Trichostatin C attenuates TNFα-induced inflammation in endothelial cells by up-regulating Krüppel-like factor 2 / 药学学报

Krüppel-like transcription factor 2 (KLF2) plays a key regulatory role in endothelial inflammation, thrombosis, angiogenesis and macrophage inflammation and polarization, and up-regulation of KLF2 expression has the potential to prevent and treatment atherosclerosis. In this study, trichostatin C (TSC) was obtained from the secondary metabolites of rice fermentation of Streptomyces sp. CPCC 203909 as a KLF2 up-regulator by using a high throughput screening model based on a KLF2 promoter luciferase reporter assay. TSC significantly inhibited the adhesion of tumor necrosis factor-α (TNFα) induced monocytes (THP-1) to human umbilical vein endothelial cells (HUVECs). Western blot results showed that TSC decreased TNFα induced the protein expression increase of vascular cell adhesion molecule-1 (VCAM-1), and thereby inhibited endothelial inflammation. The results of histone deacetylase (HDAC) overexpression and molecular docking experiments showed that TSC upregulated the expression of KLF2 by inhibiting subtypes of HDAC 4/5/7. In conclusion, this study suggests that TSC up-regulates the expression of KLF2 through inhibiting HDAC 4/5/7 and thus inhibits TNFα induced endothelial inflammation, and it has the potential to prevent and treat atherosclerosis.

Overexpression of chicken Klf2 promotes klf7 transcription and inhibits adipocyte differentiation / 生物工程学报

Overexpression of Krüppel like factor 2 (Klf2) or Klf7 inhibits adipocyte formation. However, it remains unclear whether Klf2 regulates klf7 expression in adipose tissue. In this study, oil red O staining and Western blotting were employed to study the effect of Klf2 overexpression on the differentiation of chicken preadipocytes. The results showed that Klf2 overexpression inhibited the differentiation of chicken preadipocytes induced by oleate and the expression of pparγ, while promoted klf7 expression in chicken preadipocytes. Spearman correlation analysis was used to study the correlation between the expression data of klf2 and klf7 in the adipose tissue of both human and chicken. The results showed that there was a significantly positive correlation between the expression of klf2 and klf7 in adipose tissues (r > 0.1). Luciferase reporter assay showed that overexpression of Klf2 significantly promoted the activity of chicken klf7 promoter (-241/-91, -521/-91, -1 845/-91, -2 286/-91, -1 215/-91; P < 0.05). In addition, the activity of klf7 promoter (-241/-91) reporter in chicken preadipocytes was significantly positively correlated with the amount of klf2 overexpression plasmid transfected (Tau=0.917 66, P=1.074×10-7). Moreover, Klf2 overexpression significantly promoted the mRNA expression of klf7 in chicken preadipocytes (P < 0.05). In conclusion, upregulation of klf7 expression might be one of the pathways that Klf2 inhibits chicken adipocyte differentiation, and the sequence from -241 bp to -91 bp upstream chicken klf7 translation start site might mediate the regulation of Klf2 on klf7 transcription.

Expression changes of cyclophilin A,Krüppel-like factor 2,and endothelial nitric oxide synthase in the pathological process of atherosclerosis in rats / 中国脑血管病杂志

Objective To observe the expression changes of cyclophilin A ( CyPA ) , Krüppel-like factor 2 (KLF2),and endothelial nitric oxide synthase (eNOS) in the pathological process of atherosclerosis in rats. Methods Thirty-two male Wistar rats were randomly divided into four groups:a control group and atherosclerosis 8,12,and 15 week groups (n=8 in each group). The atherosclerosis groups were fed with high-fat diet,and they were given vitamin D3 600 000 IU for a single intraperitoneal injection,and the rats in the control group were fed with the basal feed. The rats were sacrificed at 8,12,and 15 weeks. Their abdominal aortas were separated and stained with hematoxylin-eosin staining. Immunohistochemical method was used to detect the expression levels of CyPA,KLF2,and eNOS on arterial walls. Results With the progression of atherosclerosis lesion,the rats in the control group,and atherosclerosis 8,12,and 15 week groups showed different characteristics, including normal vessel structure, endothelial cell damage, smooth muscle cell proliferation,formation of atherosclerotic plaque,and formation of calcified plaque. There were significantly differences in the expression levels of CyPA,KLF2,eNOS on vessel walls among the control group,atherosclerosis 8,12,and 15 week groups (CyPA:0. 0037 ± 0. 0018,0. 0276 ± 0. 0090,0. 0526 ± 0. 0129,and 0. 1080 ± 0. 0388;KLF2:0. 0932 ± 0. 0331,0. 0415 ± 0. 0076,0. 0207 ± 0. 0059, and 0. 0014 ± 0. 0003;eNOS:0. 0358 ± 0. 0185,0. 0148 ± 0. 0080,0. 0049 ± 0. 0025,0. 0037 ± 0. 0026;F=36. 395,42. 108,and 21. 255,respectively,all P<0. 05),and the CyPA expression showed an increasing trend among groups, and there were significant differences between the pairwise comparisons (all P<0. 05). The expression level of KLF2 showed a progressive declining trend,and there were significant differences between pairwise comparisons (all P <0. 05);there was significant difference in eNOS expression between the atherosclerosis 12-week group and the atherosclerosis 15-week group, and there were significant differences among other groups (all P<0. 05). Conclusion With the progression of atherosclerotic lesions, the expression of CyPA increases progressively, and the expression levels of KLF2 and eNOS decrease progressively. This may be one of the approaches of CyPA caused atherosclerotic lesion.

Effects of KLF2 on ox-LDL induced expression of microRNA-146a and proinflammatory cytokines in human umbilical vein endothelial cells / 中华微生物学和免疫学杂志

Objective To investigate the effects of Kr üppel-like factor 2 ( KLF2 ) on oxidized low density lipoprotein (ox-LDL) induced expression of microRNA-146a (miR-146a) and proinflammatory cyto-kines (MCP-1 and IL-6) in human umbilical vein endothelial cells (HUVECs).Methods Human umbili-cal vein endothelial cells (HUVECs) were cultured and then stimulated with 50μg/ml ox-LDL for 24 hours. HUVECs were infected with adenovirus vectors over-expressing human KLF2 at an appropriate multiplicity of infection.KLF2-siRNA duplexes were transfected into HUVECs to silence the gene expression .HUVECs were collected at time points of 0 h, 3 h, 6 h, 12 h, 24 h and 48 h after infection.Real-time quantitative-PCR was performed to measure the expression of miR-146a at mRNA level.Silenced endogenous miR-146a using LNA-anti-miR-146 a was transfected into HUVECs with lipofectamine 2000 .The levels of MCP-1 and IL-6 in supernatants were detected by ELISA .Results KLF2 remarkably inhibited the expression of miR-146 a in unstimulated and ox-LDL-stimulated HUVECs in a time-dependent manner .The ox-LDL induced ex-pression of miR-146a, MCP-1 and IL-6 in HUVECs were significantly decreased by KLF2.Silenced expres-sion of miR-146a downr-egulated the ox -LDL induced expression of MCP-1 and IL-6 in HUVECs.Moreover, silenced miR-146 a could partly reverse the inhibitory effects of KLF 2 on ox-LDL induced expression of MCP-1 and IL-6 in HUVECs.Conclusion KLF2 inhibited ox-LDL induced expression of MCP-1 and IL-6 in HUVECs partly through down-regulating the expression of miR-146a.

Kruppel-Like Factor 2 Suppression by High Glucose as a Possible Mechanism of Diabetic Vasculopathy

BACKGROUND AND OBJECTIVES: Endothelial dysfunction is widely observed in diabetes mellitus, resulting in diabetic vascular complications. Kruppel-like factor 2 (KLF2) is implicated as being a key molecule that maintains endothelial function. We evaluated the expression of KLF2 in endothelial cells cultured in high glucose and investigated its functional implication in a diabetic animal model. SUBJECTS AND METHODS: Human umbilical vein endothelial cells (HUVECs) were cultured in physiologically high glucose (35 mM) condition. The Otsuka Long Evans Tokushima Fatty (OLETF) strain of rat was used as an excellent model of obese type II diabetes, and their lean littermates are Long Evans Tokushima Otsuka (LETO) rats. RESULTS: In HUVECs cultured in physiologically high glucose condition, FOXO1 was activated whereas KLF2 and endothelial nitric oxide synthase (eNOS) expression was near completely abolished, which was completely reversed by FOXO1 small interfering ribonucleic acid. In the vessels harvested from the OLETF rats, the animal model of type II diabetes, KLF2 and eNOS expression were found depleted. When vascular remodeling was induced in the left common carotid artery by reduction of blood flow with partial ligation of the distal branches, greater neointimal hypertrophy was observed in OLETF rats compared with the control LETO rats. CONCLUSION: KLF2 suppression in endothelial cells by high glucose is a possible mechanism of diabetic endothelial dysfunction. The strategy of replenishing KLF2 may be effective for preventing diabetic vascular dysfunction.