Kruppel样因子4对内毒素所致IL-6基因表达的调控及机制研究

探讨Kruppel样因子4(KLF4)对内毒素所致白介素(IL-6)的基因表达以及释放的影响,并对其调控机制做了初步研究．使用RT-PCR和Western blot检测KLF4 mRNA和蛋白质的表达．采用KLF4过表达的RAW264.7巨噬细胞株或反义寡核苷酸技术抑制内源性KLF4的表达,用RT-PCR和ELISA检测内毒素(LPS)刺激后IL-6 mRNA和蛋白质的表达．采用荧光素酶报告基因检测RAW264.7细胞中KLF4过表达对IL-6基因启动子报告基因转录活性的影响．使用EMSA法检测细胞中KLF4与IL-6基因启动子区KLF4元件的结合．结果表明：LPS可以诱导RAW264.7巨噬细胞KLF4的表达以及IL-6蛋白表达．KLF4过表达明显抑制IL-6的mRNA和蛋白质的表达,而KLF4缺失使这种作用消失．荧光素酶报告基因的结果显示,KLF4可以抑制LPS所致的IL-6基因启动子的转录活性．EMSA显示KLF4不能与IL-6启动子区的KLF4结合元件直接结合．结果表明,LPS可以促进RAW264.7小鼠巨噬细胞KLF4的表达和IL-6的释放．KLF4能抑制LPS诱导的IL-6表达和释放,其机制是抑制IL-6启动子的转录活性,但KLF4的抑制作用不是通过直接与IL-6基因的启动子区相结合而实现的．     

内毒素血症Rig-Ⅰ表达调控的机制研究北大核心

[目的]探讨内毒素血症Rig-Ⅰ表达调控的机制。[方法](1)DNA-pull down、2D-DIGE结合生物质谱技术筛选分离、鉴定对照和内毒素血症小鼠肝组织核蛋白与Rig-Ⅰ基因启动子结合的差异蛋白质;(2)q PCR和细胞免疫荧光检测LPS刺激RAW264.7细胞hnRNP A3 mRNA表达及细胞内定位。[结果](1)筛选鉴定得到hnRNP A3等7种与内毒素血症Rig-Ⅰ基因启动子结合的蛋白质;(2)LPS刺激下hnRNP A3 mRNA显著升高(P<0.01),且具有明显的细胞核定位。[结论]共有7种蛋白质参与内毒素血症Rig-Ⅰ基因表达调控,为进一步Rig-Ⅰ表达调控的研究奠定了良好基础。     

内毒素血症Rig-Ⅰ表达调控的机制研究

[目的]探讨内毒素血症Rig-Ⅰ表达调控的机制。[方法](1)DNA-pull down、2D-DIGE结合生物质谱技术筛选分离、鉴定对照和内毒素血症小鼠肝组织核蛋白与Rig-Ⅰ基因启动子结合的差异蛋白质;(2)q PCR和细胞免疫荧光检测LPS刺激RAW264.7细胞hnRNP A3 mRNA表达及细胞内定位。[结果](1)筛选鉴定得到hnRNP A3等7种与内毒素血症Rig-Ⅰ基因启动子结合的蛋白质;(2)LPS刺激下hnRNP A3 mRNA显著升高(P0.01),且具有明显的细胞核定位。[结论]共有7种蛋白质参与内毒素血症Rig-Ⅰ基因表达调控,为进一步Rig-Ⅰ表达调控的研究奠定了良好基础。     

KLFs对珠蛋白基因表达和红系分化的调控作用

Krüppel样因子(Krüppel-like factors, KLFs)是一组与真核基因转录调控密切相关的锌指蛋白.KLFs高度保守的羧基末端含3个串联的Cys2His2型锌指结构,用于结合GC盒和CACCC盒等DNA序列. 红细胞中特异表达的珠蛋白基因和许多红系调控因子中都含有CACCC盒.已有研究发现,多个KLFs通过结合CACCC盒参与调控珠蛋白基因表达和红系分化,例如,KLF1通过结合β-珠蛋白启动子和位点控制区(locus control region, LCR),促进β-珠蛋白的表达、γ-向β-珠蛋白基因的转换和红系分化;KLF2、KLF11和KLF13分别促进ε-和γ-珠蛋白基因的表达;KLF4促进α-和γ-珠蛋白基因的表达;KLF3和KLF8则抑制ε-和γ-珠蛋白基因的表达. 本文综述了KLFs调控珠蛋白基因表达和红系分化的研究进展.     

HP感染后Men1基因对非酒精性脂肪肝病及炎症反应的调控机制

为了研究HP感染后Men1基因对NAFLD小鼠的调控机理,本研究检测了Men1基因和蛋白在NAFLD+HP和NAFLD组小鼠中的表达,同时检测了炎症因子IL-6和IL-18基因以及含量的变化。结果表明,HP感染后NAFLD小鼠中Men1基因和蛋白的表达均显著下调,但是IL-6和IL-18基因和含量均显著上调和增加。结合前人的研究报道结果,本研究推断Men1基因可能会与小鼠体内的其它因子协同来影响IL-6和IL-18等炎症因子的表达,而Men1基因下调阻断了这种协同作用,从而使IL-6和IL-18等炎症因子表达上调,促进小鼠肝脏的损伤程度。因此本实验的结果表明,Men1基因可能会是治疗HP感染后NAFLD的一个有效的靶点,改变其表达量就能调节HP感染的非酒精性脂肪肝病的严重程度。     

转录因子PU.1和KLF7在小鼠组织中的基因表达分析

转录因子PU.1和KLF7在脂肪形成、造血分化、肿瘤发生和机体免疫等方面发挥重要作用,但是两者在功能上是否具有相关性尚不清楚.本研究旨在研究PU.l和KLF7在小鼠不同组织中的表达模式及相关性.利用RT-qPCR检测PU.1和KLF7在小鼠胃、肝脏、空肠、肺、腿肌、心脏、脂肪、胸肌、脾脏、肾脏和脑组织中的表达情况,并分析表达相关性.结果显示,KLF7在肺、胃和脂肪中的表达量较高,PU.1在肺、肝脏和脾脏中的表达量较高;两个基因的表达呈极显著正相关(r=0.857,P=0.001).生物信息学预测显示,在KLF7的5'侧翼区共存在5个PU.1的结合位点,PU.1可能正调控KLF7基因的表达.本研究为深入研究PU.1和KLF7的功能及相互作用机制提供重要的基础数据.     

转录因子KLF5调控宫颈癌细胞上皮-间充质转化的分子机制

上皮-间充质转化(epithelial-mesenchymal transition, EMT)是上皮细胞来源的恶性肿瘤细胞获得迁移和侵袭能力的重要生物学过程。为了探究Krüppel样因子5 (Krüppel-like factor 5, KLF5)调控宫颈癌细胞发生EMT过程的分子机制,首先在宫颈癌HeLa细胞瞬时转染Flag-KLF5质粒进行KLF5过表达,并通过MTT法、细胞划痕和Transwell实验证实, KLF5可以显著地抑制HeLa细胞的侵袭和迁移能力。然后采用Western-blot和实时定量PCR技术检测HeLa细胞中EMT相关基因的表达水平,结果显示E-cadherin表达升高, N-cadherin和MMP9表达降低;而且, E-cadherin基因的上游调控因子如SNAI1、SLUG、ZEB1/2和TWIST1等的m RNA表达下降。进一步开展对比研究,在Si Ha细胞中用si RNA沉默KLF5基因,再次验证了KLF5对EMT相关基因表达水平的影响。随后构建不同长度的SNAI1启动子截短体,用荧光素酶报告基因实验检测KLF5对SNAI1启动子活性的影响,结果显示KLF5可以抑制SNAI1启动子区域的活性,并且在HeLa细胞中过表达SNAI1基因后,可显著地促进细胞的EMT过程。以上结果表明, KLF5可通过调控SNAI1基因的表达来调节宫颈癌细胞的EMT过程,进而抑制宫颈癌细胞的迁移和侵袭能力。     

基因修饰的肝细胞脾内移植后体内分布和基因表达的实验研究

为探讨基因修饰的肝细胞经脾内移植途径介导肝脏基因治疗的可行性和有效性,体外用NeoR基因或IL-2基因修饰小鼠正常胚胎肝细胞BNL CL.2,经脾内移植至正常同系小鼠体内(2×10⁶/只),观察NeoR和IL-2基因在不同脏器的表达.结果发现脾内移植NeoR基因修饰的肝细胞后24h,即可通过RT-PCR在肝脏中检测出NeoR基因mRNA的表达,持续表达11周以上;此外,NeoR基因在脾脏中短暂表达(24h至1周),在肺组织中也有一过性表达(48～96h).脾内移植IL-2基因修饰的肝细胞后,肝脏中可检测到稳定表达的IL-2mRNA(24h至11周),外周血中维持一定水平(5～40pg/mL)的IL-2,能增强肝脏Kupffer细胞Ia抗原的表达及脾细胞的NK杀伤活性.提示基因修饰的肝细胞脾内移植后能定向分布至肝脏,并同化入肝组织中长期存活,有效地表达外源基因,可成为肝脏靶向性基因治疗的可行途径.     

雷公藤甲素致小鼠肝损伤的机制研究

本文研究雷公藤甲素致肝损伤作用机制。将雌性C57BL/6小鼠20只随机分为2组,并以雷公藤甲素造模,通过检测血清中谷丙转氨酶(ALT)水平变化,以及观察小鼠肝脏组织切片HE染色结果,了解肝脏损伤情况;RT-PCR法检测小鼠肝脏中白细胞介素(IL)-17、IL-6、维甲酸孤儿核受体(ROR-γt)mRNA表达水平,ELISA法检测IL-17、IL-6蛋白表达水平,Western blot法检测小鼠肝脏中TLR4蛋白表达水平。与对照组比较,雷公藤甲素模型组小鼠血清ALT水平显著升高(P0.005),HE染色切片显示较多的肝细胞坏死和炎症细胞浸润,IL-17、IL-6、ROR-γt mRNA表达水平和IL-17、IL-6蛋白表达水平显著升高(P0.005),此外,TLR4蛋白表达水平显著升高(P0.005)。结果表明,雷公藤甲素所导致的肝损伤可能通过激活TLR4信号,增加IL-17、IL-6的表达,影响Th17特异性转录因子ROR-γt,进而促进Th17细胞活化,增强其致炎功能。     

ApoE基因缺失幼龄小鼠动脉粥样硬化相关基因的时序表达研究

利用RT-PCR技术检测apoE基因缺失(apoE-/-小鼠在1、2和3月龄3个年龄段主动脉以及14天、1、2和3月龄4个年龄段肝脏中动脉粥样硬化(atherosclerosis,AS)重要相关基因的时序表达特点,并通过血清牛化检测结合主动脉根部病理形态学特征的分析,探讨AS重要相关基因时序表达特点与AS早期病变的关系.在主动脉检测的9条AS相关基因中,apoE-/-与野生型(WT)小鼠相比,1、2和3月龄时IL-1β的mRNA表达水平均显著上调.1月龄时VCAM-1、IKB和TGF-β,2月龄时PDGF-α和CD36,3月龄时TNF-α和MM2的mRNA表达水平均显著上调,其他年龄段无显著变化.在肝脏检测的2条AS相关基因中,C反应蛋白(CRP)的mRNA表达水平在14天到2月龄时无显著变化,3月龄时显著上调.NF-kB在各年龄段apoE-/-小鼠主动脉和肝脏中的基因表达量与同龄WT小鼠相比均无显著差异.不同年龄段的apoE-/-小鼠血清TC、TG和LDL-C水平均明显高于同龄WT小鼠.2月龄apoE-/-小鼠主动脉内膜出现散在的脂质沉积,并随年龄增长逐渐加重.上述结果显示,时序表达上调的AS重要相关基因构成了以NF-kB为核心的复杂调控网络,它们之间相互作用,共同参与慢性炎症过程,在apoE-/-小鼠AS的早期发生发展中发挥重要作用.     

Arl8a与树突状细胞TLR4两条下游途径的相关性

为探讨Arl8a（ADP—ribosylation factor-like 8A）与树突状细胞（dendritic cells．DCs）TLR4两条下游信号途径的关系,用Arl8a和GEFH1（guanine nucleotide-exchange factors H1）的siRNA转染来自野生型小鼠的DC,进行LPS刺激或未刺激处理后,检测TLR4-TRIF途径中RhoB靶蛋白MYH9的mRNA表达。然后从野生型和IFNα/β受体基因敲除小鼠中分离和培养DC,LPS刺激后收集细胞扩增总cDNA,通过实时定量PCR检测Arl8a的mRNA表达。再用Arl8a的siRNA转染DC,LPS刺激后检测IL-6和IL-12a的mRNA表达。结果表明,Arl8a和GEFH1的siRNA均能显著抑制LPS介导的MYH9的mRNA表达（P〈0．01）,而且在LPs刺激后,Arl8a的mRNA表达在野生型小鼠的DC中增加,在IFNα/β受体基因敲除小鼠的DC中则未被上调。此外,Arl8a的siRNA对IL-6和IL-12a的mRNA表达没有显著效应。以上结果提示,在转录水平,Arl8a和GEFH1均对MYH9的表达有影响,并且Arl8a基因的表达与TRIF—IFNβ途径有关,Arl8a可能与MyD88途径中细胞因子IL-6和IL-12a的表达无关。     

TGF-β synergizes with ML264 to block IL-1β-induced matrix degradation mediated by Krüppel-like factor 5 in the nucleus pulposus

Intervertebral disc degeneration causes low back pain.Interleukin-1β (IL-1β) is a well-known inflammatory mediator that is involved in disc degeneration but its molecular mechanisms on catabolic and anabolic events in nucleus pulposus (NP) cells remain unclear. Krüppel-like factor 5 (KLF5) is associated with inflammation and was previously shown to cause cartilage degradation. In this study, we revealed that KLF5 is involved in IL-1β activated NF-kB cascade by enhancing both p65 phosphorylation and p65 acetylation. Moreover, the catabolic effect of KLF5 can be abolished by transforming growth factor-β (TGF-β) via promoting the proteasomal degradation of KLF5. Therefore, a KLF5 inhibitor ML264 was further proved to synergize with TGF-β to attenuate IL-1β-induced intervertebral disc degeneration. These results indicate the critical role of KLF5 in regulating intervertebral disc metabolism and suggest KLF5 inhibitor such as ML264 as potential compound for treatment of degenerative disc disease.     

Protective effect of aescin from the seeds of Aesculus hippocastanum on liver injury induced by endotoxin in mice

To investigate the effect and underlying mechanism of aescin on acute liver injury induced by endotoxin, liver injury was established by injecting lipopolysaccharide (LPS) in mice. Animals were assigned to seven groups: the control group and groups treated with LPS (40 mg/kg), aescin (3.6 mg/kg), LPS plus dexamethasone (4 mg/kg) and LPS plus aescin (0.9, 1.8 or 3.6 mg/kg). Hepatic histopathological changes were examined under a light microscope. Activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum were determined. Levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), nitric oxide (NO) and antioxidative parameters in liver homogenate were measured. Glucocorticoid receptor (GR), 11 beta-hydroxysteroid dehydrogenase type 1 (11β-HSD1) and 11 beta-hydroxysteroid dehydrogenase type 2 (11β-HSD2) expressions in liver were determined by western blotting. Treatment with escin could inhibit immigration of inflammatory cells, alleviate the degree of necrosis, and decrease serum ALT and AST activities. Aescin also down-regulated levels of inflammation mediators (TNF-α, IL-1β and NO) and 11β-HSD2 expression in liver, up-regulated GR expression, enhanced endogenous antioxidative capacity, but have no obvious effect on 11β-HSD1 expression in liver. The findings suggest aescin has protective effects on endotoxin-induced liver injury, and the underlying mechanisms were associated with its anti-inflammatory effects, up-regulating GR expression, down-regulating 11β-HSD2 experssion, and antixoidation.     

Kruppel-like factor 5 is an important mediator for lipopolysaccharide-induced proinflammatory response in intestinal epithelial cells

Lipopolysaccharide (LPS) is a bacterially-derived endotoxin that elicits a strong proinflammatory response in intestinal epithelial cells. It is well established that LPS activates this response through NF-κB. In addition, LPS signals through the mitogen-activated protein kinase (MAPK) pathway. We previously demonstrated that the Krüppel-like factor 5 [KLF5; also known as intestine-enriched Krüppel-like factor (IKLF)] is activated by the MAPK. In the current study, we examined whether KLF5 mediates the signaling cascade elicited by LPS. Treatment of the intestinal epithelial cell line, IEC6, with LPS resulted in a dose- and time-dependent increase in KLF5 messenger RNA (mRNA) and protein levels. Concurrently, mRNA levels of the p50 and p65 subunits of NF-κB were increased by LPS treatment. Pretreatment with the MAPK inhibitor, U0126, or the LPS antagonist, polymyxin B, resulted in an attenuation of KLF5, p50 and p65 NF-κB subunit mRNA levels from LPS treatment. Importantly, suppression of KLF5 by small interfering RNA (siRNA) resulted in a reduction in p50 and p65 subunit mRNA levels and NF-κB DNA binding activity in response to LPS. LPS treatment also led to an increase in secretion of TNF-α and IL-6 from IEC6, both of which were reduced by siRNA inhibition of KLF5. In addition, intercellular adhesion molecule-1 (ICAM-1) levels were increased in LPS-treated IEC6 cells and this increase was associated with increased adhesion of Jurkat lymphocytes to IEC6. The induction of ICAM-1 expression and T cell adhesion to IEC6 by LPS were both abrogated by siRNA inhibition of KLF5. These results indicate that KLF5 is an important mediator for the proinflammatory response elicited by LPS in intestinal epithelial cells.