Inhibition of XIST attenuates abdominal aortic aneurysm in mice by regulating apoptosis of vascular smooth muscle cells through miR-762/MAP2K4 axis.

Abdominal aortic aneurysm (AAA) is a common chronic aortic degenerative disease. Long non-coding RNA X-inactive specific transcript (XIST) is associated with the progression of AAA, while the underlying mechanism is still unclear. We investigated the functional role of XIST in AAA. AAA mouse model was established by administration of Angiotensin II (Ang II). Primary mouse vascular smooth muscle cells (VSMCs) were separated from the abdominal aorta of Ang II-induced AAA mice, and then treated with Ang II. XIST was highly expressed in Ang II-treated VSMCs. Cell proliferation ability was decreased and apoptosis was increased in VSMCs following Ang II treatment. XIST knockdown reversed the impact of Ang II on cell proliferation and apoptosis in VSMCs. XIST promoted mitogen-activated protein kinase kinase 4 (MAP2K4) expression by sponging miR-762. XIST overexpression suppressed cell proliferation and apoptosis of Ang II-treated VSMCs by regulating miR-762/MAP2K4 axis. Finally, Ang II-induced AAA mouse model was established to verify the function of XIST in AAA. Inhibition of XIST significantly attenuated the pathological changes of abdominal aorta tissues in Ang II-induced mice. The expression of miR-762 was inhibited, and MAP2K4 expression was enhanced by XIST knockdown in the abdominal aorta tissues of AAA mice. In conclusion, these data demonstrate that inhibition of XIST attenuates AAA in mice, which attributes to inhibit apoptosis of VSMCs by regulating miR-762/MAP2K4 axis. Thus, this study highlights a novel ceRNA circuitry involving key regulators in the pathogenesis of AAA.

Zhang D ，Lu D ，Xu R ，Zhai S ，Zhang K ... -  《-》

Abdominal Aortic Aneurysm-Associated MicroRNA-516a-5p Regulates Expressions of Methylenetetrahydrofolate Reductase, Matrix Metalloproteinase-2, and Tissue Inhibitor of Matrix Metalloproteinase-1 in Human Abdominal Aortic Vascular Smooth Muscle Cells.

MicroRNAs (miRNAs or miRs) have been highlighted to be involved in abdominal aortic aneurysm (AAA) with the emergence of recent miRNA microarray profiling studies. miR-516a-5p has been shown to be significantly overexpressed in vascular smooth muscle cells (VSMCs) from human AAA tissues from our previous microarray study, suggesting its crucial association with AAA. In addition, further bioinformatics analysis predicted methylenetetrahydrofolate reductase (MTHFR), which regulates homocysteine (Hcy) metabolism and is proposed to be a risk gene for AAA formation and to be the downregulation target of miR-516a-5p. However, the pathogenic role of miR-516a-5p in VSMCs for AAA formation remains unresolved. This study aims to investigate the role of miR-516a-5p in human VSMCs for AAA pathogenesis. miR-516a-5p was stably overexpressed and knocked down in VSMCs explant cultured from human abdominal aortic tissues by means of lentiviral system. The MTHFR protein expression was first examined by Western blotting. In addition, the protein expressions of several key components involved in AAA pathogenic features are as follows: matrix metalloproteinase (MMP)-2, MMP-9, tissue inhibitor of matrix metalloproteinase (TIMP)-1 and TIMP-2 for elastin degradation; collagen type 1 alpha 1 for compensatory collagen synthesis; monocyte chemoattractant protein-1 for inflammation, were also evaluated. Apoptotic level of VSMCs was examined by terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Results showed that protein expression of MTHFR was significantly downregulated on miR-516a-5p overexpression (P < 0.05) in VSMCs, whereas it was significantly upregulated on miR-516a-5p knockdown (P < 0.05). Of all the AAA key components investigated, only MMP-2 and TIMP-1 protein expressions were found altered. A significant increase in MMP-2 (P < 0.05) and decrease in TIMP-1 (P < 0.05) expressions were observed on miR-516a-5p overexpression in VSMCs. Apoptosis was not promoted on miR-516a-5p overexpression or knockdown in VSMCs. Our findings suggested that miR-516a-5p may regulate MTHFR, MMP-2, and TIMP-1 expressions in human VSMCs, possibly promoting the disruption of Hcy metabolism and proteolytic degradation of elastin for AAA formation.

Chan CYT ，Cheuk BLY ，Cheng SWK 《-》

XIST knockdown suppresses vascular smooth muscle cell proliferation and induces apoptosis by regulating miR-1264/WNT5A/β-catenin signaling in aneurysm.

Long non-coding RNAs (lncRNAs) have been ascertained as vital modulators in abdominal aortic aneurysm (AAA) development. In this research, the function and molecular mechanisms of the lncRNA X-inactive specific transcript (XIST) in the evolution of vascular smooth muscle cells (VSMCs) were assessed. Results showed that XIST expression was increased but miR-1264 expression level was reduced in the serum of AAA patients. XIST depletion impeded human aorta VSMCs (HA-VSMCs') ability to proliferate and stimulate apoptosis, while repressing miR-1264 expression through an unmediated interaction. Additionally, the influence of XIST knockdown on apoptosis and proliferation could be rescued by an miR-1264 inhibitor. Subsequent molecular investigations indicated that WNT5A was miR-1264's target, and XIST functioned as a competing endogenous RNA (ceRNA) of miR-1264 to raise WNT5A expression. Further, an miR-1264 inhibitor stimulated the proliferation and suppressed the apoptosis of HA-VSMCs through the activation of WNT/β-catenin signaling. Taken together, XIST impeded the apoptosis and stimulated the proliferation of HA-VSMCs via the WNT/β-catenin signaling pathway through miR-1264, demonstrating XIST's underlying role in AAA.

Zou L ，Xia PF ，Chen L ，Hou YY ... -  《-》

Adenosine kinase inhibition protects mice from abdominal aortic aneurysm via epigenetic modulation of VSMC inflammation.

Abdominal aortic aneurysm (AAA) is a common, serious vascular disease with no effective pharmacological treatment. The nucleoside adenosine plays an important role in modulating vascular homeostasis, which prompted us to determine whether adenosine kinase (ADK), an adenosine metabolizing enzyme, modulates AAA formation via control of the intracellular adenosine level, and to investigate the underlying mechanisms. We used a combination of genetic and pharmacological approaches in murine models of AAA induced by calcium chloride (CaCl2) application or angiotensin II (Ang II) infusion to study the role of ADK in the development of AAA. In vitro functional assays were performed by knocking down ADK with adenovirus-short hairpin RNA in human vascular smooth muscle cells (VSMCs), and the molecular mechanisms underlying ADK function were investigated using RNA-sequencing, isotope tracing, and chromatin immunoprecipitation quantitative polymerase chain reaction (ChIP-qPCR). The heterozygous deficiency of ADK protected mice from CaCl2- and Ang II-induced AAA formation. Moreover, specific knockout of ADK in VSMCs prevented Ang II-induced AAA formation, as evidenced by reduced aortic extracellular elastin fragmentation, neovascularization, and aortic inflammation. Mechanistically, ADK knockdown in VSMCs markedly suppressed the expression of inflammatory genes associated with AAA formation, and these effects were independent of adenosine receptors. The metabolic flux and ChIP-qPCR results showed that ADK knockdown in VSMCs decreased S-adenosylmethionine (SAM)-dependent transmethylation, thereby reducing H3K4me3 binding to the promoter regions of the genes that are associated with inflammation, angiogenesis, and extracellular elastin fragmentation. Furthermore, the ADK inhibitor ABT702 protected mice from CaCl2-induced aortic inflammation, extracellular elastin fragmentation, and AAA formation. Our findings reveal a novel role for ADK inhibition in attenuating AAA via epigenetic modulation of key inflammatory genes linked to AAA pathogenesis.

Xu J ，Liu Z ，Yang Q ，Ma Q ，Zhou Y ，Cai Y ，Zhao D ，Zhao G ，Lu T ，Ouyang K ，Hong M ，Kim HW ，Shi H ，Zhang J ，Fulton D ，Miller C ，Malhotra R ，Weintraub NL ，Huo Y ... -  《-》

Knockdown of lncRNA PVT1 Inhibits Vascular Smooth Muscle Cell Apoptosis and Extracellular Matrix Disruption in a Murine Abdominal Aortic Aneurysm Model.

Zhang Z ，Zou G ，Chen X ，Lu W ，Liu J ，Zhai S ，Qiao G ... -  《-》