Stroke is one of the leading causes of mortality and disability worldwide. Uncovering the cellular and molecular pathophysiological processes in stroke have been a top priority. Long non-coding (lnc) RNAs play critical roles in different kinds of diseases. In recent years, a bulk of aberrantly expressed lncRNAs have been screened out in ischemic stroke patients or ischemia insulted animals using new technologies such as RNA-seq, deep sequencing, and microarrays. Nine specific lncRNAs, antisense non-coding RNA in the INK4 locus (ANRIL), metastasis-associate lung adenocarcinoma transcript 1 (MALAT1), N1LR, maternally expressed gene 3 (MEG3), H19, CaMK2D-associated transcript 1 (C2dat1), Fos downstream transcript (FosDT), small nucleolar RNA host gene 14 (SNHG14), and taurine-upregulated gene 1 (TUG1), were found increased in cerebral ischemic animals and/or oxygen-glucose deprived (OGD) cells. These lncRNAs were suggested to promote cell apoptosis, angiogenesis, inflammation, and cell death. Our Gene Ontology (GO) enrichment analysis predicted that MEG3, H19, and MALAT1 might also be related to functions such as neurogenesis, angiogenesis, and inflammation through mechanisms of gene regulation (DNA transcription, RNA folding, methylation, and gene imprinting). This knowledge may provide a better understanding of the functions and mechanisms of lncRNAs in ischemic stroke. Further elucidating the functions and mechanisms of these lncRNAs in biological systems under normal and pathological conditions may lead to opportunities for identifying biomarkers and novel therapeutic targets of ischemic stroke.

The let-7 family is the second microRNA found in C. elegans. Recent researches have found it is highly expressed in the cardiovascular system. Studies have revealed the aberrant expression of let-7 members in cardiovascular diseases, such as heart hypertrophy, cardiac fibrosis, dilated cardiomyopathy (DCM), myocardial infarction (MI), arrhythmia, angiogenesis, atherosclerosis, and hypertension. Let-7 also participates in cardiovascular differentiation of embryonic stem cells. TLR4, LOX-1, Bcl-xl and AGO1 are by now the identified target genes of let-7. The circulating let-7b is suspected to be the biomarker of acute MI and let-7i, the biomarker of DCM. Further studies are necessary for identifying the gene targets and signaling pathways of let-7 in cardiovascular diseases. Let-7 might be a potential therapeutic target for cardiovascular diseases. This review focuses on the research progresses regarding the roles of let-7 in cardiovascular development and diseases.

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Lectin-like low-density lipoprotein receptor 1 (LOX-1) is a receptor for oxidized low density lipoprotein (oxLDL) in endothelial cells. The activation of LOX-1 by oxLDL stimulates the apoptosis and dysfunction of endothelial cells, and contributes to atherogenesis. However, the regulatory factors for LOX-1 are still unclear. MicroRNAs are small, endogenous, non-coding RNAs that regulate gene expressions at a post-transcriptional level. The let-7 family is the second microRNA been discovered, which plays important roles in cardiovascular diseases. Let-7a and let-7b were predicted to target LOX-1 3′-UTR and be highly expressed in endothelial cells. The present study demonstrated that LOX-1 was a target of let-7a and let-7b. They inhibited the expression of LOX-1 by targeting the positions of 310-316 in LOX-1 3′-UTR. Over-expression of let-7a and let-7b inhibited the oxLDL-induced endothelial cell apoptosis, NO deficiency, ROS over-production, LOX-1 upregulation and endothelial nitric oxide synthase (eNOS) downregulation. Moreover, we found that oxLDL treatment induced p38MAPK phosphorylation, NF-κB nuclear translocation, IκB degradation and PKB dephosphorylation. Let-7a or let-7b over-expression attenuated these alterations significantly. The present study may provide a new insight into the protective properties of let-7a and let-7b in preventing the endothelial dysfunction associated with cardiovascular disease, such as atherosclerosis.

Coronary artery disease (CAD) and ischemic stroke (IS) are manifestations of atherosclerosis, with a high death rate. miR-146a is a microRNA that participates in the progress of CAD and IS. A single nucleotide polymorphism (SNP) in the precursor of miR-146a, rs2910164, was found to be associated with the risks of CAD and IS. However, the results were inconsistent and inconclusive. A meta-analysis was performed to assess the relationship of rs2910164 and CAD as well as IS susceptibility. The database Pubmed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), Chinese National Knowledge Infrastructure (CNKI), and Chinese Biomedical Literature Database (CBM) were searched for related studies. Crude odds ratios with 95% confidence intervals were used to investigate the strength of the association by random- or fixed-effect model. A total of eight studies, with 3138 cases and 3097 controls were identified for the meta-analysis. The results shows that rs2910164 is associated with the risk of CAD significantly in allelic model (OR = 0.86), homozygous model (OR = 0.70), heterozygous model (OR = 0.80) and dominant model (OR = 0.76). The subjects carrying the GG genotype, GG + GC genotype or G allele are at lower risks of CAD. For the susceptibility of IS, there are no significant associations between rs2910164 and total studies. However, in subgroup analysis by sample size and ethnicity, the GG, GG + GC and G allele of rs2910164 are found to be associated with higher risks of IS in large sample size group and in Koreans, under homozygous and dominant models. In conclusion, the current meta-analysis suggests lower risks of CAD for GG, GG + GC genotype and G allele of rs2910164, while rs2910164 is not associated with the risk of IS. Thus rs2910164 might be recommended as a predictor for susceptibility of CAD, but not IS.

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Angiogenesis in atherosclerotic plaque promotes plaque growth, causes plaque hemorrhage, and violates plaque stability. LINC00657 is a long noncoding RNA highly conserved and abundantly expressed in vascular endothelial cells. The present study was designed to investigate the effects and mechanisms of LINC00675 on low concentrations of oxidized low-density lipoprotein (oxLDL)-induced angiogenesis. Cell proliferation, transwell, wound healing, and tube formation assays were conducted to detect the effects of low concentrations of oxLDL on angiogenesis; the results discovered that oxLDL promoted cell proliferation, migration, and tube formation. oxLDL also upregulated LINC00657 expression. Inhibition of LINC00657 by siRNA significantly suppressed oxLDL-induced endothelial cell proliferation, migration, and tube formation. Bioinformatic assay indicated six binding sites in the LINC00657 sequence to miR-590-3p. The upregulation of LINC00657 was related to the downregulation of miR-590-3p in oxLDL-treated endothelial cells; while downregulation of LINC00657 resulted in upregulation of miR-590-3p. The antiangiogenesis effects of si-LINC00657 were partly abrogated by miR-590-3p inhibitor. Further dual-luciferase assay found miR-590-3p inhibited the expression of hypoxia-inducible factor 1 (HIF-1) by binding to the position of 689-696 in HIF-1 3'-untranslated region directly. MiR-590-3p also inhibited the oxLDL-induced upregulation of HIF-1, vascular endothelial growth factor (VEGF), matrix metalloproteinase-2 (MMP-2), and matrix metalloproteinase-9 (MMP-9). These results suggested that in oxLDL-treated endothelial cells, LINC00657 acted as a miR-590-3p sponge to attenuate the suppression of miR-590-3p on HIF-1, and to promote angiogenesis through VEGF, MMP-2, and MMP-9. The present study provided new insight into the roles of LINC00657 and miR-590-3p in preventing oxLDL-induced angiogenesis and may provide a novel strategy for atherosclerosis treatment.