Background: Long non-coding RNAs (LncRNAs) play important roles in doxorubicin (DOX)-induced apoptosis of cardiomyocytes. However, the function of lncRNA SOX2-OT is unclear. This study was carried out to investigate the function of SOX2-OT in doxorubicininduced cardiomyocyte apoptosis. Methods: qRT-PCR and immunoblotting were used to detect the expression levels of SOX2-OT, miR-942-5p and death protein-5 (DP5) in DOX-treated primary cardiomyocytes and rat models. The relationship among miR-942-5p, SOX2-OT, and DP5 was explored by luciferase reporter assay. The effects of SOX2-OT, miR-942-5p and DP5 on doxorubicininduced cardiomyocyte apoptosis were evaluated by Annexin V-FITC/PI method and caspase-3 activity assay. The effect of SOX2-OT on cardiomyocyte apoptosis was analyzed by TUNEL staining and echocardiography. Results: SOX2-OT and DP5 were highly expressed, while miR-942-5p was down-regulated in DOX-treated primary cardiomyocytes and rat model. SOX2-OT can upregulate DP5 as a sponge of miR-942-5p, which was a direct target of miR-942-5p. In addition, miR-942-5p reversed the protective effect of knockdown of SOX2-OT on cardiomyocytes by inhibiting the expression of DP5 in vitro and in vivo. Conclusion: Knockdown of SOX2-OT down-regulated DP5 via sponging miR-942-5p and inhibiting DOX-induced apoptosis of primary cardiomyocytes.
Background: Recent studies have shown that endothelial progenitor cells (EPCs) contribute to lung repair after lipopolysaccharide (LPS)-induced lung injury and infusion of LPS decreased early EPCs in human peripheral blood. However, the effects of LPS on endothelial colony-forming cells (ECFCs) remain to be determined. Objective: To investigate possible effects of LPS on the functional activity of ECFCs. Methods: ECFCs were isolated from human umbilical cord blood and characterized. ECFCs at passages 3-5 were treated for 24 h with either LPS or vehicle control. Their viability, migration and in vitro vasculogenesis activity were assayed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, modified Boyden chamber and in vitro angiogenesis assays, respectively. ECFC adhesion was assessed by replating cells on fibronectin-coated dishes and subsequent counting of adherent cells. Results: Incubation with LPS dose-dependently inhibited the viable, migratory, adhesive and in vitro vasculogenesis capacity of ECFCs. Conclusion: LPS impaired the functional activity of ECFCs.
It has been previously demonstrated that lipopolysaccharides (LPS) inhibit the viability, migration, adhesion and in vitro angiogenesis of late endothelial progenitor cells (EPCs). However, the mechanisms underlying this LPS‑induced impairment of late EPC functional activity are unknown. The aim of the present study was to investigate whether Toll‑like receptor 4 (TLR4) is expressed and functional on late EPCs, using late EPCs of 3‑5 passages. Cells were deprived of serum for 24 h prior to experiments and incubated with 10 µg/ml LPS for 24 h with or without pretreatment with 2 µg/ml TLR4 signaling inhibitor CLI‑095 for 30 min. The viability, migration, adhesion and in vitro angiogenesis, as well as the expression of silent information regulator 1 (SIRT1), in late EPCs were evaluated. Treatment with 10 µg/ml LPS decreased the viability, migration and adhesion abilities, and in vitro angiogenesis of late EPCs. Pretreatment with the TLR4 signaling inhibitor reversed this LPS‑induced dysfunction of late EPCs. LPS downregulated the expression of SIRT1 protein, however, blocking TLR4 attenuated the effect of LPS on SIRT1 expression. Therefore, the results of the present study indicate that LPS impaired the functional activity of late EPCs via TLR4, which may be associated with decreased SIRT1 expression.
Our previous study showed that epigallocatechin‐3‐gallate (EGCG) inhibition of human aortic smooth muscle cell (HASMC) proliferation might be mediated via upregulation of mitofusin 2 (Mfn‐2). Studies on the mechanism of Mfn‐2 inhibition of cell proliferation have mainly focused on downstream signaling. However, it is still not clear how upstream signaling molecules regulate Mfn‐2. The promoter region of the Mfn‐2 gene contains cis‐acting elements of peroxisome proliferator‐activated receptor‐γ coactivator‐1α (PGC‐1α) and estrogen‐related receptor‐α (ERR‐α), suggesting a possible link between EGCG, Mfn‐2, and PGC‐1α/ERR‐α. However, the effect of EGCG on PGC‐1α/ERR‐α remains unknown. In this study, we investigated the role of PGC‐1α/ERR‐α in the regulation of Mfn‐2 induced by EGCG and assessed the underlying mechanisms. The effects of EGCG on cell proliferation of cultured HASMCs were observed by a cell counting kit‐8 (CCK8) and 5‐ethynyl‐2‐deoxyuridine (EdU) incorporation assay. Mfn‐2, PGC‐1α, and ERR‐α gene and protein levels were determined by quantitative real‐time polymerase chain reaction (PCR) and Western blot analysis. PGC‐1α gene‐silencing (PGC‐1α small interfering RNA [siRNA]) was achieved by RNA interference and Mfn‐2 promoter and peroxisome proliferator response element (PPRE) functional activity was achieved by a luciferase transfection assay. The results showed that the ERR‐α‐specific antagonist XCT‐790 and PGC‐1α siRNA decreased the expression of Mfn‐2, thus antagonizing the inhibition of HASMC proliferation induced by EGCG. EGCG enhanced Mfn‐2 promoter (−352 to 459) activity, while XCT‐790 and PGC‐1α siRNA abrogated this effect. PGC‐1α stimulating Mfn‐2 expression was dependent on intact ERR‐α binding in the Mfn‐2 promoter. The transcriptional effect of PGC‐1α on the Mfn‐2 promoter required the integrity of the −432 to 459 region and supported that Mfn‐2 was a key target gene of PGC‐1α. These results imply that PGC‐1α/ERR‐α played important physiological roles in inhibiting the proliferation of HASMCs by modulating Mfn‐2 gene expression. Hence, EGCG regulated Mfn‐2 expression likely through the PGC‐1α/ERR‐α pathway.
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