畜禽PPARα基因研究进展

过氧化物酶体增殖物激活受体(Peroxisome proliferator-activated receptors,PPARs)是核激素受体家族中的配体激活受体,控制许多细胞内的代谢过程,PPARα作为过氧化物酶体增殖物激活受体家族重要成员之一,是调控机体脂质代谢的重要枢纽,在调控畜禽机体肝脏脂质代谢方面有重要作用。PPARα基因由四个结构域组成,多在机体肝脏和脂肪组织中表达,可作为细胞核受体被外源和内源的特异性配体结合并激活,进而结合靶基因发挥对肝脏脂质代谢的调控作用。就PPARα基因的结构特点及表达模式、PPARα基因对肝脏脂代谢的调控机制,以及现阶段PPARα在畜禽方面的研究进展进行阐述,旨在引起人们对PPARα基因调控脂质代谢的关注,并为畜禽肝脏脂质代谢过程的机理研究和相关疾病的治疗提供一些理论支持。     

PPARα、PPARγ及其双激动剂与动脉粥样硬化

过氧化物酶体增殖物激活受体（peroxisome proliferator-activated receptors,PPARs）是核受体超家族中的一类配体依赖的核转录因子,其中两种重要的亚型PPARα和PPARγ在脂肪细胞分化、能量代谢和炎症过程中都发挥重要作用。研究显示,PPARα和PPARγ的配体激动剂不仅可以改善包括糖尿病、高血压和肥胖等在内的胰岛素抵抗综合征,而且还可以通过作用于血管壁从而减缓动脉粥样硬化的进程。本文将就PPARα和PPARγ及其双激动剂与动脉粥样硬化发病机制和治疗的相关研究进展进行概括介绍。     

激活PPARα缓解PPARγ诱导的小鼠脂肪肝

目的研究PPARα激活后对PPARγ诱导小鼠脂肪肝的影响。方法以4~5周龄C57BL/6J小鼠为模型,实验分为4组:正常饮食组;0.125%Wy-14,643处理组;PPARγ腺病毒(Ad/PPARγ)注射组;先给予0.125%Wy-14,643饮食再注射Ad/PPARγ组。实验结束时,收集肝脏组织称重、照相,HE、油红O染色观察PPARα激活后对PPARγ诱导肝脏脂肪变性的影响。结果野生型小鼠给予PPARα激动剂Wy-14,643处理8 d,与对照组相比,处理组小鼠肝脏明显增大,呈现过氧化物酶体增殖反应;野生型小鼠给予Ad/PPARγ5 d,小鼠肝脏显著增大,出现脂肪肝;给予PPARα激动剂Wy-14,643 3 d,再给予Ad/PPARγ5 d,小鼠肝脏增大更加显著,HE染色、油红O染色结果显示小鼠肝脏脂肪变性明显减轻。结论激活PPARα能够缓解PPARγ诱导的小鼠肝脏脂肪变,为脂肪肝的预防和治疗提供了新的研究思路和靶点。     

Scaffold-Based Pan-Agonist Design for the PPARα, PPARβ and PPARγ Receptors

As important members of nuclear receptor superfamily, Peroxisome proliferator-activated receptors (PPAR) play essential roles in regulating cellular differentiation, development, metabolism, and tumorigenesis of higher organisms. The PPAR receptors have 3 identified subtypes: PPARα, PPARβ and PPARγ, all of which have been treated as attractive targets for developing drugs to treat type 2 diabetes. Due to the undesirable side-effects, many PPAR agonists including PPARα/γ and PPARβ/γ dual agonists are stopped by US FDA in the clinical trials. An alternative strategy is to design novel pan-agonist that can simultaneously activate PPARα, PPARβ and PPARγ. Under such an idea, in the current study we adopted the core hopping algorithm and glide docking procedure to generate 7 novel compounds based on a typical PPAR pan-agonist {"type":"entrez-nucleotide","attrs":{"text":"LY465608","term_id":"1257853743","term_text":"LY465608"}}LY465608. It was observed by the docking procedures and molecular dynamics simulations that the compounds generated by the core hopping and glide docking not only possessed the similar functions as the original {"type":"entrez-nucleotide","attrs":{"text":"LY465608","term_id":"1257853743","term_text":"LY465608"}}LY465608 compound to activate PPARα, PPARβ and PPARγ receptors, but also had more favorable conformation for binding to the PPAR receptors. The additional absorption, distribution, metabolism and excretion (ADME) predictions showed that the 7 compounds (especially Cpd#1) hold high potential to be novel lead compounds for the PPAR pan-agonist. Our findings can provide a new strategy or useful insights for designing the effective pan-agonists against the type 2 diabetes.     

PPARα与阿尔茨海默病的研究进展

阿尔茨海默病(Alzheimer's disease,AD)是一种进行性、破坏认知与记忆功能的持续性神经退行性疾病.它的主要病理特征是以β淀粉样蛋白(β-amyloid protein,Aβ)沉积和Tau蛋白过度磷酸化形成神经原纤维缠结(neurofibrillary tangle,NFT)为主,是一种日益严重的全球健康性问题.过氧化物酶体增殖物激活受体(peroxisome proliferators-activated receptor,PPAR)是在中枢神经系统(CNS)中表达,调节能量代谢、神经传递、氧化还原稳态、线粒体功能等生理过程的一种核受体. PPARα作为其中一个亚型,在AD控制突触可塑性和调节神经元认知功能中有重要作用,说明PPARα是治疗AD的一个很有前途的靶点.这篇综述探讨了Aβ、氧化应激、神经炎症、脂质代谢在AD中的意义,以及PPARα的潜在价值及其在AD中的作用,揭示了未来PPARα作为AD治疗靶点的可能性.     

Nutrient-dependent phosphorylation channels lipid synthesis to regulate PPARα

Peroxisome proliferator-activated receptor (PPAR)α is a nuclear receptor that coordinates liver metabolism during fasting. Fatty acid synthase (FAS) is an enzyme that stores excess calories as fat during feeding, but it also activates hepatic PPARα by promoting synthesis of an endogenous ligand. Here we show that the mechanism underlying this paradoxical relationship involves the differential regulation of FAS in at least two distinct subcellular pools: cytoplasmic and membrane-associated. In mouse liver and cultured hepatoma cells, the ratio of cytoplasmic to membrane FAS-specific activity was increased with fasting, indicating higher cytoplasmic FAS activity under conditions associated with PPARα activation. This effect was due to a nutrient-dependent and compartment-selective covalent modification of FAS. Cytoplasmic FAS was preferentially phosphorylated during feeding or insulin treatment at Thr-1029 and Thr-1033, which flank a dehydratase domain catalytic residue. Mutating these sites to alanines promoted PPARα target gene expression. Rapamycin-induced inhibition of mammalian/mechanistic target of rapamycin complex 1 (mTORC1), a mediator of the feeding/insulin signal to induce lipogenesis, reduced FAS phosphorylation, increased cytoplasmic FAS enzyme activity, and increased PPARα target gene expression. Rapamycin-mediated induction of the same gene was abrogated with FAS knockdown. These findings suggest that hepatic FAS channels lipid synthesis through specific subcellular compartments that allow differential gene expression based on nutritional status.     

有氧运动对糖尿病大鼠PPARα信号通路的影响及其与PPARγ关系*

目的: 探讨4周有氧运动对糖尿病大鼠血糖血脂的改善作用及其与PPARα和PPARγ的调控关系。方法: 6周龄雄性SD大鼠8周高脂饮食喂养后一次性腹腔注射链脲佐菌素以建立糖尿病模型大鼠。除普通膳食对照组(Con)外,建模成功的糖尿病大鼠随机分成糖尿病对照组(DM)、糖尿病运动组(TDM)、糖尿病运动加PPARγ激动剂吡格列酮组(TDP)和糖尿病运动加PPARγ抑制剂GW9662组(TDG),每组8只。TDP组和TDG组大鼠在运动前分别补充吡格列酮和GW9662,TDM、TDP和TDG组大鼠进行4周中等强度递增负荷跑台运动(第1周15 m/min,30 min;第2周15 m/min,60 min;第3周20 m/min,60 min;第4周20 m/min,90 min),每周运动6 d,每天1次。运动期间所有大鼠给予普通饲料。最后一次运动结束后36 h,大鼠麻醉、取血,然后处死大鼠、收集肝和腓肠肌。检测空腹血糖血脂指标(血糖、血胰岛素和血脂四项)。Western blot方法检测肝和腓肠肌PPARα、PPARα上游分子腺苷酸活化蛋白激酶(AMPK)和下游分子肉碱棕榈酰转移酶-1(CPT1)的蛋白水平。结果: ①与Con组大鼠比较,DM大鼠FBG(＞11.1 mmol/L)和血清TC、TG、LDL水平显著升高(P均＜0.01),表明DM造模成功。②与DM大鼠比较,TDM大鼠血糖血脂改善的同时,肝和腓肠肌PPARα、AMPK和CPT1的蛋白水平均显著升高(P均＜0.01)。③与TDM大鼠比较,TDG大鼠肝和腓肠肌的PPARα和CPT1,以及肝AMPK的蛋白水平无显著变化(仅腓肠肌AMPK显著降低(P＜0.05));而TDP大鼠的肝和腓肠肌PPARα、AMPK和CPT1蛋白水平均显著提高(P均＜0.01)。结论: 有氧运动对DM大鼠血糖血脂的改善作用-与运动激活肝和腓肠肌的AMPK-PPARα-CPT1通路有关。运动对DM大鼠PPARα通路的激活与PPARγ无关,但PPARγ激活可进一步增强运动对AMPK-PPARα-CPT1蛋白水平上调的作用。     

PPARα转基因小鼠在药物评价中的应用研究

目的研究过氧化物酶体增殖激活受体α激动剂药物在PPARα转基因小鼠体内对肝肾功能、血脂指标的影响,以评价该模型能否能应用于药效学研究中。方法选择27只6周龄的PPARα小鼠给予高脂饲料喂养一个月,随机分成3组,9只/组,分别为对照组1,高剂量组（非诺贝特60 mg/kg）和低剂量组（30 mg/kg）。同时选择9只C57BL/6小鼠作为对照组2。连续灌胃一个月,在动物给药前后分别检测肝功能指标、肾功能指标和血脂指标,并观察动物的一般生长情况。结果①给药后各组比较：与对照组1比较,非诺贝特各剂量组在PPARα转基因小鼠体内均能明显升高血脂中CHO和HDL-C（P〈0.05）,明显降低TG（P〈0.05）。各组之间的体重没有明显的差异（P〉0.05）。②给药前后比较：与给药前比较,给药后高剂量组能明显降低ALT、AST、ALP、BUN、TG（P〈0.05）;能明显升高CHO、HDL-C（P〈0.01）。而低剂量组能明显降低ALP（P〈0.05）;能明显升高CHO、HDL-C（P〈0.05）。结论 PPARα转基因小鼠评价PPARα激动剂药物比常规C57BL/6小鼠更敏感,是一个新的动物模型。     

PPARα转基因小鼠在药物毒性评价中的应用

目的研究PPARα转基因小鼠在评价PPARα激动剂类药物毒性时,是否比传统动物更敏感。方法8周龄PPARα转基因小鼠(Tg)和C57BL/6J小鼠(WT),雌雄各半,分别随机分成3组,氯贝丁酯高剂量组(400 mg/kg)、氯贝丁酯低剂量组(300 mg/kg)、溶媒对照组(10%羧甲基纤维素钠)。连续灌胃一个月,给药结束后检测血生化指标、心肝肾脏器系数及病理改变,并观察动物的一般生长情况。结果 1血生化:Tg♂高、低剂量组肌酐(CREA)、天门冬氨酸氨基转移酶(AST)分别显著高于各对应的野生型对照组(P0.01,P0.05)。2脏器系数:Tg高、低剂量组肾脏系数与Tg溶媒对照组比较均有显著增加(P0.01,P0.05)。3组织病理:Tg各剂量组肝脏、肾脏病理损伤较WT各剂量组更严重。结论 PPARα转基因小鼠评价PPARα激动剂药物肝脏毒性和肾脏毒性时比常规C57BL/6J野生小鼠更敏感,是一个新的动物模型。     

PPARα在肝脏相关疾病中作用的研究进展

过氧化物酶体增殖物激活受体α(perixisome proliferation-activated receptor alpha,PPARα)是核受体超家族成员,是参与肝脏β氧化的主要调控蛋白,通过诱导下游靶基因转录,从而发挥其重要的生物学功能。近年来,肝脏相关疾病的研究备受关注,肝癌(主要以肝细胞性肝癌为主)也呈年轻化趋势。PPARα的活化能够降低高脂喂养小鼠肝脏中甘油三酯的含量或脂肪的生成量。此外,PPARα通过调控细胞增殖与凋亡进程等多种机制参与肝癌进程。现综述PPARα在非酒精性脂肪肝、酒精性脂肪肝和肝细胞性肝癌进程中的作用。     

Modulation of PPAR subtype selectivity. Part 2: Transforming PPARα/γ dual agonist into α selective PPAR agonist through bioisosteric modification

A novel series of oxime containing benzyl-1,3-dioxane-r-2-carboxylic acid derivatives (6a-k) were designed as selective PPARα agonists, through bioisosteric modification in the lipophilic tail region of PPARα/γ dual agonist. Some of the test compounds (6a, 6b, 6c and 6f) showed high selectivity towards PPARα over PPARγ in vitro. Further, highly potent and selective PPARα agonist 6c exhibited significant antihyperglycemic and antihyperlipidemic activity in vivo, along with its improved pharmacokinetic profile. Favorable in-silico interaction of 6c with PPARα binding pocket correlate its in vitro selectivity profile toward PPARα over PPARγ. Together, these results confirm discovery of novel series of oxime based selective PPARα agonists for the safe and effective treatment of various metabolic disorders.     

人PPARαLBD在大肠杆菌中的表达纯化及鉴定

过氧化物酶体增殖物活化受体α(peroxisome prolifterator-activated receptor α,PPARα)属于Ⅱ型核受体,通过其配体结合区（1igand binding domain,LBD）结合特定的激动剂对参与机体代谢的关键酶、受体等的表达起调节作用。本研究从人肝组织提取总RNA,RT-PCR扩增出PPARαLBD的cDNA,将其克隆入表达载体pMAL-p2X麦芽糖结合蛋白（Maltose Binding Protein,MBP）编码基因malE序列的下游,重组质粒转化E coli TB1,进行了高效的可溶性融合蛋白表达。产物经多糖亲和树脂（Amylose-resin）纯化后,获得了电泳纯的MBP-PPARαLBD。MBP-PPARαLBD用Xa因子酶切,经Amylose-resin亲和层析、DE-52阴离子交换层析纯化回收,获得了电泳纯的PPARαLBD。本研究为进一步比较MBP-PPARαLBD和PPARαLBD的功能,筛选PPARα配体奠定了基础。     

全脑缺血/再灌注大鼠海马PPARα表达变化

目的观察全脑缺血/再灌注损伤大鼠海马组织中PPARα mRNA和蛋白表达的动态变化.方法采用夹闭两侧颈总动脉,颈静脉抽血再回输建立大鼠全脑缺血/再灌注模型(I/R).RT-PCR和Western Blot分别检测PPARα mRNA和蛋白在缺血再灌注不同时间的表达.结果大鼠海马PPARα mRNA表达在缺血/再灌注30 min后升高,24 h时达峰,而后降低,再灌注30 d仍略高于正常水平.PPARα蛋白表达变化与PPARα mRNA表达相似.结论全脑缺血/再灌注损伤可诱导PPARα mRNA及蛋白表达,升高时限为30 d.     

Isohumulones modulate blood lipid status through the activation of PPARα

Isohumulones derived from hops are the major bitter compounds in beer. It was recently reported that isohumulones activated peroxisome proliferator-activated receptors (PPARs) α and γ in vitro and modulated glucose and lipid metabolism in vivo. In this study, we examined the effects of isomerized hop extract (IHE) primarily containing isohumulones in C57BL/6N male mice and found that such treatment increased their liver weight and reduced their plasma triglyceride and free fatty acid levels. Microarray analysis and quantitative real time PCR (QPCR) showed that IHE dose-dependently upregulated the expression of a battery of hepatic genes that are involved in microsomal ω-oxidation and peroxisomal and mitochondrial β-oxidation. These effects were common in both genders and very similar to those found with the PPARα agonist, fenofibrate (FF). Moreover, these effects were not found in PPARα-deficient mice. Thus, our results strongly suggest that IHE intake upregulates the expression of key genes that are involved in hepatic fatty acid oxidation, and that it ameliorates the blood lipid profile by activating PPARα.     

藏绵羊PPARα基因遗传变异特征及组织表达分析

PPARα(Peroxisome proliferator activated receptorsα)基因参与调控线粒体脂肪酸β氧化,在能量代谢中具有重要作用,是动物高原低氧适应的主要候选基因之一。本研究采用PCR-SSCP和测序方法检测2个品种(藏绵羊,湖羊) PPARα基因P1区核苷酸变异及遗传特征。采用实时荧光定量PCR (quantitative real-time PCR, qRT-PCR)检测藏羊与湖羊心脏、肝脏、脾脏、肺脏、肾脏、骨骼肌6个组织的相对表达量。检测表明:在扩增区域发现2个SNPs (c.515-22AG, c.515-10CT)对应的等位基因A、B。基因频率在2个群体间具有统计学意义(p0.01),藏绵羊的优势基因型为AB,湖羊优势基因型为AA。推测AB基因型个体可能更有利于藏绵羊适应高原低氧环境,可作为藏绵羊低氧适应选育的分子标记。PPARα基因在2个绵羊的6个组织中均有不同程度的表达且具有品种间差异性。PPARα基因在藏绵羊心脏的表达量极显著的低于其余5个组织(p0.01),而2个品种间,藏绵羊各组织的表达量均低于湖羊,其中在心脏、肝脏、肺脏3个组织表达量极显著的低于湖羊(p0.01)。本研究可丰富绵羊基因组学内容,为藏绵羊低氧适应研究提供基础数据。