Akt和胞外信号调节激酶通路间的信号交流对内质网应激条件下肝癌细胞周期的调控

目的 研究内质网应激介导的磷脂酰肌醇3激酶(PI3K)/Akt和丝裂原活化蛋白激酶(MEK)/胞外信号调节激酶(ERK)途径间的信号交流及其对内质网应激条件下肝癌细胞周期的调控作用.方法 采用PI3K抑制剂LY294002、Akt激活型突变载体myr-Akt和MEK抑制剂U0126分别阻断或激活内质网应激介导的Akt和ERK活化,并利用Western blot和流式细胞技术分析内质网应激条件下PI3K/Akt和MEK/ERK途径间的信号交流及其对肝癌细胞株SMMC-7721、Hep3B和HepG2细胞周期的调控作用.数据处理采用Sperman等级相关分析,P＜0.05为差异有统计学意义.结果 阻断PI3K/Akt明显促进内质网应激介导的MEK/ERK活化,而过度激活PI3K/Akt则抑制内质网应激介导的MEK/ERK活化.阻断MEK/ERK对内质网应激介导的PI3K/Akt活化无影响.持续活化的Akt突变载体myr-Akt和MEK抑制剂U0126均明显抑制了内质网应激诱导的压力细胞G0/G1期阻滞.结论 PI3K/Akt和MEK/ERK信号途径在内质网应激肝癌细胞中存在信号交流,该信号交流对细胞周期起重要调控作用.     

洛伐他汀抑制大鼠骨髓间充质干细胞凋亡的实验研究

目的体外以缺氧无血清条件模拟心肌梗死后的心脏缺血微环境,研究洛伐他汀是否能够抑制缺氧无血清引起的骨髓间充质干细胞（MSCs）凋亡。方法以Hoechst33342染色法及AnnexinV／PI流式细胞术检测洛伐他汀的抗凋亡作用,检测线粒体膜电位变化,进一步采用Western blot方法检测洛伐他汀对细胞色素C释放及caspase-3活化的影响。结果洛伐他汀0．01～1μmol／L能够有效地抑制缺氧无血清引起的MSCs凋亡。洛伐他汀抑制线粒体凋亡途径,增强线粒体膜电位水平、抑制细胞色素C释放,降低caspase-3活化水平。结论洛伐他汀能够抑制线粒体途径介导的凋亡,阻止caspase-3的活化,发挥抗缺氧无血清引起的MSCs凋亡,为提高移植干细胞的存活率提供了一种可能有效的干预措施。     

PI3K-Akt/PKB信号通路与胰岛β细胞功能

磷脂酰肌醇3激酶-蛋白激酶B/Akt(PI3K-Akt/PKB)介导β细胞的生存通路近来较受关注。PI3K-Akt/PKB信号通路是细胞内重要的信号转导通路,与细胞生长、增殖、分化、凋亡等密切相关。PI3K-Akt/PKB信号通路激活通过下游效应分子促进β细胞增殖、生长调节、增强β细胞抗凋亡功能,改善β细胞生存。调节该通路PI3K、Akt/PKB及其上下游靶位点,可能为2型糖尿病的防治提供广阔前景。     

内脂素激活PI3K-Akt和MAPK-ERK1/2信号通路抑制MIN6细胞凋亡

探讨内脂素对胰岛β细胞株MIN6细胞信号通路和棕榈酸诱导细胞凋亡的影响,并探讨其分子机制.人重组内脂素呈剂量和时间依赖性促进MIN6细胞细胞外信号调节激酶(ERK)1/2和蛋白激酶B(Akt)的磷酸化,抑制棕榈酸诱导的MIN6细胞凋亡(P<0.05或P<0.01).激活磷脂酰肌醇3激酶(PBK)-Akt和丝裂原活化蛋白激酶(MAPK)-ERK1/2信号通路是内脂素抑制MIN6细胞凋亡的分子机制之一.     

Visfatin inhibits pancreatic β-cell line MIN6 apoptosis via PI3K-Akt and MAPK-ERK1/2 signaling pathways

探讨内脂素对胰岛β细胞株MIN6细胞信号通路和棕榈酸诱导细胞凋亡的影响,并探讨其分子机制.人重组内脂素呈剂量和时间依赖性促进MIN6细胞细胞外信号调节激酶(ERK)1/2和蛋白激酶B(Akt)的磷酸化,抑制棕榈酸诱导的MIN6细胞凋亡(P<0.05或P<0.01).激活磷脂酰肌醇3激酶(PBK)-Akt和丝裂原活化蛋白激酶(MAPK)-ERK1/2信号通路是内脂素抑制MIN6细胞凋亡的分子机制之一.     

Visfatin inhibits pancreatic β-cell line MIN6 apoptosis via PI3K-Akt and MAPK-ERK1/2 signaling pathways

探讨内脂素对胰岛β细胞株MIN6细胞信号通路和棕榈酸诱导细胞凋亡的影响,并探讨其分子机制.人重组内脂素呈剂量和时间依赖性促进MIN6细胞细胞外信号调节激酶(ERK)1/2和蛋白激酶B(Akt)的磷酸化,抑制棕榈酸诱导的MIN6细胞凋亡(P<0.05或P<0.01).激活磷脂酰肌醇3激酶(PBK)-Akt和丝裂原活化蛋白激酶(MAPK)-ERK1/2信号通路是内脂素抑制MIN6细胞凋亡的分子机制之一.     

PI3K/Akt信号通路在HIV感染中的研究进展

[摘要]　磷脂酰肌醇3-激酶（phosphoinositide 3-kinase, PI3K）/蛋白激酶B（protein kinase B, PKB,普遍写作Akt）信号通路参与调控多种细胞功能，与多种疾病的发生密切相关。PI3K/Akt信号通路在HIV感染过程中也发挥重要作用，包括调节T细胞、线粒体功能，促进HIV复制，再激活潜伏HIV以及维持病毒储存库。因此，探索PI3K/Akt信号通路在HIV感染中的作用机制具有重要意义，针对PI3K/Akt的靶向治疗可能在抗HIV中发挥关键作用。本文对PI3K/Akt信号通路与HIV感染的相关研究进行综述，旨在为HIV的治疗提供新的思路与靶点。     

PI3K/Akt信号转导通路与甲状腺结节

近年来研究发现,磷脂酰肌醇3激酶(PDK)/蛋白激酶B(Akt)信号转导通路在细胞的增殖、分化、生存和凋亡过程中起重要调节作用.结节性甲状腺肿、甲状腺腺瘤、甲状腺癌及桥本甲状腺炎病变中存在着PI3K/Akt信号转导通路的过度激活.PI3K/Akt信号转导通路的活化使甲状腺细胞增殖指数和生长指数明显升高,刺激甲状腺滤泡持续生长,促进甲状腺结节的发生、发展.研究此通路中相关分子的表达,对探索甲状腺结节的病因、发病机制和防治策略具有重要意义.     

PI3K/Akt信号转导通路与脑缺血后细胞凋亡

细胞凋亡为脑缺血时细胞死亡的重要形式之一.磷脂酰肌醇-3激酶(phosphoinositide-3 kinase,PI3K)/丝氨酸-苏氨酸蛋白激酶(serine/threonine kinase,Akt)为重要的细胞存活信号通路,c-Jun氨基端激酶(c-jun N-terminal kinase,JNK)为重要的促进细胞凋亡信号通路.这两大通路转导信号的动态平衡维持着生理状态下的细胞生存与凋亡.脑缺血刺激打破了这一生理平衡,导致大量神经细胞凋亡.多种确切的神经保护因素都与增强细胞存活信号的放大或抑制凋亡信号的放大有关,从而维持这2个通路信号的平衡.     

成纤维细胞样滑膜细胞中丝氨酸/苏氨酸蛋白激酶/丝裂原活化蛋白激酶/细胞外信号调节激酶信号通路与类风湿关节炎发病机制的研究进展

本文回顾了近年来国内外学者对丝氨酸/苏氨酸蛋白激酶(RAF)/丝裂原活化蛋白激酶(MEK)/细胞外信号调节激酶(ERK)信号通路在RA中的调控机制研究, 发现该通路在类风湿关节炎-成纤维细胞样滑膜细胞(RA-FLS)中介导免疫调控、炎症反应、氧化应激、细胞凋亡等, 并与RA-FLS自噬关系密切。此外, RAF/MEK/ERK信号通路与RA骨破坏也具有相关性, 但目前的研究鲜有报道。因此, RAF/MEK/ERK信号通路与RA骨破坏的相关性研究可能会成为未来的研究热点。同时, 提出以RAF/MEK/ERK信号通路为靶点开展RA药物靶向研究, 可能会推动RA治疗药物的发展, 为治疗RA开辟新途径。     

Hyperglycemia enhances adipogenic induction of lipid accumulation: involvement of extracellular signal-regulated protein kinase 1/2, phosphoinositide 3-kinase/Akt, and peroxisome proliferator-activated receptor gamma signaling

The molecular events of hyperglycemia-triggered increase in adipogenic induction of lipid accumulation remain unclear. We examined the effects of hyperglycemia on adipogenic induction of lipid accumulation and its involved signaling molecules, such as phosphoinositide 3-kinase (PI3K), ERKs, and peroxisome proliferator-activated receptor gamma (PPAR gamma). Bone marrow-derived mesenchymal stem cells (MSCs) isolated from FVB/N mice were capable of differentiating into adipocytes in adipogenic medium. The effects of high glucose (HG) (25.5 mm) were assessed in vitro by RT-PCR, ELISA, flow cytometry, immunostaining, and immunoblotting. The in vivo effect of hyperglycemia was further studied in streptozotocin (STZ)-induced diabetic FVB/N mice. Exposure of MSCs to HG enhanced adipogenic induction of lipid accumulation as compared with 5.5 mm glucose. HG increased PPAR gamma expression and PI3K activity and its downstream effector Akt phosphorylation during adipogenesis. Inhibition of PI3K/Akt activity with PI3K inhibitor LY294002 or by expressing the dominant negative p85 or Akt prevented the HG-enhanced PPAR gamma-dependent adipogenic induction of lipid accumulation. Moreover, HG increased the phosphorylation of ERK1/2 during adipogenesis. MAPK/ERK inhibitor PD98059 inhibited the PI3K activity, Akt phosphorylation, and lipid accumulation triggered by HG. PI3K inhibitor LY294002 did not affect the HG-increased ERK1/2 phosphorylation during adipogenesis. We next observed that adipogenic induction of lipid accumulation of MSCs isolated from STZ-induced diabetic mice is enhanced. Moreover, triglyceride, PPAR gamma expression, phosphorylated Akt and ERK1/2, and marrow fat in bones of STZ-diabetic mice were also increased. These results suggest that hyperglycemia enhances the adipogenic induction of lipid accumulation through an ERK1/2-activated PI3K/Akt-regulated PPAR gamma pathway.     

Simultaneous modulation of COX-2, p300, Akt, and Apaf-1 signaling by melatonin to inhibit proliferation and induce apoptosis in breast cancer cells

Melatonin exhibits anti-inflammatory and anticancer effects and could be a chemopreventive and chemotherapeutic agent against cancers, but the precise mechanisms involved remain largely unresolved. In this study, we evaluated the mechanism of action of melatonin in human MDA-MB-361 breast cancer cells. Melatonin at pharmacological concentrations (10(-3) m) significantly suppressed cell proliferation and induced apoptosis in a dose-dependent manner. The observed suppression of proliferation was accompanied by the melatonin-mediated inhibition of COX-2, p300, and NF-κB signaling. Melatonin significantly inhibited COX-2 expression and prostaglandin E(2) (PGE2) production, abrogated p300 histone acetyltransferase activity and p300-mediated NF-κB acetylation, thereby blocking NF-κB binding and p300 recruitment to COX-2 promoter. Pretreatment with a COX-2- or p300-selective inhibitor abrogated the melatonin-induced inhibition of cell proliferation, whereas PGE2 treatment or COX-2 transfection reversed the inhibition by melatonin. Moreover, melatonin markedly inhibited phosphorylation of PI3K, Akt, PRAS40, and GSK-3 proteins, thereby inactivating the PI3K/Akt signaling pathway. Pretreatment with a PI3K- or an Akt-selective inhibitor or an Akt-specific siRNA blocked the melatonin-mediated inhibition of cell proliferation. Conversely, gene delivery of a constitutively active Akt effectively reversed the inhibition by melatonin. Furthermore, melatonin induced Apaf-1 expression, triggered cytochrome C release, and stimulated caspase-3 and caspase-9 activities and cleavage, leading to an activation of the Apaf-1-dependent apoptotic pathway. Pretreatment with an Apaf-1-specific siRNA effectively attenuated the melatonin-induced apoptosis. These results therefore indicate that melatonin inhibits cell proliferation and induces apoptosis in MDA-MB-361 breast cancer cells in vitro by simultaneously suppressing the COX-2/PGE2, p300/NF-κB, and PI3K/Akt/signaling and activating the Apaf-1/caspase-dependent apoptotic pathway.     

间充质干细胞分泌的血管内皮生长因子对心肌细胞的保护作用

目的:探索间充质干细胞通过其分泌的血管内皮生长因子对H9C2细胞的保护作用及机制。方法: 收集骨髓源间充质干细胞的条件培养基,分别处理培养,将其置于缺氧小室缺氧处理21 h,复氧处理6 h。阻断实验利用VEGFR阻断剂SU5416与间充质干细胞的条件培养基共处理。随后,利用流式细胞术ANNEXIN/PI双标法分析其凋亡变化。Western blotting分析H9C2细胞pAkt的表达。结果: RT PCR结果显示间充质干细胞表达血管内皮生长因子,Western blotting结果显示间充质干细胞条件培养基增加了H9C2细胞pAkt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细胞缺氧复氧的凋亡,且这种抗凋亡作用能被VEGFR阻断剂SU5416或PI3 K/Akt途径阻断剂LY294002所阻断。结论: 间充质干细胞通过其分泌的血管内皮生长因子通过激活PI3 K/Akt途径保护H9C2细胞。     

DIDS通过PI3-K/Akt途径减弱缺血/再灌注损伤诱导心肌细胞凋亡

目的 探讨磷脂酰肌醇3激酶(PI3-K)/蛋白激酶B(Akt)信号通路在DIDS(4,4′-diisothiocyanostilbene-2,2′-disulfonic acid)减弱缺血/再灌注损伤（I/RI）诱导心肌细胞凋亡中的作用。方法 以I/RI诱导心肌细胞凋亡,然后用PI3-K特异性的抑制剂LY294002［22(42吗啉基)282苯基24氢212苯并吡喃242酮］进行干预。实验分为正常对照组、I/RI组、I/RI+DIDS组和I/RI+DIDS+LY294002组。通过噻唑蓝(MTT)比色法、Hoechest-33258染色和半胱天冬蛋白酶（Apo-ONETM Homogeneous Caspase）-3试剂盒以及Western blot分别检测:心肌细胞的存活率（%）、细胞核的形态变化和caspase-3活性、Akt的磷酸化。结果 ①DIDS能够显著抑制I/RI诱导的细胞存活率的下降,抑制凋亡小体的出现,抑制caspase-3的活性的增加(P<0.01)。②用LY294002预处理后,DIDS保护I/RI心肌细胞存活的作用减弱、凋亡小体增加和caspase-3活性明显升高(P<0.01)。③I/RI组与正常对照组Akt磷酸化无明显差异,DIDS能够显著增加I/RI组中Akt蛋白的磷酸化(P<0.01)。用LY294002预处理后,DIDS对I/RI组Akt蛋白磷酸化的影响明显减弱(P<0.01)。结论 DIDS可通过激活PI3-K/Akt信号通路减弱I/RI 诱导的心肌细胞的凋亡。     

Role of phosphoinositide 3-kinase and extracellular signal-regulated kinase pathways in granulocyte macrophage-colony-stimulating factor failure to delay fas-induced neutrophil apoptosis in elderly humans

Fas-stimulated neutrophils from elderly individuals show impaired granulocyte macrophage-colony-stimulating factor (GM-CSF)-induced apoptosis cell rescue. Herein, this defect was found to be associated with a significant reduction in GM-CSF-mediated Akt and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation. Using Akt and ERK1/2 inhibitors, we demonstrated that both kinases were critical for GM-CSF antiapoptotic effects. Whereas Akt inhibition also affected GM-CSF-dependent ERK1/2 phosphorylation, ERK1/2 inhibition did not affect GM-CSF-induced Akt phosphorylation, suggesting that phosphoinositide 3-kinase (PI3-K)/Akt and ERK1/2 are activated in series and that PI3-K is located upstream of ERK1/2 along the GM-CSF-dependent signaling pathway. No age-associated changes in GM-CSF receptor expression were observed. Interestingly, both suppressors of cytokine signaling (SOCS)1 and SOCS3 proteins were significantly higher in unstimulated neutrophils from elderly individuals and, unlike in young individuals, did not further increase following GM-CSF cell triggering. These results indicate that defective PI3-K/Akt/ERK1/2 activation, likely dependent on elevated SOCS1 and SOCS3 levels, may affect the GM-CSF capacity to delay neutrophil apoptosis in elderly persons.     

Effects of extracellular acid stimulation on rat vascular smooth muscle cell in Gas6/Axl or PI3K/Akt signaling pathway

Recent studies have indicated that extracellular acid stimulation inhibited the calcification of vascular smooth muscle cells (VSMCs). Cell apoptosis played an important role in the occurrence and development of vascular calcification. We further explored the effects of Gas6/Axl or PI3K/Akt signaling pathway on the inhibition of rat VSMCs calcification in response to extracellular acid stimulation. Our study demonstrated that a high concentration of phosphorus induced apoptosis and calcification of VSMCs, decreased expression of Axl, and reduced phosphorylation of Akt. Stimulation of extracellular acid counteracted the effects as above by increasing the expression of Axl and Akt phosphorylation and decreasing the expression of activated Caspase3, which thereby decreased cell apoptosis and calcification. Moreover, the effects can be attenuated by PI3K inhibitor. Our study proved that extracellular acid stimulation played a vital role in the inhibition of rat VSMCs calcification and apoptosis in Gas6/Axl or PI3K/Akt signaling pathway.     

细胞色素P450表氧化酶通过PI3K/AKT及ERK/MAPK途径抗内皮细胞凋亡的机制

目的:研究细胞色素P450表氧化酶对肿瘤坏死因子(TNF)-α诱导内皮细胞抗凋亡的机制。方法:在原代培养的牛主动脉内皮细胞(BAECs)中,分别转染细胞色素P450表氧化酶基因rAAV-F87V2周,证实其在内皮细胞中高效表达。用TNF-α(10ng/ml)和放线菌素D(ActD)(5ng/ml)诱导凋亡,流式细胞计数观察其凋亡变化,用Western blot法检测蛋白激酶B(AKT)及细胞外信号调节蛋白激酶(ERK)的磷酸化水平,用流式细胞计数的方法观察空白组及转染F87V组加入AKT抑制剂、LY294002、芹菜素及PD98059后的细胞凋亡比例。结果:与对照组比较,转染细胞色素P450表氧化酶基因后BAECs能高效表达P450表氧化酶基因F87V(P<0.05);流式计数凋亡细胞数,转染表氧化酶较对照组明显减少(P<0.05);转染CYP P450表氧化酶后,AKT及ERK的磷酸化增加;磷脂酰肌醇3激酶(PI3K)、丝裂原活化蛋白激酶(MAPK)和MKK的抑制剂后转染F87V组较对照组凋亡细胞比例明显减少(P<0.05)。结论:细胞色素P450表氧化酶基因rAAV-F87V能通过MAPK(ERK1/2)与PI3K/AKT途径发挥抗凋亡作用。     

血管生成素1增强骨髓间充质干细胞缺血环境下生存能力的研究

目的 研究血管生成素1（Ang1）对骨髓间充质干细胞（MSCs）在缺血清状态下的保护作用,探索一种改善MSCs生存能力的方法.方法 建立体外缺血清的凋亡模型,应用四甲基偶氮唑盐检测MSCs的生存能力,双苯并咪唑染色评估MSCs的凋亡,蛋白质印迹分析（Western-blot）检测丝氨酸/苏氨酸蛋白激酶（Akt）细胞生存通路的表达.结果 MSCs在缺血清处理24h后.生存能力降至（72.7±5.8）%,Ang1能够明显改善MSCs的生存能力,并呈剂量依赖性,在50μg/L时达到了高峰,生存能力提高至（92.3±1.5）%（P〈0.01）;Ang1能够降低MSCs的凋亡率,从（24.9±3.9）%降至（11.0±2.4）%（P〈0.01）;缺血清明显降低了MSCs的Akt磷酸化水平,但Ang1能够明显增加MSCs的Akt活化;应用P13K,Akt通路阻滞剂Wortman-nin后,Ang1的保护作用消失,MSCs的生存能力从（92.3±1.5）%降至（73.9±4.7）%（P〈0.01）,凋亡率从（11.0±2.4）%回升至（26.5±2.6）%（P〈0.01）. 结论 Ang1能够改善MSCs的生存能力.作用机制可能与激活P13K/Akt生存通路有关.