Calorie restriction(CR)is a dietary regime based on low calorie intake.CR without malnutrition extends lifespan in a wide range of organisms from yeast to rodents,and CR can prevent and delay the onset of age-related functional decline and diseases in human and non-human primates.CR is a safe and effective intervention to reduce vascular risk factors in humans.In recent years,studies in rodents have provided mechanistic insights into the beneficial effects of CR on vascular homeostasis,including reduced oxidative stress,enhanced nitric oxide(NO)bioactivity,and decreased inflammation.A number of important molecules,including sirtuins,AMP-activated protein kinase,mammalian targets of rapamycin,endothelial nitric oxidase and their regulatory pathways are involved in the maintenance of vascular homeostasis.Evidence has shown that these pathways are responsible for many aspects of CR’s effects,and that they may also mediate the effects of CR on vasculature.
Objective To investigate the role of lysine-specific demethylase 1 （LSD1） in the process of THP-1 monocyte-to-macrophage differentiation. Methods Quantitative reverse transcription-polymerase chain reaction （qRT-PCR） and Western blotting were performed to analyze the expression of LSD1 and interleukin-6 （IL-6） in THP-1 monocytes and THP-l-derived macrophages. Chromatin immunoprecipitation （ChiP） assay was applied to detect the occupancy of LSD1 and H3K4 methylation at IL-6 promoter during THP-1 monocyte-to-macrophage differentiation. IL-6 mRNA level and H3K4 methylation at IL-6 promoter were analyzed using qRT-PCR and ChiP assay in LSD 1 -knockdown THP- 1 cells treated with 12-O-tetradecanoylphorbol- 13-acetate （TPA） for 0 4, 8, 12, and 24 hours. Fluorescence activated flow cytometry was performed to reveal the percentage of macrophages differentiated from THP- 1 monocytes. Results The expression of LSD1 reduced during THP-1 monocyte-to-macrophage differentiation （P〈0.01）. LSD1 occupancy decreased and H3K4 methylation increased at IL-6 promoter during the differentiation. With knockdown of LSD1, H3K4 methylation at IL-6 promoter was found increased after TPA treatment at different times points （all P〈0.05, except 24 hours）. The percentage of macrophages increased significantly in theTHP-I cells with LSD1 knockdown （P〈0.05）. Conclusions LSD1 is repressed during the monocyte-to-macrophage differentiation of THP-1 cells. Suppression of LSD 1-mediated H3K4 demethylation may be required for THP-1 monocyte-to-macrophage differentiation.
Rui-feng YangGuo-wei ZhaoShu-ting LiangHou-zao ChenDe-pei Liu
Intercellular adhesion molecule-1 （ICAM-1） plays an important role in the recruitment of leukocytes to the endothelium, which causes inflammation and initiation of atherosclerosis. We have previously shown that endothelium-specific over-expression of class III deacetylase SIRT1 decreases atherosclerosis. We therefore addressed the hypothesis that SIRT1 suppresses ICAM-1 expression in the endothelial cells. Here, we found that expression of SIRT1 and ICAM-1 was significantly induced by PMA and ionomycin （PMA/Io） in human umbilical vein endothelial cells （HUVECs）. Adenovirus-mediated over-expression of SIRT1 significantly inhibited PMA/Io-induced ICAM-1 expression （RNAi） resulted in increased expression of ICAM-1 in HUVECs in HUVECs. Knockdown of SIRT1 by RNA interference Luciferase report assay showed that over-expression of SIRT1 suppressed ICAM-1 promoter activity both in basic and in PMA/Io-induced conditions. We further found that SIRT1 was involved in transcription complex binding on the ICAM-1 promoter by chromatin immunoprecipitation （CHIP） assays. Furthermore, SIRT1 RNAi increased NF-~：B p65 binding ability to the ICAM-1 promoter by ChIP assays. Overall, these data suggests that SIRT1 inhibits ICAM-1 expression in endothelial cells, which may contribute to its anti-atherosclerosis effect.
Aims:Autoantibody against the second extracellular loop ofα-adrenoceptor(α-AA) which had been found in hyperte...
Li Yan,Xiu-Li Cheng,Fan Ding,Yun-Hui Du,Hui-Rong Liu,Ji-Min Cao 1 Department of Physiology and Pathophysiology,Institute of Basic Medical Sciences,Chinese Academy of Medical Sciences,School of Basic Medicine,Peking Union Medical College,Beijing 100005,P.R.China
The rapidly increasing prevalence of diabetes mellitus worldwide is one of the most serious and challenging health problems in the 21st century. Mammalian sirtuin 1 （SIRT1） has been shown to decrease high-glucose-induced endothelial cell senescence in vitro and prevent hyperglycemia-induced vascular dysfunction. However, a role for SIRTI in prevention of hyperglyce- mia-induced vascular cell senescence in vivo remains unclear. We used endothelium-specific SIRT1 transgenic （SIRT1-Tg） mice and wild-type （WT） mice to construct a 40-week streptozotocin （STZ）-induced diabetic mouse model. In this mode, 42.9% of wild-type （WT） mice and 38.5% of SIRT1-Tg mice were successfully established as diabetic. Forty weeks of hyper- glycemia induced significant vascular cell senescence in aortas of mice, as indicated by upregulation of expression of senes- cence-associated markers including p53, p21 and plasminogen activator inhibitor-1 （PAI-1）. However, SIRT1-Tg diabetic mice displayed dramatically decreased expression of p53, p21 and PAI-I compared with diabetic WT mice. Moreover, man- ganese superoxide dismutase expression （MnSOD） was significantly downregulated in the aortas of diabetic WT mice, but was preserved in diabetic SIRT1-Tg mice. Furthermore, expression of the oxidative stress adaptor p66Shc was significantly de- creased in aortas of SIRT1-Tg diabetic mice compared with WT diabetic mice. Overall, these findings suggest that SIRT 1-mediated inhibition of hyperglycemia-induced vascular cell senescence is mediated at least partly through the reduction of oxidative stress.
SIRT1,a mammalian ortholog of yeast silent information regulator 2(Sir2),is an NAD+-dependent protein deacetylase that plays a critical role in the regulation of vascular function.The current study aims to investigate the functional significance of deacetylase activity of SIRT1 in heart.Here we show that the early postnatal hearts expressed the highest level of SIRT1deacetylase activity compared to adult and aged hearts.We generated transgenic mice with cardiac-specific expression of a dominant-negative form of the human SIRT1(SIRT1H363Y),which represses endogenous SIRT1 activity.The transgenic mice displayed dilated atrial and ventricular chambers,and died early in the postnatal period.Pathological,echocardiographic and molecular phenotype confirmed the presence of dilated cardiomyopathy.Terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling analysis revealed a greater abundance of apoptotic nuclei in the hearts of transgenic mice.Furthermore,we show that cardiomyocyte apoptosis caused by suppression of SIRT1 activity is,at least in part,due to increased p53acetylation and upregulated Bax expression.These results indicate that dominant negative form of SIRT1(SIRT1H363Y)overexpression in mouse hearts causes cardiomyocyte apoptosis and early-onset heart failure,suggesting a critical role of SIRT1 in preserving normal cardiac development during the early postnatal period.
