Inhibition of cytohesins by SecinH3 leads to hepatic insulin resistance

G proteins are an important class of regulatory switches in all living systems. They are activated by guanine nucleotide exchange factors (GEFs), which facilitate the exchange of GDP for GTP. This activity makes GEFs attractive targets for modulating disease-relevant G-protein-controlled signalling networks. GEF inhibitors are therefore of interest as tools for elucidating the function of these proteins and for therapeutic intervention; however, only one small molecule GEF inhibitor, brefeldin A (BFA), is currently available. Here we used an aptamer displacement screen to identify SecinH3, a small molecule antagonist of cytohesins. The cytohesins are a class of BFA-resistant small GEFs for ADP-ribosylation factors (ARFs), which regulate cytoskeletal organization, integrin activation or integrin signalling. The application of SecinH3 in human liver cells showed that insulin-receptor-complex-associated cytohesins are required for insulin signalling. SecinH3-treated mice show increased expression of gluconeogenic genes, reduced expression of glycolytic, fatty acid and ketone body metabolism genes in the liver, reduced liver glycogen stores, and a compensatory increase in plasma insulin. Thus, cytohesin inhibition results in hepatic insulin resistance. Because insulin resistance is among the earliest pathological changes in type 2 diabetes, our results show the potential of chemical biology for dissecting the molecular pathogenesis of this disease.     

Mechanisms linking obesity to insulin resistance and type 2 diabetes

Obesity is associated with an increased risk of developing insulin resistance and type 2 diabetes. In obese individuals, adipose tissue releases increased amounts of non-esterified fatty acids, glycerol, hormones, pro-inflammatory cytokines and other factors that are involved in the development of insulin resistance. When insulin resistance is accompanied by dysfunction of pancreatic islet beta-cells - the cells that release insulin - failure to control blood glucose levels results. Abnormalities in beta-cell function are therefore critical in defining the risk and development of type 2 diabetes. This knowledge is fostering exploration of the molecular and genetic basis of the disease and new approaches to its treatment and prevention.     

知母-黄柏配伍抗炎作用机制的网络药理学研究

知母-黄柏配伍是临床上常用的“相须”配伍药对,具有抗炎作用,但其机制研究不足。本研究采用网络药理学方法研究知母-黄柏药对的抗炎机制。结果表明,知母-黄柏药对有182个潜在抗炎靶点;知母、黄柏、炎症三者共有靶点受调控分大于等于2倍中位数的靶点有29个,如PTGS2、PTGS1、RXRA、ADRB2、AR、CHRM1、ADRA1B、CHRM3、F10、NOS3等,这些靶点都与炎症的生物过程密切相关。抗炎靶点GO(gene ontology)分析涉及RNA聚合酶II启动子转录的调控、细胞增殖调节、细胞凋亡的调节、一氧化氮生物合成调节等;KEGG(Kyoto encyclopedia of genes and genomes)通路分析涉及TNF信号通路、HIF-1信号通路、PI3K-Akt信号通路、FOXO信号通路、VEGF信号通路、T细胞受体信号通路、Toll样受体信号通路、胰岛素抵抗等。研究提示知母-黄柏“相须”配伍的分子机制是通过共同调控信号通路发挥抗炎作用, 为其临床使用提供了科学依据。     

运动对2型糖尿病胰岛素抵抗相关因子的影响研究

通过分析运动对2型糖尿病胰岛素抵抗的相关因子的影响,发现2型糖尿病主要是胰岛素抵抗和胰岛素分泌受损所导致.因此,只要了解胰腺β细胞的胰岛素抵抗程度,就可以加以弥补,使葡萄糖耐受性维持正常.     

PPAR-γ is a major driver of the accumulation and phenotype of adipose tissue Treg cells

Obesity and type-2 diabetes have increased markedly over the past few decades, in parallel. One of the major links between these two disorders is chronic, low-grade inflammation. Prolonged nutrient excess promotes the accumulation and activation of leukocytes in visceral adipose tissue (VAT) and ultimately other tissues, leading to metabolic abnormalities such as insulin resistance, type-2 diabetes and fatty-liver disease. Although invasion of VAT by pro-inflammatory macrophages is considered to be a key event driving adipose-tissue inflammation and insulin resistance, little is known about the roles of other immune system cell types in these processes. A unique population of VAT-resident regulatory T (Treg) cells was recently implicated in control of the inflammatory state of adipose tissue and, thereby, insulin sensitivity. Here we identify peroxisome proliferator-activated receptor (PPAR)-γ, the 'master regulator' of adipocyte differentiation, as a crucial molecular orchestrator of VAT Treg cell accumulation, phenotype and function. Unexpectedly, PPAR-γ expression by VAT Treg cells was necessary for complete restoration of insulin sensitivity in obese mice by the thiazolidinedione drug pioglitazone. These findings suggest a previously unknown cellular mechanism for this important class of thiazolidinedione drugs, and provide proof-of-principle that discrete populations of Treg cells with unique functions can be precisely targeted to therapeutic ends.     

T-cell clones from a type-1 diabetes patient respond to insulin secretory granule proteins

T LYMPHOCYTES reactive to pancreatic beta-cells are thought to have a central role in the autoimmune process leading to type 1 (insulin-dependent) diabetes, but the molecular targets of these T cells have not yet been defined. As identification of such antigens may enable measures to be developed to prevent the disease, we have characterized an antigen that is recognized by insulinoma membrane-reactive T-cell clones established from a newly diagnosed type-1 diabetes patient. Subcellular fractionation studies using rat insulinoma indicate that the antigenic determinant recognized by one of these clones is an integral membrane component of the insulin secretory granule. After a 5,000-fold purification, we have defined the antigen as a monomer of relative molecular mass 38,000. As granular membrane proteins are transiently exposed on the cell surface during exocytosis, their accessibility to components of the immune system may be a function of the secretory activity of beta-cells.     

Insulin signalling and the regulation of glucose and lipid metabolism.

The epidemic of type 2 diabetes and impaired glucose tolerance is one of the main causes of morbidity and mortality worldwide. In both disorders, tissues such as muscle, fat and liver become less responsive or resistant to insulin. This state is also linked to other common health problems, such as obesity, polycystic ovarian disease, hyperlipidaemia, hypertension and atherosclerosis. The pathophysiology of insulin resistance involves a complex network of signalling pathways, activated by the insulin receptor, which regulates intermediary metabolism and its organization in cells. But recent studies have shown that numerous other hormones and signalling events attenuate insulin action, and are important in type 2 diabetes.     

胰岛素受体短肽配体的亲和筛选

以高效表达胰岛素受体的中国仓鼠卵巢细胞(CHO-IR)为筛选靶标, 经过一轮酸洗脱和三轮特异性竞争洗脱筛选, 成功地富集了与胰岛素受体结合的重组噬菌体克隆. 随机挑 取噬菌体克隆检测其与胰岛素受体的结合活性, 选取结合力最强的6个单克隆, 测得其与 CHO-IR之间的Ｋ_d值为纳摩级, 表明为特异性结合; 经序列分析表明短肽之 间有明显的基序存在.     

The hormone resistin links obesity to diabetes

Diabetes mellitus is a chronic disease that leads to complications including heart disease, stroke, kidney failure, blindness and nerve damage. Type 2 diabetes, characterized by target-tissue resistance to insulin, is epidemic in industrialized societies and is strongly associated with obesity; however, the mechanism by which increased adiposity causes insulin resistance is unclear. Here we show that adipocytes secrete a unique signalling molecule, which we have named resistin (for resistance to insulin). Circulating resistin levels are decreased by the anti-diabetic drug rosiglitazone, and increased in diet-induced and genetic forms of obesity. Administration of anti-resistin antibody improves blood sugar and insulin action in mice with diet-induced obesity. Moreover, treatment of normal mice with recombinant resistin impairs glucose tolerance and insulin action. Insulin-stimulated glucose uptake by adipocytes is enhanced by neutralization of resistin and is reduced by resistin treatment. Resistin is thus a hormone that potentially links obesity to diabetes.     

Reactive oxygen species have a causal role in multiple forms of insulin resistance

Insulin resistance is a cardinal feature of type 2 diabetes and is characteristic of a wide range of other clinical and experimental settings. Little is known about why insulin resistance occurs in so many contexts. Do the various insults that trigger insulin resistance act through a common mechanism? Or, as has been suggested, do they use distinct cellular pathways? Here we report a genomic analysis of two cellular models of insulin resistance, one induced by treatment with the cytokine tumour-necrosis factor-alpha and the other with the glucocorticoid dexamethasone. Gene expression analysis suggests that reactive oxygen species (ROS) levels are increased in both models, and we confirmed this through measures of cellular redox state. ROS have previously been proposed to be involved in insulin resistance, although evidence for a causal role has been scant. We tested this hypothesis in cell culture using six treatments designed to alter ROS levels, including two small molecules and four transgenes; all ameliorated insulin resistance to varying degrees. One of these treatments was tested in obese, insulin-resistant mice and was shown to improve insulin sensitivity and glucose homeostasis. Together, our findings suggest that increased ROS levels are an important trigger for insulin resistance in numerous settings.     

Effect of dehydroepiandrosterone on insulin action and development of insulin-induced resistance in C2C12 muscle cells

Dehydroepiandrosterone (DHEA), a precursor of androgens and estrogens, has been demonstrated to have effect of preventing insulin resistance and development of diabetes mellitus. Administration of testosterone appears to induce a marked insulin resistance. How these two hormones affect insulin resistance through regulation of sensitivity of tissues to insulin deserves further studies. Here, the effects of DHEA and testosterone on response to insulin in C2C12 muscle cells are analyzed. After 24 h of DHEA (10-6 mol/L) treatment, C2C12 cells showed an increased insulin- stimulated glucose uptake and enhanced activities of glycogen synthase (GS), phosphofructokinase (PFK) and pyruvate dehydrogenase (PDH), whereas testosterone gave the opposite effects. Incubation of C2C12 cells with high-dose insulin (5×10-7 mol/L) for 24 hours decreased their sensitivity to insulin and led to a state of resistance as assessed on insulin-stimulated glucose uptake and activities of GS, PFK and PDH. Addition of DHEA to insulin-resistant C2C12 cells could reverse the response of these cells to high-dose insulin, but testosterone could further impair insulin sensitivity in insulin-resistant C2C12 cells. These results suggest that the two hormones may influence the development or inhibition of insulin-resistance in type 2 diabetes through regulating glucose uptake, glycogenesis and glycolysis to some extent.     

A central role for JNK in obesity and insulin resistance

Obesity is closely associated with insulin resistance and establishes the leading risk factor for type 2 diabetes mellitus, yet the molecular mechanisms of this association are poorly understood. The c-Jun amino-terminal kinases (JNKs) can interfere with insulin action in cultured cells and are activated by inflammatory cytokines and free fatty acids, molecules that have been implicated in the development of type 2 diabetes. Here we show that JNK activity is abnormally elevated in obesity. Furthermore, an absence of JNK1 results in decreased adiposity, significantly improved insulin sensitivity and enhanced insulin receptor signalling capacity in two different models of mouse obesity. Thus, JNK is a crucial mediator of obesity and insulin resistance and a potential target for therapeutics.     

氨基酸代谢与抗阻训练对骨骼肌mTOR的调节作用研究

抗阻训练在一定程度上能刺激肌肉生长,肌肉收缩和恢复过程中刺激蛋白质分解、合成的分子机制.从氨基酸、抗阻训练对骨骼肌mTOR的调节角度出发,综述了mTOR对细胞生长的作用、mTOR下游靶分子的调节、氨基酸对mTOR的活化作用和抗阻训练对mTOR信号转导调节的研究现状,并探讨了氨基酸与运动对mTOR的调节作用及机制.     

黄连治疗新冠肺炎的作用机理——基于网络药理学方法和分子对接技术

基于网络药理学方法和分子对接技术,初步探索了黄连治疗新冠肺炎（COVID-19）的作用机理.使用中草药系统药理学平台筛选黄连的有效活性成分与作用靶点,GeneCards和OMIM数据库筛选COVID-19的疾病靶点,R软件筛选药物与疾病的共同靶点,并利用Cytoscape软件构建“药物—活性成分—靶点—疾病”互作网络,STRING数据库构建共同靶点蛋白互作网络,ClueGo软件对共同靶点进行基因功能分析,R软件对共同靶点进行KEGG通路富集分析,然后将黄连有效成分中的核心成分与其治疗COVID-19的主要靶点进行分子对接.结果表明,黄连的有效活性成分共14种,靶点共235个;COVID-19的相关基因共341个;黄连治疗COVID-19的关键靶点包括VEGFA,IL6,POR,PLAT.分子对接结果显示,黄连中核心化合物榭皮素与PLAT,VEGFA,IL6对接效果良好.     

Abdominal obesity and metabolic syndrome

Metabolic syndrome is associated with abdominal obesity, blood lipid disorders, inflammation, insulin resistance or full-blown diabetes, and increased risk of developing cardiovascular disease. Proposed criteria for identifying patients with metabolic syndrome have contributed greatly to preventive medicine, but the value of metabolic syndrome as a scientific concept remains controversial. The presence of metabolic syndrome alone cannot predict global cardiovascular disease risk. But abdominal obesity - the most prevalent manifestation of metabolic syndrome - is a marker of 'dysfunctional adipose tissue', and is of central importance in clinical diagnosis. Better risk assessment algorithms are needed to quantify diabetes and cardiovascular disease risk on a global scale.     

Molecular mechanisms and clinical applications of angiogenesis

Blood vessels deliver oxygen and nutrients to every part of the body, but also nourish diseases such as cancer. Over the past decade, our understanding of the molecular mechanisms of angiogenesis (blood vessel growth) has increased at an explosive rate and has led to the approval of anti-angiogenic drugs for cancer and eye diseases. So far, hundreds of thousands of patients have benefited from blockers of the angiogenic protein vascular endothelial growth factor, but limited efficacy and resistance remain outstanding problems. Recent preclinical and clinical studies have shown new molecular targets and principles, which may provide avenues for improving the therapeutic benefit from anti-angiogenic strategies.     

基于网络药理学和分子对接研究丹参治疗浆细胞性乳腺炎的作用机制

利用网络药理学初步分析丹参治疗浆细胞性乳腺炎的作用机制,应用分子对接辅助研究丹参中活性化合物与浆细胞性乳腺炎主要靶点的亲和力,以证明筛选出的活性物质确实可与疾病靶点结合。基于中药系统药理学数据库与分析平台筛选丹参中的有效活性成分及这些成分的相关作用靶点,构建中药-成分-靶点网络,利用GeneCard数据库和DisGeNET数据库筛选浆细胞性乳腺炎的高相关性基因靶点,将药物成分靶点与疾病基因靶点相互映射,得到药物-成分-靶点-疾病网络,分析网络得到潜在药物活性化合物及潜在作用基因靶点,将此潜在作用靶点导入STRING数据库构建蛋白质-蛋白质相互作用网络。利用DAVID数据库对潜在作用靶点进行生物功能及代谢通路分析。对筛选到的高相关性活性成分和靶点进行分子对接,选择浆细胞性乳腺炎相关度最高的靶点IL-6、ICAM1和PGR,在PDB数据库中找到其三维蛋白结构,后在Zinc数据库中找寻丹参活性成分的分子结构,利用autodock4.0软件将蛋白与分子相对接。得到中药有效活性物质59个及其相关作用靶点132个,疾病相关靶点125个,映射后得到BCL2L1、EDNRA、ERBB2、ICAM1、IFNG、IL-4、IL-6、NR3C1、PGR、STAT3等10个潜在作用靶点,基因本体富集分析后找到潜在作用靶点共14个生物过程,京都基因与基因组百科全书分析后筛选得到16条信号转导通路,以乳腺癌通路、癌症信号通路、库欣综合征通路、NF-κB信号通路等通路为主。分子对接表明筛选出的药物活性成分与潜在作用靶点确有较大的亲和力。该研究初步筛选出了丹参治疗浆细胞性乳腺炎的物质基础,并揭示了丹参治疗该病症是通过多成分、多靶点、多途径共同调控。     

基于网络药理学结合正交设计优化复方降脂口服液的提取工艺

为了优选复方降脂口服液的提取工艺,通过网络药理学及分子对接技术分析复方降脂口服液中的功效成分,结合正交设计实验确定最佳提取工艺。结果表明,复方降脂口服液中的主要活性成分为异鼠李素、山柰酚、槲皮素等黄酮类化合物,作用于AKT1、IL6、PPARG等关键靶点,通过胰岛素抵抗、脂肪分解、AMPK等信号通路,发挥治疗单纯性肥胖的作用;以功效成分总黄酮含量及干膏得率为评价指标,正交设计试验得出最佳提取工艺条件为：焦山楂、赤小豆、决明子、茯苓、薏苡仁、枸杞子6味药加1 500 mL水浸泡60 min,煎煮45 min后下荷叶、陈皮、玫瑰花共煎25 min。可见复方降脂口服液以多成分-多靶点-多通路途径治疗单纯性肥胖,通过网络药理学及分子对接确定工艺评价指标,优选的工艺稳定,可为口服液产品开发奠定基础。     

基于网络药理学和分子对接探讨智脑胶囊改善阿尔茨海默病的作用机制

借助网络药理学和分子对接技术,探讨智脑胶囊改善阿尔茨海默病的干预机制。通过TCMSP、TCMID等多个数据库寻找与智脑胶囊相关的化学成分及其作用靶点;利用GeneCard等数据库获取阿尔茨海默病的作用靶点;运用Venny2.1网站筛选出药物与疾病的交集靶点;使用STRING平台和Cytoscape软件进行拓扑分析得到智脑胶囊治疗阿尔茨海默病的核心作用靶点;采用Metaspace数据库对潜在核心作用靶点进行GO(gene ontology)及KEGG(Kyoto encyclopedia of genes and genomes)通路富集分析;利用AutoDock软件使用分子对接验证活性化合物与核心靶点的结合能力。结果表明：在智脑胶囊中共筛选出44个活性成分和292个有效靶点,智脑胶囊与阿尔茨海默病共同靶点58个;蛋白质-蛋白质相互作用得出关键靶点包括AKT1、IL-6、TNF等;GO分析共包含1 419条,KEGG得到175条代谢通路,主要包括脂质与动脉硬化、TNF信号通路;分子对接显示关键成分与靶点具有良好的结合能力。研究表示智脑胶囊可能通过脂质与动脉硬化和TNF信号通路等途径来减轻...