PD098059对IL-6诱导的M1细胞生长停止与终末分化的影响

 为探讨 IL- 6在 M1细胞中激活 Ras/MAPK通路的意义 ,以 MEK激酶的特异性抑制剂PD0 980 59阻断 Ras/MAPK通路的组成型激活及诱导激活 ,观测 PD0 980 59对 IL - 6诱导的 M1细胞生长停止及终末分化的影响 .发现 PD0 980 59可抑制 M1细胞的生长 ,并加强 IL- 6对 M1细胞的生长抑制效应 .PD0 980 59不影响 IL - 6诱导的 M1细胞形态改变及 CD1 1 b表达 ,但可显著降低 IL-6诱导的 M1细胞获得吞噬功能 .说明 Ras/MAPK途径的组成型激活及诱导激活是有重要意义的 ,它与 JAK- STATs途径既相互拮抗又相互协同 ,共同组成了 IL- 6对急性髓系白血病细胞生物学效应的精密调控作用 .     

JAK3蛋白在鼻咽癌细胞中参与STAT活化并受EB病毒潜伏膜蛋白1调控

为了探讨在鼻咽癌细胞（NPC）中是否存在EB病毒潜伏膜蛋白1（LMP1）/JAK3/STAT信号传导途径,首先采用RT-PCR方法对NPC JAK家族4种成员检测,发现在两株鼻咽癌细胞株CNE1和HNE2中该家族4种成员均有表达.选择最有可能与LMP1相互作用的JAK家族成员JAK3作为我们的研究对象.利用已建立的一株受四环素衍生物强力霉素(doxycycline,Dox)调控的LMP1表达的鼻咽癌细胞系(Tet-on-LMP1 HNE2),诱导Tet-on-LMP1 HNE2细胞LMP1动态表达,蛋白质印迹发现JAK3的表达方式呈剂量和时间依赖性.采用瞬间转染方法将STAT报告基因质粒（GRR-Luc）转染入pTet-on-LMP1 HNE2细胞中,不同剂量的Dox促使LMP1的表达可以激活STAT报告基因活性,在0.06mg/L Dox诱导36 h时,STAT活性最高.在该条件下,加入3 μmol/L JAK3特异性抑制剂WHI-P131时,可抑制STAT的活性.结果表明：JAK3的表达在NPC细胞中受LMP1的调控,LMP1可以通过调控JAK3的表达参与STAT的活化.在鼻咽癌细胞中存在LMP1/JAK3/STAT信号途径并可能在其发生发展过程中起重要作用.     

人胚肺成纤维细胞WI-38中AngⅡ信号转导途径的研究

本文采用免疫荧光染色、凝胶阻滞电泳(EMSA)和Western blot等方法,观察AngⅡ刺激人胚肺二倍体成纤维细胞WI-38细胞前后,细胞中信号转导子和转录激活子STAT3、STAT1的活化状态,进而了解AngⅡ的信号转导通路.结果显示AngⅡ通过其AT1受体诱导WI-38细胞中STAT3、STAT1的磷酸化,形成以磷酸化的STAT3同源二聚体SIF-A为主的复合物,并转位入核与DNA结合,参与调控基因的表达;AngⅡ的作用存在量效及时效效应,10-3mmol/L的AngⅡ刺激60min能最强诱导WI-38细胞STAT3、STAT1的活化.因此JAK/STAT途径参与介导了An-gⅡ在WI-38中的信号转导.     

IL-39:IL-12家族的新成员

白细胞介素-39(interleukin,IL-39)是最近发现的IL-12家族新成员,由IL-23p19和EB病毒诱导基因3两个亚基组成。它主要由脂多糖刺激的B细胞和狼疮小鼠体内活化的GL7~+B细胞产生,IL-23R/gp130为其受体,在狼疮小鼠体内通过激活信号转导与转录激活因子1(STAT1)/STAT3信号通路介导炎症反应。因此,深入研究IL-39的结构、信号通路以及生物学功能,对系统性红斑狼疮和其它自身免疫性疾病的治疗具有重要价值。     

Ras蛋白信号途径及其对线虫生长发育的调控作用

Ras蛋白是一个分子质量为21 kD左右的单体GTP酶,具有两种构象:GTP结合构象(Ras.GTP)及GDP结合构象(Ras.GDP),这两种构象在一定条件下可发生互变.由生长因子介导的Ras信号传导途径是诸多信号途径中与细胞增殖、分化密切相关的重要信号途径.受体型TPK/Ras/MAPK信号转导途径是是目前研究的最为清楚的受Ras蛋白调节的信号传导途径,该途径包括受体型酪氨酸蛋白激酶(RTK)、接头蛋白、鸟苷酸释放因子(GNEF)、Ras蛋白以及MAPK级联反应体系.目前,TPK/Ras/MAPK信号转导途径在秀丽杆线虫(Caenorhabolitis elegans中研究的最为清楚:Ras信号途径对于许多发育进程是必需的,包括阴门、子宫、交合刺、P12以及排泄管细胞的诱导分化;控制着性肌原细胞迁移、轴突导向;对细胞减数分裂粗线期具有促进作用.对C.elegans的研究加深了对TPK/Ras/MAPK信号途径结构、突变体表型以及与其他信号途径的互作的了解,将会促进Ras信号途径对植物寄生线虫调控作用的研究.     

JAK/STAT信号通路及其对昆虫免疫的调控

JAK/STAT信号通路参与细胞的生长、分化、凋亡和免疫调节等重要的生物学过程,是细胞因子介导的最重要的信号转导途径之一。在昆虫中,JAK/STAT是一条相对保守的信号途径,与Toll途径和Imd途径共同作为主要免疫途径以抵御病原物入侵,在昆虫免疫、激素调控和其他生理调节过程中发挥着十分重要的作用。本文介绍了细胞因子受体超家族、JAKs家族、STATs家族和JAK/STAT信号通路及其负反馈调节的作用机制,分析了寄生物、病毒和真菌感染昆虫时,JAK/STAT信号通路的重要功能及最新研究进展,并提出了JAK/STAT信号通路研究中尚待解决的问题,以期为该领域后续深入研究提供方向和参考。     

Role of the JAK/STAT signal transduction pathway in the regulation of gene expression in CNS

Over the last 20 years the JAK/STAT signal transduction pathway has been extensively studied. An enormous amount of data on different cell signal transduction pathways is now available. The JAK/STAT signal transduction pathway is one of the intracellular signaling pathways activated by cytokines and growth factors that was first studied in the hematopoietic system, but recent data demonstrate that this signal transduction is also greatly utilized by other systems. The JAK/STAT pathway is a signaling cascade that links the activation of specific cell membrane receptors to nuclear gene expression. This review is focused on the role of JAK/STAT signal transduction pathway activation in the central nervous system (CNS).     

The Ras/Raf/MEK/extracellular signal-regulated kinase pathway induces autocrine-paracrine growth inhibition via the leukemia inhibitory factor/JAK/STAT pathway

Sustained activation of the Ras/Raf/MEK/extracellular signal-regulated kinase (ERK) pathway can lead to cell cycle arrest in many cell types. We have found, with human medullary thyroid cancer (MTC) cells, that activated Ras or c-Raf-1 can induce growth arrest by producing and secreting an autocrine-paracrine factor. This protein was purified from cell culture medium conditioned by Raf-activated MTC cells and was identified by mass spectrometry as leukemia inhibitory factor (LIF). LIF expression upon Raf activation and subsequent activation of JAK-STAT3 was also observed in small cell lung carcinoma cells, suggesting that this autocrine-paracrine signaling may be a common response to Ras/Raf activation. LIF was sufficient to induce growth arrest and differentiation of MTC cells. This effect was mediated through the gp130/JAK/STAT3 pathway, since anti-gp130 blocking antibody or dominant-negative STAT3 blocked the effects of LIF. Thus, LIF expression provides a novel mechanism allowing Ras/Raf signaling to activate the JAK-STAT3 pathway. In addition to this cell-extrinsic growth inhibitory pathway, we find that the Ras/Raf/MEK/ERK pathway induces an intracellular growth inhibitory signal, independent of the LIF/JAK/STAT3 pathway. Therefore, activation of the Ras/Raf/MEK/ERK pathway can lead to growth arrest and differentiation via at least two different signaling pathways. This use of multiple pathways may be important for "fail-safe" induction and maintenance of cell cycle arrest.     

JAK/STAT3-dependent activation of the RalGDS/Ral pathway in M1 mouse myeloid leukemia cells.

The Ras-related GTPase (Ral) is converted to the GTP-bound form by Ral guanine nucleotide dissociation stimulator (RalGDS), a putative effector protein of Ras. Recently, it was proven that Ral regulates c-Src activity and subsequent phosphorylation of its substrate, STAT3. Here, we show that STAT3 inversely regulates activation of Ral through induction of expression of RalGDS. To identify new leukemia inhibitory factor-induced genes, we have performed representational difference analysis using M1 mouse myeloid leukemia cells and cloned RalGDS. The expression of RalGDS and subsequent activation of RalA were clearly suppressed by a dominant negative form of STAT3 and a JAK inhibitor, JAB/SOCS1/SSI-1, indicating that RalGDS/RalA signaling requires the activation of the JAK/STAT3 pathway. An experiment using a Ras inhibitor demonstrated that full activation of RalA also requires activation of Ras. These results suggest a novel cross-talk between JAK/STAT3 and the Ras/RalGDS/Ral signaling pathways through gp130.     

Prolactin-stimulated activation of ERK1/2 mitogen-activated protein kinases is controlled by PI3-kinase/Rac/PAK signaling pathway in breast cancer cells

There is strong evidence that deregulation of prolactin (PRL) signaling contributes to pathogenesis and chemoresistance of breast cancer. Therefore, understanding cross-talk between distinct signal transduction pathways triggered by activation of the prolactin receptor (PRL-R), is essential for elucidating the pathogenesis of metastatic breast cancer.In this study, we applied a sequential inhibitory analysis of various signaling intermediates to examine the hierarchy of protein interactions within the PRL signaling network and to evaluate the relative contributions of multiple signaling branches downstream of PRL-R to the activation of the extracellular signal-regulated kinases ERK1 and ERK2 in T47D and MCF-7 human breast cancer cells.Quantitative measurements of the phosphorylation/activation patterns of proteins showed that PRL simultaneously activated Src family kinases (SFKs) and the JAK/STAT, phosphoinositide-3 (PI3)-kinase/Akt and MAPK signaling pathways. The specific blockade or siRNA-mediated suppression of SFK/FAK, JAK2/STAT5, PI3-kinase/PDK1/Akt, Rac/PAK or Ras regulatory circuits revealed that (1) the PI3-kinase/Akt pathway is required for activation of the MAPK/ERK signaling cascade upon PRL stimulation; (2) PI3-kinase-mediated activation of the c-Raf-MEK1/2-ERK1/2 cascade occurs independent of signaling dowstream of STATs, Akt and PKC, but requires JAK2, SFKs and FAK activities; (3) activated PRL-R mainly utilizes the PI3-kinase-dependent Rac/PAK pathway rather than the canonical Shc/Grb2/SOS/Ras route to initiate and sustain ERK1/2 signaling. By interconnecting diverse signaling pathways PLR may enhance proliferation, survival, migration and invasiveness of breast cancer cells.