SIRT1及其与自身免疫性疾病和纤维化相关性

SIRT1是哺乳动物Sirtuins蛋白家族中的一类去乙酰化酶,通过去乙酰化作用在细胞寿命调节等多个方面起着很重要的生理作用,并在代谢性疾病、肿瘤等多种疾病的发生过程中起到重要作用。近年来研究提示,SIRT1与多种自身免疫性疾病的发生关系密切。SIRT1与组织器官纤维化病变之间的关系亦有很多研究,可能与转化生长因子(transforming growth factor,TGF)βSmad信号通路相关。本文旨在对近年来关于SIRT1及其与自身免疫性疾病和纤维化等相关研究做一综述。     

沉默信息调节因子1与脑缺血

沉默信息调节因子1(silent information regulator 1,SIRT1)是一种NAD+依赖性组蛋白去乙酰化酶,在脑缺血中起着重要作用,主要表现为稳定脑血管内膜、防止血管狭窄以及脑缺血后的抗炎和抗氧化应激作用.文章对STRT1在脑缺血中的保护作用及其相关机制进行了综述.     

SIRT1与糖尿病相关肿瘤的关系

糖尿病不仅增加肿瘤的患病风险,而且促进肿瘤的复发和转移.沉默信息调节因子1(SIRT1)是机体的能量感受器,具有调节糖、脂代谢,抑制慢性非特异性炎性反应,改善胰岛素抵抗等作用,其表达及活性异常参与了糖尿病及其并发症的发生.同时近期研究发现SIRT1也与肿瘤的发生、发展密切相关.通过去乙酰化调节机制SIRT1可调控大量转录因子及组蛋白的活性,从而参与染色质沉默、细胞凋亡、自噬途径及DNA损伤修复的调控,是联系细胞能量代谢与染色质结构的关键蛋白,因而可能是联系糖尿病及糖尿病相关肿瘤的重要中介.积极干预糖尿病患者中SIRT1信号途径异常,可能具有降低肿瘤风险的作用.     

SIRT3与胰岛素抵抗

沉默信息调节因子(SIRT)3是哺乳动物类NAD+依赖性组蛋白去乙酰化酶家族中的一员.研究表明,SIRT3可以改善胰岛素抵抗、增加胰岛素敏感性.其通过保护胰岛β细胞、促进骨骼肌葡萄糖摄取、调节骨骼肌代谢、减轻氧化应激、抵抗高糖诱导的细胞毒性等途径发挥作用.SIRT3为治疗2型糖尿病、肥胖、线粒体功能障碍等疾病带来了新的研究方向.     

SIRT1在呼吸道病原微生物感染中的作用研究进展

SIRT1称为沉默信息调节因子1,是一种烟酰胺腺嘌呤二核苷酸依赖的组蛋白去乙酰化酶,在能量代谢、细胞生长周期调节、DNA损伤修复、抗氧化应激、延缓衰老、抗炎等方面发挥作用.本文结合国内外最新研究报道对SIRT1的抗炎作用信号转导通路进行总结;对细胞水平或动物试验已证实的机体SIRT1在呼吸道病原微生物感染中的作用进行综述.     

SIRT1与代谢及肿瘤的关系

沉默信息调节因子1(SIRT1)是一种依赖烟酰胺腺嘌呤二核苷酸(NAD+)的去乙酰化酶,它在正常的胚胎发育、分化及维持自身平衡中是必不可少的.SIRT1在维持健康及疾病中发挥着很多重要的作用,包括SIRT1在基因组稳定性中的作用[1],在时钟调节下的基因组重构及昼夜节律控制中的作用[2],以及神经元基因和阿尔茨海默病之间关系的调节作用[3].之前也有很多有关健康及疾病中SIRT1的综述[4,5].作为sirtuin家族中一员,SIRT1表现出了对氧化还原代谢物NAD+先天的辅酶需求.这与SIRT1控制关键代谢调节的能力一起,证明了SIRT1在哺乳动物代谢中即是一个感受器,又是一个调节器.SIRT1的大多数功能是通过对基因表达过程中起关键作用的调节蛋白针对性的去乙酰化实现的.SIRT1的作用靶点包括转录因子及代谢调节中的辅酶因子.我们对SIRT1活性与代谢稳态关系的最新研究进展作一综述,并且基于细胞生存中SIRT1的作用,我们研究了相应的治疗方法.     

沉默调节蛋白1在非酒精性脂肪性肝病发生发展中的作用

沉默调节蛋白1(SIRT1)为Sirtuin家族的一员,是依赖于烟酰腺嘌呤二核苷酸(NAD+)的去乙酰化酶,其主要作用是参与能量代谢﹑细胞生存、衰老及凋亡。而非酒精性脂肪性肝病(NAFLD)是一种与胰岛素抵抗、氧化应激及脂质过氧化等密切相关的慢性肝脏疾病。从SIRT1与NAFLD者的能量代谢关系﹑SIRT1与氧化应激、脂质过氧化、内质网应激等方面进行了阐述,认为SIRT1与NAFLD的发生发展密切相关。     

SIRT1在神经退行性疾病中的作用研究新进展

SIRT1是高度保守的去乙酰化酶家族成员,是酵母沉默信息调节因子Sir2的同源物。SIRT1具有组蛋白/非组蛋白去乙酰化酶活性,通过其可逆的乙酰化—去乙酰化循环反应参与调节多种细胞功能,可参与抗凋亡、抗炎、抗氧化应激、调节能量代谢、调控细胞周期等过程。近年来,其在神经退行性疾病中的作用受到越来越广泛关注,本文就SIRT1在神经退行性疾病中的作用研究新进展作一综述。     

白藜芦醇与糖尿病关系的研究进展

白藜芦醇属于一种酚类植物抗毒素,是天然的抗氧化物和自由基廓清剂.近期研究发现,白藜芦醇除具有抗动脉粥样硬化的作用外,还具有明显的降低血糖,改善糖尿病的作用.其机制与抗氧化应激、抗炎性反应、改善胰岛素敏感性、改善胰岛素分泌等有关.白藜芦醇的上述作用可能与其激活组蛋白去乙酰化酶(SIRT)1有关,也可能还有其他非SIRT1依赖机制.因此,对白藜芦醇改善糖尿病作用的深入研究可能为研究新型降糖药物开辟新的方向.     

SIRT1去乙酰化酶在热量限制法中的作用机制

在延缓衰老的研究中,热量限制是目前唯一经过科学实验证实有效的方法,研究显示长寿基因SIRT1去乙酰化酶在此过程中发挥了重要的作用.SIRT1通过将P53、FOXO3a和Ku70等蛋白去乙酰化而抑制细胞凋亡,通过作用于PGC-1α和PPAR-γ等蛋白来调节糖代谢和脂肪代谢.本文就热量限制法延缓衰老中SIRT1的作用机制进行了综述.     

Cross-talk between SIRT1 and p66Shc in vascular diseases

Accumulating evidence indicates that oxidative stress can occur through overproduction of reactive oxygen species (ROS) and/or reduced anti-oxidant potentials under pathophysiological conditions and plays an important role in the development of cardiovascular diseases (CVDs). Adapter protein p66Shc has the property to directly stimulate mitochondrial ROS generation by an oxidoreductase activity. A growing body of evidence implies that p66Shc plays a critical role in the pathophysiology of age-related vascular diseases. Silent mating type information regulator 2 homolog 1 (SIRT1), a nicotinamide adenine dinucleotide (NAD+)-dependent class III histone deacetylase (HDAC), has also been implicated in protection against vascular aging and age-related vascular diseases. Recently, we demonstrated that SIRT1 protects blood vessels from hyperglycemia-induced endothelial dysfunction through a novel mechanism involving the downregulation of p66Shc expression. In this review, we discuss the cross-talk between these two longevity genes as a mechanism of preventing vascular diseases by involving anti-oxidative stress responses and inhibiting endothelial senescence.     

The reduction of SIRT1 in livers of old mice leads to impaired body homeostasis and to inhibition of liver proliferation

Age declines liver functions, leading to the development of age-associated diseases. A member of the sirtuins family, SIRT1, is involved in the control of glucose homeostasis and fat metabolism. Because aging livers have alterations in glucose and fat metabolism, we examined a possible role of SIRT1 in these alterations. We found that aged livers have a reduced expression of SIRT1 and have lost proper control of the regulation of SIRT1 after partial hepatectomy (PH). Down-regulation of SIRT1 in the liver of old mice is mediated by CCAAT/Enhancer Binding Protein/histone deacetylase 1 (C/EBPβ-HDAC1) complexes, which bind to and repress the SIRT1 promoter. In the livers of young mice, SIRT1 is activated after PH and supports high levels of glucose and triglycerides during liver regeneration. In old mice, however, C/EBPβ-HDAC1-mediated repression of the SIRT1 promoter blocks activation of SIRT1, leading to low levels of glucose and triglycerides during liver regeneration. Down-regulation of SIRT1 in the livers of young mice resulted in alterations similar to those observed in the livers of old mice, whereas the normalization of SIRT1 in the livers of old mice corrects the levels of glucose and triglycerides after PH. The normalization of SIRT1 in old mice also improves liver regeneration via the elimination of the C/EBPα-Brm complex. These studies showed a critical role of the reduction of SIRT1 in age-associated liver dysfunctions and provide a potential tool for the correction of liver functions in old patients after surgical resections.     

SIRT1 deficiency compromises mouse embryonic stem cell hematopoietic differentiation, and embryonic and adult hematopoiesis in the mouse

SIRT1 is a founding member of a sirtuin family of 7 proteins and histone deacetylases. It is involved in cellular resistance to stress, metabolism, differentiation, aging, and tumor suppression. SIRT1(-/-) mice demonstrate embryonic and postnatal development defects. We examined hematopoietic and endothelial cell differentiation of SIRT1(-/-) mouse embryonic stem cells (ESCs) in vitro, and hematopoietic progenitors in SIRT1(+/+)(+/-), and (-/-) mice. SIRT1(-/-) ESCs formed fewer mature blast cell colonies. Replated SIRT1(-/-) blast colony-forming cells demonstrated defective hematopoietic potential. Endothelial cell production was unaltered, but there were defects in formation of a primitive vascular network from SIRT1(-/-)-derived embryoid bodies. Development of primitive and definitive progenitors derived from SIRT1(-/-) ESCs were also delayed and/or defective. Differentiation delay/defects were associated with delayed capacity to switch off Oct4, Nanog and Fgf5 expression, decreased β-H1 globin, β-major globin, and Scl gene expression, and reduced activation of Erk1/2. Ectopic expression of SIRT1 rescued SIRT1(-/-) ESC differentiation deficiencies. SIRT1(-/-) yolk sacs manifested fewer primitive erythroid precursors. SIRT1(-/-) and SIRT1(+/-) adult marrow had decreased numbers and cycling of hematopoietic progenitors, effects more apparent at 5%, than at 20%, oxygen tension, and these progenitors survived less well in vitro under conditions of delayed growth factor addition. This suggests a role for SIRT1 in ESC differentiation and mouse hematopoiesis.     

全国住院糖尿病患者慢性并发症及其相关危险因素10年回顾性调查分析

目的 了解我国糖尿病(DM)患者慢性并发症及相关大血管病变状况及其危险因素，为DM防治提供依据。方法 回顾性分析1991年1月1日至2000年12月31日期间在全国30个省、市、自治区医院内分泌科住院的T1DM及T2DM患者24496例的临床及实验室资料。结果 近10年我国住院DM患者DM并发症患病率分别为：高血压31．9％；脑血管病变12．2％；心血管病变15．9％下肢血管病变5．0％；眼部疾患34．3％；肾脏病变33．6％；神经病变60．3％，DM慢性并发症总患病率为73．2％。与各种DM慢性并发症相关的危险因素包括发病年龄、病程、人院时收缩压，人院时体重指数(BMI)、血糖、血脂，吸烟状况也与DM慢性并发症相关。结论我国住院DM患者慢性并发症患病率显著高于非DM者，接近国外资料报告的水平。与各种DM慢性并发症相关的可控制危险因素是收缩压。     

Risk factors for asymptomatic atherosclerosis in Japanese type 2 diabetic patients without diabetic microvascular complications

Atherosclerotic vascular diseases are frequently associated with diabetes mellitus. There has been increasing evidence showing that the atherosclerotic diseases in diabetic patients are distinct from diabetic microvascular complications as to their pathophysiology and epidemiology. However, we have no information on the prevalence of asymptomatic atherosclerosis in diabetic patients before the onset of microvascular diseases. In the present investigation, we aimed to evaluate risk factors for the atherosclerosis in type 2 diabetic patients without the microvascular diseases. For this purpose, we evaluated atherosclerotic change of carotid arteries in 125 Japanese type 2 diabetic patients who had neither atherosclerotic vascular diseases nor diabetic microvascular complications. When atherosclerotic change was defined as the mean intima-media thickness (IMT) of >/= 1.1 mm and/or the presence of plaque lesion, 50% of patients had atherosclerosis of the carotid arteries. Risk factors for the carotid atherosclerosis were age, low-density lipoprotein (LDL)-cholesterol, hypertension, and diabetes treatment. Age and LDL-cholesterol were associated with mean IMT. Age, diabetes treatment, LDL-cholesterol, and hypertension were positively associated with plaque lesion, while high-density lipoprotein (HDL)-cholesterol was negatively associated with it. Fasting plasma glucose, glycosylated hemoglobin (HbA(1c)), and known diabetes duration remained unassociated with any parameters of asymptomatic atherosclerosis of the carotid arteries. These results indicate that glycemic control is unrelated with asymptomatic atherosclerosis in type 2 diabetic patients without diabetic microvascular complications. Conventional risk factors and diabetes treatment are independently associated with atherosclerosis of the carotid arteries in these patients.     

Elevated plasma prostaglandins and acetylated histone in monocytes in Type 1 diabetes patients

Aims/hypothesis Inflammation is implicated in diabetes and cyclooxygenase (COX) is involved in vascular inflammatory processes, participating in both atherosclerosis and thrombosis. The aims were to determine whether levels of monocyte COX and plasma COX metabolites are increased in Type 1 diabetic patients and to determine whether these could be linked to histone hyperacetylation. Materials and methods Monocytes from 19 Type 1 diabetic and 39 non‐diabetic control subjects were probed for COX and acetylated histone H4 proteins by immunoblotting. Plasma COX metabolite levels [thromboxane B₂ (TXB₂) and prostaglandin E₂ (PGE₂)] were determined by enzyme immunoassay. Results Monocyte COX‐2 expression was significantly up‐regulated (1.3‐fold) in diabetic relative to the non‐diabetic control subjects and plasma PGE₂ was markedly elevated (2.7‐fold). In diabetic subjects, monocyte acetylated histone H4 levels were significantly elevated; sub‐group analysis indicated that the increased histone acetylation was found only in the complication‐free group. Conclusions Results support increased inflammatory activity in Type 1 diabetes that involves COX‐2 and increased prostaglandin production, which may predispose patients to cardiovascular events. The observation of elevated histone acetylation only in complication‐free diabetic subjects suggests that this may be a protective mechanism. This merits further investigation as histone hyperacetylation has been associated with reduced expression of factors involved in vascular injury and remodelling.     

Sirtuin 1 regulation of developmental genes during differentiation of stem cells

The longevity-promoting NAD⁺–dependent class III histone deacetylase Sirtuin 1 (SIRT1) is involved in stem cell function by controlling cell fate decision and/or by regulating the p53-dependent expression of NANOG. We show that SIRT1 is down-regulated precisely during human embryonic stem cell differentiation at both mRNA and protein levels and that the decrease in Sirt1 mRNA is mediated by a molecular pathway that involves the RNA-binding protein HuR and the arginine methyltransferase coactivator-associated arginine methyltransferase 1 (CARM1). SIRT1 down-regulation leads to reactivation of key developmental genes such as the neuroretinal morphogenesis effectors DLL4, TBX3, and PAX6, which are epigenetically repressed by this histone deacetylase in pluripotent human embryonic stem cells. Our results indicate that SIRT1 is regulated during stem cell differentiation in the context of a yet-unknown epigenetic pathway that controls specific developmental genes in embryonic stem cells.