LncRNA SCIRT is downregulated in atherosclerosis and suppresses the proliferation of human aortic smooth muscle cells (HAOSMCs) by sponging miR-146a in cytoplasm

Background SCIRT has been characterized as a key player in cancer biology, while its role in other human diseases is unclear. This study explored its role in atherosclerosis, with a specific focus on its interaction with SCIRT and miR-146a. Methods The expression of SCIRT and miR-146a in atherosclerosis-affected tissues and healthy tissues from 56 atherosclerosis patients were analyzed by RT-qPCR. The expression of SCIRT in nuclear and cytoplasm samples was detected by RNA fractionation assay. The direct interaction between SCIRT and miR-146a was detected by RNA pull-down assay. SCIRT and miR-146a were overexpressed in human aortic smooth muscle cells (HAOSMCs) to study the crosstalk between them. The role of SCIRT and miR-146a in the proliferation of HAOSMCs was analyzed with BrdU assay. Results SCIRT was downregulated by atherosclerosis, while miR-146a was upregulated by atherosclerosis. SCIRT was detected in both cytoplasm and nuclear samples, and it directly interacted with miR-146a. In HAOSMCs, overexpression of SCIRT and miR-146a did not affect the expression of each other. Interestingly, SCIRT suppressed the proliferation of HAOSMCs and reduced the enhancing effects of miR-146a on cell proliferation. Conclusion Therefore, SCIRT is downregulated in atherosclerosis and it suppresses the proliferation of HAOSMCs by sponging miR-146a in cytoplasm.

Circ_ROBO2/miR-149 Axis Promotes the Proliferation and Migration of Human Aortic Smooth Muscle Cells by Activating NF-κB Signaling

Atherosclerosis is the leading global cause of mortality. The occurrence of coronary artery disease (CAD) is regulated by a diversity of pathways, including circRNAs. However, the potential mechanisms of circRNAs in CAD remain unclear. Here, qRT-PCR was used to examine the expressions of miR-149 and circ_ROBO2. Their influences on cell proliferation, migration, and apoptosis were measured by CCK-8, trans­well, and flow cytometry assays, respectively. The protein levels of p-IκBα and NF-κB p65 were examined using western blot. The molecular interactions were validated using dual luciferase reporter and RNA pull-down assays. The expression patterns of circ_ROBO2 and miR-149 in CAD patients and PDGF-BB-treated human aortic smooth muscle cells (HASMCs) were upregulated and downregulated, respectively. Knockdown of circ_ROBO2 could markedly inhibit the capabilities of proliferation and migration, enhance the apoptotic rate, and suppress NF-κB signaling in PDGF-BB-treated HASMCs. Mechanistically, circ_ROBO2 acted as a sponge of miR-149 to activate TRAF6/NF-κB signaling. Rescue studies demonstrated that neither silencing miR-149 nor activation of NF-κB signaling obviously abolished the biological roles of circ_ROBO2 knockdown in PDGF-BB treated-HASMCs. This discovery elucidated a functional mechanism of circ_ROBO2 in CAD, suggesting that circRNAs serve a vital role in the progression of CAD.

Expression and Functional Analysis of lncRNAs Involved in Platelet-Derived Growth Factor-BB-Induced Proliferation of Human Aortic Smooth Muscle Cells

Abnormal proliferation of vascular smooth muscle cells (VSMCs) is a common feature of many vascular remodeling diseases. Because long non-coding RNAs (lncRNAs) play a critical role in cardiovascular diseases, we analyzed the key lncRNAs that regulate VSMC proliferation. Microarray analysis identified 2,643 differentially expressed lncRNAs (DELs) and 3,720 differentially expressed coding genes (DEGs) between fetal bovine serum (FBS) starvation-induced quiescent human aortic smooth muscle cells (HASMCs) and platelet-derived growth factor-BB (PDGF-BB)-stimulated proliferative HASMCs. Gene Ontology and pathway analyses of the identified DEGs and DELs demonstrated that many lncRNAs were enriched in pathways related to cell proliferation. One of the upregulated lncRNAs in proliferative HASMC was HIF1A anti-sense RNA 2 (HIF1A-AS2). HIF1A-AS2 suppression decreased HASMC proliferation via the miR-30e-5p/CCND2 mRNA axis. We have thus identified key DELs and DEGs involved in the regulation of PDGF-BB induced HASMC proliferation. Moreover, HIF1A-AS2 promotes HASMC proliferation, suggesting its potential involvement in VSMC proliferative vascular diseases.

ALKBH5 Exacerbates Aortic Dissection by Promoting Inflammatory Response and Apoptosis of Aortic Smooth Muscle Cells via Regulating lnc-TMPO-AS1/EZH2/IRAK4 Signals in an m6A Modification Manner

Recently, mounting evidence indicates that N6-methyladenosine (m6A) modification functions as a pivotal posttranscriptional modification that regulates noncoding RNA biogenesis to influence the progression of multiple diseases. However, whether m6A modification is involved in aortic dissection (AD) development has never been reported. Meanwhile, numerous studies have shown that AngII-induced inflammatory damage and excessive apoptosis of human aortic smooth muscle cells (HASMCs) are the crucial pathological features of AD development. Therefore, in this study, we intended to explore whether m6A modification can regulate AD progression by influencing the damage effects of AngII on HASMCs and elucidate the underlying mechanisms. Firstly, we screened and confirmed the high expression of alkylation repair homolog protein 5 (ALKBH5), a key m6A demethylase, in aortic tissues from AD patients, indicating that m6A modification may indeed be involved in AD progression. Subsequently, we demonstrated that ALKBH5 can exacerbate the AngII-induced HASMC inflammatory injury as well as apoptosis and shorten the survival time of AngII-infused mice. Mechanistically, we revealed that lncRNA TMPO-AS1 is a downstream target for ALKBH5 to affect AD progression in vitro and vivo. Meanwhile, we confirmed that ALKBH5-mediated m6A demethylation downregulates lnc-TMPO-AS1 by decreasing the stability of its nascent. Further, we demonstrated that lnc-TMPO-AS1 exhibits its functions in HASMCs, at least partly, through downregulating IRAK4 at the epigenetic level by combining with EZH2. Finally, the direct positive correlation between ALKBH5 and IRAK4 in terms of the expression level and biological function was confirmed, which further enforced the preciseness and correctness of our findings. In conclusion, our study demonstrated that ALKBH5 aggravates AD by promoting inflammatory response and apoptosis of HASMCs via regulating lnc-TMPO-AS1/EZH2/IRAK4 signals in an m6A modification manner and may provide a novel molecular basis for subsequent researchers to searching for novel therapeutic approaches to improve the health of patients fighting AD and other cardiovascular diseases.