Abstract:

Objective To investigate the role of miRNAs in maternal amniotic fluid exosomes in development of isolated ventriculomegaly (VM) in fetuses. Methods Amniotic fluid samples were collected from 9 cases of moderate isolated VM and 8 normal control cases to extract exosomal miRNA, and miRNA sequencing technique was used to identify differentially expressed miRNAs between the two groups. Three miRNAs with significant differential expression between the two groups, whose high expression was associated with VM, were selected for verification with RT-qPCR. Dual luciferase reporter assays were used to verify the regulatory effect of miR-122-5p on its predicted target genes AKT3 and CCDC88C. Gene ontology (GO) and KEGG pathway analyses were performed to explore the possible roles of the top 40 significant differential miRNAs in the pathophysiology of VM. Results We identified a total of 272 differentially expressed miRNAs in VM cases, including 43 up-regulated and 229 down-regulated miRNAs. The target genes of these differential miRNAs were associated with DNA and transcription factor binding, transmembrane transporter and nucleic acid binding transcription factor activity, and cell developmental process. These miRNAs were mostly enriched in the MAPK, cGMP-PKG and Wnt signaling pathways. Verification with RT-qPCR showed that miR-122-5p expression level was significantly lower in VM group than in the control group (P<0.05), which was consistent with miRNA sequencing results; let-7b-5p expression level was significantly lower in VM group, which was contrary to miRNA sequencing result. Dual luciferase reporter assays showed that miR-122-5p was not capable of regulating AKT3 or CCDC88C expressions. Conclusions The highly abundant differentially expressed miRNAs in maternal amniotic fluid exosomes play important roles in the occurrence of fetal VM possibly by regulating the MAPK, PI3K-Akt, Wnt and cGMP-PKG signaling pathways.

Key words: fetal isolated ventriculomegaly, amniotic fluid, exosomes, miRNA