Ambra1 regulates autophagy and development of the nervous system

Autophagy is a self-degradative process involved both in basal turnover of cellular components and in response to nutrient starvation or organelle damage in a wide range of eukaryotes. During autophagy, portions of the cytoplasm are sequestered by double-membraned vesicles called autophagosomes, and are degraded after fusion with lysosomes for subsequent recycling. In vertebrates, this process acts as a pro-survival or pro-death mechanism in different physiological and pathological conditions, such as neurodegeneration and cancer; however, the roles of autophagy during embryonic development are still largely uncharacterized. Beclin1 (Becn1; coiled-coil, myosin-like BCL2-interacting protein) is a principal regulator in autophagosome formation, and its deficiency results in early embryonic lethality. Here we show that Ambra1 (activating molecule in Beclin1-regulated autophagy), a large, previously unknown protein bearing a WD40 domain at its amino terminus, regulates autophagy and has a crucial role in embryogenesis. We found that Ambra1 is a positive regulator of the Becn1-dependent programme of autophagy, as revealed by its overexpression and by RNA interference experiments in vitro. Notably, Ambra1 functional deficiency in mouse embryos leads to severe neural tube defects associated with autophagy impairment, accumulation of ubiquitinated proteins, unbalanced cell proliferation and excessive apoptotic cell death. In addition to identifying a new and essential element regulating the autophagy programme, our results provide in vivo evidence supporting the existence of a complex interplay between autophagy, cell growth and cell death required for neural development in mammals.     

The role of autophagy during the early neonatal starvation period

At birth the trans-placental nutrient supply is suddenly interrupted, and neonates face severe starvation until supply can be restored through milk nutrients. Here, we show that neonates adapt to this adverse circumstance by inducing autophagy. Autophagy is the primary means for the degradation of cytoplasmic constituents within lysosomes. The level of autophagy in mice remains low during embryogenesis; however, autophagy is immediately upregulated in various tissues after birth and is maintained at high levels for 3-12 h before returning to basal levels within 1-2 days. Mice deficient for Atg5, which is essential for autophagosome formation, appear almost normal at birth but die within 1 day of delivery. The survival time of starved Atg5-deficient neonates (approximately 12 h) is much shorter than that of wild-type mice (approximately 21 h) but can be prolonged by forced milk feeding. Atg5-deficient neonates exhibit reduced amino acid concentrations in plasma and tissues, and display signs of energy depletion. These results suggest that the production of amino acids by autophagic degradation of 'self' proteins, which allows for the maintenance of energy homeostasis, is important for survival during neonatal starvation.     

短期有氧运动对糖尿病大鼠肾功能的影响

糖尿病肾病是非常严重的糖尿病并发症,其可以导致终末期肾衰,也是心血管疾病的一个危险因素。糖尿病肾病引起的重要的临床问题是尿蛋白和肾功能减退。运动作为糖尿病管理中的一个手段得到广泛共识。但急性运动引起尿蛋白和降低肾小球滤过率,所以运动对糖尿病肾病的影响存在争议。研究的目的是调查有氧运动对糖尿病大鼠微白蛋白尿和肾小球滤过率的影响。链脲霉素建立糖尿病大鼠模型,跑台上进行8周的有氧运动。大鼠分为4组：坐式对照组（ZD）;运动对照组（YD）;坐式糖尿病组（ZT）和运动糖尿病组（YT）。分别取建模成功稳定期（第四周末）和运动8周后的血样测定血糖水平。测定肌酐清除率（CCr）和微白蛋白尿（MA）评价肾功能。数据分析显示,与ZT组相比,有氧运动显著降低YT组血糖水平（p〈0.05）;与ZT组相比,有氧运动显著降低YT组微白蛋白尿水平（p〈0.01）;与ZD组相比,YD组和YT组肌酐清除率显著降低。研究结果表明,尽管肌酐清除率下降,有氧运动对微白蛋白尿的发生有预防作用。因此可能延迟糖尿病大鼠肾病的发生。     

耐力运动处方锻炼对大学生心肺耐力和身体成分 的影响研究

以大学生为研究对象,采用耐力性运动处方指导其进行运动锻炼,通过比较锻炼前后心脏功能能力、最大摄氧量、身体成分、身高、体重、基础代谢率变化,探讨应用耐力运动处方锻炼对大学生心肺耐力和身体成分的影响,为耐力性运动处方锻炼提高心肺机能,改善身体成分提供实践依据。研究结果表明:应用耐力性运动处方锻炼可致大学生心脏功能能力、最大摄氧量、基础代谢率显著增强(P 0.01),体脂率下降(P 0.05),可有效增强青年大学生心肺耐力并改善体成分,但体重变化未见统计学意义。     

游泳运动治疗对T2DM焦虑样行为小鼠的影响

为研究游泳运动对二型糖尿病（type 2 diabetes mellitus, T2DM）小鼠的焦虑样行为的影响机制。通过高脂联合链脲佐菌素构建T2DM小鼠,随机分为正常组（control,C）,正常+锻炼（exercise, E）组（CE）,T2DM组（T2）,T2DM+锻炼组（T2E）。CE组和T2E组的小鼠进行游泳运动,并观察小鼠体重、血糖波动,行为学焦虑、胰腺病理和血清谷胱甘肽（glutathione,GSH）、丙二醛（malondialdehyde,MDA）和谷胱甘肽二硫醚（glutathione?disulfide,GSSG）的表达变化。结果表明： 在游泳运动3周后显著降低T2DM小鼠体重和血糖波动幅度（P<0.05）,行为学焦虑水平明显改善。CE组和T2E组小鼠胰岛坏死面积减小,葡萄糖和胰岛素抵抗稳态指数降低（P<0.001）,T2E组小鼠大脑MDA水平降低（P<0.05）,GSH水平升高（P<0.01）。游泳运动可以改善T2DM小鼠的胰岛素抵抗和大脑氧化应激反应,对焦虑样行为有改善和保护作用。     

Suppression of basal autophagy in neural cells causes neurodegenerative disease in mice

Autophagy is an intracellular bulk degradation process through which a portion of the cytoplasm is delivered to lysosomes to be degraded. Although the primary role of autophagy in many organisms is in adaptation to starvation, autophagy is also thought to be important for normal turnover of cytoplasmic contents, particularly in quiescent cells such as neurons. Autophagy may have a protective role against the development of a number of neurodegenerative diseases. Here we report that loss of autophagy causes neurodegeneration even in the absence of any disease-associated mutant proteins. Mice deficient for Atg5 (autophagy-related 5) specifically in neural cells develop progressive deficits in motor function that are accompanied by the accumulation of cytoplasmic inclusion bodies in neurons. In Atg5-/- cells, diffuse, abnormal intracellular proteins accumulate, and then form aggregates and inclusions. These results suggest that the continuous clearance of diffuse cytosolic proteins through basal autophagy is important for preventing the accumulation of abnormal proteins, which can disrupt neural function and ultimately lead to neurodegeneration.     

Autophosphorylation at serine 1987 is dispensable for murine Atm activation in vivo

The ATM (ataxia telangiectasia mutated) protein kinase is activated under physiological and pathological conditions that induce DNA double-strand breaks (DSBs). Loss of ATM or failure of its activation in humans and mice lead to defective cellular responses to DSBs, such as cell cycle checkpoints, radiation sensitivity, immune dysfunction, infertility and cancer predisposition. A widely used biological marker to identify the active form of ATM is the autophosphorylation of ATM at a single, conserved serine residue (Ser 1981 in humans; Ser 1987 in mouse). Here we show that Atm-dependent responses are functional at the organismal and cellular level in mice that express a mutant form of Atm (mutation of Ser to Ala at position 1987) as their sole Atm species. Moreover, the mutant protein does not exhibit dominant-negative interfering activity when expressed physiologically or overexpressed in the context of Atm heterozygous mice. These results suggest an alternative mode for stimulation of Atm by DSBs in which Atm autophosphorylation at Ser 1987, like trans-phosphorylation of downstream substrates, is a consequence rather than a cause of Atm activation.     

壳寡糖及其衍生物对CCl4诱导的小鼠肝损伤的保护作用

研究壳寡糖（COS）、氨基葡萄糖（GlcNH2）和N-乙酰氨基葡萄糖(GlcNAc)对CCl4诱导的雄性昆明种小鼠肝毒性的保护作用，并探讨其可能机制. 小鼠腹腔注射CCl4（20mg/kg体重）24h后，血清天门冬氨酸转氨酶(AST)和丙氨酸转氨酶(ALT)活性明显提高，引起肝脏脂质过氧化反应，巯基含量降低，总抗氧化能力（T-AOC）减弱，诱发基因毒性. 提前连续12天分别灌胃给予COS，GlcNH2 和GlcNAc（1.5g/kg体重）能够显著诱导金属硫蛋白（MT）的表达，体内的抗氧化防御系统随之增强以抵抗CCl4诱导的氧化损伤. 血清AST和ALT活性明显降低，肝脏丙二醛（MDA）生成被抑制，巯基含量，T-AOC明显恢复. 但是，从DNA电泳结果反应出的基因毒性并未减轻. 实验结果证明，提前给予COS，GlcNH2和GlcNAc对CCl4诱导的小鼠肝损伤能够起到有效的保护作用，其中，GlcNH2的作用效果最显著.     

饥饿对日本沼虾代谢及SOD活性的影响

在20℃条件下,对日本沼虾进行了不同时间的饥饿处理,研究饥饿对日本沼虾代谢及免疫水平的影响,探讨日本沼虾对饥饿的适应对策.结果表明,日本沼虾代谢率在饥饿处理的2~4 d和8~10 d分别出现2个相对的代谢稳定区,即饥饿适应代谢区和饥饿存活代谢区,SOD比活力在饥饿处理期间显著下降.     

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。     

细胞应激条件下嗜热四膜虫线粒体膜电位变化研究

单细胞线虫纲原生动物四膜虫(Tetrahymena),在H2O2的诱导下可发生凋亡样死亡.另外,最新研究表明细胞中活性氧簇(ROS)的积累可有效地诱导细胞自噬途径的发生.通过流式细胞技术和荧光显微技术,检测了经饥饿和ROS诱导剂处理后,线粒体内膜电位变化及细胞内ROS的积累.此外,应用两种抗氧化剂氮乙酰半胱氨酸(NAC)和过氧化氢酶(Catalase)分别对四膜虫细胞进行处理,检测了在氧化应激条件下的抗氧化作用效果.结果表明,Oligomycin和Menadione可有效抑制线粒体膜电位的维持,从而导致细胞内ROS积累.同时,H2O2处理和饥饿处理可以导致嗜热四膜虫细胞线粒体膜电位丧失以及细胞质ROS积累.另外,N-acetylcystine和Catalase可有效地降低四膜虫细胞内ROS的积累,以及保持四膜虫细胞线粒体内膜电位,维持通透性.     

牺牲局部、成就整体的细胞自噬——2016年度诺贝尔生理学或医学奖成果简介

 自噬是一种细胞自身成分降解并回收利用的基本过程。日本科学家Yoshinori Ohsumi（大隅良典）因阐明细胞自噬的分子机制和生理功能而获得2016年度诺贝尔生理学或医学奖。这项工作不但为理解机体适应饥饿、感染免疫应答等诸多生化过程打开了一扇窗,也为治疗自噬相关疾病及开发针对自噬的潜在药物靶标奠定了基础。本文解读细胞自噬分子机制的科学背景及内涵,综述自噬相关研究的进展,并探讨其对人类健康的重大意义。     

A nuclear-receptor-dependent phosphatidylcholine pathway with antidiabetic effects

Nuclear hormone receptors regulate diverse metabolic pathways and the orphan nuclear receptor LRH-1 (also known as NR5A2) regulates bile acid biosynthesis. Structural studies have identified phospholipids as potential LRH-1 ligands, but their functional relevance is unclear. Here we show that an unusual phosphatidylcholine species with two saturated 12 carbon fatty acid acyl side chains (dilauroyl phosphatidylcholine (DLPC)) is an LRH-1 agonist ligand in vitro. DLPC treatment induces bile acid biosynthetic enzymes in mouse liver, increases bile acid levels, and lowers hepatic triglycerides and serum glucose. DLPC treatment also decreases hepatic steatosis and improves glucose homeostasis in two mouse models of insulin resistance. Both the antidiabetic and lipotropic effects are lost in liver-specific Lrh-1 knockouts. These findings identify an LRH-1 dependent phosphatidylcholine signalling pathway that regulates bile acid metabolism and glucose homeostasis.     

刺五加提取物对无氧运动训练效果的影响

设计大鼠负重游泳训练动物模型,经过为期8周的训练后,比较药物运动组与安静对照组和运动对照组的大鼠生理学指标、免疫学指标的变化,研究刺五加提取物对于大鼠无氧运动效果的影响.结果表明:在大负重的无氧运动压力下,运动对照组大鼠的免疫功能下降;使用刺五加提取物后,大鼠的免疫功能得到提高;刺五加提取物从机体力量、肌肉含量、代谢效率和免疫学功能等方面提高了机体的无氧运动效果.     

Autophagy in immunity and inflammation

Autophagy is an essential, homeostatic process by which cells break down their own components. Perhaps the most primordial function of this lysosomal degradation pathway is adaptation to nutrient deprivation. However, in complex multicellular organisms, the core molecular machinery of autophagy - the 'autophagy proteins' - orchestrates diverse aspects of cellular and organismal responses to other dangerous stimuli such as infection. Recent developments reveal a crucial role for the autophagy pathway and proteins in immunity and inflammation. They balance the beneficial and detrimental effects of immunity and inflammation, and thereby may protect against infectious, autoimmune and inflammatory diseases.     

发酵代谢物对葡萄糖氧化酶生物合成的影响

用膜透析技术和静息细胞系统，对影响葡萄糖氧化酶（ＧＯＤ）发酵的控制因素进行了研究。静息细胞系统显示：鸟氨酸、谷氨酸、甘氨酸、丙氨酸、丝氨酸和胱氨酸等氨基酸对ＧＯＤ的合成有促进作用；葡萄糖酸和丙酮酸对ＧＯＤ的合成有阻遏作用，１．５ｍｍｏｌ／Ｌ的丙酮酸使酶活降低４６．２４％；２０ｍｍｏｌ／Ｌ的葡萄糖酸使酶活降低２１％左右，但葡萄糖酸浓度增大，有被菌体作为碳源利用的可能。利用膜透析技术可除去部分发酵过程中产生的葡萄糖酸和丙酮酸等阻遏物，减少它们对ＧＯＤ合成的分解代谢物的阻遏作用，与分批发酵相比．提高酶活４０％左右。