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CircRNA Chordc1 protects mice from abdominal aortic aneurysm by contributing to the phenotype and growth of vascular smooth muscle cells.

ABSTRACT: Circular RNAs (circRNAs) have important potential in modulating vascular smooth muscle cell (VSMC) activity, but their roles in abdominal aortic aneurysm (AAA) are unknown. We performed in situ hybridization and immunohistochemistry and determined that circChordc1 (cysteine and histidine-rich domain containing 1) was markedly downregulated in aneurysm tissue compared with normal arteries. A gene gain and loss strategy was used to confirm that circChordc1 transformed VSMCs into a contracted phenotype and improved their growth, which significantly suppressed aneurysm formation and reduced the risk of rupture in mouse models of angiotensin (Ang) II- and CaCl₂-induced AAA. RNA pull-down, immunoprecipitation, and immunoblotting indicated that circChordc1 facilitated the VSMC phenotype and growth determination by binding to vimentin and ANXA2 (annexin A2), which not only increased vimentin phosphorylation to promote its degradation but also promoted the interaction between ANXA2 and glycogen synthase kinase 3 beta (GSK3β) to induce the nuclear entry of β-catenin. Thus, our present study revealed that circChordc1 optimized the VSMC phenotype and improved their growth by inducing vimentin degradation and increasing the activity of the GSK3β/β-catenin pathway, thereby extenuating vascular wall remodeling and reversing pathological aneurysm progression.

SUBMITTER: He X

PROVIDER: S-EPMC8649900 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Background: Abdominal aortic aneurysm (AAA) is a potentially life-threatening condition, but approved medical therapies to prevent AAA progression and rupture are currently lacking. Sphingolipids metabolism disorders are associated with the occurrence and development of AAA. It has been discovered that ganglioside GM3, a sialic acid-containing type of glycosphingolipid, plays a protective role in atherosclerosis which is an important risk factor for AAA, but the potential contribution of GM3 to AAA development has not been investigated. Methods: We performed a metabolomics study to evaluated GM3 level in plasma of human AAA patients. We profiled GM3 synthase (ST3GAL5) expression in the mouse model of aneurysm and human AAA tissues through western blotting and immunofluorescence staining. RNA sequencing, proteomic analysis, affinity purification and mass spectrometry, surface plasmon resonance (SPR) analysis, and functional studies were used to dissect the molecular mechanism of GM3-regulating ferroptosis. We conditionally deleted and overexpressed St3gal5 in smooth muscle cells (SMCs) in vivo to investigate its role in AAA. Results: We found significantly reduced plasma levels of the GM3 in human AAA patients. GM3 content and ST3GAL5 expression were all decreased in abdominal aortic VSMCs in AAA patients and mouse model. RNA-sequencing analysis showed that ST3GAL5 silencing in human aortic SMCs (HASMCs) induced ferroptosis. Importantly, we showed that GM3 interacted directly with the extracellular domain of transferrin receptor 1 (TFR1), a cell membrane protein critical for cellular iron uptake, disrupted its interaction with holo-transferrin. SMC-specific St3gal5 knockout exacerbated iron accumulation at lesion sites and significantly promoted AAA development, while GM3 supplementation suppressed lipid peroxidation, reduced iron deposition in aortic VSMCs and markedly decreased AAA incidence. Conclusions: Together, these results suggest that GM3 dysregulation promotes ferroptosis of VSMCs in AAA. Furthermore, GM3 may constitute a new therapeutic target for the treatment of AAA.

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CircRNA Chordc1 protects mice from abdominal aortic aneurysm by contributing to the phenotype and growth of vascular smooth muscle cells.

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