Mourin, M. | Search bioRxiv

bioRxiv2025

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

RationaleCircular RNAs (circRNAs) can function as disease biomarkers. Their profile in abnormal lung development in congenital diaphragmatic hernia (CDH) is unknown. ObjectiveTo evaluate circRNA expression profile in CDH-associated abnormal lung development. MethodsWe profiled circRNAs in rat CDH and control lungs at embryonic day (E)15 and E21 by microarray. We validated identified circRNAs using back-splice junction amplicon sequencing, RT-qPCR, and in situ hybridization. We modified a CircRNA Function prediction Tool to predict CircRNA::micro(mi)RNA::messenger(m)RNA interactions and compared these with Oxford Nanopore RNA sequencing and existing human CDH datasets. Measurements and Main ResultsMicroarrays 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. ConclusionA 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. CircRNAs may serve as biomarkers to guide prenatal management and mitigate aberrant lung development in CDH.

developmental biology↗

bioRxiv2025

Restoring Cholesterol Efflux in Vascular Smooth Muscle Cells Transitioning into Foam Cells Through Liver X Receptor Activation

ObjectiveMacrophage foam cells derived from vascular smooth muscle cells (VSMCs) account for 30-70% of foam cells in atherosclerotic lesions. Liver X receptor (LXR) agonists promote high-density lipoprotein (HDL)-mediated cholesterol efflux from macrophages. This study aimed to investigate the effects of LXR activation on the reverse cholesterol transport (RCT) rate from VSMCs to feces in vivo. Approach and ResultsCholesterol efflux induced by serum and HDL was evaluated in human and mouse VSMCs treated with the LXR agonist T090137 before and after methyl-{beta}-cyclodextrin (MBD)-cholesterol loading. Additional experiments included treatment with an acyl-coenzyme A: cholesterol acyltransferase (ACAT) inhibitor. Cholesterol-radiolabeled VSMCs were injected into the peritoneal cavity of mice, and RCT was assessed by measuring radiolabeled cholesterol in serum, liver, and feces over 48 hours. Serum and HDL induced cholesterol efflux at similar levels in both human and mouse VSMCs. Cholesterol efflux was significantly reduced following MBD-cholesterol loading; however, treatment with the LXR agonist significantly enhanced efflux. Radiolabeled foam-like VSMCs injected into mice exhibited impaired cholesterol transfer to serum, HDL, and feces compared to non-lipid-laden VSMCs. Pre-treatment with the LXR agonist increased radiolabeled cholesterol levels in serum and HDL and doubled its fecal excretion. Additionally, LXR activation restored RCT from MBD-cholesterol-loaded VSMCs to feces, reaching levels comparable to those of non-lipid-laden cells. Treatment with an ACAT inhibitor fully restored RCT rates in foam-like VSMCs, and the combination of the ACAT inhibitor and the LXR agonist further enhanced RCT. ConclusionsHDL-mediated cholesterol efflux is significantly impaired in VSMCs during their transition into foam cells. Pharmacological activation of LXR enhances RCT from VSMCs to feces in vivo and restores the impaired RCT from transitioning VSMCs. The combination of LXR agonists and ACAT inhibitors holds promise as a synergistic therapeutic approach to restoring cholesterol homeostasis in lipid-laden VSMCs, offering potential strategies to mitigate atherosclerosis. HighlightsO_LILXR activation enhances cholesterol efflux in VSMCs in vitro, even after their transition into foam cells. C_LIO_LIVSMCs transitioning into foam cells exhibit reduced cholesterol transfer to HDL and feces in mice. C_LIO_LILXR agonist treatment enhances reverse cholesterol transport (RCT) from VSMCs to feces in vivo. C_LIO_LISelective ACAT inhibition restores RCT in foam-like VSMCs, with further enhancement observed upon LXR activation. C_LI

biochemistry↗