Tumorigenicity of adenovirus-transformed rat cells and expression of class I major histocompatibility antigen

The expression of class I major histocompatibility antigens was studied in six syngeneic adenovirus 12 (Ad12)-transformed LIS rat cell lines of varying tumorigenicity. The concentration of MHC class I product was estimated by indirect immunofluorescence staining of viable cells in suspension with specific antibody and cytofluorographic analysis, and by sensitivity to killing by allogeneic cytolytic T cells (CTLs) elicited by immunization with spleen cells in vivo and in mixed lymphocyte reactions in vitro. None of the rat cell lines examined was devoid of MHC class I antigen. When compared to syngeneic Ad2-transformed cells or fibroblasts, the average intensity of fluorescence of Ad12-transformed lines was lower, suggesting that the concentration of MHC class I antigen is somewhat lower in Ad12-transformed cells. Sensitivity to killing by both in vivo and in vitro induced allogeneic CTLs, however, was not markedly lower with Ad12-transformed cells and correlation was not found between tumorigenic potential in vivo and sensitivity to allogeneic T-cell killing in vitro.     

CTL recognition of adenovirus-transformed cells infected with influenza virus: lysis by anti-influenza CTL parallels adenovirus-12-induced suppression of class I MHC molecules

We examined the ability of influenza-specific cytotoxic T lymphocytes to lyse adenovirus-transformed cells infected with influenza virus. Cytotoxic T lymphocyte lysis of Ad12-transformed cells was greatly reduced relative to that of Ad5-transformed cells. Lysability of adenovirus-12-transformed cells was restored in parallel with interferon-gamma induced increases in major histocompatibility complex class I gene products. These findings establish that recognition of foreign molecules by self-restricted cytotoxic T lymphocytes is reduced in adenovirus-12-transformed cells. This provides further evidence that Ad12 tumorigenicity is related to its ability to suppress class I major histocompatability complex molecule expression thereby avoiding recognition by the host immune system.     

应用染色质免疫沉淀技术分析DNMT3b和HDAC1蛋白与SLC22A18基因启动子的结合

目的 建立优化的染色质免疫沉淀技术(ChIP),分析乳腺癌细胞MDA-MB-231中DNA甲基转移酶3b(Dnmt3b)和组蛋白去乙酰化酶1(HDAC1)与SLC22A18基因启动子区的结合情况. 方法 建立并优化ChIP实验技术,运用ChIP技术检测DNA甲基转移酶抑制剂5-氮杂-2′-脱氧胞苷(5-aza-dc)和组蛋白去乙酰化酶抑制剂曲古霉素A(TSA)分别单独和联合作用于人乳腺癌细胞MDA-MB-231后,用Dnmt3b和HDAC1特异性抗体沉淀DNA,聚合酶链式反应(PCR)检测SLC22A18基因5＇端特异性序列,免疫印迹法(Western blotting)检测Dnmt3b和HDAC1蛋白的表达情况. 结果 获得了优化的ChIP实验条件,Dnmt3b和HDAC1抗体沉淀的染色质片段中扩增出SLC22A18基因5＇端特异性序列.5-aza-dc、TSA单独用药可抑制DNMT3b、HDAC1与SLC22A18启动子区特异序列的结合,5-aza-dc和TSA联合作用可以明显抑制DNMT3b、HDAC1与SLC22A18启动子的结合;Western blotting结果表明,5-aza-dc、TSA单独及联合用药不影响DNMT3b和HDAC1蛋白的表达. 结论 DNMT3b和HDAC1在MDA-MB-231细胞内结合于SLC22A18基因启动子的特异区域,参与该基因的表达调控.     

Cellular transformation by E1 genes of enteric adenoviruses.

The ability of Ad40 and Ad41 E1A plus E1B genes to transform BRK cells was considerably lower than that of Ad5 and Ad12 corresponding genes. However, as for Ad5, the E1A genes of enteric adenoviruses could cooperate with an activated ras oncogene for full cell transformation and the Ad41 E1B could be complemented by E1A gene of Ad5 or Ad12 for cell transformation. Complementation studies suggested that the conserved region 1 of Ad41 E1A was responsible for this inefficient transformation. The Ad40- and Ad41-transformed cell lines exhibited a low level of major histocompatibility complex (MHC) class I antigens correlated to the low level of Ad12-transformed cells. Class I MHC antigen amounts expressed at the surface of the cells transformed by the weakly oncogenic Ad3 were between the high level of Ad5- and the low level of Ad12-transformed cells.     

组蛋白化学修饰改变对c-Myb结合的影响及其在职业性苯中毒患者造血损伤中的作用

 目的:研究职业性苯中毒造血损伤患者中与拓扑异构酶Ⅱα启动子调控因子c-Myb结合的组蛋白化学修饰改变, 证实组蛋白乙酰化修饰水平改变在职业性苯中毒造血损伤中发挥一定的作用。方法:25例职业性苯中毒再生障碍性贫血患者为病例组,25例正常人为对照组,提取骨髓单个核细胞,用染色质免疫沉淀(ChIP)探讨与c-Myb结合的组蛋白乙酰化和甲基化水平的改变,RT-PCR法检测c-Myb的mRNA表达水平,组蛋白去乙酰化酶(HDAC)试剂盒检测HDAC活性的变化。结果:与正常对照组相比,职业性苯中毒再生障碍性贫血患者c-Myb与乙酰化组蛋白H4、H3结合的水平下降(P<0.01), 而与甲基化组蛋白H3K4和H3K9结合的水平无明显改变,差异无统计学显著性。与正常对照组相比,职业性苯中毒再生障碍性贫血患者c-Myb的mRNA表达水平降低,HDAC活性明显升高,差异均有统计学显著性(P<0.05)。结论:拓扑异构酶Ⅱα启动子调控因子c-Myb可能通过组蛋白乙酰化修饰的改变在职业性苯中毒造血损伤中发挥作用。     

Ikaros DNA-binding proteins direct formation of chromatin remodeling complexes in lymphocytes

The Ikaros gene family encodes zinc finger DNA-binding proteins essential for lineage determination and control of proliferation in the lymphoid system. Here, we report that, in the nucleus of a T cell, a major fraction of Ikaros and Aiolos proteins associate with the DNA-dependent ATPase Mi-2 and histone deacetylases, in a 2 MD complex. This Ikaros-NURD complex is active in chromatin remodeling and histone deacetylation. Upon T cell activation, Ikaros recruits Mi-2/HDAC to regions of heterochromatin. These studies reveal that Ikaros proteins are capable of targeting chromatin remodeling and deacetylation complexes in vivo. We propose that the restructuring of chromatin is a key aspect of Ikaros function in lymphocyte differentiation.     

Differential expression of LFA-3, Fas and MHC Class I on Ad5- and Ad12-transformed human cells and their susceptibility to lymphokine-activated killer (LAK) cells

Adenovirus (Ad) E1A is a potent oncogene and has been shown to deregulate the expression of a large number of cellular genes leading to cellular transformation. Here we have analysed the expression of several immunomodulatory molecules on the surface of a set of human cell lines transformed with either Ad12 or Ad5. Human cells transformed with Ad12 demonstrated reduced expression of cell surface LFA-3, Fas and MHC class I when compared to Ad5-transformed cells. Furthermore, Ad12-transformed human cell lines demonstrated greater susceptibility to lysis by lymphokine-activated killer (LAK) cells, compared to Ad5-transformed human cell lines. In contrast, previous studies with rodent cells showed that both Ad5- and Ad12-transformed rat cells were susceptible to LAK cells. Thus, transformation of human cells with Ad5 or Ad12 results in differences in the expression of immunomodulatory molecules on the cell surface and differential recognition of these virus-transformed cells by immune effector cells.