Defective lipolysis and altered energy metabolism in mice lacking adipose triglyceride lipase

Fat tissue is the most important energy depot in vertebrates. The release of free fatty acids (FFAs) from stored fat requires the enzymatic activity of lipases. We showed that genetic inactivation of adipose triglyceride lipase (ATGL) in mice increases adipose mass and leads to triacylglycerol deposition in multiple tissues. ATGL-deficient mice accumulated large amounts of lipid in the heart, causing cardiac dysfunction and premature death. Defective cold adaptation indicated that the enzyme provides FFAs to fuel thermogenesis. The reduced availability of ATGL-derived FFAs leads to increased glucose use, increased glucose tolerance, and increased insulin sensitivity. These results indicate that ATGL is rate limiting in the catabolism of cellular fat depots and plays an important role in energy homeostasis.     

TRB3 links the E3 ubiquitin ligase COP1 to lipid metabolism

During fasting, increased concentrations of circulating catecholamines promote the mobilization of lipid stores from adipose tissue in part by phosphorylating and inactivating acetyl-coenzyme A carboxylase (ACC), the rate-limiting enzyme in fatty acid synthesis. Here, we describe a parallel pathway, in which the pseudokinase Tribbles 3 (TRB3), whose abundance is increased during fasting, stimulates lipolysis by triggering the degradation of ACC in adipose tissue. TRB3 promoted ACC ubiquitination through an association with the E3 ubiquitin ligase constitutive photomorphogenic protein 1 (COP1). Indeed, adipocytes deficient in TRB3 accumulated larger amounts of ACC protein than did wild-type cells. Because transgenic mice expressing TRB3 in adipose tissue are protected from diet-induced obesity due to enhanced fatty acid oxidation, these results demonstrate how phosphorylation and ubiquitination pathways converge on a key regulator of lipid metabolism to maintain energy homeostasis.     

日粮不同能量水平对乌金猪脂肪组织Leptin和RBP4基因表达的影响

 研究日粮不同能量水平对乌金猪脂肪组织中脂肪细胞分泌因子leptin和RBP4基因表达的影响。选取体重约15kg的乌金猪54头,随机分为3组,分别饲喂消化能为14.22,12.89,11.74MJ/kg的日粮,在30,60,100kg体重时屠宰,分别测定血液中胰岛素和葡萄糖含量及胴体脂肪沉积率,取皮下脂肪组织用荧光定量PCR检测leptin和RBP4基因的表达水平。结果显示,饲喂高能量日粮乌金猪胴体脂肪沉积率和血液胰岛素含量高于饲喂低能量日粮组（P<0.05）,日粮能量水平对血液葡萄糖含量无明显影响（P>0.05）;脂肪组织中leptin基因的表达水平升高（P<0.05）,RBP4基因的表达水平降低（P<0.05）。表明高能量日粮通过上调leptin基因的表达、下调RBP4基因的表达,和胰岛素的作用促进脂肪沉积。     

Defining a link with asthma in mice congenitally deficient in eosinophils

Eosinophils are often dominant inflammatory cells present in the lungs of asthma patients. Nonetheless, the role of these leukocytes remains poorly understood. We have created a transgenic line of mice (PHIL) that are specifically devoid of eosinophils, but otherwise have a full complement of hematopoietically derived cells. Allergen challenge of PHIL mice demonstrated that eosinophils were required for pulmonary mucus accumulation and the airway hyperresponsiveness associated with asthma. The development of an eosinophil-less mouse now permits an unambiguous assessment of a number of human diseases that have been linked to this granulocyte, including allergic diseases, parasite infections, and tumorigenesis.     

雷公藤甲素对哮喘小鼠白介素13和嗜酸性粒细胞趋化因子表达的影响

目的观察雷公藤甲素(TL)对哮喘小鼠肺组织中白介素13(IL-13)和嗜酸性粒细胞趋化因子(Eotaxin)表达的影响,探讨TL治疗哮喘的作用机理。方法40只雄性昆明小鼠随机分成4组:正常对照组、哮喘未治疗组、地塞米松治疗组及TL治疗组,以卵清蛋白致敏和激发方法建立哮喘小鼠动物模型并给予相应治疗。24 d后处死小鼠,检测各组支气管肺泡灌洗液(BALF)中白细胞总数及嗜酸性粒细胞(Eos)计数;采用逆转录-聚合酶链反应(RT-PCR)方法检测各组小鼠肺组织匀浆中IL-13、eotaxin mRNA的表达量;采用免疫组化法检测各组小鼠肺组织切片中IL-13、eotaxin蛋白的表达水平;并探讨他们之间的关系。结果哮喘未治疗组小鼠肺组织IL-13、eotaxin mRNA及蛋白的表达量均明显高于正常对照组(P<0.01),TL治疗组及地塞米松治疗组低于哮喘未治疗组(P<0.01或<0.05)。肺组织IL-13蛋白的表达与BALF中的白细胞总数、Eos计数及肺组织eotaxin蛋白的表达呈正相关(r分别为0.513、0.604、0.625,P<0.01)。肺组织eotaxin蛋白的表达与BALF中的白细胞总数、Eos计数呈正相关(r分别为0.679、0.718,P<0.01)。结论TL抑制哮喘气道炎症的机制可能与其抑制肺组织中IL-13及eotaxin的表达有关。     

Neuronal pathway from the liver modulates energy expenditure and systemic insulin sensitivity

Coordinated control of energy metabolism and glucose homeostasis requires communication between organs and tissues. We identified a neuronal pathway that participates in the cross talk between the liver and adipose tissue. By studying a mouse model, we showed that adenovirus-mediated expression of peroxisome proliferator-activated receptor (PPAR)-g2 in the liver induces acute hepatic steatosis while markedly decreasing peripheral adiposity. These changes were accompanied by increased energy expenditure and improved systemic insulin sensitivity. Hepatic vagotomy and selective afferent blockage of the hepatic vagus revealed that the effects on peripheral tissues involve the afferent vagal nerve. Furthermore, an antidiabetic thiazolidinedione, a PPARg agonist, enhanced this pathway. This neuronal pathway from the liver may function to protect against metabolic perturbation induced by excessive energy storage.     

大黄素对胰岛素抵抗大鼠脂肪组织11β-羟基类 固醇脱氢酶1表达的影响

观察大黄素对胰岛素抵抗大鼠脂肪组织11β-HSDl表达的影响,探讨其改善胰岛素抵抗的可能机制。采用30只雄性Wistar大鼠作为研究对象,随机分为对照组、模型组和给药组,每组10只。模型建立通过高脂饲料喂养结合地塞米松刺激的方式。12周后造模成功,给药组予大黄素200 mg·kg-1灌胃。给药4周后,进行胰岛素耐量试验,检测血糖、血脂、血液胰岛素及皮质酮水平,计算肝指数、内脏肥胖指数及HOMA-IR指数和11β-HSD1基因及蛋白表达情况。结果表明,与模型组比较,给药组胰岛素抵抗状态显著改善,血糖、胰岛素及血脂水平明显降低,肝指数及内脏肥胖指数也明显下降,同时内脏脂肪组织11β-HSD1基因及蛋白表达明显下调。可见大黄素可显著改善胰岛素抵抗大鼠的糖脂代谢及胰岛素敏感性,其作用机制可能与抑制11β-HSD1基因及蛋白表达有关。     

Brominating oxidants generated by human eosinophils

Eosinophils are white blood cells that in humans are found in association with helminthic infections and various inflammatory disease processes. These cells contain a unique lysosomal peroxidase that oxidizes halides to generate highly reactive and toxic hypohalous acids. Although chloride is found in vivo at concentrations at least 1000-fold greater than those of other halides, human eosinophils did not preferentially oxidize chloride under physiologic conditions. Instead, eosinophils used bromide, a halide with a hitherto unknown function in humans, to generate a halogenating oxidant with characteristics similar, if not identical, to those of hypobromous acid. These results indicate that physiological concentrations of bromide arm human eosinophils with the ability to generate and release an unusual oxidant capable of destroying a wide range of prokaryotic and eukaryotic targets.     

Fat mobilization in adipose tissue is promoted by adipose triglyceride lipase

Mobilization of fatty acids from triglyceride stores in adipose tissue requires lipolytic enzymes. Dysfunctional lipolysis affects energy homeostasis and may contribute to the pathogenesis of obesity and insulin resistance. Until now, hormone-sensitive lipase (HSL) was the only enzyme known to hydrolyze triglycerides in mammalian adipose tissue. Here, we report that a second enzyme, adipose triglyceride lipase (ATGL), catalyzes the initial step in triglyceride hydrolysis. It is interesting that ATGL contains a "patatin domain" common to plant acyl-hydrolases. ATGL is highly expressed in adipose tissue of mice and humans. It exhibits high substrate specificity for triacylglycerol and is associated with lipid droplets. Inhibition of ATGL markedly decreases total adipose acyl-hydrolase activity. Thus, ATGL and HSL coordinately catabolize stored triglycerides in adipose tissue of mammals.     

Local macrophage proliferation, rather than recruitment from the blood, is a signature of TH2 inflammation

A defining feature of inflammation is the accumulation of innate immune cells in the tissue that are thought to be recruited from the blood. We reveal that a distinct process exists in which tissue macrophages undergo rapid in situ proliferation in order to increase population density. This inflammatory mechanism occurred during T helper 2 (T(H)2)-related pathologies under the control of the archetypal T(H)2 cytokine interleukin-4 (IL-4) and was a fundamental component of T(H)2 inflammation because exogenous IL-4 was sufficient to drive accumulation of tissue macrophages through self-renewal. Thus, expansion of innate cells necessary for pathogen control or wound repair can occur without recruitment of potentially tissue-destructive inflammatory cells.     

Rapamycin-induced insulin resistance is mediated by mTORC2 loss and uncoupled from longevity

Rapamycin, an inhibitor of mechanistic target of rapamycin complex 1 (mTORC1), extends the life spans of yeast, flies, and mice. Calorie restriction, which increases life span and insulin sensitivity, is proposed to function by inhibition of mTORC1, yet paradoxically, chronic administration of rapamycin substantially impairs glucose tolerance and insulin action. We demonstrate that rapamycin disrupted a second mTOR complex, mTORC2, in vivo and that mTORC2 was required for the insulin-mediated suppression of hepatic gluconeogenesis. Further, decreased mTORC1 signaling was sufficient to extend life span independently from changes in glucose homeostasis, as female mice heterozygous for both mTOR and mLST8 exhibited decreased mTORC1 activity and extended life span but had normal glucose tolerance and insulin sensitivity. Thus, mTORC2 disruption is an important mediator of the effects of rapamycin in vivo.     

西门塔尔牛肌内和皮下脂肪miRNA表达谱及miR-27b靶基因分析

【目的】通过分析西门塔尔牛肌内脂肪和皮下脂肪差异表达miRNA,及对重要的候选miRNA-27b进行靶基因预测及相关生物信息学分析,探索miRNA在动物肌内脂肪生长、发育过程中的作用及其调控机制。【方法】利用miRNA微阵列芯片技术对肌内脂肪和皮下脂肪miRNA表达谱进行检测和分析以筛选差异表达miRNA;qRT-PCR方法验证4个在肌内脂肪显著高表达的候选miRNAs;采用Targetscan生物信息学计算方法预测目标miR-27b（对肌内脂肪沉积可能起重要调节作用）的靶基因,并对靶基因进行GO注释描述、富集分析及KEGG富集。【结果】miRNA芯片分析发现肌内脂肪和皮下脂肪共有88个差异表达极显著miRNA（P＜0.01）。候选的4个在肌内脂肪高表达miRNAs（miR-140、miR-145、miR-143、miR-27b）的qRT-PCR检测结果与芯片分析结果具有很好的一致性。KEGG富集显示,目标miR-27b的预测靶基因在MAPK、Wnt、Hedgehog、TGF-beta、GnRH等信号通路中显著富集,其中在MAPK信号通路中富集度最高。【结论】牛肌内脂肪和皮下脂肪组织中确实存在一些差异表达的miRNAs,某些重要的在差异高表达miRNA（如miR-27b）可能以独特的通路（如MAPK信号）来调节牛肌内脂肪的形成过程。     

Nonphosphorylating respiration of mitochondria from brown adipose tissue of rats

Mitochondria from brown adipose tissue of cold-acclimated rats (6 degrees C) oxidize alpha-ketoglutarate at a rate twice that of controls (26 degrees C). In both groups, however, the phosphorus: oxygen ratio with alpha-ketoglutarate never exceeded unity, and it is essentially zero with either succinate or alpha-glycerophosphate. Adenosine triphosphatase activity of these mitochondria is very low and it is not stimulated by 2,4-dinitrophenol. In addition, both respiration and phosphorylation are unaffected by adenosine diphosphate, 2,4-dinitrophenol, bovine serum albumin, or glutathione. Endogenous respiration of tissue slices is not stimulated by 2-4-dinitrophenol. It is suggested that brown fat mitochondria are not capable of oxidative phosphorylation, but do phosphorylate at the substrate level. Since these findings provide an unusual example of electron transport by means of an energetically nonconservative pathway, their significance to thermogenesis by brown adipose tissue is particularly emphasized.     

猪皮下与内脏脂肪组织mRNA转录组的构建与差异分析

【目的】研究猪皮下脂肪和内脏脂肪的表型和代谢差异,找出差异转录本。【方法】选取长白母猪的皮下脂肪(背部皮下脂肪)和内脏脂肪(大网膜脂肪和肠系膜脂肪)进行表型测定及高通量转录组测序(RNA-Seq)。【结果】①背部皮下脂肪体积最大,大网膜次之,肠系膜的脂肪体积最小;与皮下脂肪相比,内脏脂肪中饱和脂肪酸含量更高(P<0.01)而不饱和脂肪酸的含量相对较低(P<0.05);②转录组测序共获得30 532 913～33 479 707个唯一比对到基因组的读段(reads),鉴定了22 015个转录本,覆盖猪已注解转录本的80.2%,同时还发现4 583～4 765个新的转录本、936～1 029个可变剪切、16 559个单核苷酸多态位点(SNPs)和1 481个插入/缺失位点(INDELs)。③皮下脂肪和内脏脂肪间差异表达的基因共有183个,基因注释(GO)和代谢通路(Pathway)分析发现它们在不饱和脂肪酸合成、羧酸代谢和炎症反应过程中有重要作用。【结论】提供了猪皮下脂肪和内脏脂肪的完善转录组信息,获得了影响脂肪酸代谢的潜在候选基因,为进一步揭示皮下脂肪和内脏脂肪的功能特征与差异提供了数据基础。     

从绵羊脂肪组织提取总RNA方法的改进及应用

以绵羊脂肪组织为材料,对脂肪组织总RNA提取方法进行了改进,并分析了脂肪酸合成酶基因(fattyacid synthase,FAS)在绵羊腹部皮下脂肪组织、肠系膜脂肪组织和尾部脂肪组织中表达的差异性.结果表明:利用改进后的方法从绵羊脂肪组织中提取出的RNA无DNA污染、均一、完整、质量可靠.绵羊腹部皮下脂肪中FASmRNA的表达量极显著高于尾部脂肪组织和肠系膜脂肪组织(P<0.01),且尾部脂肪组织和肠系膜脂肪组织中FAS mRNA的表达量差异不显著(P>0.05).     

Cachectin/TNF and IL-1 induced by glucose-modified proteins: role in normal tissue remodeling

Proteins undergo a series of nonenzymatic reactions with glucose over time to form advanced glycosylation end products (AGEs). Macrophages have a receptor that recognizes the AGE moiety and mediates the uptake and degradation of AGE proteins. This removal process is associated with the production and secretion of cachectin (tumor necrosis factor) and interleukin-1, two cytokines with diverse and seemingly paradoxical biological activities. The localized release and action of these cytokines could account for the coordinated removal and replacement of senescent extracellular matrix components in normal tissue homeostasis.     

Allosteric activators of glucokinase: potential role in diabetes therapy

Glucokinase (GK) plays a key role in whole-body glucose homeostasis by catalyzing the phosphorylation of glucose in cells that express this enzyme, such as pancreatic beta cells and hepatocytes. We describe a class of antidiabetic agents that act as nonessential, mixed-type GK activators (GKAs) that increase the glucose affinity and maximum velocity (Vmax) of GK. GKAs augment both hepatic glucose metabolism and glucose-induced insulin secretion from isolated rodent pancreatic islets, consistent with the expression and function of GK in both cell types. In several rodent models of type 2 diabetes mellitus, GKAs lowered blood glucose levels, improved the results of glucose tolerance tests, and increased hepatic glucose uptake. These findings may lead to the development of new drug therapies for diabetes.     

来源于脂环酸芽孢杆菌的GH1家族β-葡萄糖苷酶的葡萄糖耐受性分子改造

豆粕中大豆异黄酮主要以无活性的结合型存在。在玉米豆粕型日粮为主的饲料领域,β-葡萄糖苷酶可以将结合型大豆异黄酮转化为游离型活性苷元,但转化过程受肠道中较高浓度葡萄糖的抑制。和GH3家族相比,GH1家族β-葡萄糖苷酶不仅具有较高的葡萄糖耐受性,而且一定浓度范围内的葡萄糖对其具有酶活促进效应,因此在饲料领域显示出巨大的应用潜力。从脂环酸芽孢杆菌Alicyclobacillus sp.A4中克隆表达了一个具有较高葡萄糖耐受性(IC50800 mmol/L)的GH1家族β-葡萄糖苷酶As BG1。为了进一步提高As BG1的葡萄糖耐受性,通过同源建模、序列比对、分子对接技术等生物信息学手段,聚焦于催化通道的非催化葡萄糖结合位点,对As BG1进行了理性设计的分子突变研究。对不同突变体的葡萄糖耐受性测定表明:以5 mmol/L p NPG为底物,100 mmol/L葡萄糖对WT(野生型)、H315R和M325K酶活促进作用分别为125%、163%和162%,其中H315R的IC50提高至1 200 mmol/L;以1 mmol/L大豆苷为底物,10 mmol/L的葡萄糖对WT、H315R和M325K分别具有163%、212%和226%的酶活促进作用,结果表明突变体具有更好的在动物胃肠道水解大豆异黄酮能力。上述结果丰富了对GH1家族葡萄糖耐受性机制的认识,为日后进行耐受性相关的分子改造提供了重要的指导意义。     

Brown adipose cells: spontaneous mobilization of endogenously synthesized lipid

Isolated brown adipose cell devoid of a basement membrane, readily synthesized a variety of lipids from radioctive acetate, a reactionaugmented by glucose and insulin. A large proportion of the newly formed fatty acids passed into the incubation medium. In intact brown adipose slices and isolated white adipose cells, most of the synthesized lipid was retained as glyceride esters. The date suggest that the rapid turnover of endogenously synthesized lipid in brown adipose cells is almost totally obscured in studies with intact tissue slices because of interstitial barriers to the egress of fatty acid.     

北方主要造林树种耐旱机理及其分类模型的研究(Ⅰ)——苗木叶水势与土壤含水量的关系及分类

本文详细研究了我国北方部分主要造林树种苗木叶水势与土壤含水量的关系,结果表明:①苗木叶水势Ψ_w与土壤含水量SWC呈明显的“反J型”关系,应用双曲线方程y=a+b/x和指数方程y=ae~(b/x)拟合效果最优.②不同树种Ψ_w随SWC下降的变化差异很大,从而表明不同树种对土壤干旱胁迫的反应和适应不尽相同.依据Levitt和Kramer以及李吉跃等人对植物适应干旱方式的分类方法,应用系统聚类法将21个树种分为两大类4个亚类,即高水势延迟脱水树种(包括油松、樟子松、长白松、白皮松,华山松),亚高水势延迟脱水树种(包括二白杨、火炬树、华北落叶松),亚低水势忍耐脱水树种(包括文冠果、杜仲、沙枣、栾树、花椒、白榆、新疆杨.毛条、胡杨、红柳、侧柏),低水势忍耐脱水树种(包括山杏和山桃).相应于每一类为其建立了Fuzzy模式识别模型.这一模型可以在更为广阔的范围内判别其它树种的耐旱机理及其类型.