mTOR信号通路与自噬在神经退行性疾病中的 研究进展

哺乳动物雷帕霉素靶蛋白（mTOR）是一种保守的丝氨酸/ 苏氨酸激酶，mTOR 在上游信号 分子Rheb、TSC1/2 的调控下使下游4E-BP和p70S6K 做出相应的反应，进而影响蛋白质合成来调节细胞 生长和增殖。自噬是细胞的一种自我保护机制，神经退行性疾病中某些聚集蛋白的清除主要依靠自噬 来完成。近些年研究表明，诸如阿尔茨海默病等神经退行性疾病与甲状腺功能、mTOR信号通路和自噬 的异常有关。因此，对甲状腺功能、mTOR 通路及自噬的研究有助于了解神经退行性疾病的发生机制， 以更好预防和治疗该疾病。     

自噬与神经退行性疾病

自噬(Autophagy)是真核细胞中普遍存在的生物学过程,通过溶酶体的介导作用完成对于一些大分子、细胞器以及一些半衰期较长的蛋白质的降解,从而使细胞维持正常的物质代谢,保持正常的生理状态。神经退行性疾病是一类由神经元不可逆性降解、神经胶质细胞过度增生以及一些异常蛋白在胞内累积从而产生细胞毒性,造成细胞代谢失调所引起的慢性、进展性认知障碍疾病。目前研究表明,神经退行性疾病的产生常伴随有细胞自噬过程的下调,而激活细胞自噬过程可以缓解神经退行性疾病的症状。因此,通过研究细胞自噬过程及其与神经退行性疾病的关联,可以为神经退行性疾病的临床治疗提供新的思路。     

自噬与神经退行性疾病

自噬是细胞通过单层或双层膜包裹待降解物形成自噬体,然后运送到溶酶体形成自噬溶酶体并进行多种酶的消化及降解,以实现细胞本身的代谢需要和某些细胞器的更新,细胞对这种合成与降解的精细调节,对维持细胞的自身稳态有重要意义。自噬分为三种类型：巨自噬、微自噬、分子伴侣介导的自噬。细胞的自噬清除或降解异常聚集的蛋白对神经退行性疾病有重要作用。     

线粒体自噬与神经退行性疾病

<正>线粒体是双层单位膜围成封闭囊状结构的细胞器,通过氧化磷酸化为细胞提供超过90%的能量,被喻为细胞的动力工厂。2005年,Lemasters[1]首次提出线粒体自噬(mitophagy)这一概念,主要指细胞内的线粒体在细胞衰老、活性氧产生过多等刺激下发生去极化损伤,被双层膜结构特异性包裹后与溶酶体融合,最终降解,维持细胞内环境稳定。神经退行性疾病(neurodegenerative disease)是一组由慢性进行性     

高迁移率族蛋白1在神经退行性疾病中的研究进展

<正>高迁移率族蛋白1(HMGB1)为一种非组蛋白染色体结合蛋白,是稳定核小体结构的重要调节子。HMGB1通过晚期糖化终末产物(RAGE)以及Toll样受体(TLR)信号转导通路参与神经炎症反应,通过与自噬蛋白Beclin1相互作用调节自噬功能。细胞核中HMGB1水平的降低与DNA损伤所导致的神经元功能障碍相关。大多数神经退行性病患者的内源性HMGB1水平是升高的。HMGB1是Alzheimer's病(AD)、帕金     

核因子-κB在神经退行性疾病中的研究进展

核因子-κB (nuclear factor-κB，NF—κB)由两个亚单元组成，均属于Rel家族蛋白。它在细胞内与NF-κB抑制蛋白(I-κB)结合呈非活性状态，当被神经生长因子(NGF)、β-淀粉样蛋白前体(βAPP)等刺激物激活后便与I-κB解离而转入核内与特定的启动子结合，从而调控基因表达。NF-κB不仅促进神经的发育与神经可塑性，还与神经细胞的凋亡有关，在脑卒中、阿尔茨海默病、帕金森病等神经退行性疾病中发挥着重要作用。     

核转录相关因子2和自噬在血管性痴呆中的作用机制研究

自噬和氧化应激在血管性痴呆(VD)的发生、发展中起着重要作用,但确切的机制目前尚不清楚。而核转录相关因子2(Nrf2)在氧化应激中扮演着重要的角色,本文将进一步探讨自噬和Nrf2信号通路所调控的氧化应激在VD的发生、发展中的作用,并寻求两者之间的联系,为预防和治疗VD提供新的思路。     

线粒体相关内质网膜上的连接蛋白与神经退行性疾病的研究进展

线粒体相关内质网膜(MAM)是典型的细胞器间物理连接所形成的复合结构,通过调控内质网和线粒体之间钙离子流,介导细胞凋亡和细胞自噬信号传导。MAM上的多种连接蛋白参与了神经退行性疾病的发生和发展,了解其作用机制对研究相关神经退行性疾病的发病机制至关重要。本文将对IP3R、VDAC1、PACS-2、Fis1、Bap31、Mfn2、PDZD8、VAPB和PTPIP51等MAM上的连接蛋白,以及其与细胞凋亡和细胞自噬、神经退行性疾病之间关系的研究进展进行综述。     

核分布因子同源蛋白E在神经系统疾病中的作用机制

核分布因子同源蛋白E(NDEL1)是一个神经发育相关蛋白,与LIS1和DISC1结合形成三聚体复合物,并在动力蛋白以及驱动蛋白的介导下,延微管运输线粒体、溶酶体等物质。这一过程还受到Aurora-A以及CDK家族的CDK1、CDK4和CDK5等蛋白的磷酸化修饰。另外,NDEL1通过影响细胞骨架相关蛋白、纺锤体重组、染色体排布以及神经元增殖、生长发育、分化和迁移等过程,参与了无脑回畸形、癫痫和神经退行性疾病等神经科疾病发病机制的调控。     

抑制beclin-1信号通路对缺血再灌注后神经母细胞瘤N2a细胞自噬的影响

目的观察抑制beclin-1信号通路对缺血再灌注后神经母细胞瘤N2a细胞自噬的影响。方法体外培养神经母细胞瘤系N2a细胞,脂质体转染beclin-1的miRNA干扰质粒,以缺氧、缺营养方式模拟缺血再灌注,甲基噻唑基四唑法检测各组N2a细胞活性,免疫印迹法测定各组N2a细胞beclin-1、微管相关蛋白1轻链3(LC3)、天冬氨酸特异性半胱氨酸蛋白酶3(Caspase3)的表达,电镜观察该细胞自噬活性。结果在缺血90min、再灌注24h干扰组较相应假干扰组细胞活性明显升高(P<0.05);干扰组beclin-1和Caspase3表达水平明显低于相应的假干扰组(P<0.05),但两组之间LC3表达无明显差异(P>0.05);而在缺血30min再灌注24h细胞活性,beclin-1、Caspase3和LC3的表达真假干扰组间无明显差异(P>0.05)。电镜下在正常组没有观察到细胞自噬现象;在缺血30min和90min再灌注24h,真假干扰组均观察到明显的细胞自噬现象,且两组间无明显差异。结论缺血90min,再灌注24h时,干扰beclin-1的表达虽不能明显改变N2a细胞自噬水平,却减少了凋亡,有利细胞存活。     

The role of sequestosome 1/p62 protein in amyotrophic lateral sclerosis and frontotemporal dementia pathogenesis

Amyotrophic lateral sclerosis and frontotemporal lobar degeneration are multifaceted diseases with genotypic, pathological and clinical overlap. One such overlap is the presence of SQSTM1/p62 mutations. While traditionally mutations manifesting in the ubiquitin-associated domain of p62 were associated with Paget's disease of bone, mutations affecting all functional domains of p62 have now been identified in amyotrophic lateral sclerosis and frontotemporal lobar degeneration patients. p62 is a multifunctional protein that facilitates protein degradation through autophagy and the ubiquitin-proteasome system, and also regulates cell survival via the Nrf2 antioxidant response pathway, the nuclear factor-kappa B signaling pathway and apoptosis. Dysfunction in these signaling and protein degradation pathways have been observed in amyotrophic lateral sclerosis and frontotemporal lobar degeneration, and mutations that affect the role of p62 in these pathways may contribute to disease pathogenesis. In this review we discuss the role of p62 in these pathways, the effects of p62 mutations and the effect of mutations in the p62 modulator TANK-binding kinase 1, in relation to amyotrophic lateral sclerosis-frontotemporal lobar degeneration pathogenesis.     

基于p38丝裂原活化蛋白激酶通路的胰高血糖素样肽-1对大鼠脑缺血再灌注损伤的影响及机制

目的基于p38丝裂原活化蛋白激酶(p38MAPK)通路探讨胰高血糖素样肽-1(GLP-1)对大鼠脑缺血再灌注(I/R)损伤的影响及机制。方法将雄性SD大鼠分为假手术组、模型组、GLP-1组和p38MAPK抑制剂组,每组12只。模型组、GLP-1组和p38MAPK抑制剂组通过大脑中动脉栓塞及再灌注建立脑I/R损伤模型,GLP-1组给予利拉鲁肽(70μg/kg)、p38MAPK抑制剂组给予p38MAPK抑制剂SB202190(10μmol/L、5μl)干预。比较四组大鼠的脑梗死体积、水迷宫行为参数及梗死脑组织细胞凋亡率、氧化应激指标、炎症细胞因子、p38MAPK通路分子的差异。结果与模型组比较,GLP-1组和p38MAPK抑制剂组大鼠的脑梗死体积明显降低,逃避潜伏期明显缩短、穿越平台次数明显增多,梗死脑组织中的细胞凋亡率及丙二醛(MDA)、超氧化物歧化酶(SOD)、TNF-α、IL-1β、IL-6、p-p38水平显著减少,SOD、谷胱甘肽过氧化物酶(GPx)水平明显增加(均P<0.05),p-ERK1/2、p-JNK的表达水平无明显变化。与假手术组比较,模型组大鼠的逃避潜伏期明显延长、穿越平台次数明显减少,梗死脑组织的细胞凋亡率及MDA、ROS、TNF-α、IL-1β、IL-6、p-p38水平明显增高,SOD、GPx水平明显减少(均P<0.05),p-ERK1/2、p-JNK的表达水平无明显变化。结论GLP-1能够通过抑制p38介导的氧化应激及炎症反应减轻大鼠脑I/R损伤。     

Activation of the Nrf2-ARE signal pathway after blast induced traumatic brain injury in mice

Background: Treatment of blast-induced traumatic brain injury (bTBI) has been hindered. Previous studies have demonstrated that oxidative stress may contribute to the pathophysiological process. The nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) signaling pathway exhibits a protective effect after traumatic brain injury (TBI). This study explored whether the Nrf2-ARE pathway was activated in a modified bTBI mouse model.

Method: Mice were randomly divided into six groups: the 6?h, 1 d, 3 d, 7 d and 14 d after bTBI groups and a sham group. The protein levels of nuclear Nrf2, heme oxygenase-1 (HO-1) and NAD(P)H: quinone oxidoreductase-1 (NQO1) were detected using western blot, and HO-1 and NQO1 mRNA levels were determined by real-time quantitative polymerase chain reaction. Moreover, HO-1 and Nrf2 were localized using histological staining.

Results: The protein level of the Nrf2-ARE pathway in the frontal lobe increased significantly in the 3 d after bTBI. The HO-1 and NQO1 mRNA levels also reached a peak in the frontal lobe 3 d after bTBI. The histological staining demonstrated higher expression of HO-1 in the frontal lobe and hippocampus 3 d after bTBI, when nuclear import of Nrf2 reached a peak in the frontal lobe.

Conclusions: bTBI activated the Nrf2-ARE signaling pathway in the brain. The peak activation time in the frontal lobe may be 3 d after injury, and activating the Nrf2 pathway could be a new direction for treatment.     

A novel palmitic acid hydroxy stearic acid (5-PAHSA) plays a neuroprotective role by inhibiting phosphorylation of the m-TOR-ULK1 pathway and regulating autophagy

AimsType 2 diabetes mellitus (T2DM) can lead to brain dysfunction and a series of neurological complications. Previous research demonstrated that a novel palmitic acid (5‐PAHSA) exerts effect on glucose tolerance and chronic inflammation. Autophagy was important in diabetic‐related neurodegeneration. The aim of the present study was to investigate whether 5‐PAHSA has specific therapeutic effects on neurological dysfunction in diabetics, particularly with regard to autophagy.Methods5‐PAHSA was successfully synthesized according to a previously described protocol. We then carried out a series of in vitro and in vivo experiments using PC12 cells under diabetic conditions, and DB/DB mice, respectively. PC12 cells were treated with 5‐PAHSA for 24 h, while mice were administered with 5‐PAHSA for 30 days. At the end of each experiment, we analyzed glucolipid metabolism, autophagy, apoptosis, oxidative stress, cognition, and a range of inflammatory factors.ResultsAlthough there was no significant improvement in glucose metabolism in mice administered with 5‐PAHSA, ox‐LDL decreased significantly following the administration of 5‐PAHSA in serum of DB/DB mice (p < 0.0001). We also found that the phosphorylation of m‐TOR and ULK‐1 was suppressed in both PC12 cells and DB/DB mice following the administration of 5‐PAHSA (p < 0.05 and p < 0.01), although increased levels of autophagy were only observed in vitro (p < 0.05). Following the administration of 5‐PAHSA, the concentration of ROS decreased in PC12 cells and the levels of CRP increased in high‐dose group of 5‐PAHSA (p < 0.01). There were no significant changes in terms of apoptosis, other inflammatory factors, or cognition in DB/DB mice following the administration of 5‐PAHSA.ConclusionWe found that 5‐PAHSA can enhance autophagy in PC12 cells under diabetic conditions. Our data demonstrated that 5‐PAHSA inhibits phosphorylation of the m‐TOR‐ULK1 pathway and suppressed oxidative stress in PC12 cells, and exerted influence on lipid metabolism in DB/DB mice.     

人脑星形细胞瘤中p57kip2、cyelinD1的表达及相关性研究

目的探讨p57kip2蛋白、cyclinD1蛋白在人脑星形细胞瘤中的表达情况及其临床意义。方法采用免疫组织化学sP法检测p57kip2、cyclinD1在48例人脑星形细胞瘤和20例正常脑组织中的表达。结果在48例星形细胞瘤中,p57kip2蛋白阳性率为33．3％,显著低于正常脑组织80％。p57kip2蛋白表达在低度恶性（Ⅰ～Ⅱ级）组显著高于高度恶性（Ⅲ～Ⅳ级）组,生存时间≥2年组显著高于〈2年组。星形细胞瘤中cyclinD1蛋白阳性率为62．5％,显著高于正常脑组织15％。cyclinD1蛋白表达在高度恶性（Ⅲ一Ⅳ级）组显著高于低度恶性（Ⅰ一Ⅱ级）组,生存时间〈2年组显著高于≥2年组。p57kip2蛋白的表达与cyclinDI蛋白的表达存在相关。结论p57kip2蛋白和cyctinD1蛋白在星形细胞瘤的发生、发展中起重要作用。且与肿瘤的分化程度、患者预后密切相关。     

Mitogen- and stress-activated protein kinase 1: convergence of the ERK and p38 pathways in Alzheimer's disease

Two of the earliest manifestations of the selective neurodegeneration that occurs in Alzheimer's disease (AD) involve the oxidative modification of various biomacromolecules and the reexpression of a multitude of cell cycle-related proteins. Taken together with the proximal and ectopic increases in activated components of the ERK and p38 pathways, involved in mitotic and cellular stress signaling, respectively, there is a clear and important role for mitotic and oxidative insults in the pathogenesis of AD. Despite the mounting evidence, however, for the causal role of mitogenic abnormalities and oxidative stress in AD pathogenesis, the effect of the converging relevant pathways due to chronic stimulation in AD remains largely unknown. To delineate further the mechanism by which mitogenic and stress signaling cascades converge, we focused on one of the downstream effectors of activated ERK and p38, mitogen- and stress-activated kinase 1 (MSK1). Activated MSK1, phosphorylated at residues Ser376 and Thr581, was upregulated in vulnerable neurons in AD when compared to that in age-matched controls, whereas MSK1 phosphorylated at residue Ser360 was not increased in AD. Furthermore, activated MSK1 phosphorylated at Thr581 colocalized strongly with activated p38 but only weakly with activated ERK, whereas MSK1 phosphorylated at Ser376 colocalized strongly with activated ERK but only weakly with activated p38, suggesting potential preferential phosphorylation sites for the two upstream effectors.     

Potential of cystamine and cysteamine in the treatment of neurodegenerative diseases

Neurodegenerative disorders are a subset of disabling pathologies characterized, in part, by a progressive and specific loss of certain brain cell populations. Current therapeutic approaches for the treatment of these disorders are mainly designed towards symptom management and do not manifestly block their typified neuronal loss. However, research conducted over the past decade has reflected the increasing interest and need to find disease-modifying molecules. Among the several neuroprotective agents emerging from experimental animal work, cystamine, as well as its reduced form cysteamine, have been identified as potential candidate drugs. Given the significant benefits observed in a Huntington's disease (HD) model, cysteamine has recently leaped to clinical trial. Here, we review the beneficial properties of these compounds as reported in animal studies, their mechanistic underpinnings, and their potential implications for the future treatment of patients suffering from neurodegenerative diseases, and more specifically for HD and Parkinson's disease (PD).     

Activation of the Nrf2-ARE pathway in muscle and spinal cord during ALS-like pathology in mice expressing mutant SOD1

Oxidative stress plays a key role in the neuronal loss exhibited in amyotrophic lateral sclerosis (ALS), an event precipitating irreversible muscle atrophy. By crossing ALS mouse models (SOD(G93A) and SOD(H46RH48Q)) with an antioxidant response element (ARE) reporter mouse, we identified activation characteristics of the ARE system throughout the timecourse of motor neuron disease. Surprisingly, the earliest and most significant activation of this genetic sensor of oxidative stress occurred in the distal muscles of mutant SOD mice. The resultant data supports existing hypotheses that the muscle is somehow implicated during the initial pathology of these mice. Subsequently, Nrf2-ARE activation appears to progress in a retrograde fashion along the motor pathway. These data provide timely information concerning the contributions of the Nrf2-ARE pathway in ALS disease progression.