GTF2H2通过介导AKT信号通路影响肝癌细胞Hep3B的增殖和迁移*

目的:探讨通用转录因子II H亚基2(GTF2H2)是否影响肝癌细胞Hep3B的增殖和迁移及其潜在的分子机制。方法:通过转染GTF2H2-siRNA构建GTF2H2敲低的Hep3B肝癌细胞模型;实时定量聚合酶链反应(q-RT-PCR)和蛋白质印迹实验检测肝癌细胞Hep3B的GTF2H2敲低效果;细胞计数实验(MTS)检测GTF2H2敲低的肝癌细胞Hep3B的增殖能力;Transwell细胞迁移实验检测GTF2H2敲低的肝癌细胞Hep3B的迁移能力;蛋白质印迹分析实验检测GTF2H2敲低后是否影响肿瘤相关分子信号通路。结果: GTF2H2敲低组的Hep3B细胞的增殖能力较对照组的Hep3B细胞增强,迁移能力亦有增强;蛋白质印迹实验显示GTF2H2敲低后,p-AKT通路蛋白的表达明显升高。结论:GTF2H2可能通过介导AKT分子信号通路,影响肝癌细胞Hep3B的增殖和迁移能力。     

瓜蒂醇提物通过调控Wnt/β-catenin信号通路对肝癌细胞Hep3B恶性生物学行为的影响

该文探讨了瓜蒂醇提物对肝癌细胞Hep3B增殖、迁移、侵袭和凋亡的影响及其分子机制。肝癌细胞Hep3B被分为NC组、不同浓度瓜蒂醇提物(1.0、5.0、10.0、20.0μg/mL)组、LiCl组、20.0μg/mL瓜蒂醇提物+LiCl组。采用CCK-8法检测细胞活性;克隆形成实验检测Hep3B细胞克隆形成数量;流式细胞术检测Hep3B细胞的凋亡情况;蛋白质印迹法检测蛋白表达情况; Transwell检测Hep3B细胞的迁移和侵袭数。不同浓度瓜蒂醇提物处理Hep3B细胞后, Hep3B细胞的活性降低,克隆数量以及迁移侵袭数减少, Hep3B细胞的凋亡率升高, Cleaved-caspase-3表达水平升高, procaspase-3、MMP2、MMP9表达水平降低, Wnt3a、cyclinD1、c-myc、核β-catenin蛋白表达水平降低,APC和质β-catenin蛋白表达水平升高(P<0.05)。Wnt/β-catenin信号通路激活剂LiCl可以逆转瓜蒂醇提物对Hep3B细胞增殖、迁移、侵袭和凋亡的影响。瓜蒂醇提物通过调控Wnt/β-catenin信号通路抑制Hep3B...     

肝细胞生长因子诱导人肝癌细胞上皮间质转化

上皮间质转化(epithelial-mesenchymal transition,EMT)与肿瘤侵袭转移密切相关.虽然肝细胞生长因子(hepatocyte growth factor,HGF)已被证实为肿瘤EMT的主要诱导剂,但是HGF诱导肿瘤EMT发生的分子机制尚不完全清楚.本研究旨在探讨Snail在HGF诱导肝癌细胞上皮间质转化中的作用.用HGF处理肝癌Hep G2和Hep3B细胞,显微镜观察细胞形态变化,划痕试验及Transwell试验检测细胞迁移能力,Western印迹检测Met,AKT的磷酸化及蛋白质表达的变化,Western印迹与real-time RT-PCR检测上皮细胞表面标志E-Cadherin和间质细胞表面标志NCadherin、Fibronectin的表达变化,以及EMT相关转录因子的表达变化.经HGF处理的Hep G2、Hep3B细胞,Met和AKT的磷酸化水平显著增强;相差倒置显微镜下观察细胞形态向间质型细胞形态转化;细胞划痕和Transwell试验检测细胞的迁移能力较对照组显著增强;Real-time RT-PCR和Western印迹实验显示HGF的诱导能上调间质标记蛋白的表达及下调上皮型标志蛋白的表达.进一步发现,HGF能上调转录因子Snail的表达,干扰Snail能逆转HGF对Hep G2和Hep 3B细胞EMT发生的诱导作用.由此可见,HGF可能通过诱导Snail的表达促进肝癌细胞EMT的发生.这为阐明肝癌细胞侵袭转移机制,以及肝癌的防治提供新线索.     

丹参酮通过VEGF/VEGFR信号通路抑制肝癌细胞迁移和侵袭能力的实验研究

目的:探究丹参酮通过VEGF/VEGFR信号通路抑制肝癌细胞迁移和侵袭能力的机制。方法:体外培养人肝癌细胞Hep3B、HepG2,并分为:实验组、阳性对照组和空白对照组,实验组使用丹参酮处理,阳性对照组使用阿霉素处理,空白对照为加入10μL DMSO或生理盐水,使用CCK8检测肝癌细胞的增殖情况;分别加入浓度为31μmol/L和2.5μmol/L的丹参酮及阿霉素显微镜下观察细胞形态变化;使用流式细胞术检测肝癌细胞的凋亡情况和细胞周期情况;使用Western blot检测肝癌细胞VEGF及VEGFR蛋白表达情况。结果:MTT实验结果显示,随着丹参酮和阿霉素使用浓度的升高人肝癌细胞Hep3B、HepG2生长受到显著的抑制(P0.05);显微镜下观察发现丹参酮可以抑制肝癌肿瘤细胞增殖;流式细胞检测发现相比空白对照组,阳性对照组和实验组(人肝癌细胞Hep3B、HepG2)细胞凋亡率显著增加(P0.05);相比空白对照组,实验组和阳性对照组G0/G1期细胞百分比显著增加(P0.05),S期和G2/M期细胞百分比显著降低(P0.05);蛋白质印记实验结果显示,相比空白对照组,实验组和阳性对照组VEGF及VEGFR蛋白表达显著降低(P0.05),且实验组表达显著低于阳性对照组(P0.05)。结论:参酮通可以通过抑制VEGF/VEGFR信号通路,将肝癌细胞分裂阻滞在G0/G1,达到抑制肝癌细胞的增殖及迁移和侵袭能力的效果。     

沉默脂肪细胞增强子结合蛋白2通过PI3K/Akt途径抑制肝癌细胞增殖和迁移

脂肪细胞增强子结合蛋白2(AEBP2)作为多梳抑制复合物2(PRC2)的组成蛋白质,参与多种肿瘤细胞的增殖和迁移,然而其在肝癌中的作用尚不清楚。本研究基于UALCAN和Kaplan-Meier Plotter数据库分析发现,AEBP2在肝癌组织中高表达,并且与患者的不良预后呈正相关。实时荧光定量PCR和蛋白质印迹结果证实,AEBP2在肝癌细胞中的表达高于正常肝细胞。在HepG2和Huh-7细胞中转染AEBP2 siRNA,平板克隆、CCK-8、流式细胞术、划痕愈合和Transwell结果显示,沉默AEBP2可以抑制肝癌细胞增殖、迁移和侵袭,并促进细胞凋亡(P＜0.05)。免疫荧光检测和蛋白质印迹结果显示,沉默AEBP2能够抑制肝癌细胞上皮-间质转化(EMT)(P＜0.05)。生物信息学分析结果表明,AEBP2参与调控PI3K/Akt信号通路。蛋白质印迹结果证实,沉默AEBP2能下调PI3K、p-AKT (S473)、mTOR、MMP-2和MMP-9的蛋白质表达水平(P＜0.05)。此外,沉默AEBP2对HepG2细胞迁移和侵袭的影响可被PI3K/Akt通路激动剂胰岛素样生长因子1(IGF-1)部分逆转(P＜0.01)。综上所述,AEBP2可能通过调节PI3K/Akt途径促进肝癌细胞增殖和迁移。本研究为AEBP2在肝癌中的作用提供理论依据。     

肝细胞生长因子诱导人肝癌细胞上皮间质化

上皮间质转化（epithelial-mesenchymal transition,EMT）与肿瘤侵袭转移密切相关.虽然肝细胞生长因子（hepatocyte growth factor,HGF）已被证实为肿瘤EMT的主要诱导剂,但是HGF诱导肿瘤EMT发生的分子机制尚不完全清楚.本研究旨在探讨Snail在HGF诱导肝癌细胞上皮间质转化中的作用.用HGF处理肝癌HepG2和Hep3B细胞,显微镜观察细胞形态变化,划痕试验及Transwell试验检测细胞迁移能力,Western印迹检测Met,AKT的磷酸化及蛋白质表达的变化,Western印迹与real-time RT-PCR检测上皮细胞表面标志E-Cadherin和间质细胞表面标志N-Cadherin、Fibronectin的表达变化,以及EMT相关转录因子的表达变化.经HGF处理的HepG2、Hep3B细胞,Met和AKT的磷酸化水平显著增强;相差倒置显微镜下观察细胞形态向间质型细胞形态转化;细胞划痕和Transwell试验检测细胞的迁移能力较对照组显著增强;Real-time RT-PCR和Western印迹实验显示HGF的诱导能上调间质标记蛋白的表达及下调上皮型标志蛋白的表达.进一步发现,HGF能上调转录因子Snail的表达,干扰Snail能逆转HGF对HepG2和Hep 3B细胞EMT发生的诱导作用.由此可见,HGF可能通过诱导Snail的表达促进肝癌细胞EMT的发生.这为阐明肝癌细胞侵袭转移机制,以及肝癌的防治提供新线索.     

野鸦椿酸对人肝癌细胞的抑制作用及机理研究

探讨圆齿野鸦椿中野鸦椿酸(EA)对人肝癌细胞增殖、侵袭和迁移能力的影响及其机制研究。从圆齿野鸦椿果皮中提取得到EA,通过培养人肝癌细胞Hep G2细胞,以MTT法分析EA对Hep G2细胞增殖的影响,流式细胞术评价不同浓度(20、40、80μmol/L)的EA对Hep G2细胞的凋亡状态和周期分布情况,细胞划痕、Transwell小室实验考察对Hep G2细胞侵袭转移能力的变化,用Western blot法和荧光定量PCR法检测野鸦椿酸对上皮-间质转化(EMT)相关标志物E-Cadherin、N-Cadherin、Vimentin、MMP-2和MMP-9的蛋白和mRNA表达的影响。结果显示,EA抑制人肝癌细胞Hep G2细胞的增殖,24、48、72 h的IC50分别为32. 16±4. 58、26. 45±3. 79、和16. 76±4. 01μmol/L。随EA浓度的增大,细胞的凋亡率逐渐升高,且发生显著的G0/G1期阻滞。EA可降低Hep G2细胞的侵袭和迁移能力,上调E-Cadherin的蛋白和mRNA的水平,下调N-Cadherin、Vimentin、MMP-2和MMP-9的蛋白和mRNA表达。EA抑制人肝癌细胞增殖和侵袭转移能力,可能与其调控EMT相关信号通路有关。     

慢病毒介导的低表达RNF20肝癌稳转细胞系的构建及其生物学功能分析

该文探讨了环指蛋白(RNF20)缺陷对肝细胞肝癌的细胞增殖和迁移的影响,及其可能的作用机制。针对RNF20基因设计3组短发夹RNA序列(RNF20-shRNA1、RNF20-shRNA2和RNF20-shRNA3),通过构建pLent-U6-GFP-Puro-shRNF20慢病毒载体,包装慢病毒后感染人肝癌细胞SMMC-7721和Huh7,经嘌呤霉素抗性筛选建立RNF20敲低的肝细胞肝癌稳转细胞系。同时,设感染对照慢病毒pLV-shCtrl-EGFP的对照组(shCtrl-7721/shCtrl-Huh7)。实时荧光定量PCR检测RNF20 mRNA表达,荧光显微镜观察其绿色荧光蛋白表达,免疫荧光染色法和蛋白免疫印迹法检测RNF20、T-Akt及p-Akt蛋白的表达情况,BrdU掺入实验及CCK-8法检测各组细胞增殖能力,划痕实验检测各组细胞迁移能力,转录组测序分析基因转录水平。结果显示,RNF20-shRNA2对应肝癌细胞中的RNF20 mRNA表达最低,稳转细胞感染效率均高于85%,RNF20缺陷的SMMC-7721和Huh7较对照组细胞内RNF20、Wee1、p27、p53基因转录水平及RNF20蛋白表达水平明显降低,增殖与迁移能力明显增加,且p-Akt蛋白表达上调。Akt抑制剂派立福新处理的RNF20缺陷的肝癌细胞较未处理组增殖与迁移能力降低。实验结果提示,RNF20下调后促进肝癌细胞体外增殖与迁移,且其可能通过Akt通路进行调节。     

17β-雌二醇通过PI3K/Akt/mTOR通路抑制白介素1β诱导的大鼠椎间盘髓核细胞的凋亡

髓核细胞(nucleus pulposus cells,NPCs)的异常凋亡是导致椎间盘退变(intervertebral disc degeneration,IVDD)的主要原因。本研究组前期研究显示,17β-雌二醇(17β-estradiol,E2)能够通过PI3K/Akt信号通路抑制白介素1β(interleukin-1β,IL-1β)诱导的大鼠椎间盘NPCs凋亡。本研究旨在探讨PI3K/Akt途径的下游蛋白是否参与E2对NPCs凋亡的抑制作用。用胰蛋白酶消化法分离原代大鼠NPCs,采用E2和PI3K/Akt信号通路下游蛋白的不同抑制剂预处理后用IL-1β处理,用Annexin V/PI染色法检测凋亡率,用CCK-8法检测细胞活力,用细胞黏附试验检测NPCs与Ⅱ型胶原的黏附能力,用Western blot检测哺乳动物雷帕霉素靶蛋白(mammalian target of Rapamycin,mTOR)、糖原合成酶激酶-3β(glycogen synthase kinase-3β,GSK-3β)和核因子κB(nuclear factor kappaB,NF-κB)磷酸化水平。结果显示,E2显著抑制IL-1β诱导的NPCs凋亡,逆转由IL-1β引起的细胞活力和黏附能力的降低,抑制IL-1β对mTOR磷酸化水平的下调作用,而雷帕霉素可以阻断E2的这些保护作用。以上结果提示,E2可能通过PI3K/Akt/mTOR信号通路抑制IL-1β诱导的NPCs凋亡。     

趋化因子受体CX3CR1对人肝癌细胞7721和HepG2的作用及其机制的研究

目的:探究趋化因子受体CX3CR1(C-X3-C motif chemokine receptor 1,CX3CR1)对人肝癌细胞7721和Hep G2增殖、迁移和侵袭的影响及其机制。方法:采用Q-PCR和Western blot法分别检测人正常肝细胞LO2和两种肝癌细胞(7721和Hep G2)中CX3CR1的基因表达情况(mRNA和蛋白质);以过表达CX3CR1的质粒转染7721细胞,用抑制CX3CR1的干扰RNA转染Hep G2细胞,通过Q-PCR和Western blot法检测CX3CR1的变化;应用MTT和流式细胞实验检测各组细胞的增殖能力;用集落形成实验检测各组细胞的自我更新和增殖能力;借助划痕愈合和Transwell检测各组细胞的迁移和侵袭能力;利用Western blot法检测PI3K/AKT、MAPK/ERK信号通路的激活情况。结果:CX3CR1在7721细胞中mRNA和蛋白质呈低表达趋势,而在Hep G2细胞中则呈高表达趋势;转染过表达CX3CR1质粒后7721细胞中CX3CR1的mRNA和蛋白水平有明显的升高,细胞的增殖、迁移、侵袭能力增强,p-AKT和p-ERK水平升高;转染干扰RNA后Hep G2细胞中的CX3CR1表达水平明显下降,增殖、迁移、侵袭能力减弱,p-AKT和p-ERK水平降低。结论:趋化因子受体CX3CR1可以促进人肝癌细胞增殖、迁移和侵袭能力,该作用可能与PI3K/AKT、MAPK/ERK信号通路激活有关。     

Polarization and Migration of Hematopoietic Stem and Progenitor Cells Rely on the RhoA/ROCK I Pathway and an Active Reorganization of the Microtubule Network

Understanding the physiological migration of hematopoietic progenitors is important, not only for basic stem cell research, but also in view of their therapeutic relevance. Here, we investigated the role of the Rho kinase pathway in the morphology and migration of hematopoietic progenitors using an ex vivo co-culture consisting of human primary CD34⁺ progenitors and mesenchymal stromal cells. The addition of the Rho kinase inhibitor Y-27632 led to the abolishment of the uropod and microvillar-like structures of hematopoietic progenitors, concomitant with a redistribution of proteins found therein (prominin-1 and ezrin). Y-27632-treated cells displayed a deficiency in migration. Time-lapse video microscopy revealed impairment of the rear pole retraction. Interestingly, the knockdown of ROCK I, but not ROCK II, using RNA interference (RNAi) was sufficient to cause the referred morphological and migrational changes. Unexpectedly, the addition of nocodazole to either Y-27632- or ROCK I RNAi-treated cells could restore their polarized morphology and migration suggesting an active role for the microtubule network in tail retraction. Finally, we could demonstrate using RNAi that RhoA, the upstream regulator of ROCK, is involved in these processes. Collectively, our data provide new insights regarding the role of RhoA/ROCK I and the microtubules in the migration of stem cells.     

犬皮肤成纤维细胞的分离、培养及鉴定

目的探索和建立适用于犬皮肤成纤维细胞的体外分离、培养及鉴定的技术方法。方法采用组织贴块培养法和胰蛋白酶、胶原酶Ⅰ联合消化法对犬皮肤成纤维细胞进行体外培养、传代。并对所培养的细胞进行倒置显微镜观察和苏木素-伊红染色,观察成纤维细胞形态,并对培养细胞行波形蛋白免疫荧光染色。结果倒置相差显微镜下可见长梭形细胞生长,苏木素-伊红染色可见细胞呈漩涡状、平行排列,第5代细胞免疫荧光检测波形蛋白(vimentin)表达阳性。结论建立了高效快速分离和稳定培养成纤维细胞的方法,为诱导犬心房纤维化提供了充足的种子细胞。     

An overview of the KIN1/PAR-1/MARK kinase family

Members of the KIN1/PAR-1/MARK kinase family are conserved from yeast to humans and share a similar primary structural organization. Several kinases of this family appear to be at the crossroads of various biological functions including cell polarity, cell cycle control, intracellular signalisation, microtubules stability and protein stability. Here we present an overview of known roles of KIN1/PAR-1/MARK kinases including pEg3 a newly identified member which is regulated during the cell cycle and is a potential regulator of the cell cycle progression. Some common modes of action can be deciphered for this protein kinase family.     

Critical role of lipid membranes in polarization and migration of cells: a biophysical view

Cell migration plays vital roles in many biologically relevant processes such as tissue morphogenesis and cancer metastasis, and it has fascinated biophysicists over the past several decades. However, despite an increasing number of studies highlighting the orchestration of proteins involved in different signaling pathways, the functional roles of lipid membranes have been essentially overlooked. Lipid membranes are generally considered to be a functionless two-dimensional matrix of proteins, although many proteins regulating cell migration gain functions only after they are recruited to the membrane surface and self-organize their functional domains. In this review, we summarize how the logistical recruitment and release of proteins to and from lipid membranes coordinates complex spatiotemporal molecular processes. As predicted from the classical framework of the Smoluchowski equation of diffusion, lipid/protein membranes serve as a 2D reaction hub that contributes to the effective and robust regulation of polarization and migration of cells involving several competing pathways.     

miR-125a-5p转染对肝癌细胞增殖、侵袭、迁移的影响及相关机制研究

摘要 目的：探究miR-125a-5p转染对肝癌细胞增殖、侵袭、迁移的影响及相关机制。方法：将肝癌细胞分为对照组、下调组和上调组,并通过细胞转染建立稳定转染的下调组和上调组。MMT法检测细胞增殖能力,流式细胞仪检测细胞凋亡能力,Transwell小室实验检测细胞侵袭能力,细胞划痕实验检测细胞迁移能力,Western blot法检测P13K/Akt通路中AKT、Bax、Bcl-2、P13K、P-AKT蛋白表达量。结果：与上调组相比,下调组24、48、72 h细胞增殖率,细胞侵袭、迁移细胞数,AKT、Bcl-2、P13K、P-AKT蛋白表达量显著降低,具有统计学差异（29.67±9.87 vs 17.34±5.71,t=5.192,P＜0.05、34.75±11.56 vs 15.17±5.04,t=7.365,P＜0.05、38.48±12.81 vs 12.51 ±4.13,t=9.153,P＜0.05,72.53±24.17 vs 36.28±12.07,t=6.365,P＜0.05、86.51±28.75 vs 46.28±15.32,t=5.858,P＜0.05,1.26±0.41 vs 0.81±0.26,t=4.397,P＜0.05、1.35±0.44 vs 0.76±0.24,t=5.584,P＜0.05、1.48±0.46 vs 0.79±0.26,t=6.194,P＜0.05、1.22±0.39 vs 0.73±0.24,t=5.584,P＜0.05）;与上调组相比,下调组24、48、72h细胞凋亡率,Bax蛋白表达量显著升高,具有统计学差异（17.62±5.84 vs 29.31±9.75,t=4.879,P＜0.05、14.97±4.65 vs 34.19±11.36,t=7.427,P＜0.05、11.26±3.74 vs 38.62±12.86,t=9.690,P＜0.05,0.75±0.24 vs 1.33±0.43,t=5.587,P＜0.05）。结论：下调miR-125a-5p的表达,可通过作用于P13K/Akt通路,调控AKT、Bax、Bcl-2、P13K、P-AKT蛋白表达量,进而起到抑制肝癌细胞增殖、促进肝癌细胞凋亡以及抑制肝癌细胞的侵袭、迁移能力。     

A Scalable Approach to Prevent Teratoma Formation of Human Embryonic Stem Cells

As the renewable source of all cell types in the body, human embryonic stem cells (hESCs) hold great promise for human cell therapy. However, one major bottleneck that hinders the clinic application of hESCs is that hESCs remaining with their differentiated derivatives pose cancer risk by forming teratomas after transplantation. NANOG is a critical pluripotency factor specifically expressed in hESCs but rarely in their differentiated derivatives. By introducing a hyperactive variant of herpes simplex virus thymidine kinase gene into the 3′-untranslated region of the endogenous NANOG gene of hESCs through homologous recombination, we developed a safe and highly scalable approach to efficiently eliminate the teratoma risk associated with hESCs without apparent negative impact on their differentiated cell types. As thymidine kinase is widely used in human gene therapy trials and is the therapeutic target of U. S. Food and Drug Administration-approved drugs, our strategy could be effectively applied to the clinic development of hESC-based human cell therapy.     

Cell separation with horizontal cell electrophoresis under near-isopycnic conditions on a “density cushion”

This report describes an improvement made to the horizontal cell electrophoresis methodology. It involves using two liquid layers differing in density to produce an interface described as a "density cushion". The electrophoretic system that employed an anti-convective porous matrix to separate red blood cells (RBC) and charged dyes effectively was found to be unsuitable for some other mammalian cells. The "density cushion" method was found to be more versatile and applicable to studies on the separation of a variety of cell types. The experiments described show the differences between the electrophoretic mobilities of a human eosinophilic leukaemia cell line (Eol-1) and RBC, both with and without the modification of the cell surface properties.     

The influence of cell volume changes on tumour cell proliferation

Ion channels and cell volume control participate in a wide variety of cellular functions, including cell proliferation. According to the pump-leak model or the double Donnan system, the cell volume is constant in physiological medium so long as the cell metabolism and the Na-K pump are not inhibited and the passive Na⁺ permeability is not dramatically increased. At short term, this model has been supported by a large number of experiments made on different cell types. However, at long term, it may be insufficient to describe the volume control because it does not take into account the fact that cells possess a large number of membrane transporters and interconnected volume regulatory mechanisms. In this review, we present recent results indicating that, in physiological conditions, ion channels may have important roles in cell volume control. Furthermore, we emphasize that cell proliferation and volume are phenomenologically correlated. On the basis of the macromolecular crowding theory, the possibility that the cell osmolyte and water content mediates this correlation is discussed.Abbreviations 4-AP 4-aminopyridine - NPPB 5-nitro-2-(3-phenylpropylamino)benzoic acid - TEA tetraethylammonium - TOR target of rapamycin Presented at the Biophysical Society Meeting on Ion channels—from structure to desease held in May 2003, Rennes, France     

Cell electrophoresis — a method for cell separation and research into cell surface properties

In this paper, we discuss the application of various methods of cell electrophoresis in research into cell surface properties (analytical methods), and the separation of uniform cell subpopulations from cell mixtures (preparative methods). The emphasis is on the prospects of the development of simplified and versatile methodologies, i.e. microcapillary cell electrophoresis and horizontal cell electrophoresis under near-isopycnic conditions. New perspectives are considered on the use of analytical and preparative cell electrophoresis in research on cell differentiation, neoplastic transformation, cell-cell interactions and the biology of stem cells. Paper authored by participants of the international conference: XXXIV Winter School of the Faculty of Biochemistry, Biophysics and Biotechnology of Jagiellonian University, Zakopane, March 7–11, 2007, “The Cell and Its Environment”. Publication cost was covered by the organisers of this meeting.     

Molecular basis for T cell response induced by altered peptide ligand of type II collagen

Mounting evidence from animal models has demonstrated that alterations in peptide-MHC interactions with the T cell receptor (TCR) can lead to dramatically different T cell outcomes. We have developed an altered peptide ligand of type II collagen, referred to as A9, which differentially regulates TCR signaling in murine T cells leading to suppression of arthritis in the experimental model of collagen-induced arthritis. This study delineates the T cell signaling pathway used by T cells stimulated by the A9·I-A(q) complex. We have found that T cells activated by A9 bypass the requirement for Zap-70 and CD3-ζ and signal via FcRγ and Syk. Using collagen-specific T cell hybridomas engineered to overexpress either Syk, Zap-70, TCR-FcRγ, or CD3-ζ, we demonstrate that A9·I-A(q) preferentially activates FcRγ/Syk but not CD3-ζ/Zap-70. Moreover, a genetic absence of Syk or FcRγ significantly reduces the altered peptide ligand induction of the nuclear factor GATA3. By dissecting the molecular mechanism of A9-induced T cell signaling we have defined a new alternate pathway that is dependent upon FcRγ and Syk to secrete immunoregulatory cytokines. Given the interest in using Syk inhibitors to treat patients with rheumatoid arthritis, understanding this pathway may be critical for the proper application of this therapy.