STING信号通路的研究进展

干扰素基因刺激因子(Stimulator of interferon gene, STING)作为固有免疫系统的关键性接头蛋白,在外源或内源DNA介导的免疫应答中发挥重要作用,广泛参与宿主体内的多种信号传导过程。概述了STING信号通路分子机制及其在抗病毒感染、自身免疫疾病、神经系统疾病和肿瘤中的作用,介绍了常见的STING激动剂和抑制剂,以期为STING的进一步研究提供参考。     

ERK3信号通路的活化阻止细胞增殖

ERK3是ERK家族中结构较为独特的成员,尤其在分子生物学特征上与ERK家族其他成员明显不同,如基因结构中外显子之间的大内含子、蛋白质结构中活化环的丝氨酸单磷酸化位点以及激酶C端的延伸序列等.ERK3具有独特的丝氨酸单磷酸化位点,导致所有以苏氨酸/酪氨酸双磷酸化位点为磷酸化靶点的MEK分子均不能活化ERK3.ERK3的C端延伸序列能与细胞周期蛋白D3结合并调控ERK3的亚细胞定位,从而影响ERK3对细胞周期的调节.据目前文献推测,ERK3调控细胞周期的信号通路可能为:Ras→B-Raf→ERK3激酶→ERK3→G1期CDK复合物减少→S期抑制因子增多→细胞增殖阻滞于S期→细胞停止增殖,进入分化.此外,ERK3信号通路的活化与细胞分化、胚胎发育、胰岛素分泌以及肿瘤的发生密切相关.     

沙眼衣原体感染活化NOD1信号通路的研究

目的:探索沙眼衣原体(Chlamydia trachomatis,Ct)持续感染状态下,NOD1、IL-6及STAT3分子的表达情况和相互关系。方法:利用HeLa229细胞或STAT3基因沉默的HeLa229细胞,分别建立沙眼衣原体的急性感染和持续感染模型;应用Western Blot及ELISA等方法检测不同感染状态下STAT3及NOD1蛋白表达水平以及细胞因子IL-6的分泌水平。结果:HeLa229细胞在Ct感染状态下,STAT3和NOD1以及IL-6表达水平均升高,且于持续感染状态下的升高较急性感染状态下的升高更明显;沉默STAT3基因后,Ct感染的细胞NOD1及IL-6的表达水平下降明显。结论:HeLa229细胞在Ct持续感染状态下,STAT3能上调NOD1及IL-6表达水平,上述分子间存在NOD1-IL-6-STAT3正反馈信号通路。     

低氧诱导因子-1的转录活性调控及其信号传导

低氧诱导因子-1(hypoxia-inducible factor-1,HIF-1)是氧平衡调控相关的转录因子.依赖HIF-1的基因表达调控系统广泛影响葡萄糖代谢、细胞增殖、凋亡和血管发生,与机体低氧适应、胚胎发育、各种缺血性疾病及肿瘤相关.HIF-1自身活性调节是低氧应答基因表达调控的中心环节.调控主要发生在源于Ras的两条信号途径：Ras/Raf/MEK介导的HIF-1反式激活功能调控,PI(3)K/Akt依赖的HIF-1alpha蛋白稳定性调控.这两个信号传导途径分别独立又协调地调控着HIF-1的转录活性.     

Signaling Pathway in the Osmotic Resistance Induced by Angiotensin II AT2 Receptor Activation in Human Erythrocytes

Background:Angiotensin II regulates blood volume via AT1 (AT1R) and AT2 (AT2R) receptors. As cell integrity is an important feature of mature erythrocyte, we sought to evaluate, in vitro, whether angiotensin II modulates resistance to hemolysis and the signaling pathway involved.Methods:Human blood samples were collected and hemolysis assay and angiotensin II signaling pathway profiling in erythrocytes were done.Results:Hemolysis assay created a hemolysis curve in presence of Ang II in several concentrations (10^-6 M, 10^-8 M, 10^-10 M, 10^-12 M). Angiotensin II demonstrated protective effect, both in osmotic stressed and physiological situations, by reducing hemolysis in NaCl 0.4% and 0.9%. By adding receptors antagonists (losartan, AT1R antagonist and PD 123319, AT2R antagonist) and/or signaling modulators for AMPK, Akt/PI3K, p38 and PKC we showed the protective effect was enhanced with losartan and abolished with PD 123319. Also, we showed activation of p38 as well as PI3K/Akt pathways in this system.Conclusion:Ang II protects human erythrocytes from hypo-osmotic conditions-induced hemolysis by activating AT2 receptors and triggering intracellular pathways.Key Words: Angiotensin II, Erythrocyte, Osmotic fragility, Signaling pathway     

经典Wnt信号通路与人类肿瘤

近年来,随着对肿瘤的深入研究,Wnt信号的研究也受到了高度的关注．Wnt信号通路是一条在进化上保守的信号途径,在控制胚胎发育,调节细胞生长、迁移、分化,调控正常组织重建等生命活动中发挥重要的作用,其异常活化与众多人类肿瘤的发生、发展密切相关．Wnt信号途径异常的核心是β-catenin在细胞内累积,并通过其下游途径引起特异靶基因的转录．本文着重介绍Wnt/β-catenin信号转导通路的研究进展及其与肿瘤的关系,了解该通路在肿瘤发生过程中的具体分子机制有助于为临床诊断提供依据,为早期干预治疗提供方法．     

Manipulating the Interferon Signaling Pathway: Implications for HIV Infection

During human immunodeficiency virus(HIV) infection, type I interferon(IFN-I) signaling induces an antiviral state that includes the production of restriction factors that inhibit virus replication, thereby limiting the infection. As seen in other viral infections, type I IFN can also increase systemic immune activation which, in HIV disease, is one of the strongest predictors of disease progression to acquired immune deficiency syndrome(AIDS) and non-AIDS morbidity and mortality.Moreover, IFN-I is associated with CD4 T cell depletion and attenuation of antigen-specific T cell responses. Therefore,therapeutic manipulation of IFN-I signaling to improve HIV disease outcome is a source of much interest and debate in thefield. Recent studies have highlighted the importance of timing(acute vs. chronic infection) and have suggested that specific targeting of type I IFNs and their subtypes may help harness the beneficial roles of the IFN-I system while avoiding its deleterious activities.     

Activation of NOTCH1 or NOTCH3 Signaling Skews Human Airway Basal Cell Differentiation toward a Secretory Pathway

Airway basal cells (BC) function as stem/progenitor cells capable of differentiating into the luminal ciliated and secretory cells to replenish the airway epithelium during physiological turnover and repair. The objective of this study was to define the role of Notch signaling in regulating human airway BC differentiation into a pseudostratified mucociliated epithelium. Notch inhibition with γ-secretase inhibitors demonstrated Notch activation is essential for BC differentiation into secretory and ciliated cells, but more so for the secretory lineage. Sustained cell autonomous ligand independent Notch activation via lentivirus expression of the intracellular domain of each Notch receptor (NICD1-4) demonstrated that the NOTCH2 and 4 pathways have little effect on BC differentiation into secretory and ciliated cells, while activation of the NOTCH1 or 3 pathways has a major influence, with persistent expression of NICD1 or 3 resulting in a skewing toward secretory cell differentiation with a parallel decrease in ciliated cell differentiation. These observations provide insights into the control of the balance of BC differentiation into the secretory vs ciliated cell lineage, a balance that is critical for maintaining the normal function of the airway epithelium in barrier defense against the inhaled environment.     

Activation of NF-kB Pathway by Virus Infection Requires Rb Expression

The retinoblastoma protein Rb is a tumor suppressor involved in cell cycle control, differentiation, and inhibition of oncogenic transformation. Besides these roles, additional functions in the control of immune response have been suggested. In the present study we investigated the consequences of loss of Rb in viral infection. Here we show that virus replication is increased by the absence of Rb, and that Rb is required for the activation of the NF-kB pathway in response to virus infection. These results reveal a novel role for tumor suppressor Rb in viral infection surveillance and further extend the concept of a link between tumor suppressors and antiviral activity.     

Complement Alternative Pathway Activation in Human Nonalcoholic Steatohepatitis

The innate immune system plays a major role in the pathogenesis of nonalcoholic steatohepatitis (NASH). Recently we reported complement activation in human NASH. However, it remained unclear whether the alternative pathway of complement, which amplifies C3 activation and which is frequently associated with pathological complement activation leading to disease, was involved. Here, alternative pathway components were investigated in liver biopsies of obese subjects with healthy livers (n = 10) or with NASH (n = 12) using quantitative PCR, Western blotting, and immunofluorescence staining. Properdin accumulated in areas where neutrophils surrounded steatotic hepatocytes, and colocalized with the C3 activation product C3c. C3 activation status as expressed by the C3c/native C3 ratio was 2.6-fold higher (p<0.01) in subjects with NASH despite reduced native C3 concentrations (0.94±0.12 vs. 0.57±0.09; p<0.01). Hepatic properdin levels positively correlated with levels of C3c (r_s = 0.69; p<0.05) and C3c/C3 activation ratio (r_s = 0.59; p<0.05). C3c, C3 activation status (C3c/C3 ratio) and properdin levels increased with higher lobular inflammation scores as determined according to the Kleiner classification (C3c: p<0.01, C3c/C3 ratio: p<0.05, properdin: p<0.05). Hepatic mRNA expression of factor B and factor D did not differ between subjects with healthy livers and subjects with NASH (factor B: 1.00±0.19 vs. 0.71±0.07, p = 0.26; factor D: 1.00±0.21 vs. 0.66±0.14, p = 0.29;). Hepatic mRNA and protein levels of Decay Accelerating Factor tended to be increased in subjects with NASH (mRNA: 1.00±0.14 vs. 2.37±0.72; p = 0.22; protein: 0.51±0.11 vs. 1.97±0.67; p = 0.28). In contrast, factor H mRNA was downregulated in patients with NASH (1.00±0.09 vs. 0.71±0.06; p<0.05) and a similar trend was observed with hepatic protein levels (1.12±0.16 vs. 0.78±0.07; p = 0.08). Collectively, these data suggest a role for alternative pathway activation in driving hepatic inflammation in NASH. Therefore, alternative pathway factors may be considered attractive targets for treating NASH by inhibiting complement activation.     

Proteasome Inhibitor PS-341 Effectively Blocks Infection by the Severe Fever with Thrombocytopenia Syndrome Virus

Severe fever with thrombocytopenia syndrome(SFTS) is an emerging hemorrhagic fever disease caused by SFTSV, a newly discovered phlebovirus that is named after the disease. Currently, no effective vaccines or drugs are available for use against SFTSV infection, as our understanding of the viral pathogenesis is limited. Bortezomib(PS-341), a dipeptideboronic acid analog, is the first clinically approved proteasome inhibitor for use in humans. In this study, the antiviral efficacy of PS-341 against SFTSV infection was tested in human embryonic kidney HEK293 T(293 T) cells. We employed four different assays to analyze the antiviral ability of PS-341 and determined that PS-341 inhibited the proliferation of SFTSV in 293 T cells under various treatment conditions. Although PS-341 did not affect the virus absorption, PS-341 treatment within a non-toxic concentration range resulted in a significant reduction of progeny viral titers in infected cells.Dual-luciferase reporter assays and Western blot analysis revealed that PS-341 could reverse the SFTSV-encoded nonstructural protein(NS) mediated degradation of retinoic acid-inducible gene-1(RIG-I), thereby antagonizing the inhibitory effect of NSs on interferons and blocking virus replication. In addition, we observed that inhibition of apoptosis promotes virus replication. These results indicate that targeting of cellular interferon pathways and apoptosis during acute infection might serve as the bases of future therapeutics for the treatment of SFTSV infections.     

Wnt/beta-catenin 信号通路在高脂血症中的激活

目的:建立大鼠高脂血症模型,观察活体内高脂刺激下血管平滑肌细胞内wnt/-catenin信号通路的激活及血管平滑肌细胞增殖情况,探讨活体内wnt/-catenin信号通路的激活与血管平滑肌细胞增殖的关系。方法:以雄性SD大鼠为研究对象,体重200~250g。通过饲以高脂饲料建立高脂血症模型。12周后处死大鼠,获取主动脉。苏丹III染色检测血管壁粥样硬化病变,HE染色、透射电镜检测血管平滑肌细胞增殖及表型变化,实时定量RT-PCR及Western Blot检测β-catenin、T cell factor 4(TCF-4)、cyclin D1的变化。结果:通过3个月的高脂饮食饲养,成功建立大鼠高脂血症模型,但大鼠主动脉壁粥样硬化病变不明显。高脂刺激下,mRNA及蛋白水平的β-catenin、TCF-4、cyclin D1表达均增加;同时血管壁内平滑肌细胞增殖增加、表型由收缩型向合成型变化。结论:高脂饮食可以成功建立大鼠高脂血症模型,但由于大鼠本身的代谢特点,不容易出现动脉粥样硬化斑块。Wnt/-catenin信号通路在高脂情况下被激活,同时平滑肌细胞增殖增加、表型改变,提示wnt/-catenin信号通路的激活与平滑肌细胞增殖之间存在联系。     

Alteration of Mitochondrial Proteome Due to Activation of Notch1 Signaling Pathway

The Notch signaling pathway, a known regulator of cell fate decisions, proliferation, and apoptosis, has recently been implicated in the regulation of glycolysis, which affects tumor progression. However, the impact of Notch on other metabolic pathways remains to be elucidated. To gain more insights into the Notch signaling and its role in regulation of metabolism, we studied the mitochondrial proteome in Notch1-activated K562 cells using a comparative proteomics approach. The proteomic study led to the identification of 10 unique proteins that were altered due to Notch1 activation. Eight of these proteins belonged to mitochondria-localized metabolic pathways like oxidative phosphorylation, glutamine metabolism, Krebs cycle, and fatty acid oxidation. Validation of some of these findings showed that constitutive activation of Notch1 deregulated glutamine metabolism and Complex 1 of the respiratory chain. Furthermore, the deregulation of glutamine metabolism involved the canonical Notch signaling and its downstream effectors. The study also reports the effect of Notch signaling on mitochondrial function and status of high energy intermediates ATP, NADH, and NADPH. Thus our study shows the effect of Notch signaling on mitochondrial proteome, which in turn affects the functioning of key metabolic pathways, thereby connecting an important signaling pathway to the regulation of cellular metabolism.     

A Discrete Dynamical System Approach to Pathway Activation Profiles of Signaling Cascades

In living organisms, cascades of covalent modification cycles are one of the major intracellular signaling mechanisms, allowing to transduce physical or chemical stimuli of the external world into variations of activated biochemical species within the cell. In this paper, we develop a novel method to study the stimulus–response of signaling cascades and overall the concept of pathway activation profile which is, for a given stimulus, the sequence of activated proteins at each tier of the cascade. Our approach is based on a correspondence that we establish between the stationary states of a cascade and pieces of orbits of a 2D discrete dynamical system. The study of its possible phase portraits in function of the biochemical parameters, and in particular of the contraction/expansion properties around the fixed points of this discrete map, as well as their bifurcations, yields a classification of the cascade tiers into three main types, whose biological impact within a signaling network is examined. In particular, our approach enables to discuss quantitatively the notion of cascade amplification/attenuation from this new perspective. The method allows also to study the interplay between forward and “retroactive” signaling, i.e., the upstream influence of an inhibiting drug bound to the last tier of the cascade.     

两种具有调节血管生成作用的氨基酰-tRNA合成酶

氨基酰-tRNA合成酶是生物体内蛋白质合成过程中的一类关键酶,它催化体内tRNA的氨基酰化反应.作为一类古老的蛋白质,氨基酰-tRNA合成酶在其漫长的进化过程中,通过其他结构域的插入或融合逐渐演化出许多新的功能.最近的研究结果表明,人酪氨酰-tRNA合成酶的片段具有促进血管生成的功能,而人色氨酰-tRNA合成酶的片段则具有抑制血管生长的功能.在哺乳动物细胞中,蛋白质的生物合成途径与细胞信号转导途径紧密相连.今后,随着对氨基酰-tRNA合成酶研究的不断深入,可以通过它们与细胞因子和信号转导相连的功能治疗人类的疾病.