Circ_Lrp6, a Circular RNA Enriched in Vascular Smooth Muscle Cells, Acts as a Sponge Regulating miRNA-145 Function. Issue 4 (15th February 2019)

• Record Type: Journal Article
• Authors: Hall, Ignacio Fernando; Climent, Montserrat; Quintavalle, Manuela; Farina, Floriana Maria; Schorn, Tilo; Zani, Stefania; Carullo, Pierluigi; Kunderfranco, Paolo; Civilini, Efrem; Condorelli, Gianluigi; Elia, Leonardo
• Is Part Of: Circulation research. Volume 124:Issue 4(2019)
• Publication Date: 2019-02-15
• Subjects: alternative splicing -- circular RNA -- epigenomics -- gene expression -- microRNAs -- smooth muscle cells -- vascular diseases; Cardiovascular system -- Periodicals; Blood -- Circulation -- Periodicals; Blood Circulation; Cardiovascular System; Vascular Diseases; Sang -- Circulation -- Périodiques; Appareil cardiovasculaire -- Périodiques; 612.1
• DOI: 10.1161/CIRCRESAHA.118.314240
• Languages: English
• ISSNs: 0009-7330

Abstract

Abstract : Rationale: : microRNAs (miRNAs) modulate gene expression by repressing translation of targeted genes. Previous work has established a role for miRNAs in regulating vascular smooth muscle cell (VSMC) activity. Whether circular RNAs are involved in the modulation of miRNA activity in VSMCs is unknown. Objective: : We aimed to identify circular RNAs interacting with miRNAs enriched in VSMCs and modulating the cells' activity. Methods and Results: : RNA sequencing and bioinformatics identified several circular RNAs enriched in VSMCs; however, only one, possessing multiple putative binding sites for miR-145, was highly conserved between mouse and man. This circular RNA gemmed from alternative splicing of Lrp6 (lipoprotein receptor 6), a gene highly expressed in vessels and implicated in vascular pathologies and was thus named circ_Lrp6. Its role as a miR-145 sponge was confirmed by determining reciprocal interaction through RNA immunoprecipitation, stimulated emission depletion microscopy, and competitive luciferase assays; functional inhibition of miR-145 was assessed by measuring expression of the target genes ITGβ8 (integrin-β8), FASCIN (fascin actin-bundling protein 1), KLF4 (Kruppel-like factor 4), Yes1 (YES proto-oncogene 1), and Lox (lysyl oxidase). The interaction was preferentially localized to P-bodies, sites of mRNA degradation. Using loss- and gain-of-function approaches, we found that circ_Lrp6 hindered miR-145-mediated regulation of VSMC migration, proliferation, and differentiation. Differential expression of miR-145 and circ_Lrp6 in murine and human vascular diseases suggests that the ratio of circ_Lrp6 bound to miR-145 versus unbound could play a role in vascular pathogenesis. Viral delivery of circ_Lrp6 shRNA prevented intimal hyperplasia in mouse carotids. Conclusions: : circ_Lrp6 is an intracellular modulator and a natural sponge for miR-145, counterbalancing the functions of the miRNA in VSMCs. Abstract : Supplemental Digital Content is available in the text.