磷脂酰肌醇-3激酶/蛋白激酶B信号系统

质膜成分磷脂酰肌醇被其3位激酶(PI3K)活化后,可以使蛋白激酶B(PKB)由细胞浆定位于胞膜,继而被磷酸化激活。PKB是原癌基因akt的产物,具有丝/苏氨酸蛋白激酶活性,介导细胞代谢、生长、增殖等效应。PI3K/PKB系统是近年来发现的一个生长因子信号转导通路。     

磷脂酰肌醇3激酶／蛋白激酶B通路在缺氧血管内皮细胞凋亡中的作用

目的：探讨磷脂酰肌醇3激酶／蛋白激酶B（PI3 K／Akt）通路在缺氧血管内皮细胞凋亡中的作用。方法（1）常规培养人血管内皮细胞株EA．hy926细胞,取部分人血管内皮细胞株EA．hy926按照随机数字表法分为两组：正常对照组：置于气体成分体积分数5％二氧化碳培养箱中常规培养;缺氧组：置于气体成分体积分数1％氧气、5％二氧化碳和94％氮气的三气培养箱中进行缺氧培养。采用蛋白质印迹法检测正常对照组内皮细胞和缺氧处理3、6、24 h的内皮细胞中Akt活化状态（以pAkt／Akt值表示）,流式细胞仪检测细胞凋亡率。（2）另取部分人血管内皮细胞株EA．hy926按照随机数字表法分为4组：正常对照组,缺氧组：培养方法同前,正常对照＋阻断剂组：用含50μmol／L的LY294002（PI3 K／Akt阻断剂）的培养液常规培养内皮细胞;缺氧＋阻断剂组：用含50μmol／L 的LY294002的培养液缺氧处理内皮细胞。均于培养3 h后收集内皮细胞,采用流式细胞仪检测细胞凋亡率。对Akt活化状态与细胞凋亡率行单因素方差分析和LSD-t检验。结果（1）正常对照组细胞和缺氧处理3、6、24 h的内皮细胞pAkt／Akt值分别为0．67、0．79、0．34和0．35;正常内皮细胞和缺氧处理3、6、24 h 的内皮细胞凋亡率分别为（3．11±0．21）％、（4．57±0．85）％、（6．93±0．58）％、（9．96±2．62）％,组间比较差异有统计学意义（F＝8．96,P＝0．030）。与正常对照组细胞比较,缺氧处理3、6 h的内皮细胞凋亡率升高,差异无统计学意义（t＝1．03、2．70,P＝0．360、0．054）;缺氧处理24 h的内皮细胞凋亡率显著升高,差异有统计学意义（t＝4．99,P＝0．008）。（2）正常对照组、正常对照＋阻断剂组、缺氧组、缺氧＋阻断剂组培养3 h后细胞凋亡率为（2．39±0．50）％、（5．77±1．21）％、（3．76±1．05）％     

磷脂酰肌醇3激酶/蛋白激酶B/雷帕霉素靶蛋白信号通路在肺部疾病中的研究进展

磷脂酰肌醇3激酶/蛋白激酶B/雷帕霉素靶蛋白(phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin,PI3K/Akt/mTOR)是细胞内重要信号通路,在细胞生长、增殖、分化和蛋白合成等过程中起重要作用.肺癌、哮喘、肺动脉高压、肺纤维化、慢性阻塞性肺疾病(chronic pulmonary obstructive disease,CORD)等疾病是呼吸系统常见疾病,其病理机制涉及细胞增殖及凋亡等,与PI3K/Akt/mTOR信号通路关系密切.     

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.     

机械张应变诱导的大鼠血管平滑肌细胞磷脂酰肌醇3激酶/蛋白激酶B信号通路相关基因的筛选

目的 筛选机械张应变诱导的大鼠血管平滑肌细胞(VSMCs)磷脂酰肌醇3激酶/蛋白激酶B(PI3K/Akt)信号通路的相关基因.方法 应用FX-4000T 细胞应变加载系统,对大鼠主动脉VSMCs施加1 Hz、10 % 张应变,Western blotting检测细胞在不同加载时间下Akt磷酸化水平的变化;用抑制消减杂交法(SSH) ,筛选给予PI3K的抑制剂Wortmannin和给予DMSO 两组细胞在加载张应变24 h后的差异表达基因片段,得到的消减杂交产物连接到T 载体上,经过蓝白斑筛选,对所有阳性克隆进行菌液PCR筛选及测序,应用BLASTN进行序列比对.结果 机械张应变改变了VSMCs磷酸化Akt水平;SSH所获得的54个克隆随机挑选30个送测序,得到10个不同差异表达序列标签(EST),发现6个EST代表的大鼠基因可能与机械张应变诱导的VSMCs PI3K/Akt信号通路相关,它们是:High mobility group box 1(HMGB1), Neural precursor cell expressed(Nedd4a ), Cyclin-dependent kinase 5(CDK5), Histone deacetylase 3(HDAC3), Ubiquitin-like 1(Uble1a), Heterogeneous nuclear ribonucleoprotein H1(hnRNP).结论 SSH有效筛选到了机械张应变诱导的VSMCs PI3K/Akt信号通路的相关基因,为进一步研究机械张应变诱导的血管病理生理改变提供了资料.     

蛋白激酶C及磷脂酰肌醇3激酶参与心力衰竭患者心肌重构

目的探讨蛋白激酶C(PKC)/丝裂原活化蛋白激酶(MAPK)、磷脂酰肌醇3激酶(PI3K)/蛋白激酶B(Akt)信号通路参与心力衰竭(CHF)患者心肌重塑的机制。方法选择因瓣膜性心脏病接受二尖瓣置换术的CHF患者39例,正常对照38例(其中8例来自意外伤亡的器官捐献者)。彩色多普勒超声心动仪检测心脏扩大和心功能参数,放射免疫法检测血浆及心肌组织中AngⅡ浓度,竞争蛋白结合法检测PKC,免疫沉淀法检测MAPK活性,免疫沉淀法测心肌组织PI3K/Akt磷酸化、C-FOS、α-骨骼肌动蛋白(α-skeletal-actin)的表达。结果CHF患者心肌组织呈典型重构心肌的病理改变。血浆及心肌组织AngⅡ浓度与心功能级别呈正相关。CHF患者心肌组织PKC和MAPK活性明显高于对照组(P<0.01),并随心功能恶化其表达逐渐增加;CHFⅡ级组患者心肌组织PI3K/Akt磷酸化明显强于正常对照组(P<0.01)和CHFⅢ、Ⅳ级组(P<0.01)。CHFⅢ、Ⅳ级组间没有差异。正常心肌组织中无C-FOS蛋白表达,CHFⅡ级组C-FOS蛋白表达明显高于Ⅲ、Ⅳ级组(P<0.01)。CHF患者心肌组织α-skeletal-actin表达明显高于对照组(P<0.01),并随心功能恶化其表达逐渐增加。结论PKC/MAPK及PI3K/Akt信号通路共同参与调节CHF患者心肌重构的病理过程。     

子宫内膜癌中磷脂酰肌醇3激酶/蛋白激酶通路活化及临床意义

目的 探讨磷脂酰肌醇3激酶/蛋白激酶( PI3 K/AKT)信号通路的重要组分PTEN、PIK3CA和p-AKT在子宫内膜癌组织中的改变及其预后意义.方法 免疫组织化学EnVision二步法检测PTEN、p-AKT、雌激素受体(ER)和孕激素受体在71例子宫内膜癌组织中的表达,聚合酶链反应测序法分析其中34例PIK3CA基因外显子9和20的突变情况.结果 (1)71例子宫内膜癌组织中,子宫内膜样癌( EEC) 65例,非子宫内膜样癌(NEEC)6例.PTEN失表达率为63.4％( 45/71),在EEC中的比例(66.2％,43/65)高于NEEC( 2/6;P=0.18).PTEN失表达患者(45例)预后优于PTEN正常表达者(26例;P=0.07).进一步分组分析显示在ER阴性病例中,PTEN失表达者(12例)的预后优于PTEN正常表达者(7例),差异有统计学意义(P=0.04).(2)本组34例中PIK3CA突变率为41.2％ (14/34),突变热点为外显子9的T544.PIK3CA突变在EEC中的发生比例(44.8％,13/29)高于NEEC( 1/5;P ＞0.05).外显子9突变全部见于Ⅰ期EEC病例中,且在高、中分化的EEC中发生率高于低分化肿瘤(P＞0.05).外显子20突变在早期病例组(14.3％,4/28)的发生率显著低于晚期病例组(4/6;P=0.0l).(3)p-AKT的阳性率为59.2％ (42/71),在EEC中的阳性率(60.0％,39/65)高于NEEC(3/6;P=0.68);但高、中分化组EEC的阳性比例(75.0％,21/28;53.6％,15/28)高于低分化组(3/9),差异有统计学意义(P=0.02).p-AKT阳性与ER阳性相关(r=0.339,P=0.00).结论 PI3K/AKT信号通路的关键分子,如PTEN失表达、p-AKT阳性提示预后好.PIK3CA基因外显子9和20的突变对子宫内膜癌的预后影响可能不同.子宫内膜癌中PTEN和p-AKT的功能可能受到ER状态的影响.     

磷脂酰肌醇生物合成通路中的新肿瘤抑制基因INPP4B

磷脂酰肌醇信号通路参与许多的癌症和其他疾病发生发展。该通路中存在多个肿瘤相关基因,其中抑癌基因PTEN、癌基因 PI3K是被广泛研究的两个基因。最近这条通路中的另一个磷脂酰磷酸酶,磷脂酰肌醇4-磷酸酶Ⅱ型（INPP4B）,被证实是一个潜在的肿瘤抑制基因,其在前列腺癌、乳腺癌中低表达或突变,与该疾病的发生、预后相关。该文重点阐述了 INPP4B的分子结构和功能,及其介导的 Akt-mTOR 信号传导通路,与 PTEN 的协同作用及与几种肿瘤的相关性,并探讨 INPP4B 在细胞核内维护基因组稳定性的潜在作用。总之,对 INPP4B的深入研究不仅为磷脂酰肌醇信号调控肿瘤发生提供了新机制,而且为抗肿瘤药物研究提供了有价值的分子靶点。     

磷脂酰肌醇3激酶促进支气管哮喘大鼠气道平滑肌细胞增殖

目的探讨磷脂酰肌醇3激酶(PI3K)在支气管哮喘大鼠气道重构中的作用。方法将24只SD大鼠随机分为3组:正常对照组,哮喘4周组和6周组,每组8只。测定气道反应性并观察气道壁嗜酸性粒细胞的浸润情况;图像分析软件测定支气管壁厚度、支气管平滑肌厚度及支气管平滑肌细胞核数量;用免疫组织化学染色方法检测PI3K蛋白表达;逆转录聚合酶链反应(RT-PCR)检测PI3KmRNA表达。结果PI3K P85α主要在气道上皮细胞、气道平滑肌细胞表达。哮喘4周和6周组PI3K P85α蛋白及mRNA表达显著高于对照组(P<0.01),且6周组高于4周组(P<0.05,P<0.01);哮喘4周和6周组支气管壁厚度、支气管平滑肌厚度及平滑肌细胞核数量均较对照组明显增加(P<0.01),且6周组高于4周组(P<0.01);哮喘4周和6周组的气道反应性均高于对照组(P<0.01),且6周组高于4周组(P<0.05)。结论PI3K信号通路可能通过促进气道平滑肌细胞增殖参与哮喘气道高反应性及气道重构过程。     

磷脂酰肌醇3激酶在支气管哮喘大鼠气道平滑肌细胞中的表达

 目的： 探讨磷脂酰肌醇3激酶(PI3K)在支气管哮喘大鼠气道平滑肌细胞（ASMC）的表达。方法: 根据随机化分配原则将16只Wistar大鼠随机均分成2组，即哮喘组和正常对照组；模型建立后分别从每只大鼠分离培养ASMC，流式细胞检测方法检测ASMC的生长分数，用免疫细胞化学荧光染色及Western blotting方法进行PI3K表达的检测，并利用图像分析系统进行半定量对比分析。结果: 流式细胞仪检测发现哮喘组ASMC的S+G2/M期细胞所占细胞总数的百分比 (27.90±3.44) %显著高于正常对照组(13.00±1.56)%,P<0.05；免疫细胞化学荧光染色及Western blotting方法检测发现哮喘组和正常对照组ASMC胞浆内均有PI3Kp85阳性表达，且哮喘组的表达明显高于正常对照组；大鼠ASMC中PI3K的表达与大鼠ASMC的生长分数呈显著正相关。 结论: PI3K表达的增加可能在哮喘ASMC增殖中起重要作用。     

磷脂酰肌醇-3激酶/蛋白激酶B/FoxO1信号通路和白细胞介素17在小鼠实验性自身免疫性脑脊髓炎中的表达变化

目的 探讨磷脂酰肌醇-3激酶(PI3K)/蛋白激酶B(Akt)/FoxO1和白细胞介素17(IL-17)与自身免疫性脑脊髓炎(EAE)发病的相关机制.方法 将C57BL/6小鼠60只随机分为对照组和模型组(EAE),每组30只.采用髓鞘少突胶质细胞糖蛋白(MOG35～55)联合完全弗氏佐剂诱导建立EAE模型.观察各组小...     

Age-associated alterations in cardiac and skeletal muscle glucose transporters, insulin and IGF-1 receptors, and PI3-kinase protein contents in the C57BL/6 mouse

We investigated potential age-related changes in cardiac and skeletal muscle protein contents of glut-4 and glut-1 transporters, insulin and insulin-like growth factor-1 (IGF-1) receptors, and phosphatidylinositol 3-kinase (PI3-kinase) in the C57B1/6 mouse. Myocardial glut-4 content increased four- to five-fold between mid- to late-adulthood with no further age-related changes. Increases in myocardial glut-1 preceded the increase in glut-4 and was of a much smaller magnitude (25-40%). Skeletal muscle glut-4 was also increased (38-49%) and no further changes were noted between adulthood and old age. Cardiac insulin receptor and the p85 alpha subunit of PI3-kinase both declined by about 40%, whereas the skeletal muscle content of these two proteins were unaffected by aging. Cardiac (-23 to -24%) and skeletal muscle (-40 to -62%) IGF-1 receptor levels were decreased in adult and old animals with senescence being associated with a further decrease in cardiac IGF-1 receptor levels to 20% of controls. A two- to three-fold increase in both basal and maximal in vitro autophosphorylation of the cardiac insulin and IGF-1 receptors by their respective ligands was observed with senescence. It appears that cardiac and skeletal muscle demonstrate differential responses in terms of the magnitude and temporal responses of age-associated alterations in glucose transport related protein contents in the C57B1/6 mouse.     

黏蛋白16基因通过磷酸肌醇3-激酶/蛋白激酶B通路调节胆囊癌细胞活力和迁移

目的 探讨黏蛋白16基因（MUC16）是否通过磷酸肌醇3-激酶/蛋白激酶B（PI3K/Akt）通路调节胆囊癌细胞（GBC-SD）活力和迁移。 方法 过表达MUC16后,通过Real-time PCR筛选相关基质金属蛋白酶（MMP）家族的蛋白质。其次,过表达MUC16、敲低MUC16和PI3K/Akt通路抑制剂BKM120处理后,通过免疫印迹法检测PI3K/Akt通路和MMP-9的蛋白水平。最后,过表达MUC16或敲低MUC16,通过细胞计数试剂盒8（CCK-8）和刮伤实验检测GBC-SD的活力和迁移情况。 结果 过表达MUC16后,MMP-9 mRNA的相对表达量显著升高（P<0.05）。过表达MUC16后, MMP-9、p-Akt、PI3K的蛋白水平明显升高（P<0.05）,但是PI3K抑制剂BKM120可以避免这现象。而敲低MUC16后,发现MMP-9、p-Akt、PI3K的蛋白水平明显降低（P<0.05）。过表达MUC16后,GBC-SD的细胞活力和迁移能力明显增高（P<0.05）,而敲低了MUC16后,GBC-SD的细胞活力和迁移能力明显降低（P<0.05）。另外,敲低MMP-9后,GBC-SD的细胞活力和迁移能力也明显降低（P<0.05）。但是,在过表达MUC16的同时敲低MMP-9,发现GBC-SD的细胞活力和迁移能力与对照组相比差异无显著性（P>0.05）。 结论 MUC16激活PI3K/Akt通路促进MMP-9的蛋白表达,进而提升胆囊癌细胞GBC-SD的细胞活力和迁移能力。     

E6 variants of human papillomavirus 18 differentially modulate the protein kinase B/phosphatidylinositol 3-kinase (akt/PI3K) signaling pathway

Intra-type genome variations of high risk Human papillomavirus (HPV) have been associated with a differential threat for cervical cancer development. In this work, the effect of HPV18 E6 isolates in Akt/PKB and Mitogen-associated protein kinase (MAPKs) signaling pathways and its implication in cell proliferation were analyzed. E6 from HPV types 16 and 18 are able to bind and promote degradation of Human disc large (hDlg). Our results show that E6 variants differentially modulate hDlg degradation, rebounding in levels of activated PTEN and PKB. HPV18 E6 variants are also able to upregulate phospho-PI3K protein, strongly correlating with activated MAPKs and cell proliferation. Data was supported by the effect of E6 silencing in HPV18-containing HeLa cells, as well as hDlg silencing in the tested cells. Results suggest that HPV18 intra-type variations may derive in differential abilities to activate cell-signaling pathways such as Akt/PKB and MAPKs, directly involved in cell survival and proliferation.     

Effect of M35, a neuropeptide galanin antagonist on glucose uptake translated by glucose transporter 4 in trained rat skeletal muscle

In this study, we used M35, a galanin antagonist to explore the effect of an increase in galanin release induced by exercise on glucose transporter 4 (GLUT4) content and function. The rats tested were divided into four groups: rats from sedentary and trained drug groups were injected by M35, 5 times per week during four weeks. Rats from sedentary and trained control groups by 0.1 mol/l citrate buffer. The rats from both exercise groups swam after each injection. The results showed that M35 significantly decreased glucose infusing speeds in euglycemic–hyperinsulinemic clamp tests. M35 treatment elevated plasma insulin levels in both drug groups. And the insulin levels in both drug groups were higher also than that after experiments in each control group respectively. The four weeks swimming enhanced the plasma galanin contents. The galanin levels after experiments in both exercise groups were higher than that in each sedentary control group respectively too. The GLUT4 densities were attenuated by M35 at plasma membranes and total cell membranes. The change ratios of GLUT4 immunoreaction at plasma membranes to total cell membranes were lower in both drug groups compared to each control group. Those results suggest that endogenous galanin has an important attribute to elevate the insulin sensitivity by increasing GLUT4 contents and promoting GLUT4 transportation from intracellular membranes to plasma membranes in muscle cells. Galanin is an important hormone to elevate insulin sensitivity in rest and exercise conditions.     

The cAMP-mediated protein kinase signal transduction pathway is involved in the pyrogenic effect of CRH in rats

The cAMP-mediated protein kinase signal transduction pathway is involved in the pyrogenic effect of CRH in rats     

Effects of contraction and insulin on protein synthesis, AMP-activated protein kinase and phosphorylation state of translation factors in rat skeletal muscle

In rat epitrochlearis skeletal muscle, contraction inhibited the basal and insulin-stimulated rates of protein synthesis by 75 and 70%, respectively, while increasing adenosine monophosphate-activated protein kinase (AMPK) activity. Insulin, on the other hand, stimulated protein synthesis (by 30%) and increased p70 ribosomal protein S6 kinase (p70S6K) Thr389, 40S ribosomal protein S6 (rpS6) Ser235/236, rpS6 Ser240/244 and eukaryotic initiation factor-4E-binding protein-1 (4E-BP1) Thr37/46 phosphorylation over basal values. Electrical stimulation had no effect on mammalian target of rapamycin complex 1 (mTORC1) signalling, as reflected by the lack of reduction in basal levels of p70S6K, rpS6 Ser235/236, rpS6 Ser240/244 and 4E-BP1 phosphorylation, but did antagonize mTORC1 signalling after stimulation of the pathway by insulin. Eukaryotic elongation factor-2 (eEF2) Thr56 phosphorylation increased rapidly on electrical stimulation reaching a maximum at 1 min, whereas AMPK Thr172 phosphorylation slowly increased to reach threefold after 30 min. Eukaryotic elongation factor-2 kinase (eEF2K) was not activated after 30 min of contraction when AMPK was activated. This could not be explained by the expression of a tissue-specific isoform of eEF2K in skeletal muscle lacking the Ser398 AMPK phosphorylation site. Therefore, in this skeletal muscle system, the contraction-induced inhibition of protein synthesis could not be attributed to a reduction in mTORC1 signalling but could be due to an increase in eEF2 phosphorylation independent of AMPK activation.