mTOR信号通路与细胞凋亡

哺乳类动物雷帕霉素靶蛋白(mTOR)主要通过上游信号转导通路磷脂酰肌醇3-激酶(PI3K)/蛋白激酶B(PKB/Akt)/mTOR信号通路及下游信号通路mTOR/ eIF4E结合蛋白1(4EBP1)、mTOR/p70S6激酶(p70S6K)在细胞生长、增值与分化和在血管再生、蛋白合成与降解中发挥作用.细胞凋亡是细胞的一种程序性死亡,在机体发育、组织代谢中有着重要作用,而细胞凋亡的异常调节与许多疾病的发生和发展紧密相连.近年研究发现,mTOR信号通路在细胞凋亡过程中扮演了重要角色,并已被作为新的药物治疗靶点.     

mTOR信号通路与调节

哺乳动物雷帕霉素靶蛋白mTOR是一种非典型丝氨酸/苏氨酸蛋白激酶,可整合细胞外信号,磷酸化下游靶蛋白核糖体p70S6激酶,如S6K1及4E-BP1,影响转录与翻译,从而参与调控细胞生长、增殖等过程.近年来研究发现,调控mTOR通路可以干预某些疾病的病理过程.mTOR研究的新发现,可望为今后相关疾病的治疗提供新的靶点.     

mTOR的结构与功能

哺乳动物雷帕霉素靶蛋白(mTOR)参与细胞内一系列生理病理过程,其存在形式主要有两种:mTOR-Raptor复合物和mTOR-R ictor复合物。mTOR-Raptor复合物的发现早于mTOR-R ictor复合物,作用主要是通过调节蛋白质的合成影响细胞生长和增殖,其活性能够被雷帕霉素抑制。mTOR-R ictor复合物的活性不能被雷帕霉素抑制,主要参与细胞骨架蛋白的构造,具体功能仍在进一步研究之中。对两种复合物的研究能够帮助寻找新的治疗肿瘤和代谢性疾病的药物。     

LKB1/AMPK/mTOR信号通路与血液肿瘤

血液肿瘤已成为严重威胁儿童生命的主要疾病之一,其发病率逐年升高.随着研究的不断深入,LKB1/AMPK/mTOR信号转导通路在多种常见肿瘤如乳腺癌、前列腺癌、肝癌、肺癌及淋巴瘤等的研究中凸现出日益重要的作用,并为肿瘤的治疗提供了新的靶点,成为目前研究的热点.现就LKB1/AMPK/mTOR信号通路的组成及其与血液肿瘤的关系以及分子机制作一综述.     

腺嘌呤核苷酸活化蛋白激酶与哺乳动物雷帕霉素靶蛋白信号转导通路的相互作用

背景：腺嘌呤核苷酸活化蛋白激酶的下游靶分子哺乳动物雷帕霉素靶蛋白对细胞生长、分裂和蛋白质合成有重要意义。 目的：综述腺嘌呤核苷酸活化蛋白激酶与哺乳动物雷帕霉素靶蛋白信号转导相互调节的最新研究进展,以期揭示腺嘌呤核苷酸活化蛋白激酶和哺乳动物雷帕霉素靶蛋白信号转导的交互作用对蛋白质合成的影响。 方法：以“(mammalian target of rapamycin OR mTOR) AND (AMP activated protein kinase OR AMPK) AND signal transduction”为检索式,计算机检索PubMed数据库相关内容的文献,最终纳入30篇可反映腺嘌呤核苷酸活化蛋白激酶与哺乳动物雷帕霉素靶蛋白信号转导通路相互作用的文献,并进行归纳总结。 结果与结论：腺嘌呤核苷酸活化蛋白激酶活化导致哺乳动物雷帕霉素靶蛋白信号转导减弱一定程度上抑制蛋白质合成,腺嘌呤核苷酸活化蛋白激酶通过多个位点磷酸化和活化而调节哺乳动物雷帕霉素靶蛋白信号转导。腺嘌呤核苷酸活化蛋白激酶磷酸化马铃薯球蛋白会抑制Akt,ERK1/ERK2和p90rsk等其他蛋白激酶的作用。明确腺嘌呤核苷酸活化蛋白激酶对哺乳动物雷帕霉素靶蛋白的调节过程所起的作用,对揭示腺嘌呤核苷酸活化蛋白激酶-哺乳动物雷帕霉素靶蛋白途径调控能量代谢和蛋白合成方面有重要意义。     

mTOR介导转录因子调控细胞糖脂代谢的研究进展

哺乳动物雷帕霉素靶蛋白(mTOR)是一种重要的信号分子,参与体内蛋白质合成,细胞增殖、细胞周期、能量代谢和自噬等过程.mTOR的失活可导致肿瘤和代谢性疾病的发生.其中,HIF1α、c-Myc、FoxO1、SREBPs、PPARγ/PPARα及TFEB作为mTOR的下游信号,与细胞的糖脂代谢密切相关.     

AKT/mTOR信号分子在小鼠海马发育中的表达

目的:观察蛋白激酶B(AKT)/哺乳动物雷帕霉素靶蛋白(mTOR)信号分子在小鼠胚胎发育晚期和生后早期海马中的表达变化.方法:在E18、P1、P7、P14、P21和P28时间点取昆明小鼠海马组织,利用4',6-二脒基-2-苯基吲哚(DAPI)染色观察海马细胞数量;利用免疫组织化学和Western Blot检测各时间点海...     

GPI锚固蛋白与T细胞活化信号转导

GPI锚固蛋白在T淋巴细胞表面形成富含胆固醇和糖鞘酯的脂微区(1ipidmicrodomains)。被激活的GPI锚固蛋白与糖鞘酯发生侧向交联引起脂微区胞浆面PTK的聚集和活化,转导级联细胞活化信号,同时还引起细胞骨架的改变。胆固醇不仅参予构成GPI锚固蛋白脂微区,还影响到GPI锚固蛋白的信号转导。TCR／CD3在GPI锚固蛋白信号转导中起着重要作用．两条信号途径相互影响共同促使T细胞的活化增殖。G蛋白可能通过PLC和AC等信号分子活性调节参与GPI信号转导。     

IL-1β通过PI3K/Akt/mTOR途径促进神经元活化

目的:观察白细胞介素-1β(IL-1β)刺激对神经元活化的影响。方法:利用IL-1β刺激体外培养的原代神经元,运用慢病毒转染shRNA使PI3K的p85亚基(PI3K-p85)沉默、哺乳动物雷帕霉素靶蛋白(mammalian target of rapamycin,m TOR)抑制剂雷帕霉素预处理阻断m TOR、酪氨酸激酶家族抑制剂PP2抑制p85向IL-1受体I型(IL-1RI)募集等方式预处理神经元,检测PI3K-p85、与IL-1RI结合的PI3K-p85、p-Akt、p-p70S6K以及微管相关蛋白2(MAP2)在神经元内的变化及相互作用;利用FM4-64染色观察各组神经元突触胞吞情况。结果:利用IL-1β刺激体外培养的海马神经元可增加细胞内PI3K-p85、p-Akt、p-p70S6K、MAP2以及与IL-1RI结合的PI3K-p85的水平(P0.05),并且神经元突触的胞吞作用明显加剧(P0.05);抑制PI3K-p85可以下调IL-1β所致的p-Akt、pp70S6k和MAP2水平增加(P0.05),神经元突触的胞吞作用减弱(P0.05);抑制m TOR也能下调IL-1β所致的PI3K-p85、p-Akt、p-p70S6K和MAP2水平增加(P0.05),神经元突触的胞吞作用减弱(P0.05);抑制p85亚基与IL-1RI的结合也可以下调IL-1β所致的p-Akt、p-p70S6K和MAP2水平增加(P0.05)。结论:促炎因子IL-1β通过IL-1RI与PI3K-p85结合使PI3K-p85活化,进而磷酸化Akt和m TOR下游物质p70S6K,促进神经元突触增生及活化,这可能是内侧颞叶癫痫向慢性化进展的机制之一。     

葡萄糖通过mTORC1信号通路调控成纤维细胞增殖

目的 研究葡萄糖对小鼠皮肤成纤维细胞增殖的影响.方法 将小鼠皮肤成纤维细胞培养在含不同浓度葡萄糖的培养基里,用MTT法检测细胞增殖,7-MGTP pulldown实验检测细胞翻译起始情况,Western blot检测mTORC1信号通路分子的活化.结果 与培养基葡萄糖浓度为5.5 mmol/L相比较,当浓度为15 mmol/L时,促进细胞增殖,与7-MGTP结合的翻译起始复合物增加,mTORC1信号通路活化;当25 mmol/L时,抑制细胞增殖,与7-MGTP结合的翻译始复合物减少,mTORC1信号通路中与细胞增殖相关的4EBP1和与细胞生存相关的Akt的磷酸化减弱.结论 葡萄糖通过对mTORC1信号通路的双向调节作用调控成纤维细胞增殖.     

mTOR Signaling in T Cell Immunity and Autoimmunity

The mammalian target of rapamycin (mTOR), a phosphoinositide-3-kinase-related protein kinase, acts as a rheostat capable of integrating a variety of environmental cues in the form of nutrients, energy, and growth factors to modulate organismal processes and homeostasis. Recently, there is a growing appreciation of mTOR in adaptive immunity for its crucial roles in keeping a proper balance between T cell quiescence and activation. Under steady-state circumstances, mTOR is subtly inhibited by multiple mechanisms to maintain normal T cell homeostasis. Antigen recognition by naïve T cells leads to mTOR activation, which subsequently promotes the differentiation of these cells into distinct effector T cell subsets. This review focuses primarily on the recent literature with respect to the regulatory effects and mechanisms of mTOR signaling in dictating T cell fate, and discusses the therapeutic implications of mTOR modulation in T-cell-mediated autoimmunity.     

亚硒酸钠通过AMPK/mTOR通路调控白血病NB4细胞凋亡

 目的 研究亚硒酸钠对白血病NB4细胞中AMPK及其下游靶蛋白对细胞凋亡的调控作用。方法 分别用亚硒酸钠、AICAR和AMPK干扰序列处理NB4细胞。用Western blot检测细胞AMPK、mTOR及其下游蛋白P70S6K的磷酸化水平及激活和干扰AMPK后AMPK、mTOR及P70S6K的磷酸化水平、流式细胞术检测NB4细胞凋亡率;免疫共沉淀法检测AMPK和mTOR的相互作用。结果 亚硒酸钠可以上调NB4细胞中AMPK的磷酸化水平,下调mTOR及P70S6K的磷酸化水平;AICAR和亚硒酸钠单独处理具有类似的促进NB4细胞凋亡的效果;干扰AMPK后,mTOR及P70S6K的磷酸化水平上升,亚硒酸钠对NB4细胞的促凋亡作用被拮抗;AMPK和mTOR有直接相互作用。结论 亚硒酸钠可通过激活AMPK表达,抑制mTOR及P70S6K,促进NB4细胞凋亡。     

The influence of mTOR on T helper cell differentiation and dendritic cell function

The mammalian target of rapamycin (mTOR) integrates signalling responses to growth factors and nutrients. The macrolide rapamycin inhibits mTOR function and has been used extensively to demonstrate a critical role for mTOR in immune responses. This mini-review summarizes recent evidence demonstrating an integral role for mTOR in the differentiation of T helper cell subsets and the development, maturation and antigen-presenting capacity of DCs in both mice and humans.     

Ghrelin attenuates the growth of HO-8910 ovarian cancer cells through the ERK pathway

Ovarian cancer is one of the most common causes of death from gynecologic tumors and is an important public health issue. Ghrelin is a recently discovered bioactive peptide that acts as a natural endogenous ligand of the growth hormone secretagogue receptor (GHSR). Several studies have identified the protective effects of ghrelin on the mammalian reproductive system. However, little research has been done on the effects of ghrelin on ovarian cancer cells, and the underlying mechanisms of these effects. We sought to understand the potential involvement of mitogen-activated protein kinases (MAPKs) in ghrelin-mediated inhibition of growth of the ovarian line HO-8910. We applied different concentrations of ghrelin and an inhibitor of the ghrelin receptor (D-Lys3-GHRP-6) to HO-8910 cells and observed the growth rate of cells and changes in phosphorylation of the MAPKs ERK1/2, JNK and p38. We discovered that ghrelin-induced apoptosis of HO-8910 cells was though phosphorylated ERK1/2, and that this phosphorylation (as well as p90^rsk phosphorylation) was mediated by the GHSR. The ERK1/2 pathway is known to play an essential part in the ghrelin-mediated apoptosis of HO-8910 cells. Hence, our study suggests that ghrelin inhibits the growth of HO-8910 cells primarily through the GHSR/ERK pathway.     

Progesterone suppresses the mTOR pathway and promotes generation of induced regulatory T cells with increased stability

While induced FoxP3⁺ T cells (iTreg cells) are promising cellular therapeutics to treat inflammatory diseases, a limitation in utilizing iTreg cells prepared in vitro is their low stability in inflammatory conditions. Progesterone (P4) is an immune regulatory nuclear hormone with a potent Treg induction activity. We reasoned that this function of progesterone would be utilized to generate iTreg cells with highly suppressive activity and improved stability in vivo. Here we generated iTreg cells with progesterone in vitro and found that progesterone generates iTreg cells that are highly stable in inflammatory conditions. Moreover, P4‐induced iTreg cells highly express latency‐associated peptide TGF‐β1 and are efficient in regulating inflammation in multiple tissues, whereas control iTreg cells induced with TGF‐β1 alone are less stable and ineffective in suppressing inflammation. The function of progesterone in inducing iTreg cells with improved regulatory activity is associated with the function of P4 in suppressing the mTOR pathway. Moreover, the function of progesterone in inducing FoxP3⁺ T cells is decreased but not completely abolished on nuclear progesterone receptor‐deficient T cells, suggesting that both nuclear and nonnuclear progesterone receptors are involved in mediating the function. We conclude that P4 can be utilized to generate iTreg cells with a high therapeutic potential in treatment of tissue inflammation.     

Targeting antigen to CD19 on B cells efficiently activates T cells

CD19 is a B cell-surface molecule that participates as an important regulatory signaling complex for antigen bound at the surface by Ig. Triggering of CD19 through its linkage with CD21 amplifies signals transduced through the Src family kinases and modulates B cell differentiation in response to antigen. This study examines the kinetics of antigen uptake and processing of antigen directly targeted to the CD19 protein on purified B cells. We have demonstrated that the antigen internalized within minutes through CD19 forms a cap at the B cell surface and can be found within lysosomes in the cytoplasm in 90 min. B cells acquiring antigen via CD19 express elevated levels of B7-1 and B7-2 co-stimulatory molecules. Moreover, antigen-anti-CD19 complexes administered intravenously bind B cells in vivo and activate antigen-specific T cells more efficiently than non-specific uptake and in a manner similar to antigen taken up through surface IgM on B cells. This work illustrates an important and previously unrecognized mechanism for targeting proteins to B lymphocytes for antigen presentation and activation of CD4 T cells.     

mTOR抑制剂一雷帕霉素对T细胞功能调控的研究进展

哺乳动物雷帕霉素靶蛋白（mTOR）作为信号通路的调节分子参与多条重要的信号转导通．路,能形成细胞对多种刺激的应答,mTOR至少存在两种功能性多蛋白复合物形式：mTORCl和mTORC2,其可发挥不同的生物学作用。雷帕霉素作为mTOR的特异性抑制剂可阻断mTOR信号通路信息的传导,调节T细胞的分化、发育、失能以及调节性T细胞（Treg）的增殖和功能,影响生长因子和细胞因子等生物活性物质的分泌,表现出有效的免疫抑制作用。