人c-myc转基因细胞的建立

目的:建立人c-myc转基因细胞。方法:通过成功构建c-myc逆转录病毒表达载体,并经脂质体介导转染包装细胞293T,收集产重组病毒的293T培养上清,运用NIH3T3细胞测定了病毒滴度,用适当浓度的病毒感染L929细胞,经用Zeocin选择性培养基筛选细胞。结果:得到稳定高表达c-myc基因的L929转基因细胞。结论:运用逆转录病毒转染法可得到高表达的转基因细胞。     

Changes in the Gene Expression of C-myc and CD38 in HL-60 Cells during Differentiation Induced by Nicotinic Acid-Related Compounds

Changes in gene expression levels of c-myc and CD38 were examined during the differentiation of HL-60 cells to granulocytes due to three nicotinic acid-related compounds. CD38 expression was increased by isonicotinic acid and all-trans-retinoic acid (ATRA). Nicotinamide and nicotinamide N-oxide drastically decreased c-myc expression, but isonicotinic acid had no effect, suggesting that these compounds differentiate HL-60 to granulocytes through different pathways. These results should provide useful information as to the mechanisms of cell differentiation.     

增强p53、p21及抑制c-myc表达对MCF-7细胞增殖的协同抑制作用

为了探讨增强p53、p21基因表达水平和降低c-myc基因表达水平对乳腺癌细胞MCF-7增殖的协同抑制作用,以及这些基因对细胞产生效应时的相互关系,本研究中首先构建了正义的p53、p21和反义的c-myc3种真核细胞表达载体,并根据析因实验设计三种载体不同剂量组合。按照组合用质粒转染细胞,然后对转染细胞的增殖抑制率进行检测,并采用金正均Q值法、单因素方差分析中的LSD法、聚类分析法等统计学方法对结果进行统计分析。结果显示,不同量的p53、p21反义c-myc对MCF-7细胞的增殖均有抑制作用,抑制的程度各基因间存在差异。在各基因组合中,p21与反义c-myc,p53与反义c-myc联用具有协同作用,对MCF-7细胞的增殖产生更强的抑制,而p53与p21之间未显示出协同作用。对三基因协同结果进行聚类分析后,发现第一类组合协同作用最明显,第九类组合的抑制率最高。由此推测,作为抑癌基因的p53或CDK抑制基因p21高表达,同时原癌基因c-myc表达受到抑制,可相互协同显著增强对MCF-7细胞增殖的抑制作用。     

Relationship of cellular oncogene expression to inhibition of growth and induction of differentiation of Daudi cells by interferons or TPA

Human alpha or beta interferons inhibit the proliferation of Daudi Burkitt lymphoma cells and induce the differentiation of these cells towards a mature plasma cell phenotype. Similar responses are seen when Daudi cells are treated with the phorbol ester, TPA. Both interferons and TPA down-regulate expression of the c-myc oncogene in these cells. Although TPA can mimic the effect of interferon on cell differentiation, it does not induce 2'5' oligoadenylate synthetase or the interferon-sensitive mRNAs, 6-16 or 9-27. Thus chronic stimulation of protein kinase C by TPA cannot mimic all of the effects of interferon treatment on gene expression. Inhibition of ADP-ribosyl transferase activity by 3-methoxybenzamide impairs interferon- or TPA-induced differentiation of Daudi cells. This agent induces a higher level of c-myc mRNA in the cells and stimulates the incorporation of [3H]thymidine into DNA; although these effects are partially counteracted by interferon or TPA treatment, the elevated expression of the c-myc gene may be sufficient to prevent terminal differentiation and allow cell proliferation to continue.     

4-Hydroxynonenal affects pRb/E2F pathway in HL-60 human leukemic cells

4-Hydroxynonenal (HNE), a highly reactive product of lipid peroxidation, has an antiproliferative effect in several tumor cell lines and provokes alteration of cell cycle progression in HL-60 cells. HNE down-regulates c-myc expression in K562, HL-60, and MEL cells. This prompted us to study the cascade of phenomena that, starting from the CKIs expression and the phosphorylation of pRb, arrives at the E2F binding to consensus sequence in the P2 promoter of the c-myc gene. Treatment of HL-60 cells with HNE (1 microM) causes a p53-independent increase of p21(WAF1/CIP1) expression, pRb dephosphorylation, a decrease of low molecular weight E2F complexes and an increase of high molecular weight E2F complexes bound to P2 c-myc promoter. E2F4 expression is reduced by HNE treatment as well as the amount of pRb/E2F4 complexes, whereas the amount of pRb/E2F1 complexes is increased. In conclusion, HNE can affect the pRb/E2F pathway by modifying the expression of several genes involved in the control of cell proliferation.     

Clades within the ‘higher land birds’, evaluated by nuclear DNA sequences

In this study we investigated the phylogenetic relationships within the ‘higher land birds’ by parsimony analysis of nucleotide DNA sequences obtained from the two nuclear, protein-coding genes, c- myc and RAG-1. Nuclear genes have not previously been used to address this phylogenetic question. The results include high jackknife support for a monophyletic Apodiformes (including the Trochilidae). This arrangement was further supported by the observation of an insertion of four amino acids in the c- myc gene in all apodiform taxa. Monophyly was also inferred for each of the two piciform groups Galbulae and Pici. Within Pici, the Capitonidae was found to be paraphyletic, with the New World barbets more closely related to the Ramphastidae than to the Old World barbets. Another clade with high jackknife support consists of the Upupidae, Phoeniculidae and Bucerotidae. The families Momotidae and Todidae, and Coraciidae and Brachypteraciidae, respectively, also form well supported monophyletic clades. The results are inconclusive regarding the monophyly of the orders Coraciiformes and Piciformes, respectively.     

反义c-myc重组腺病毒载体的构建及其对大鼠胸腺淋巴细胞的增殖抑制作用

目的:观察反义c-myc重组腺病毒载体对大鼠胸腺淋巴细胞的增殖抑制作用.方法:构建大鼠反义及正义c-myc细菌质粒,并将所得细菌质粒与E1缺失腺病毒质粒导入293细胞系,经共转染得到正义及反义重组腺病毒载体.MTS法检测重组腺病毒载体对大鼠淋巴细胞增殖的抑制作用,RT-PCR检测重组腺病毒载体对c-myc mR-NA表达的影响.结果:反义c-myc重组腺病毒载体可抑制大鼠淋巴细胞增殖,降低淋巴细胞c-myc mRNA的表达.结论:反义c-myc重组腺病毒载体可抑制大鼠淋巴细胞增殖.