound (CoCl2) on HIF1A expression and how it affected EDN2 levels, using transformed human granulosa cells (thGCs) and primary bovine granulosa cells (GCs). CoCl2 elevated HIF1A protein levels in thGCs in a dose-dependent manner. Forskolin alone had no significant effect; however, forskolin and CoCl2 together further induced HIF1A protein and EDN2 mRNA expression in thGCs. Similarly, in primary GCs, LH with CoCl2 synergistically augmented HIF1A protein levels, which resulted in higher expression of EDN2 and another well-known hypoxia-inducible gene, VEGF (VEGFA). Importantly, LH alone elevated HIF1A mRNA but not its protein. The successful knockdown of HIF1A in thGCs using siRNA abolished hypoxia-induced EDN2 and also the additive effect of forskolin and CoCl2. We then examined the roles of ROS in thGCs: hydrogen peroxide (20 and 50 μM) elevated HIF1A protein as well as the expression of EDN2, implying that induction of HIF1A protein levels is sufficient to stimulate the expression of EDN2 (and VEGF) in normoxia. A broad-range ROS scavenger, butylated hydroxyanisole, inhibited CoCl2-induced HIF1A protein with a concomitant reduction in the mRNA expression of EDN2 and VEGF in thGCs. The results obtained in this study suggest that HIF1A, induced by various stimuli, is an essential mediator of EDN2 mRNA expression. The results may also explain the rise in the levels of HIF1A-dependent genes (EDN2 and VEGF) in the developing CL.//////////////////
Production and binding of endothelin-2 (EDN2) in the rat ovary: endothelin receptor subtype A (EDNRA)-mediated contraction. Bridges PJ et al. Endothelin-2 (EDN2)-mediated contraction has been proposed as a final mechanical signal facilitating ovulation. The objectives herein were to determine (1) whether ovarian endothelins were increased before ovulation; (2) whether a specific endothelin-converting enzyme (ECE) was mediating their production; (3) which receptor was facilitating ovarian contraction; and (4) whether receptor-specific antagonism affected ovulation. Follicular development was induced in immature rats with 10 IU pregnant mare serum gonadotrophin (PMSG) and the ovulatory cascade was initiated 48 h later with 10 IU human chorionic gonadotrophin (hCG). In Experiment 1, an immunoassay revealed that the ovarian concentration of endothelin peptide was increased 7-fold 12 h after hCG when compared with 48 h after PMSG (P < 0.05). In Experiment 2, real-time PCR indicated that mRNA for Ece1, but not Ece2, was increased in granulosa cells collected 12 h after hCG when compared with those collected before the ovulatory stimulus (P < 0.05). In Experiment 3, isometric tension analysis revealed that the contractile effect of EDN2 was mediated by endothelin receptor A (EDNRA), not B (EDNRB). In Experiment 4, no effect was observed on the rate of ovulation when rats were treated with an antagonist specific to EDNRA (BQ123) or EDNRB (BQ788), or when mice were treated with BQ123, BQ788 or BQ123 + BQ788. In conclusion, endothelin peptide is produced before ovulation and the contractile action of EDN2 within the ovary is facilitated via EDNRA. In addition, findings of this study indicate synergistic interactions among contractile factors affect ovulatory outcome, while the role of EDNRB alone in the process of ovulation requires further investigation.
Endothelin-2 (ET2), which was originally identified in human, is a bioactive peptide of 21 amino acids with strong vasoconstrictive and pressor effects. Uchide T, et al report the cDNA cloning and characterization of bovine preproendothelin-2 (PPET2), the precursor form of ET2. The bovine cDNA encodes 177 amino acids of the PPET2 polypeptide, in which a 21-amino acid mature ET2 peptide and a 16-amino acid ET2-like peptide as well as a 23-amino acid putative signal peptide were found. The bovine ET2-like peptide sequence was missing a dibasic amino acid pair at the C-terminal, in contrast to human, mouse and rat, for which the ET2-like sequence is flanked by dibasic pairs at both the N- and C-terminals. Gene expression analysis by RT-PCR showed that the transcript is expressed in various organs including heart, lung, liver, kidney, gastrointestinal tract, uterus and ovary, but not in spleen. Within the gastrointestinal tract, gene expression was detected in rumen, a ruminant-specific digestive organ, as well as stomach, duodenum and colon.
Expression regulated by
LH, Steroids, progesterone, mir210
Comment
Sirtuin-1 Inhibits Endothelin-2 Expression in Human Granulosa-Lutein Cells via HIF1A and Epigenetic Modifications†. Szymanska M et al. (2020) Endothelin-2 (EDN2) expression in granulosa cells was previously shown to be highly dependent on the hypoxic mediator, HIF1A. Here we investigated whether sirtuin-1 (SIRT1), by deacetylating HIF1A and class III histones, modulates EDN2 in human granulosa-lutein cells (hGLCs). We found that HIF1A was markedly suppressed in the presence of resveratrol or a specific SIRT1 activator, SRT2104. In turn, hypoxia reduced SIRT1 levels, implying a mutually inhibitory interaction between hypoxia (HIF1A) and SIRT1. Consistent with reduced HIF1A transcriptional activity, SIRT1 activators, resveratrol, SRT2104, and metformin, each acting via different mechanisms, significantly inhibited EDN2. In support, knockdown of SIRT1 with siRNA markedly elevated EDN2, while adding SRT2104 to SIRT1-silenced cells abolished the stimulatory effect of siSIRT1 on EDN2 levels further demonstrating that EDN2 is negatively correlated with SIRT1. Next, we investigated whether SIRT1 can also mediate the repression of the EDN2 promoter via histone modification. Chromatin immunoprecipitation (ChIP) analysis revealed that SIRT1 is indeed bound to the EDN2 promoter and that elevated SIRT1 induced a 40% decrease in the acetylation of histone H3, suggesting that SIRT1 inhibits EDN2 promoter activity by inducing a repressive histone configuration. Importantly, SIRT1 activation, using SRT2104 or resveratrol, decreased the viable numbers of hGLC, and silencing SIRT1 enhanced hGLC viability. This effect may be mediated by reducing HIF1A and EDN2 levels, shown to promote cell survival. Taken together, these findings propose novel, physiologically relevant roles for SIRT1 in downregulating EDN2 and survival of hGLCs.//////////////////
MiR-210 and GPD1L regulate EDN2 in primary and immortalized human granulosa-lutein cells. Shrestha K et al. (2018) Endothelin-2 (EDN2), expressed at a narrow window during the periovulatory period, critically affects ovulation and corpus luteum (CL) formation. LH (acting mainly via cAMP) and hypoxia are implicated in CL formation; therefore, we aimed to elucidate how these signals regulate EDN2 using human primary (hGLCs) and immortalized (SVOG) granulosa-lutein cells. The hypoxiamiR, microRNA-210 (miR-210) was identified as a new essential player in EDN2 expression. Hypoxia (either mimetic compound-CoCl2, or low O2) elevated hypoxia inducible factor 1A (HIF1A), miR-210, and EDN2. Hypoxia-induced miR-210 was suppressed in HIF1A-silenced SVOG cells, suggesting that miR-210 is HIF1A dependent. Elevated miR-210 levels in hypoxia or by miR-210 overexpression, increased EDN2. Conversely, miR-210 inhibition reduced EDN2 levels, even in the presence of CoCl2, indicating the importance of miR-210 in the hypoxic induction of EDN2. A molecule that destabilizes HIF1A protein, glycerol-3-phosphate dehydrogenase 1-like gene-GPD1L, was established as a miR-210 target in both cell types. It was decreased by miR-210-mimic and was increased by miR-inhibitor. Furthermore, reducing GPD1L either by endogenously elevated miR-210 (in hypoxia), miR-210-mimic, or by GPD1L siRNA resulted in elevated HIF1A protein and EDN2 levels, implying a vital role for GPD1L in the hypoxic induction of EDN2. Under normoxic conditions, forskolin (adenylyl cyclase activator) triggered changes typical of hypoxia. It elevated HIF1A, EDN2, and miR-210 while inhibiting GPD1L. Furthermore, HIF1A silencing greatly reduced forskolin's ability to elevate EDN2 and miR-210. This study highlights the novel regulatory roles of miR-210 and its gene target, GPD1L, in hypoxia and cAMP-induced EDN2 by human granulosa-lutein cells.//////////////////
Regulatory Effect of Hypoxia-Inducible Factor-1a on hCG-Stimulated Endothelin-2 Expression in Granulosa Cells from the PMSG-Treated Rat Ovary. Zhang J et al. Endothelin (ET)-2 plays a crucial role in ovarian ovulation in mammals. The present study was designed to test the hypothesis that hypoxia-inducible factor (HIF)-1a-mediated transcriptional activation contributes to the increased expression of ET-2 gene in response to hCG in rat ovarian granulosa cells (GCs) during gonadotropin-induced superovulation. By real-time RT-PCR analysis, ET-2 mRNA expression was found to significantly increase in cultured ovarian GCs after treatment with hCG, or even N-carbobenzoxyl-L-leucinyl-L-leucinyl-L-norvalinal (MG-132), while this increased ET-2 mRNA expression could also be blocked by ferrous ammonium sulfate (FAS) under human chorionic gonadotropin (hCG) treatment. Further analysis also found that these changes of ET-2 mRNA were consistent with HIF-1a expression or HIF-1 activity, and HIF-1a inhibitor echinomycin inhibited ovulation in rats. Taken together, these results indicate that ET-2 is transcriptionally activated by hCG through HIF-1a-mediated mechanism in GCs. This HIF-1a-induced transcriptional activation may be one of the important mechanisms mediating the increase of ET-2 expression in GCs during the gonadotropin-induced mammalian ovulatory process in vivo.
Effects of Echinomycin on Endothelin-2 Expression and Ovulation in Immature Rats Primed with Gonadotropins. Wang Z et al. Echinomycin is a small-molecule inhibitor of hypoxia-inducible factor-1 DNA-binding activity, which plays a crucial role in ovarian ovulation in mammalians. The present study was designed to test the hypothesis that hypoxia-inducible factor (HIF)-1alpha-mediated endothelin (ET)-2 expressions contributed to ovarian ovulation in response to hCG during gonadotropin-induced superuvulation. By real-time RT-PCR analysis, ET-2 mRNA level was found to significantly decrease in the ovaries after echinomycin treatment, while HIF-1alpha mRNA and protein expression was no obviously changes. Further analysis also found that these changes of ET-2 mRNA were consistent with HIF-1 activity in the ovaires, which is similar with HIF-1alpha and ET-2 expression in the granulosa cells with gonadotropin and echinomycin treatments. The results of HIF-1alpha and ET-2 expression in the granulosa cells transfected with cis-element oligodeoxynucleotide (dsODN) under gonadotropin treatment further indicated HIF-1alpha directly mediated the transcriptional activation of ET-2 during gonadotropin-induced superuvulation. Taken together, these results demonstrated this HIF-1alpha-mediated ET-2 transcriptional activation is one of the important mechanisms regulating gonadotropin-induced mammalian ovulatory precess in vivo.
Induction of Endothelin-2 Expression by Luteinizing Hormone and Hypoxia: Possible Role in Bovine Corpus Luteum Formation. Klipper E et al. The pattern and regulation of endothlin-2 (EDN2) expression and its putative roles in bovine ovaries were investigated. EDN2 mRNA was determined in corpus luteum (CL) and during folliculoluteal transition induced by GnRH in vivo. EDN2 was elevated only in the early CL and was not present in older CL. In the young CL, EDN2 mRNA was identified mainly in luteal cells but not endothelial cells that expressed the EDN1 gene. Similarly, in preovulatory follicles, EDN2 was expressed in the granulosa cells (GCs) and not in the vascular theca interna. LH and hypoxia are two major stimulants of CL formation. Therefore, GCs were cultured with bovine LH, under hypoxic conditions. GCs incubated with bovine LH resulted in increased EDN2 mRNA 42 h later. CoCl2, a hypoxia-mimicking agent, elevated EDN2 in GCs in a dose-dependent manner. Incubation of the human GC line (Simian virus 40 large T antigen) under low oxygen tension (1%) augmented EDN2 6 and 24 h later. In these two cell types, along with EDN2, hypoxia augmented VEGF. EDN2 induced in GCs changes that characterize the developing CL: cell proliferation as well as up-regulation of vascular endothelial growth factor and cyclooxygenase-2 (mRNA and protein levels). Human chorionic gonadotropin also up-regulated these two genes. Small interfering RNA targeting EDN-converting enzyme-1 effectively reduced its mRNA levels. This treatment, expected to lower the mature EDN2 peptide production, inhibited VEGF mRNA levels and GC numbers. Together these data suggest that elevated EDN2 in the early bovine CL, triggered by LH surge and hypoxia, may facilitate CL formation by promoting angiogenesis, cell proliferation, and differentiation.
A NOVEL PATHWAY INVOLVING PROGESTERONE RECEPTOR, ENDOTHELIN-2, AND ENDOTHELIN RECEPTOR B CONTROLS OVULATION IN MICE. Palanisamy GS et al. The steroid hormone progesterone (P) plays a pivotal role during ovulation. Mice lacking P receptor (Pgr) gene fail to ovulate due to a defect in follicular rupture. The P receptor (PGR)-regulated pathways that modulate ovulation, however, remain poorly understood. To identify these pathways, we performed gene expression profiling using ovaries from mice subjected to gonadotropin-induced superovulation in the presence and in the absence of CDB-2914, a synthetic PGR antagonist. Prominent among the genes that were down regulated in response to CDB-2914 was endothelin-2 (ET-2), a potent vasoactive molecule. ET-2 mRNA was transiently induced in mural granulosa cells of the preovulatory follicles immediately preceding ovulation. This induction was absent in the ovaries of PGR null mice, indicating a critical role of this receptor in ET-2 expression. To investigate the functional role of ET-2 during ovulation, we employed selective antagonists of endothelin receptors, ETR-A and ETR-B. Mice treated with an ETR-B antagonist exhibited a dramatic (>85%) decline in the number of released oocytes. Strong expression of ETR-B was observed in the mural and cumulus granulosa cells of the preovulatory follicles as well as in the capillaries lining the inner border of the theca interna. We also identified cGMP-dependent protein kinase II, a previously reported PGR-regulated gene, as a downstream target of ET-2 during ovulation. Collectively, our studies uncovered a unique pathway in which ET-2, produced by PGR in mural granulosa cells, acts in a paracrine or autocrine manner on multiple cell-types within the preovulatory follicle to control the final events leading to its rupture.
Ovarian localization
Granulosa, Luteal cells, smooth muscle
Comment
Endothelin-2 in Ovarian Follicle Rupture Ko C, et a .
The ovulatory process is activated by a surge of LH (LH), a pituitary gonadotropin, which initiates a cohort of dramatic changes in biochemical, physical, and gene expression in the ovary, leading to follicle rupture and oocyte release. Here we report the identification of endothelin-2 (EDN2) as a last moment-trigger of follicle rupture. In the ovary, EDN2 is exclusively and transiently expressed in the granulosa cells immediately before ovulation. Administration of EDN2 to the ovarian tissue induced rapid contraction, while addition of tezosentan, an endothelin receptor antagonist, diminishes the EDN2 effect. In vivo, treatment of tezosentan before ovulation substantially decreases gonadotropin-induced superovulation. As a target tissue of EDN2 action, we identified a layer of smooth muscle cells in the follicular wall of each follicle. Taken together, our data indicate that EDN2 induces follicular rupture by constricting periovulatory follicles.
Changes in mouse granulosa cell gene expression during early luteinization. McRae RS et al. Changes in gene expression during granulosa cell luteinization have been measured using serial analysis of gene expression (SAGE). Immature normal mice were treated with pregnant mare serum gonadotropin (PMSG) or PMSG followed, 48 h later, by human chorionic gonadotropin (hCG). Granulosa cells were collected from preovulatory follicles after PMSG injection or PMSG/hCG injection and SAGE libraries generated from the isolated mRNA. The combined libraries contained 105,224 tags representing 40,248 unique transcripts. Overall, 715 transcripts showed a significant difference in abundance between the two libraries of which 216 were significantly down-regulated by hCG and 499 were significantly up-regulated. Among transcripts differentially regulated, there were clear and expected changes in genes involved in steroidogenesis as well as clusters of genes involved in modeling of the extracellular matrix, regulation of the cytoskeleton and intra and intercellular signaling. The SAGE libraries described here provide a base for functional investigation of the regulation of granulosa cell luteinization.
Follicle stages
Preovulatory, Corpus luteum
Comment
Expression pattern of endothelin system components and localization of smooth muscle cells in the human pre-ovulatory follicle. Choi DH et al. BACKGROUND Whether ovarian follicular rupture involves contractile activity or not has been debated for decades. Recently, study in the rodents has indicated that an endogenously produced potent vasoconstrictive peptide, endothelin-2 (EDN2), may induce follicular constriction immediately prior to ovulation. This study was aimed to systematically characterize the human ovarian endothelin system and localize smooth muscle cells to assess the possible involvement of contractile activity in human ovulation. METHODS This is a prospective experimental study. Study subjects were 20 women aged 20-38 years who underwent IVF owing to tubal or male factors. Expression patterns of messenger RNAs (mRNAs) for EDN1, EDN2, EDN3, endothelin-converting enzyme-1 (ECE1?and ECE2), endothelin receptor A (ET(A)) and ET(B) in the granulosa cells (GCs) and cumulus cells and endothelin peptide concentration in the pre-ovulatory follicles were measured at 36 h after hCG injection. In addition, localization of ovarian smooth muscle cells and endothelin receptor expression were determined in normal (non-IVF patient) ovaries. RESULTS Pre-ovulatory follicles express mRNA for EDN1 and EDN2, ECE1, ECE2, ET(A) and ET(B), but not EDN3, contain highly concentrated endothelin peptides (105.9 pg/ml) and are surrounded by theca externa that are made mostly of multicell layer non-vascular smooth muscle cells. ET(A) expression is localized in the smooth muscle cells of theca externa, theca interna and GC, whereas ET(B) expression is confined to theca interna. CONCLUSIONS Pre-ovulatory follicles contain highly concentrated endothelins and are surrounded by non-vascular smooth muscle cells that express endothelin receptor, suggesting involvement of endothelin-induced contractile action in ovulation in the human ovary.
Role of hypoxia in the regulation of periovulatory EDN2 expression in the mouse. Na G et al. We have previously proposed endothelin-2 (EDN2) as a granulosa cell-derived contractile signal that facilitates ovulation. Spatially, Edn2 mRNA expression is restricted to granulosa cells of periovulatory follicles. Temporally, mRNA for this contractile peptide is expressed immediately before follicle rupture. The primary objective of this study was to test the hypothesis that hypoxia mediates EDN2 expression in granulosa cells at ovulation, and if it does, to determine the region within the promoter responsible for this effect. To determine the effect of hypoxia on mRNA expression, immature mice were treated with 5 IU of PMSG followed 48 h later by 5 IU of human chorionic gonadotropin (hCG). Granulosa cells were isolated at 9 h after hCG, cultured under normal or hypoxic conditions, and the expression level of mRNA was compared. mRNA expression was increased when granulosa cells were cultured in a hypoxic environment (p < 0.05). Subsequent promoter analysis found that the 5′ upstream region of the EDN2 promoter (between -1894 bp and -1407 bp) was responsible for hypoxia-mediated changes in EDN2 expression. This promoter region contains multiple sites for potential transcriptional regulation, including that by hypoxia-inducible factor 1 (HIF-1, ACGTG) at -1297 bp. The second objective of this study was to determine whether the progesterone receptor (PR) or cyclooxygenase-2 (COX-2), two key regulators of periovulatory events, controlled EDN2 expression. To accomplish this, gonadotropin-primed mice were treated with RU-486 or indomethacin and expression of mRNA for Edn2 was determined in ovaries collected at 12 h after hCG. Treatment with RU-486 or indomethacin did not affect expression of mRNA for Edn2 (p > 0.05). Taken together, we believe that hypoxia, but not the PR or COX-2, regulate gonadotropin-induced EDN2 expression in the periovulatory follicle.
Phenotypes
PCO (polycystic ovarian syndrome)
Mutations
1 mutations
Species: mouse
Mutation name: None
type: null mutation fertility: subfertile Comment: Loss of Function of Endothelin-2 Leads to Reduced Ovulation and CL Formation. Cacioppo JA 2014 et al.
Endothelin-2 (EDN2), a potent vasoconstrictive peptide, is transiently produced by periovulatory follicles at the time of ovulation when corpus luteum (CL) formation begins. EDN2 induces contraction of ovarian smooth muscles ex vivo via an endothelin receptor A-mediated pathway. In this study, we aimed to determine if EDN2 is required for normal ovulation and subsequent CL formation in?vivo. In the ovaries of a mouse model that globally lacks the Edn2 gene (Edn2 knockout mouse; Edn2KO), histology showed that post-pubertal Edn2KO mice possess follicles of all developmental stages, but no corpora lutea. When exogenous gonadotropins were injected to induce super-ovulation, Edn2KO mice exhibited significantly impaired ovulation and CL formation compared to control littermates. Edn2KO ovaries that did ovulate in response to gonadotropins did not contain histologically and functionally identifiable CL. Intra-ovarian injection of EDN2 peptide results suggest partial induction of ovulation in Edn2KO mice. Endothelin receptor antagonism in wild type mice similarly disrupted ovulation, CL formation, and progesterone secretion. Overall, this study suggests that EDN2 is necessary for normal ovulation and CL formation.
/////////////////////////