The endothelin system is composed of three endothelin isoforms (ET-1, ET-2, and ET-3), the endothelin receptors ETA and ETB, and the endothelin-converting enzyme (ECE). Besides having a major vasoactive role, endothelins have roles in different cell types at a local level. Endothelin-converting enzyme-1 (ECE-1) is the key enzyme of endothelin biosynthesis, catalyzing the final processing step. Schmidt et al. (1994) purified a membrane-bound protease activity from bovine endothelial cells that specifically converts the inactive form to endothelin 1. Sequencing analysis confirmed it to be a zinc-chelating metalloprotease containing the typical HEXXH (HELTH) motif.
General function
Enzyme, Hydrolase, Peptidase/Protease
Comment
Endothelin-converting enzyme-1 (ECE-1) is the key enzyme of endothelin biosynthesis, catalyzing the final
processing step.
Yoshioka et al.(1998) reported that in the preovulatory follicles, immunohistochemical study showed that ECE-1 was expressed, with moderate intensity, on the theca interna cells and weakly on the granulosa cells. In the menstrual and pregnant corpus luteum, ECE-1 was highly expressed on both large and small luteal cells, indicating that ECE-1 expression increases during luteinization. The activity of ECE-1 was also detected on cultured luteinizing granulosa cells by measuring endothelin-1 production from its precursor. The activity of ECE-1 was significantly enhanced by the treatment of human CG and interleukin (IL)-1 during 4-day culture, whereas no significant alteration was observed by IL-4 and IL-10 treatment.
Ovarian localization
Granulosa, Theca, Luteal cells
Comment
Korth et al (1999) investigated the cellular distribution of ECE-1 in a variety of human tissues by in situ hybridization and immunohistochemistry. Widespread expression of the ECE-1 gene was noted, with a similar distribution pattern for mRNA and protein in normal human tissues, suggesting a major biological role for ECE-1. ECE-1 levels were particularly high in the cardiovascular, reproductive, and endocrine systems. There was strong and consistent labeling for ECE-1 in the vascular endothelial cells of all organs examined and in various nonvascular cells, especially some glandular cells. A large amount of ECE-1 protein and mRNA was detected in the Leydig cells of the testis and in the granulosa and theca cells of the ovary. Karam et al reported that ECE was present in internal theca cells of secondary, Graafian, atretic follicles, and in luteinized granulosa cells of the corpora lutea of human and monkey ovaries.
Endothelin-1, endothelin converting enzyme-1 and endothelin receptors in the porcine corpus luteum. Zorrilla LM et al. Porcine corpora lutea (CL) fail to show a luteolytic response to prostaglandin-F-2alpha (PGF-2alpha) (ie, luteolytic sensitivity, LS) until about day 12-13 of the estrous cycle. Although little is known of the control of LS in any species, endothelin-1 (EDN1) is believed to play a role in LS control in ruminants. Therefore, we measured mRNA and protein expression and examined the cellular localization of EDN1 precursor (pre-pro EDN1, or ppEDN1), EDN-converting enzyme-1 (ECE1), and EDN receptors (A, EDNRA and B, EDNRB) in porcine CLs collected on days 4, 7, 10, 13, and 15 of the estrous cycle to look for differences between CLs displaying (days 13-15) versus those lacking (days 4-10) LS. Abundance of ppEDN1 mRNA was greatest (and significant vs all other days) on day 7 of the cycle, whereas EDN1 protein expression did not vary during the cycle and was localized exclusively to endothelial cells (EC). Abundance of ECE1 mRNA was also greatest on day 7 (vs all other days), but ECE1 protein was significantly elevated on day 10 (vs day 4) and was immunolocalized to ECs and large luteal cells (LLC). Abundance of EDNRA mRNA was also maximal on day 7 (vs all other days) of the cycle, whereas EDNRA protein expression was not significantly changed during the cycle and was observed in LLCs, ECs, and small luteal cells (SLC). On day 13, EDNRB mRNA was significantly decreased (versus day 7). Expression of EDNRB protein was decreased on day 10 (versus all other days), and on days 13-15 (vs day 4), and was primarily localized to ECs. In conclusion, the observed elevation in ECE1 protein concentrations on day 10 and the presence of EDNRA on LLC suggests a possible role for EDN1 (resulting from the actions of ECE1) acting via EDNRA in the control of LS in the pig.
Follicle stages
Secondary, Antral, 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 (ECE1and 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.
Levy N, et al 2003 reported that hormonal regulation and cell-specific expression of endothelin-converting enzyme 1 isoforms in bovine ovarian endothelial and steroidogenic cells.
Endothelin-converting enzyme 1 (ECE-1) is a key enzyme in the biosynthesis of endothelin 1 (ET-1), a potent regulator of ovarian function. Different ECE-1 isoforms are localized in distinct intracellular compartments. Thus, the spatial and temporal pattern of ECE-1 expression determines the site of big ET-1 activation and the bioavailability of ET-1. This study was undertaken to investigate the hormonal regulation and cell-specific expression of ECE-1 isoforms in endothelial and steroidogenic cells of bovine follicles and corpora lutea (CL). ECE-1 gene is expressed by both endothelial and steroidogenic cells; however, the intracellular ECE-1a isoform was present only in ET-1-expressing endothelial cells. Steroidogenic cells in follicles or in CL, deficient in ET-1, expressed only the plasma membrane ECE-1b isoform. The intensity of antisense ECE-1 labeling in the granulosa cell layer increased with follicular size; insulin-like growth factor I and insulin upregulated ECE-1 expression when cultured with granulosa cells, suggesting that these growth factors may increase ECE-1 in growing follicles. In contrast, ET-1 and LH downregulated ECE-1 in steroidogenic cells. This effect could account for low ECE (and ET-1) levels, which characterize the early luteal phase. These findings suggest that ECE-1 is regulated during different stages of the cycle in a physiologically relevant manner. The hormonal regulation and intracellular localization of bovine ECE-1 isoforms revealed in this study may provide new insights into ET-1 biosynthesis and mode of action in different cellular microenvironments within the ovary.
Phenotypes
Mutations
1 mutations
Species: mouse
Mutation name: None
type: null mutation fertility: unknown Comment:Hofstra et al. (1999) reported a loss-of-function mutation in the endothelin-converting enzyme 1 (ECE-1) associated with Hirschsprung disease characterized by cardiac defects, and autonomic dysfunction.