SIRT1在运动防治糖尿病患者骨骼肌胰岛素抵抗中的作用

沉默交配型信息调节因子2同源蛋白1(SIRT1)是NAD+依赖的组蛋白去乙酰化酶,参与葡萄糖/脂质代谢、线粒体生物合成、炎症、自噬和生理节律等.最近研究表明,SIRT1在糖尿病发病中发挥重要作用,糖尿病发病率升高与饮食结构的改变和久坐的生活方式密切相关,运动可以通过SIRT1介导的调控通路改善糖尿病患者骨骼肌的胰岛素敏感性,降低胰岛素抵抗.概括了近几年腺苷酸活化蛋白激酶(AMPK),SIRT1,过氧化物酶体增殖物激活受体γ协同刺激因子1α(PGC-1α)在运动防治糖尿病中的研究现状及发展趋势,为通过运动改善骨骼肌代谢功能防治糖尿病提供新的思路.     

阿司匹林乙酰化修饰HDAC1抑制人结肠癌细胞HCT116增殖

大量研究表明阿司匹林具有重要的抗肿瘤作用。阿司匹林的乙酰基可以乙酰化大量蛋白质，从而影响体内的乙酰化水平，但其乙酰化作用在抗肿瘤上的具体机制还不清楚。组蛋白去乙酰化酶抑制剂(HDACi)已用于肿瘤治疗或处于临床研究，通过抑制组蛋白去乙酰化酶(Histone Deacetylases, HDACs)的去乙酰化酶活发挥抗癌作用。组蛋白去乙酰化酶1(Histone Deacetylase1, HDAC1)是Zn²⁺依赖的Ⅰ类HDAC家族成员，在多种癌症中表达上调，是组蛋白去乙酰化酶抑制剂(Histone Deacetylase Inhibitors, HDACi)发挥抗癌作用最关键的靶点之一。在抗肿瘤的过程中，阿司匹林是否乙酰化调控HDAC1尚未见报道。在本文中，我们发现阿司匹林可以乙酰化HDAC1并抑制其去乙酰化酶活，赖氨酸(K)200位点是阿司匹林乙酰化HDAC1的关键位点。有趣的是，HDAC1可以对自身去乙酰化，但不能发生在K200上。沉默信息调节因子2相关酶1(SIRT1),而不是HDAC1,可以对HDAC1的K200位点去乙酰化。进一步细胞学实验发现，在敲除H...     

穿心莲内酯通过影响SIRT3-p53信号通路诱导鼻咽癌C666-1细胞凋亡的机制研究

在前期研究工作中发现穿心莲内酯(Andrographolide,Andro)可以抑制鼻咽癌C666-1细胞活力并诱导其凋亡,但相关的分子机制并不清楚.为了明确穿心莲内酯调控C666-1细胞活力的具体机制,本课题组在体外培养的 C666-1 细胞中给予穿心莲内酯处理,并通过 Real-time PCR 检测 Sirutins 家族成员(SIRT1-7)的mRNA表达进行初步筛选;通过siRNA干扰的方法沉默SIRT3之后进一步检测穿心莲内酯对C666-1细胞活力和凋亡的影响;采用Western Blotting的方法检测沉默SIRT3之后穿心莲内酯对C666-1细胞中SIRT3/p53表达的影响.结果表明:穿心莲内酯能够显著增加SIRT3的mRNA表达,而对其它亚型的影响较小;沉默SIRT3能够部分逆转穿心莲内酯对C666-1细胞活力和凋亡的影响;穿心莲内酯可通过影响SIRT3的蛋白表达调控其下游凋亡相关蛋白p53的水平进而诱导细胞凋亡.本实验为进一步研究穿心莲内酯抑制鼻咽癌的机制奠定了基础.     

EBNA1 和Vav1 共同调控Bim表达影响细胞凋亡的研究

Burkitt's淋巴瘤是一种具有高度侵袭性的恶性肿瘤,主要发生在非洲赤道地区,病理特征表现为颌部或腹部肿大成瘤.在我国广东地区发病率较高,目前治疗效果较差.发现在Burkitt's淋巴瘤细胞Raji中EBNA1和Vav1蛋白可以影响Bim的表达和细胞凋亡.组蛋白去乙酰化酶抑制剂丁酸钠(NaB)刺激Burkitt's 淋巴瘤Raji 发现促凋亡蛋白Bim表达上调.进一步实验发现病毒蛋白EBNA1和细胞蛋白Vav1的共表达可以抵消NaB对Bim启动子转录活性的影响. 因此,认为EBNA1 和Vav1 蛋白具有协同作用,共同调控组蛋白的乙酰化水平影响细胞凋亡.     

植物蛋白乙酰化/去乙酰化与代谢和基因表达调控研究进展

植物细胞中组蛋白赖氨酸乙酰化修饰对基因表达具有重要的作用,同时影响糖酵解、三羧酸循环和光合作用途径中非组蛋白的代谢酶活性。因此,识别参与调控代谢酶活性的HAT和HDAC具有重要意义。相反,代谢物如乙酰-Co A和NAD+参与蛋白可逆乙酰化进程,并且它们在细胞内的水平可能影响组蛋白乙酰化酶和组蛋白去乙酰化酶的活性。从组蛋白质赖氨酸乙酰化可逆过程、蛋白乙酰化酶和组蛋白去乙酰化酶分类及其细胞内分布和代谢酶的活性研究阐述了HAT和HDAC的作用及其研究进展。     

钾离子及钾通道在细胞凋亡时线粒体变化中的作用

细胞凋亡在多种生命活动及疾病中均具有重要作用,线粒体是决定细胞凋亡的关键因素.近年研究发现,细胞内高钾可以保护细胞免于凋亡.但也有研究表明,钾离子及钾离子通道可参与线粒体的结构和功能改变,影响细胞凋亡.明确细胞内钾离子对线粒体的影响,可以更好的理解细胞凋亡及其相关的多种生理、病理机制.综述了钾离子及钾离子通道在细胞凋亡时对线粒体的作用.     

线粒体与人类疾病

线粒体自身携带DNA，可自我复制、表达。研究表明，线粒体DNA突变的积累和氧化损伤与人类疾病、衰老和肿瘤密切相关。     

西达本胺通过线粒体凋亡途径诱导结肠癌HCT-15细胞凋亡

研究西达本胺(Chidamide)对结肠癌细胞系HCT-15的增殖抑制作用及机制. 以不同浓度西达本胺处理HCT-15细胞,CCK-8法检测细胞增殖情况及细胞的药物敏感性;平板克隆形成实验检测细胞体外克隆形成能力;流式细胞术检测细胞凋亡;EdU实验检测细胞增殖周期;Western blot检测乙酰化组蛋白、线粒体凋亡途径相关蛋白、细胞周期相关蛋白表达水平的变化. 结果表明:西达本胺抑制HCT-15细胞增殖呈浓度和时间依赖性,细胞体外克隆形成能力减弱,凋亡增多,细胞分裂相明显减少、总周期变慢,乙酰化组蛋白H3和H4、线粒体介导的相关凋亡蛋白表达上调、p21、p27表达上调、CDK2、CyclinA2蛋白表达下调. 西达本胺可抑制HCT-15细胞增殖,通过线粒体途径诱导细胞凋亡并阻滞细胞周期.     

乙酰基转移酶TIP60蛋白乙酰化位点定位的研究

乙酰基转移酶TIP60(tat-interaction protein,60ku)介导众多蛋白的乙酰化修饰,如核心组蛋白、p53、ATM、H2AX、RB和E2F1等,参与调控细胞凋亡、周期阻滞、DNA损伤修复和细胞衰老等多种重要细胞生理活动,并且与肿瘤发生密切相关.与另外2种乙酰基转移酶p300和PCAF相似,TIP60也可以介导自乙酰化.目前,TIP60自乙酰化修饰的精确位点和细胞功能并不清楚,因此在体外条件下,对TIP60蛋白的乙酰化位点进行了初步定位.构建了4种GST-TIP60原核表达质粒,利用大肠杆菌(Escherichia coli)表达型菌株BL21系统,诱导表达并纯化含有TIP60全长和不同片段的GST融合蛋白,通过体外乙酰化实验证实TIP60蛋白的乙酰化位点集中在N端,而不是含有保守的MYST结构域的中间段.这些实验结果为进一步研究TIP60自乙酰化调控方式及其对TIP60蛋白细胞功能的影响提供了必要条件.     

衰老与疾病及饮食中主要营养素的抗衰老作用

目的 概述衰老与疾病的关系及饮食中主要营养素的抗衰老作用研究进展。方法 结合大量文献,探讨了衰老的本质,引起疾病的原因,阐释饮食主要营养抗衰老机制。结果 衰老本质上是细胞随时间微观损伤积累产生衰老细胞(SC),伴有衰老相关分泌表型(SASP)细胞特异性表达增加,引起全身性慢性炎症及其免疫系统功能下降,是不同年龄相关人类疾病共同潜在病因,也增大了老年人患癌症和糖尿病以及COVID-19大流行等严重疾病的频率和易感性。衰老与年龄不呈正相关,科学的饮食营养能延缓衰老。结论 在控制碳水化合物摄入量的前提下,复合碳水化合物与其代谢中间产物,可通过调节细胞衰老、蛋白质平衡和炎症来抗衰老。植物蛋白及蛋白质和高碳水化合物类饮食以低于1∶10的比例,在衰老过程中有利健康和延长寿命。脂肪酸,特别是富含ω-3-多不饱和脂肪酸(PUFA)在改善与年龄相关疾病,显示有益作用。饮食中维生素如D、E、B2,合适的矿物质如Mg、Zn、Fe等,植物多酚类化合物及益生菌均有抗衰老,促进健康长寿的作用。     

DBC1 is a negative regulator of SIRT1

The NAD-dependent protein deacetylase Sir2 (silent information regulator 2) regulates lifespan in several organisms. SIRT1, the mammalian orthologue of yeast Sir2, participates in various cellular functions and possibly tumorigenesis. Whereas the cellular functions of SIRT1 have been extensively investigated, less is known about the regulation of SIRT1 activity. Here we show that Deleted in Breast Cancer-1 (DBC1), initially cloned from a region (8p21) homozygously deleted in breast cancers, forms a stable complex with SIRT1. DBC1 directly interacts with SIRT1 and inhibits SIRT1 activity in vitro and in vivo. Downregulation of DBC1 expression potentiates SIRT1-dependent inhibition of apoptosis induced by genotoxic stress. Our results shed new light on the regulation of SIRT1 and have important implications in understanding the molecular mechanism of ageing and cancer.     

Small molecule activators of SIRT1 as therapeutics for the treatment of type 2 diabetes

Calorie restriction extends lifespan and produces a metabolic profile desirable for treating diseases of ageing such as type 2 diabetes. SIRT1, an NAD+-dependent deacetylase, is a principal modulator of pathways downstream of calorie restriction that produce beneficial effects on glucose homeostasis and insulin sensitivity. Resveratrol, a polyphenolic SIRT1 activator, mimics the anti-ageing effects of calorie restriction in lower organisms and in mice fed a high-fat diet ameliorates insulin resistance, increases mitochondrial content, and prolongs survival. Here we describe the identification and characterization of small molecule activators of SIRT1 that are structurally unrelated to, and 1,000-fold more potent than, resveratrol. These compounds bind to the SIRT1 enzyme-peptide substrate complex at an allosteric site amino-terminal to the catalytic domain and lower the Michaelis constant for acetylated substrates. In diet-induced obese and genetically obese mice, these compounds improve insulin sensitivity, lower plasma glucose, and increase mitochondrial capacity. In Zucker fa/fa rats, hyperinsulinaemic-euglycaemic clamp studies demonstrate that SIRT1 activators improve whole-body glucose homeostasis and insulin sensitivity in adipose tissue, skeletal muscle and liver. Thus, SIRT1 activation is a promising new therapeutic approach for treating diseases of ageing such as type 2 diabetes.     

SIRT1与糖脂代谢及在运动医学领域的研究展望

SIRT1(silent mating type information regulation 2 homolog1),哺乳动物sir2同系物,一种NAD+依赖的组蛋白脱乙酰化酶。越来越多的证据表明SIRT1通过其脱乙酰化酶活性参与糖脂代谢,其对胰岛β细胞功能和胰岛素信号通路起着正性调节作用,对改善胰岛素的敏感性和维持糖脂代谢稳态具有重要作用。运动疗法是防治2型糖尿病、非酒精性脂肪肝和动脉粥样硬化等慢性疾病主要方法之一,但运动改善慢性疾病的机理还未完全阐明。已有研究表明运动训练能够诱导大鼠骨骼肌和心肌组织中SIRT1表达。运动改善慢性疾病机理是否与SIRT1有关尚不确定。在总结SIRT1与糖脂代谢关系的基础上,结合运动与SIRT1的研究现状,展望SIRT1在运动医学领域的研究前景。     

Structure and function of bak gene and its apoptosis-inducing mechanism

The Bcl-2 family plays an important role in the regulation of apoptosis. Some members in the family prevent apoptosis while others promote it. The newly discovered bcl-2 homolog, bak, promotes the apoptosis induced by a variety of stimuli. It can interact with the anti-apoptotic members through its BH3 domain and antagonize their activity. Investigation results suggest that the expression of bak gene becomes altered in some diseases, such as cancer. The preferential stimulation of Bak-induced apoptosis, therefore, may be involved in the mechanisms of some an-titumor drugs.     

SIRT6 is a histone H3 lysine 9 deacetylase that modulates telomeric chromatin

The Sir2 deacetylase regulates chromatin silencing and lifespan in Saccharomyces cerevisiae. In mice, deficiency for the Sir2 family member SIRT6 leads to a shortened lifespan and a premature ageing-like phenotype. However, the molecular mechanisms of SIRT6 function are unclear. SIRT6 is a chromatin-associated protein, but no enzymatic activity of SIRT6 at chromatin has yet been detected, and the identity of physiological SIRT6 substrates is unknown. Here we show that the human SIRT6 protein is an NAD+-dependent, histone H3 lysine 9 (H3K9) deacetylase that modulates telomeric chromatin. SIRT6 associates specifically with telomeres, and SIRT6 depletion leads to telomere dysfunction with end-to-end chromosomal fusions and premature cellular senescence. Moreover, SIRT6-depleted cells exhibit abnormal telomere structures that resemble defects observed in Werner syndrome, a premature ageing disorder. At telomeric chromatin, SIRT6 deacetylates H3K9 and is required for the stable association of WRN, the factor that is mutated in Werner syndrome. We propose that SIRT6 contributes to the propagation of a specialized chromatin state at mammalian telomeres, which in turn is required for proper telomere metabolism and function. Our findings constitute the first identification of a physiological enzymatic activity of SIRT6, and link chromatin regulation by SIRT6 to telomere maintenance and a human premature ageing syndrome.     

Acetylation-dependent regulation of endothelial Notch signalling by the SIRT1 deacetylase

Notch signalling is a key intercellular communication mechanism that is essential for cell specification and tissue patterning, and which coordinates critical steps of blood vessel growth. Although subtle alterations in Notch activity suffice to elicit profound differences in endothelial behaviour and blood vessel formation, little is known about the regulation and adaptation of endothelial Notch responses. Here we report that the NAD(+)-dependent deacetylase SIRT1 acts as an intrinsic negative modulator of Notch signalling in endothelial cells. We show that acetylation of the Notch1 intracellular domain (NICD) on conserved lysines controls the amplitude and duration of Notch responses by altering NICD protein turnover. SIRT1 associates with NICD and functions as a NICD deacetylase, which opposes the acetylation-induced NICD stabilization. Consequently, endothelial cells lacking SIRT1 activity are sensitized to Notch signalling, resulting in impaired growth, sprout elongation and enhanced Notch target gene expression in response to DLL4 stimulation, thereby promoting a non-sprouting, stalk-cell-like phenotype. In vivo, inactivation of Sirt1 in zebrafish and mice causes reduced vascular branching and density as a consequence of enhanced Notch signalling. Our findings identify reversible acetylation of the NICD as a molecular mechanism to adapt the dynamics of Notch signalling, and indicate that SIRT1 acts as rheostat to fine-tune endothelial Notch responses.     

细胞凋亡与肿瘤治疗

细胞凋亡与许多疾病特别是肿瘤的发生发展有关，许多癌基因与抑癌基因参与细胞凋亡过程。对细胞凋亡以及在肿瘤治疗中的有关系进行了综述。