P13-K／Akt信号通路对阿尔茨海默病神经元凋亡的调节作用

磷脂酰肌醇3-激酶（P13-K／Akt）途径是细胞内重要的促细胞存活通路之一，P13-K被细胞外信号活化后，激活下游蛋白激酶Akt。在阿尔茨海默病（AD）的发病过程中，凋亡相关基因Bad、GSK-3、转录因子家族、caspases家族等参与了神经元的凋亡，导致神经元的大量丢失。而活化的Akt通过磷酸化Bad、GSK-3、转录因子家族、IB、caspases等使促凋亡基因失活，从而起到抑制神经元凋亡及促进神经元存活的作用，进而减少AD神经元的大量丢失，改善AD的病理变化。     

丝胶对2型糖尿病大鼠海马蛋白激酶B信号转导通路的作用

目的探讨丝胶(彩色蚕茧经浸泡、水煎、浓缩获得)对2型糖尿病大鼠海马蛋白激酶B(Akt)信号转导通路的作用。方法 36只雄性SD大鼠随机分为3组(n=12):正常对照组、糖尿病模型组和丝胶治疗组。小剂量链脲佐菌素(25mg/kg)连续腹腔注射(1次/d,3d)建立2型糖尿病大鼠模型。丝胶治疗组大鼠给予丝胶灌胃[2.4g/(kg·d),35d]。TUNEL法检测海马CA1区神经元凋亡,Western blotting法和RT-PCR法检测海马Akt信号转导通路相关因子Akt、核转录因子kappa B(NF-κB)和前凋亡因子Bad蛋白和mRNA的表达。结果与正常对照组比较,糖尿病模型大鼠海马CA1区神经元的凋亡指数明显升高(P0.01);海马Akt、NF-κB的表达明显降低,Bad的表达明显升高(P0.01)。与糖尿病模型组比较,丝胶治疗组大鼠海马CA1区神经元的凋亡指数明显降低(P0.05);海马Akt、NF-κB的表达明显升高,Bad的表达明显降低(P0.01,P0.05)。结论丝胶可通过调节糖尿病模型大鼠海马Akt信号通路的异常变化减少海马神经元凋亡,对糖尿病海马损伤具有一定的拮抗作用。     

参芎化瘀胶囊通过磷脂酰肌醇激酶/蛋白激酶B信号通路抑制全脑缺血大鼠神经细胞凋亡

目的:探讨参芎化瘀胶囊对大鼠脑缺血/再灌注损伤神经细胞凋亡的影响.方法:雄性SD大鼠被分成假手术组,模型组,参芎化瘀胶囊高、低剂量组,以改良的Pulsineli 4血管阻断(4-VO)法制作全脑缺血模型.免疫组织化学法检测海马区磷脂酰肌醇3-激酶(PI3-K)、蛋白激酶B(PKB/Akt)的表达.原位缺口末端标记法(TUNEL)检测凋亡细胞.结果:与假手术组比较,模型组中PI3-K、Akt表达增高,凋亡神经细胞数量增多;与模型组比较,参芎化瘀胶囊组中PI3-K、Akt表达进一步增多,凋亡神经细胞数量减少,上述变化在高剂量参芎化瘀胶囊组更为明显.结论:参芎化瘀胶囊可抑制全脑缺血大鼠神经细胞凋亡,其机制与PI3-K/Akt信号通路有关.     

PI3-K-AKT信号转导途径与凋亡的关系

PI3-K(phosphatidylinositol3-kinase,磷脂酰肌醇3-激酶)-AKT(v-aktmurinethymomaviraloncogenehomo-log)信号转导途径是细胞内重要的信号转导通路,在细胞的凋亡、存活、增殖以及细胞骨架的变化等活动中发挥重要的生物学功能,其中尤为重要的是它对细胞凋亡、存活的调节作用。细胞凋亡是一个瀑布式的基因表达结果,在其发生与调控过程中有许多基因产物的参与,PI3-K-AKT信号转导途径通过对这些凋亡相关基因的调节作用在凋亡的发生与调控过程中发挥重要的生物学功能。     

PI-3K/Akt信号传递途径与T细胞反应

PI 3K/Akt信号传递途径是T细胞最为重要的信号转导途径之一 ,与T细胞的增殖、分化、活化和抗病毒能力等密切相关 ,其功能主要表现为与CD2 8协同刺激信号一道促进T细胞活化 ;调节周期蛋白和促T细胞增殖因子等表达使T细胞周期正常进行 ;通过调控凋亡信号转导相关激酶活性和凋亡调控因子表达以拮抗P5 3、Fas等诱导的T细胞凋亡以及增强T细胞的抗病毒能力等。     

一种阿尔茨海默病诊断的分子标记AD7c-NTP

阿尔茨海默病 ( Alzheimer's disease,AD)也称老年性痴呆 ,主要的神经病理学特征是脑内出现神经元纤维缠结 ( neu-rofibrillary tangle,NFT)和神经变性斑 ,并有轴突的异常增生和大量神经元细胞凋亡。家族性 AD约占总 AD发病率的 5 %～ 10 % ,其余 90 %为散发性 [1 ]。家族性 AD与 2 1号染色体上的淀粉样前体蛋白 ( amyloid precusor protein,APP)基因 ,及 1号和 14号染色体上的早老蛋白 ( presenilins,PS)基因的突变有关 ;载脂蛋白ε4基因也是发生 AD的高危因子[2 ] ;另外 ,Aβ1-4 2、Tau蛋白、GAP- 4 3、apo J、S- 10 0蛋白、黑…     

组织激肽释放酶对酸敏离子通道介导的神经元缺血/再灌注损伤的影响

为了解缺血/再灌注过程中组织激肽释放酶(tissu kallikrein,TK)对神经元的保护作用与酸敏感离子通道(acid-sensing ion channels,ASICs)激活的关系以及其可能涉及的细胞内信号通路,本研究建立大鼠原代皮层神经元缺氧缺糖(oxygen-glucose deprivation,OGD)、缺氧缺糖-酸中毒(OGD-Acidosis)损伤模型以模拟在体缺血/再灌注损伤,应用细胞免疫化学方法观察损伤前后神经元形态学的变化,并检测ASIC1a的分布变化;用活细胞计数试剂盒CCK-8了解神经元存活情况并检测Caspase-3酶活性了解神经元凋亡情况。观察OGD和OGD-酸中毒对培养神经元的存活率和Caspase-3活性的影响及TK预处理、缓激肽(bradyki-nin,BK)预处理、ASIC1a特异性和非特异阻断剂预处理对OGD-酸中毒损伤神经元上述指标的影响,并检测细胞外信号调节激酶(ERK)、C-Jun-N末端激酶(JNK)和磷酸肌醇-3激酶/蛋白激酶B或Akt(PI3K/Akt)信号通路抑制剂对TK作用的影响。结果显示:OGD-酸中毒对神经元的损伤明显重于单纯OGD,阻断ASICs的激活能提高OGD-酸中毒神经的存活率、降低Caspase-3活性;TK和BK预处理能促进OGD-酸中毒损伤神经元存活、抑制Caspase-3激活;阻断ERK和PI3K/Akt信号通路能够抑制TK促OGD-酸中毒损伤神经元存活效应。结果表明,ASICs的激活参与了OGD-酸中毒神经元损伤过程;TK对OGD-酸中毒神经元的保护作用可能是拮抗了ASICs介导的谷氨酸非依赖的神经元毒性作用,并可能与ERK和PI3K/Akt信号通路的激活有关。     

骨髓间充质干细胞分泌基质细胞衍生因子1保护心肌细胞

背景：有研究显示表达CXCR4的干细胞能够沿着基质细胞衍生因子1的浓度梯度迁移到心肌梗死部位再生心肌和血管而改善心脏的功能。 目的：探索间充质干细胞通过其分泌的基质细胞衍生因子1对心肌细胞的保护作用。 方法：收集培养2 d的间充质干细胞条件培养基。在缺氧条件,利用基质细胞衍生因子1受体CXCR4阻断剂AMD3100或PI3-K/Akt途径阻断剂LY294002预处理H9C2细胞后,利用AnnexinV/PI双标法流式细胞术分析间充质干细胞条件培养基作用下H9C2细胞凋亡的变化;Western blotting分析H9C2细胞磷酸化Akt蛋白的表达;RT-PCR分析间充质干细胞基质细胞衍生因子1的表达。 结果与结论：RT-PCR结果显示间充质干细胞表达基质细胞衍生因子1,Western blotting结果显示间充质干细胞条件培养基增加了H9C2细胞磷酸化Akt蛋白的水平。AnnexinV/PI分析发现间充质干细胞条件培养基明显降低了H9C2细胞缺氧复氧后的凋亡,且这种抗凋亡作用能被CXCR4阻断剂AMD3100或PI3-K/Akt途径阻断剂LY294002所阻断。说明间充质干细胞通过其分泌的基质细胞衍生因子1通过激活PI3-K/Akt途径保护H9C2细胞,增加H9C2细胞的幸存能力。     

髓细胞白血病—1基因及其产物研究进展

髓细胞白血病-1(myeloid cell lekemia-1,MCL-1)基因是高度可调节的分化早期活化基因,属于抗凋亡基因家族成员,其编码产物Mcl-1蛋白与正常和异常造血细胞的生存及分化有密切关系.细胞外调节蛋白激酶通路、Janus激酶/信号转导与转录活化因子(JAK/STAT)通路、磷酸肌醇3-激酶(PI3K)/丝氨酸/苏氨酸激酶Akt通路等多个信号转导途径参与了正常和异常造血细胞内MCL-1表达的调控.     

缺氧预处理保护机制的研究进展

缺氧预处理可触发机体的内源性保护机制,使机体对严重缺氧或其它致死性应激产生防御和抵抗。缺氧预处理的保护作用与缺氧诱导因子及其调控基因、PI3-K/Akt促细胞生存信号转导通路、活性氧、ATP敏感钾离子通道、Bcl-2等多种蛋白和信号分子的作用密切相关。     

Extracellular HIV-1 Tat protein activates phosphatidylinositol 3- and Akt/PKB kinases in CD4+ T lymphoblastoid Jurkat cells

The biological basis for the pleiotropic activity of extracellular human immunodeficiency virus (HIV)-1 Tat protein on lymphoid T cell survival is not well understood. We have here demonstrated that the addition in culture of 0.1–10 nM Tat protein to 36-h serum-starved lymphoblastoid Jurkat T cells rapidly stimulates the catalytic activity of phosphatidylinositol 3-kinase (PI 3-K). The peak of activation was observed 30 min after Tat addition. Extracellular Tat also stimulated the catalytic activity of the Akt/PKB kinase, a major target of PI 3-K lipid products. Pretreatment of serum-starved Jurkat cells with 100 nM wortmannin (WT) or 10 μM LY294002, two unrelated pharmacological inhibitors of PI 3-K, markedly suppressed the catalytic activity of both PI 3-K and Akt/PKB in Jurkat cells. Moreover, at low concentrations (0.1–1 nM), extracellular Tat showed a small but reproducible protection of Jurkat cells from apoptosis induced by serum deprivation (p < 0.05), while the combination of Tat plus 100 nM WT significantly (p < 0.05) increased the percentage of apoptosis with respect to cells left untreated or treated with Tat alone. Taken together, these data suggest that the anti-apoptotic activity of low concentrations of Tat protein on Jurkat cells is mediated by a PI 3-kinase/Akt pathway.     

Involvement of extracellular signal-regulated kinases 1/2 and (phosphoinositide 3-kinase)/Akt signal pathways in acquired resistance against neurotoxin of 6-hydroxydopamine in SH-SY5Y cells following cell-cell interaction with astrocytes

Glial cells interact with neurons and play important roles in the development, differentiation, maintenance and repair of the nervous system. Human neuroblastoma cells (SH-SY5Y) became dramatically resistant to neurotoxin 6-hydroxydopamine (6-OHDA), when co-cultured with mouse astrocytes. In order to further delineate the molecular mechanism involved in the neuroprotection in this selective cell-cell interaction, we assessed the activation of two signal pathways, namely, the MAP kinases (extracellular signal-regulated kinases, ERK1/2) and phosphoinositide 3-kinase (PI3-K)/Akt signal pathways in response to 6-OHDA insult and subsequent neuronal survival. Western blot revealed that 6-OHDA significantly increased the phosphorylation of ERK1/2 and Akt in mono-cultured SH-SY5Y cells. However, the increase in ERK1/2 in SH-SY5Y cells after co-cultured with astrocytes occurred as early as 3 h after 6-OHDA treatment in oppose to the increase after 12 h in monocultures. The phosphorylation of Akt in the co-cultured SH-SY5Y cells was much pronounced 3 h after 6-OHDA treatment compared with that in the mono-cultured cells. The anti-apoptotic protein bcl-2 was also increased in the co-cultured SH-SY5Y cells 3 h after treatment with 6-OHDA. Selective inhibitor of PI3-K/Akt signal pathway blocked the acquired resistance to 6-OHDA in SH-SY5Y cells following interaction with astrocytes. Inhibition of ERK1/2 signal pathway did not affect the cell survival. Our data suggest that PI3-K/Akt signal pathway, but not ERK1/2, is involved the acquired resistance in SH-SY5Y cells following cell-cell interaction with astrocytes against the neurotoxic 6-OHDA insult.     

NGF促进神经细胞生长发育的信号通路及与哮喘发病的关系

神经生长因子(NGF)作为第一个被发现的神经营养因子,具有促进神经细胞存活和生长发育的作用。NGF结合酪氨酸受体TrkA,引起胞内四条信号通路:Ras/Raf/Erk蛋白激酶通路,磷脂酰肌醇-3激酶(PI3-K)/Akt激酶通路,磷脂酶c(PLC-γ)通路以及SNT。NGF的另一个受体P75神经营养因子受体(P75NTR)的信号通路仍不是十分清楚,但可与TrkA协同作用,也可单独作用促进神经细胞的存活或凋亡。另外,NGF介导下TrkA的信号通路与哮喘的发病之间有着密切的联系。本文主要就NGF与TrkA和P75NTR蛋白结合后,胞内传导系统及尚待研究解决的问题进行综述。     

PTEN regulates apoptotic cell death through PI3-K/Akt/GSK3β signaling pathway in DMH induced early colon carcinogenesis in rat

Phosphatidylinositol 3-kinase (PI3-K) and Akt (protein kinase B), are both essential signaling molecules that are up-regulated in various cancers. Here, we examined the molecular mechanisms by which PI3-K and Akt expression are regulated by glycogen synthase kinase-3β (GSK-3β) and the phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in the early stages of experimental colon carcinogenesis. 1,2-dimethylhydrazine (DMH) was utilized for the induction of colon cancer while piroxicam, a traditional non-steroidal anti-inflammatory drug and c-phycocyanin, a biliprotein from Spirulina platensis (cyanobacterium) as the chemopreventive agents. Western blotting and immunofluorescence results indicated that the expression of PI3-K and Akt was promoted in the DMH group while least apoptosis was detected in this group as analyzed by Hoechst 33342-propidium iodide co-staining. DMH group further detected lower GSK-3β and PTEN expression as compared to other groups. Piroxicam and c-phycocyanin treatment resulted significant apoptotic cell death while showing low PI3-K and Akt expressions. Mitochondrial membrane potential (ΔΨ(M)) alterations (examined by JC-1 and rhodamine 123 labeling of colonocytes) and fluorescence intensity measurement of ROS level, were also analyzed showing the raised ΔΨ(M) while reduced ROS levels in DMH group, however piroxicam and c-phycocyanin treatment resulted in falling of ΔΨ(M) although both stimulated the ROS production as analyzed by flow cytometry. The present study thus identified that piroxicam, a traditional NSAID and c-phycocyanin, a newly discovered COX-2 selective inhibitor, constitute remarkable chemopreventive targets in mediating apoptosis in the DMH induced early rat colon carcinogenesis via regulating PI3-K/Akt/GSK-3β/PTEN signaling pathways. Further, a combination of the two drugs provides a better therapeutic option, than the monotherapy regimen.     

Infectious bursal disease virus activates the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway by interaction of VP5 protein with the p85α subunit of PI3K

Phosphatidylinositol 3-kinase (PI3K)/Akt signaling is commonly activated upon virus infection and has been implicated in the regulation of diverse cellular functions such as proliferation and apoptosis. The present study demonstrated for the first time that infectious bursal disease virus (IBDV), the causative agent of a highly contagious disease in chickens, can induce Akt phosphorylation in cultured cells, by a mechanism that is dependent on PI3K. Inhibition of PI3K activation greatly enhanced virus-induced cytopathic effect and apoptotic cell death as evidenced by cleavage of poly-ADP ribose polymerase and activation of caspase-3. Investigations into the mechanism of PI3K/Akt activation revealed that IBDV activates PI3K/Akt signaling through binding of the non-structural protein VP5 to regulatory subunit p85α of PI3K resulting in the suppression of premature apoptosis and improved virus growth after infection. The results presented here provide a basis for understanding molecular mechanism of IBDV infection.     

Stepholidine protects against H2O2 neurotoxicity in rat cortical neurons by activation of Akt

The fundamental pathological process(es) associated with schizophrenia (SZ) remain(s) uncertain, but multiple lines of evidence suggest that this condition is associated with excessive stimulation of striatal dopamine (DA) D2 receptors, deficient stimulation of medial prefrontal cortex (mPFC) D1 receptors as well as neuronal apoptosis. Unlike typical antipsychotics, stepholidine (SPD), which is isolated from the Chinese herb stephania, has D1 and D2 dual properties and regulates neuronal cell differentiation and proliferation. It is unknown, however, whether it possesses a neuroprotective property. Here, we report that SPD prevented neuronal cell death from H2O2 exposure and increased the levels of phosphorylated Akt (pAkt), a serine/threonine protein kinase. The SPD-induced neuroprotection and activation of Akt were blocked by LY294002, a PI3-K inhibitor, suggesting that the anti-apoptotic action of SPD is mediated via the PI3-K/Akt signaling pathway. Thus, as a survival or anti-apoptotic factor for neuronal cells, SPD may contribute to the therapeutic action of SPD in SZ treatment.     

ERK1/2和PI3-K通路在蛛网膜下腔出血大鼠海马区对神经细胞自噬的调控作用

目的:探讨细胞外信号调节激酶(extracellular regulated protein kinases,ERK1/2)和磷脂酰肌醇3-激酶(phosphatidylinositol 3-kinase,PI3-K)通路对大鼠蛛网膜下腔出血(subarachnoid hemorrhage,SAH)后神经细胞自噬的调控作用。方法:雄性SD大鼠160只,分为假手术(Sham)组、模型(SAH)组、ERK1/2抑制剂U0126组和PI3-K抑制剂LY294002组。采用二次注血法制作SAH大鼠模型,HE染色观察海马区神经细胞的形态变化;免疫组织化学染色法检测海马区磷酸化ERK1/2、PI3-K、自噬相关蛋白Beclin-1和微管相关蛋白1轻链(LC3)-II的表达实时荧光定量PCR检测海马区ERK1/2、PI3-K、自噬相关蛋白Beclin-1和微管相关蛋白LC3的表达。结果:SAH组海马区神经细胞存活率低于Sham组,ERK1/2、PI3-K、Beclin-1和LC3的表达水平高于Sham组(P0.05);U0126组和LY294002组海马区神经细胞存活率均高于SAH组,ERK1/2、PI3-K、Beclin-1和LC3表达均低于SAH组(P0.05);U0126组和LY294002组两组间海马区神经细胞存活率差异无统计学意义(P0.05),U0126组ERK1/2、Beclin-1和LC3表达水平低于LY294002组(P0.05),PI3-K表达水平高于LY294002组(P0.05)。结论:ERK1/2和PI3-K通路激活共同参与SAH后神经细胞自噬的调节,且以PI3-K通路更为主要。     

Interleukin-1 beta impairs brain derived neurotrophic factor-induced signal transduction

The expression of IL-1 is elevated in the CNS in diverse neurodegenerative disorders, including Alzheimer's disease. The hypothesis was tested that IL-1β renders neurons vulnerable to degeneration by interfering with BDNF-induced neuroprotection. In trophic support-deprived neurons, IL-1β compromised the PI3-K/Akt pathway-mediated protection by BDNF and suppressed Akt activation. The effect was specific as in addition to Akt, the activation of MAPK/ERK, but not PLCγ, was decreased. Activation of CREB, a target of these signaling pathways, was severely depressed by IL-1β. As the cytokine did not influence TrkB receptor and PLCγ activation, IL-1β might have interfered with BDNF signaling at the docking step conveying activation to the PI3-K/Akt and Ras/MAPK pathways. Indeed, IL-1β suppressed the activation of the respective scaffolding proteins IRS-1 and Shc; this effect might involve ceramide generation. IL-1-induced interference with BDNF neuroprotection and signal transduction was corrected, in part, by ceramide production inhibitors and mimicked by the cell-permeable C2-ceramide. These results suggest that IL-1β places neurons at risk by interfering with BDNF signaling involving a ceramide-associated mechanism.