Possible involvement of a ZC3H4 gene splicing defect in the etiology of pre-eclampsia

Introduction: Alternative RNA splicing adds diverse variations to gene function, and its abnormalities are occasionally associated with the etiology of disease. We examined this possibility in pre-eclampsia. Methods: We performed transcriptome analysis of placentas from pre-eclamptic and normotensive pregnancies and screened for disease-specific aberrant splicing. Results: We identified aberrant splicing at exon 14 in the ZC3H4 gene. This in-frame exon is generally skipped in placentas from normal pregnancies but often observed in those from pre-eclampsia patients. The level of exon inclusion did not correlate with disease severity, such as blood pressure or fetal weight, but showed an association with the decrease in placental weight. Significantly, placental blood flow resistance measured by Doppler ultrasound correlated with the level of ZC3H4 exon 14 inclusion, suggesting that this retention leads to the onset and/or symptoms of pre-eclampsia. ZC3H4 is known to act on transcriptional regulation via suppression of lncRNA expression. Moreover, the SOD1 gene, encoding superoxide dismutase that eliminates toxic free superoxide radicals, was identified in the downstream gene group for ZC3H4. Indeed, the expression of SOD1 was found in this current study to be decreased in the pre-eclamptic placenta in correlation with the levels of ZC3H4 exon 14 retention. Discussion: Aberrant splicing of ZC3H4 gene may induce excessive oxidative stress in the placenta via the downregulation of downstream SOD1 expression thereby leading to the onset and development of pre-eclampsia.