Deregulation of miR-324/KISS1/kisspeptin in early ectopic pregnancy: mechanistic findings with clinical and diagnostic implications

Abstract

Background: Ectopic pregnancy (EP) is a life-threatening condition, for which novel screening tools enabling early accurate diagnosis would improve clinical outcomes. Kisspeptins, encoded by KISS1, play an essential role in human reproduction, at least partially by regulating placental function and possibly embryo implantation. Kisspeptin levels are massively elevated in normal pregnancy and reportedly altered in various gestational pathologies. Yet, the pathophysiological role of KISS1/kisspeptin in EP has not been investigated previously. Methods: Measurements of plasma kisspeptins and KISS1 expression analyses in human embryonic/placental tissue were conducted in EP and their controls (women undergoing voluntary termination of pregnancy, VTOP) during early gestational window (<12-wks). Putative miRNA regulators of KISS1 were predicted in silico, followed by expression analyses of selected miRNAs and validation of repressive interactions in vitro. Circulating levels of these miRNAs were also assayed in EP vs. VTOP. Results: Circulating kisspeptins gradually increased during the first trimester of normal pregnancy, but were massively reduced in EP. This profile correlated with expression levels of KISS1 in human embryonic/placental tissue, which increased in VTOP but remained suppressed in EP. Bioinformatic predictions and expression analyses identified miR-27b-3p and miR-324-3p as putative repressors of KISS1 in human embryonic/placental tissue at <12-wks gestation, when expression of both miRNAs was low in VTOP controls, but significantly increased in EP. Yet, a significant repressive interaction was documented only for miR-324-3p, occurring at the predicted 3'-UTR of KISS1. Interestingly, circulating levels of miR-324-3p, but not of miR-27b-3p, were dramatically suppressed in EP, despite elevated tissue expression of the pre-miRNA, suggesting defective export in EP. A decision-tree model using kisspeptin and miR-324-3p levels was successful in discriminating EP vs. VTOP, with a receiver-operating characteristic (ROC) AUC of 0.95 ± 0.02 (95% CI). Conclusions: Our results document a massive down-regulation of KISS1/kisspeptins in early stages of EP, likely via a repressive interaction with miR-324-3p. Our data identify circulating kisspeptins and miR-324-3p as novel biomarkers for accurate for screening of EP at early gestational ages.

Tachykinins and Kisspeptins in the Regulation of Human Male Fertility

“…Much has been published about the peripheral regulatory roles of kisspeptin in female fertility. Kisspeptin and its receptor KISS1R have important roles in regulating follicle development, oocyte maturation, ovulation, ovarian steroidogenesis, implantation, pregnancy, and placentation [36,[54][55][56]. However, less is known about the peripheral reproductive roles of the tachykinin family and the roles of kisspeptins and tachykinins in male reproductive tissues.…”

“…In female reproductive tissues, kisspeptins are involved in the regulation of a wide variety of processes including follicular development, oocyte maturation, ovulation, ovarian steroidogenesis, embryo implantation, and placentation [53][54][55][56]. In the case of males, kisspeptins are suggested to play important regulatory roles in spermatogenesis, testicular steroidogenesis, and spermatozoa function, as is discussed in the following sections [43,54].…”

The Role of Kisspeptin in the Ovarian Cycle, Pregnancy, and Fertility

“…A study by de Roux et al demonstrated that humans with a defect in the GPR54 gene exhibit isolated hypogonadotrophic hypogonadism, suggesting that kisspeptin is an important regulator of gonadal axis development [59]. This finding was then reproduced by an independent study by Seminara et al, who evaluated a large family with idiopathic hypogonadotrophic hypogonadism and generated GPR54 knockout mice, which failed to undergo adult sexual development and had low serum gonadotropin levels [47]. In contrast, exogenous kisspeptin administration in prepubertal rodents and primates has been shown to induce precocious puberty [60].…”

“…Kisspeptin has been shown to be massively downregulated in the case of ectopic pregnancy [47]. Ectopic pregnancy occurs when a fertilized ovum implants and develops outside the uterine cavity.…”

MiR-324/SOCS3 Axis Protects Against Hypoxia/Reoxygenation-Induced Cardiomyocyte Injury and Regulates Myocardial Ischemia via TNF/NF-κB Signaling Pathway

“…23,24) miR-324 is located on 17p13.1 and has been confirmed to take effects on various physiological function in many diseases, such as cancers, [25][26][27][28] Parkinson's disease, 29) polycystic ovarian syndrome, 30) and early ectopic pregnancy. 31) In addition, miR-324 has been proven to participate in the protection of urocortin against myocardial ischemia-reperfusion injury. 32) However, details on the regulatory and potential functional mechanisms of miR-324 in myocardial ischemia have never been reported.…”