The pathogenesis of unexplained miscarriage (UM) is largely unclear. Environmental Zn pollution is widely present in various environments and inevitably ingested by pregnant women, which has shown reproductive toxicity. Disulfidptosis is a newly identified programmed cell death caused by excessive disulfide stress. Notably, the association, causation, and underlying mechanisms among Zn exposure, disulfidptosis, and unexplained miscarriage are completely unknown. In this study, based on two UM case-control groups, four ZnCl 2 -exposed mouse models, and a ZnCl 2 -exposed trophoblast Swan 71 cell model, we obtain a consistent conclusion that excessive Zn exposure causes disulfidptosis and thus induces miscarriage by up-regulating the GATA1/METTL1/SLC7A11 axis. In the mechanism, Zn exposure up-regulates GATA1 expression levels, which promotes GATA1-mediated METTL1 and SLC7A11 transcription. Meanwhile, Zn exposure also promotes METTL1-mediated m7G modification on SLC7A11 mRNA and thus increases SLC7A11 mRNA stability. Ultimately, Zn exposure up-regulates SLC7A11 expression levels at both transcription and post-transcription levels and thus causes disulfidptosis. Knockdown of murine Slc7a11, Gata1, or Mettl1, or supplement with NADPH suppresses mouse placental disulfidptosis and alleviates mouse miscarriage. This study not only discovers pathogenesis and biological mechanisms of Zn exposure-induced unexplained miscarriage but also provides potential targets, uncovering new health risk effects of Zn exposure in the environment-health field.
Summary Cancer cells selectively promote translation of specific oncogenic transcripts to facilitate cancer survival and progression, but the underlying mechanisms are poorly understood. Here, we find that N 7 -methylguanosine (m 7 G) tRNA modification and its methyltransferase complex components, METTL1 and WDR4, are significantly upregulated in intrahepatic cholangiocarcinoma (ICC) and associated with poor prognosis. We further reveal the critical role of METTL1/WDR4 in promoting ICC cell survival and progression using loss- and gain-of-function assays in vitro and in vivo . Mechanistically, m 7 G tRNA modification selectively regulates the translation of oncogenic transcripts, including cell-cycle and epidermal growth factor receptor (EGFR) pathway genes, in m 7 G-tRNA-decoded codon-frequency-dependent mechanisms. Moreover, using overexpression and knockout mouse models, we demonstrate the crucial oncogenic function of Mettl1-mediated m 7 G tRNA modification in promoting ICC tumorigenesis and progression in vivo . Our study uncovers the important physiological function and mechanism of METTL1-mediated m 7 G tRNA modification in the regulation of oncogenic mRNA translation and cancer progression.
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