BAG3的结构和功能的研究进展

Bcl2相关永生基因3(BAG3)被鉴定为抗凋亡和前自噬因子,包含BAG、WW和PXXP三个结构域。BAG3与多种蛋白相互作用,被多种信号激活,又能激活多种信号通路,调控多种生理和病理过程,提示开发其特异性抑制剂可能为肿瘤的化学治疗提供候选药物,而开发其特异性激活剂可能为肌肉及神经退行性疾病的防治提供候选药物。现对人源BAG3的结构特征、相互作用蛋白、信号通路及生物学功能进行综述。     

关于食管癌亚型食管基底细胞样鳞癌的基因芯片数据分析

分析食管基底细胞样鳞癌(basaloid squamous cell carcinoma of the esophagus,BSCCE)的组织样本基因表达情况,探讨其病理学过程和肿瘤免疫逃逸机制,同时对BSCCE独特的肿瘤微环境及潜在的临床指标在对其远期预后的病理基础进行讨论,以期为临床工作中更好的治疗BSCCE提供一定的理论基础。利用临床术中获取的组织样本及其基因芯片数据,进一步获取BSCCE组织样本与同体正常组织样本的基因差异表达情况(log|FC|≥2,p0.05),其中BSCCE组织相对于正常组织的上调表达差异表达基因共489个,下调差异表达基因922个,利用DAVID在线分析系统对差异表达基因进行京都基因与基因组百科全书(kyoto encyclopedia of genes and genomes,KEGG)信号通路分析获取对BSCCE组织病理情况相关的分析结果,进一步利用STRING-OL工具对差异表达基因的可信度(可信度≥0.4)进行筛选,获取差异表达基因的蛋白质相互作用分析(protein-protein interaction,PPI)结果,进一步利用Cytoscape软件对筛选后的PPI结果制作相应的基因相互作用网状图,并进一步筛选核心表达的差异基因。在上调差异基因的KEGG分析中获得了88个结果,如p53signaling pathway、Cytokine-cytokine receptor interaction pathway、Toll-like receptor signaling pathway等,在下调的差异基因KEGG分析中获得了125个结果,如Drug metabolism-cytochrome P450 pathway、MAPK signaling pathway、Calcium signaling pathway、Cytokine-cytokine receptor interaction pathway等,这些相关的信号通路对进一步理解BSCCE的肿瘤微环境变化及肿瘤病理相关机制有重要意义,通过PPI分析,我们筛选出了一些与肿瘤远期生存率(overall survival,OS)相关的基因:CDC6、CDC20、TOP2A、NEK2、CDC25A等,这为我们进一步研究BSCCE及其肿瘤病理标志物和远期生存的关系提供了理论基础。     

小鼠正常黑素细胞和小鼠B16黑素瘤细胞的环状RNAs表达谱

黑素瘤是一种多发于皮肤的恶性肿瘤,因其侵袭性强,预后差等特点一直是科研人员关注的热点。环状RNAs(circRNAs)是一种新型内源性非编码RNA,广泛参与动物生长发育、细胞分化和信号转导等生理过程,但circRNAs在黑素瘤细胞内的分子机制尚未被充分解析。本研究以小鼠(C57BL/6J)正常黑素细胞及B16黑素瘤细胞为研究对象,采用二代测序技术分析两种细胞间circRNAs表达特性。测序结果显示,小鼠正常黑素细胞和黑素瘤细胞中共有851个circRNAs,其中195个差异表达circRNAs(DECs)。GO及KEGG数据库注释发现,DECs的来源基因主要参与细胞周期(cell cycle)、紧密结合(tight junction)、Rap1 信号通路(Rap1 signaling pathway)、TGF-beta 信号通路(TGF-beta signaling pathway)等与细胞增殖、迁移相关的信号通路;探究发现,黑素瘤细胞中显著性高表达的circE2F5(circ-3:14578602|14606309)通过上调E2F5的表达促进黑素瘤细胞增殖。circRNA靶基因预测发现,73个DECs 存在miRNA的结合位点,多个潜在靶向miRNAs参与黑素细胞增殖和迁移等过程。本研究通过对DECs来源基因功能注释、DECs靶向miRNAs预测,获得多个与黑素瘤细胞增殖和迁移相关的DECs,期望为黑素瘤研究提供新的见解。     

BAG2在恶性肿瘤中的作用

Bcl-2相关抗凋亡基因2(Bcl-2-associated athanogene 2,BAG2)属于BAG基因家族成员,其特征是含有一种新型热休克蛋白70核苷酸交换因子结构域,即“BNB”结构域,可以通过各种机制介导细胞凋亡、肿瘤生长、神经元分化和应激反应等。BAG2通过与肿瘤微环境中的相关信号分子相互作用,从而在不同恶性肿瘤的发生发展中发挥重要作用。本文主要就BAG2的结构和功能及其在结直肠癌、胶质瘤、胃癌、T细胞急性淋巴细胞白血病、口腔癌、食管癌、肝细胞癌、肺癌、乳腺癌等恶性肿瘤中的作用和机制进行综述,并对BGA2在各种恶性肿瘤诊断和治疗中的潜力进行展望。     

基于网络药理学研究杨桃根防治糖尿病肾病的作用机制

基于网络药理学研究杨桃根防治糖尿病肾病( DKD) 的作用机制。利用PubChem Search、Chemspider、Swiss Target Prediction 和GeneCards 数据库获取杨桃根主要药效成分和治疗DKD 的作用靶点，活性成分-靶点网络图采用Cytoscape 进行构建。通过String 在线数据库构建靶蛋白相互作用网络，并利用CytoHubba 插件筛选关键靶点。利用WebGestalt 在线数据库对关键靶点进行GO 和KEGG 富集分析。最后，通过动物实验对筛选的关键靶点和信号通路进行初步验证。结果共筛选到24 个活性成分，成分-疾病的共同靶点59 个。进一步网络分析显示，主要活性成分为桃根环己二酮、苦瓜苷C、樱桃素和胡萝卜甾醇等14 个，关键靶点为MMP9、MMP2、EGFＲ、FGF2、STAT3、MAPK1、VEGFA 和CASP3，主要涉及的信号通路包括AGE-ＲAGE 信号通路、Ｒelaxin 信号通路、胰岛素抵抗信号通路和缺氧诱导因子信号通路。胱抑素C( CysC) 和HE 染色均提示杨桃根提取物能改善糖尿病小鼠肾功能。Westernblot 显示，杨桃根提取物可以通过降低AGE-ＲAGE 信号通路相关的TGFβ1 和NF-κB 蛋白发挥防治DKD 的作用。综上，杨桃根发挥防治DKD 的作用是通过多成分、多靶点、多途径而实现的。     

基于mRNA-miRNA相互作用网络研究阿尔茨海默病机理

本研究基于表达谱数据系统分析了阿尔茨海默病中的差异表达基因;进一步的GO和KEGG富集分析研究了差异表达基因参与的生物学功能和生物学过程;最后通过mRNA-miRNA相互作用网络,挖掘了阿尔茨海默病中的关键基因和调控机理。研究表明,990个基因在阿尔茨海默病中差异表达(p-value≤0.01,|log FC|≥2),其中332个基因(33.5%)上调,658个基因(66.5%)下调。功能富集(GO)表明,差异基因参与了Regulation of macrophage activation、Myelin sheath和structural constituent of cytoskeleton等功能。KEGG通路富集分析表明,差异基因参与了,Synaptic vesicle cycle、PI3K-Akt signaling pathway、Nicotine addiction、Dopaminergic synapse和Retrograde endocannabinoid signaling等重要的生物学通路。最后,mRNA-miRNA相互作用网络鉴定了在阿尔茨海默病中6个关键的基因,包括TP53INP1、MET、MBNL3、CEBPB、GNAS和SMARCA4,其中TP53INP1和MET在前人的研究中有报道与阿尔茨海默病密切相关,MBNL3、CEBPB、GNAS和SMARCA4是新发现的一些基因。这些基因可能参与了阿尔茨海默病的发生和发展,可以作为其调控位点和药物靶点。     

牛痘病毒感染人巨噬细胞基因表达谱的RNA-Seq分析

[目的] 利用RNA-Seq,分析人巨噬细胞在牛痘病毒（VACV）感染前后基因表达的变化,探索牛痘病毒与宿主细胞相互作用的机制。[方法] 用牛痘病毒感染人巨噬细胞,采用RNA-Seq比较感染组和对照组的差异表达基因,并进行KEGG、GO以及STRING网络分析。[结果] 感染组与对照组相比,筛选出显著性差异表达基因4796个,其中上调表达2416个,下调表达2380个。KEGG富集分析表明差异基因主要参与新陈代谢、信号转导、免疫系统和感染疾病等通路。GO功能注释显示这些基因富集在细胞功能调控、物质代谢和免疫调控等生命过程。运用STRING在线蛋白互作数据库,对NOD样信号通路进行分析,鉴定出以JUN、CHUK、IL1B和PYCARD 为核心的调控基因。[结论] 牛痘病毒感染可以诱导人巨噬细胞基因差异性表达,涉及的生物学过程有很多,对免疫相关的信号通路进行深入的分析,发现C型凝集素受体信号通路（C-type lectin receptor signaling pathway）、Toll样受体信号通路以及NOD样通路等多条通路可能参与调控牛痘病毒感染引起的炎症反应,该研究为解析牛痘病毒的感染机制和免疫逃逸机制以及其在临床上治疗感染性疾病和癌症提供了新思路。     

Ras信号通路通过激活转录因子Myc促进核内复制细胞生长

【目的】果蝇Ras信号通路在细胞增殖与生长过程中发挥着重要的作用。Myc基因是bHLH转录因子家族基因,可调控细胞生长、竞争和再生增殖等生理过程。本研究旨在明确Ras信号通路与Myc的关系,探索Ras信号调控核内复制细胞生长的作用机制。【方法】生物信息学分析转基因家蚕Bombyx mori后部丝腺Myc基因的转录水平,并通过qPCR验证;在黑腹果蝇Drosophila melanogaster Kc细胞中,分别转染pAc5.1-HisB-Ras~(V12)-V5或pAc5.1-HisB-Raf-Flag过表达Ras~(V12)或Raf后,通过qPCR和Western blot技术分别检测Myc基因在mRNA和蛋白水平的相对表达量;在黑腹果蝇幼虫脂肪体和唾液腺中,结合黑腹果蝇遗传工具和分子生物学手段,验证Ras信号通路对Myc基因的调控作用。【结果】家蚕后部丝腺过表达Ras1~(CA)上调Myc转录水平。激活Ras信号使得黑腹果蝇Kc细胞内Myc在转录水平和蛋白水平上的表达量上调;黑腹果蝇幼虫唾液腺和脂肪体中,游走期Myc基因的表达量高于取食期;过表达Myc或激活Ras信号可以促进细胞核内周期进程;激活Ras信号促进Myc表达。【结论】Ras信号通路激活Myc表达,促进细胞核内周期进程,促进器官发育。     

基于RNA-seq研究胶质母细胞瘤中差异表达基因及蛋白相互作用网络

本研究基于RNA-seq数据分析了胶质母细胞瘤中的差异表达基因,并对差异表达基因进行了功能(GO term)和通路(KEGG)富集分析。进一步通过蛋白相互作用网络挖掘了胶质母细胞瘤的调控机理。结果表明,405个基因在肿瘤组织中差异表达(p-value≤0.05,|log FC|≥1.5),其中216个(53.3%)基因上调,189个(46.6%)基因下调。基因本体(gene ontology,GO)富集结果表明,这些差异表达基因参与了离子转运,神经冲动传递,细胞信号转导和细胞粘附等。此外,KEGG通路富集结果表明,差异基因参与了许多重要的生物学通路,包括ECM受体相互作用、黏着和钙信号等通路。进一步的蛋白相互作用网络分析鉴定了5个关键的hub基因,包括PTK2B、CDK1、FN1、CCND1和FOS。这5个关键基因对于胶质母细胞瘤的发生和发展可能起到了关键作用,可以作为潜在的调控位点和筛选的标志物。     

基于网络药理学研究南五味子对肝损伤的保护作用机制分析

通过网络药理学和分子对接的方式探究南五味子治疗肝损伤的作用机制。通过多个数据库检索并筛选出南五味子的活性成分和其治疗肝损伤的相关靶点。采用Cytoscape3.2.1软件构建活性成分-潜在靶点的网络图;运用String数据库做蛋白相互作用分析。使用R project对南五味子治疗肝损伤的关键靶点进行GO和KEGG的富集分析和网络构建,最后通过分子对接验证。最终筛选出南五味子有效化学成分31个,与肝损伤相关的靶点358个,KEGG富集分析主要在168条相关信号通路,分析表明南五味子可能通过PIK3CA、MAPK1、MAPK3、STAT3等核心靶点发挥作用,这些靶点主要富集Neuroactive ligand-receptor interaction、Proteoglycans in cancer、Prostate cancer、EGFR tyrosine kinase inhibitor resistance、Hepatitis B、ErbB signaling pathway等多条通路上,分子对接结果也显示良好的结合效果。本研究揭示了南五味子中的多成分作用于多靶点、多信号通路治疗肝损伤的作用机制,为生物实验提供理论基础。     

BAG1 down-regulation increases chemo-sensitivity of acute lymphoblastic leukaemia cells

BCL2-associated athanogene-1 (BAG1) is a multi-functional protein that is found deregulated in several solid cancers and in paediatric acute myeloid leukaemia. The investigation of BAG1 isoforms expression and intracellular localization in B-cell acute lymphoblastic leukaemia (B-ALL) patient-derived specimens revealed that BAG1 levels decrease during disease remission, compared to diagnosis, but drastically increase at relapse. In particular, at diagnosis both BAG1-L and BAG1-M isoforms are mainly nuclear, while during remission the localization pattern changes, having BAG1-M almost exclusively in the cytosol indicating its potential cytoprotective role in B-ALL. In addition, knockdown of BAG1/BAG3 induces cell apoptosis and G1-phase cell cycle arrest and, more intriguingly, shapes cell response to chemotherapy. BAG1-depleted cells show an increased sensitivity to the common chemotherapeutic agents, dexamethasone or daunorubicin, and to the BCL2 inhibitor ABT-737. Moreover, the BAG1 inhibitor Thio-2 induces a cytotoxic effect on RS4;11 cells both in vitro and in a zebrafish xenograft model and strongly synergizes with pan-BCL inhibitors. Collectively, these data sustain BAG1 deregulation as a critical event in assuring survival advantage to B-ALL cells.     

BAG5 regulates PTEN stability in MCF-7 cell line

The phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a tumor-suppressing lipid phosphatase that is frequently absent in breast tumors. Thus, the stability of PTEN is essential for tumor prevention and therapy. The ubiquitinproteasome pathway has an important role in regulating the functions of PTEN. Specifically, carboxyl terminus Hsp70-interacting protein (CHIP), the E3 ubiquitin ligase of PTEN, can regulate PTEN levels. In this study, we report that BCL-2- associated athanogene 5 (BAG5), a known inhibitor of CHIP activity, reduces the degradation of PTEN and maintains its levels via an ubiquitylation-dependent pathway. BAG5 is identified as an antagonist of cell tumorigenicity. [BMB Reports 2013; 46(10): 490-494]     

BAG3 gene silencing sensitizes leukemic cells to Bortezomib-induced apoptosis

Proteasome inhibition has emerged as a powerful option for the treatment of a number of malignancies including leukemias. However, Bortezomib showed limited single-agent activity for patients with leukemia. Here, we report for the first time that Bortezomib up-regulated a novel antiapoptotic protein, BAG3, in human leukemic cells. BAG3 gene knockdown with shRNA greatly potentiated the generation of apoptosis by Bortezomib in leukemia cells. Furthermore, BAG3 silencing enhanced the antitumor activity of Bortezomib dramatically in a nude mouse model. Our results indicate that knocking down BAG3 gene is a promising new approach to enhance the therapeutic potency of Bortezomib in leukemia.     

BAG3: a multifaceted protein that regulates major cell pathways

Bcl2-associated athanogene 3 (BAG3) protein is a member of BAG family of co-chaperones that interacts with the ATPase domain of the heat shock protein (Hsp) 70 through BAG domain (110–124 amino acids). BAG3 is the only member of the family to be induced by stressful stimuli, mainly through the activity of heat shock factor 1 on bag3 gene promoter. In addition to the BAG domain, BAG3 contains also a WW domain and a proline-rich (PXXP) repeat, that mediate binding to partners different from Hsp70. These multifaceted interactions underlie BAG3 ability to modulate major biological processes, that is, apoptosis, development, cytoskeleton organization and autophagy, thereby mediating cell adaptive responses to stressful stimuli. In normal cells, BAG3 is constitutively present in a very few cell types, including cardiomyocytes and skeletal muscle cells, in which the protein appears to contribute to cell resistance to mechanical stress. A growing body of evidence indicate that BAG3 is instead expressed in several tumor types. In different tumor contexts, BAG3 protein was reported to sustain cell survival, resistance to therapy, and/or motility and metastatization. In some tumor types, down-modulation of BAG3 levels was shown, as a proof-of-principle, to inhibit neoplastic cell growth in animal models. This review attempts to outline the emerging mechanisms that can underlie some of the biological activities of the protein, focusing on implications in tumor progression.     

Co-chaperone BAG3 enters autophagic pathway via its interaction with microtubule associated protein 1 light chain 3 beta

The co-chaperone BAG3 is a hub for a variety of cellular pathways via its multiple domains and its interaction with chaperones of the HSP70 family or small HSPs. During aging and under cellular stress conditions in particular, BAG3, together with molecular chaperones, ensures the sequestration of aggregated or aggregation-prone ubiquitinated proteins to the autophagic-lysosomal system via ubiquitin receptors. Accumulating evidence for BAG3-mediated selective autophagy independent of cargo ubiquitination led to analyses predicting a direct interaction of BAG3 with LC3 proteins. Phylogenetically, BAG3 comprises several highly conserved potential LIRs, LC3-interacting regions, which might allow for the direct targeting of BAG3 including its cargo to autophagosomes and drive their autophagic degradation. Based on pull-down experiments, peptide arrays and proximity ligation assays, our results provide evidence of an interaction of BAG3 with LC3B. In addition, we could demonstrate that disabling all predicted LIRs abolished the inducibility of a colocalization of BAG3 with LC3B-positive structures and resulted in a substantial decrease of BAG3 levels within purified native autophagic vesicles compared with wild-type BAG3. These results suggest an autophagic targeting of BAG3 via interaction with LC3B. Therefore, we conclude that, in addition to being a key co-chaperone to HSP70, BAG3 may also act as a cargo receptor for client proteins, which would significantly extend the role of BAG3 in selective macroautophagy and protein quality control.     

BAG3 mediates chaperone-based aggresome-targeting and selective autophagy of misfolded proteins

Increasing evidence indicates the existence of selective autophagy pathways, but the manner in which substrates are recognized and targeted to the autophagy system is poorly understood. One strategy is transport of a particular substrate to the aggresome, a perinuclear compartment with high autophagic activity. In this paper, we identify a new cellular pathway that uses the specificity of heat-shock protein 70 (Hsp70) to misfolded proteins as the basis for aggresome-targeting and autophagic degradation. This pathway is regulated by the stress-induced co-chaperone Bcl-2-associated athanogene 3 (BAG3), which interacts with the microtubule-motor dynein and selectively directs Hsp70 substrates to the motor and thereby to the aggresome. Notably, aggresome-targeting by BAG3 is distinct from previously described mechanisms, as it does not depend on substrate ubiquitination.     

IGFBP3 and BAG1 enhance radiation-induced apoptosis in squamous esophageal cancer cells

Identification of reliable markers of radiosensitivity and the key molecules that enhance the susceptibility of esophageal cancer cells to anticancer treatments would be highly desirable. To identify molecules that confer radiosensitivity to esophageal squamous carcinoma cells, we assessed the radiosensitivities of the TE-5, TE-9 and TE-12 cloneA1 cell lines. TE-12 cloneA1 cells showed significantly greater susceptibility to radiotherapy at 5 and 10 Gy than either TE-5 or TE-9 cells. Consistent with that finding, 24 h after irradiation (5 Gy), TE-12 cloneA1 cells showed higher levels of caspase 3/7 activity than TE-5 or TE-9 cells. When we used DNA microarrays to compare the gene expression profiles of TE-5 and TE-12 cloneA1 cells, we found that the mRNA and protein expression of insulin-like growth factor binding protein 3 (IGFBP3) and Bcl-2-associated athanogene 1 (BAG1) was five or more times higher in TE-12 cloneA1 cells than TE-5 cells. Conversely, knocking down expression of IGFBP3 and BAG1 mRNA in TE-12 cloneA1 cells using small interfering RNA (siRNA) significantly reduced radiosensitivity. These data suggest that IGFBP3 and BAG1 may be key markers of radiosensitivity that enhance the susceptibility of squamous cell esophageal cancer to radiotherapy. IGFBP3 and BAG1 may thus be useful targets for improved and more individualized treatments for patients with esophageal squamous cell carcinoma.