Dysregulated circRNA expression profile and associated miRNA sponging in abnormal lung development in congenital diaphragmatic hernia [circRNA array]

Microarrays revealed a unique circRNA biosignature during CDH lung development. CircAnp32e was expressed in a sex-specific and spatiotemporal expression pattern in the epithelium at E15. The predicted mature sequence of circAnp32e overlapped >90% with its human orthologue.

CircRNA::miRNA::mRNA interaction networks in E15 and E21 revealed enrichment in inflammation/infection, smooth muscle cell function, cell proliferation/cell cycle regulation, and response to hypoxia pathways. Parental genes of differential expressed circRNAs at E15 enriched pathways linked to cell proliferation/cell cycle/cancer, while at end-gestation, inflammation and cardiovascular processes were also overrepresented.

Rat and human CDH lungs showed overlapping pathways with additional enrichment for RNA processing and protein binding/modification in humans. In a human bronchial epithelial (BEAS-2B) nitrofen-injury model, ANP32E and circANP32E were downregulated, and the predicted let-7 target significantly dysregulated. A unique circRNA signature during abnormal lung development in CDH may mediate inflammatory responses, smooth-muscle-cell function, and cell proliferation regulation via miRNA sponging.

Overlap of downstream pathways in rat and human CDH suggest conserved functions across species. This circRNA biosignature defines strong candidate biomarkers for CDH and future prospective prenatal investigation.