Zearalenone induces GnRH neurons activation related to central precocious puberty by triggering MKRN3 auto-ubiquitination and down-regulation

Abstract Central precocious puberty (CPP) refers to gonadotropin-dependent sexual precocity that results from the early activation of the hypothalamic–pituitary-gonadal (HPG) axis. Zearalenone (ZEA), a non-steroidal mycotoxin, is one of the important triggering factors for the development of CPP; however, its regulatory mechanism remains unclear. In this study, the correlation between urinary zearalenone (ZEA) levels and the blood expression of MKRN3 (makorin RING-finger protein-3) in patients with central precocious puberty (CPP) was investigated. Subsequently, the regulatory mechanism of ZEA on MKRN3, as well as its association with gonadotropin-releasing hormone (GnRH) production, cell proliferation, and the expression and localization of the G protein-coupled estrogen receptor (GPER) were explored in the hypothalamic cell line GT1–7. Analysis of clinical samples revealed that urinary ZEA levels were negatively correlated with blood MKRN3 expression in CPP patients. The in vitro experiments revealed that ZEA treatment up-regulated cell proliferation as well as the expressions of GnRH and GPER and re-location of GPER in GT1–7 cells by triggering MKRN3 auto-ubiquitination and down-regulation. However, such effects were attenuated by GPER overexpression. In conclusion, this study reveals a novel mechanism by which ZEA influences CPP using clinical samples and an in vitro model. The findings suggest that MKRN3 may serve as a potential therapeutic target and a diagnostic biomarker for CPP.