同源盒基因IRX1的启动子克隆及其在人胃黏膜细胞中的启动活性分析

目的 克隆同源盒基因IRX1的核心启动子序列,并探讨其转录调控机制.方法 通过生物信息学预测IRX1基因启动子范围：利用PCR方法扩增并构建含有IRX1基因启动子不同片段的真核报告基因质粒,瞬时转染GES-1胃黏膜细胞,通过检测不同片段的荧光素酶报告质粒活性,判断不同片段的启动子活性.结果 生物信息学预测IRX1基因启动子位于转录起始点上游700 bp范围内.通过PCR技术扩增获得IRX1基因5＇侧翼区8个截短片段报告基因质粒,其活性由大到小依次为p-416＞p-584＞p-715＞p-350＞p-687＞p-320＞p-188＞p-92 除p-92与p-188片段外,其余各片段与PGL3-basic空载体的差异均有统计学意义（均P＜0.05）,其中以p-416片段活性最强,片段p-320与片段p-188之间出现较大活性落差.结论 IRX1基因上游序列启动子以p-416转录活性最高,核心启动子位于-320～-188区间,该区间具有Sp1、TFⅡD等转录因子结合序列,是下一步转录调控机制研究的重要位点.     

热休克因子1对白细胞介素-10的转录调控作用及其机制

目的 探讨热休克因子1(HSFl)对白细胞介素(IL)-10的转录调控作用及其机制.方法 合成IL-10基因启动子区含热休克元件(HSE)位点的寡核苷酸探针进行凝胶电泳迁移率实验(EMSA),分析HSF1与IL-10基因启动子区的HSE的结合情况,并构建IL-10基因启动子的萤光素酶报告基因质粒,与HSF1表达质粒共转染RAW264.7细胞,检测萤光素酶活性,观察HSF1转染对启动子活性的影响.结果 生物素标记的HSFl结合片段(-376～- 369 bp)和核蛋白提取物孵育后能观察到阻滞带,阻滞现象能够被自身非标记探针竞争,但不被非标记的突变探针竞争,加入HSFl单克隆抗体,可以观测到超阻滞带,表明HSF1可以特异性结合于"HSFI识别序列",HSE核心结合位点突变后,相对萤光素酶活性突变体(34.23±2.14)相对野生型(110.09±5.48)下降3.2倍(P<0.01),通过EMSA证实了IL-10启动子区域(-688～+64 bp)存在HSF1的结合位点HSE(-376～-369 bp);突变体双萤光素酶活性分析发现HSF1的结合位点核心碱基的突变,其转录活性下降.结论 HSF1可以特异性结合于IL-10启动子区HSE(-376～-369 bp),相对萤光素酶活性分析提示HSF1可以转录激活IL-10,上调其表达.     

Ribosome inactivating protein B-chain induces osteoclast differentiation from monocyte/macrophage lineage precursor cells

Human osteoclast formation from mononuclear phagocyte precursors involves interactions between lectins and their receptors. A type-2 ribosome inactivating protein consists of an A chain and a B chain. The glycosylated B chain binds specifically to galactose moieties of sugar molecules. In this study we showed that the recombinant ribosome inactivating protein B-chain (rRBC) could induce osteoclast formation from human monocytes and murine RAW264.7 macrophages. Tartrate-resistant acid phosphatase (TRAP) staining and bone resorption assays demonstrated that differentiation of osteoclast-like cells was induced in the presence of rRBC in a dose-dependent manner. The rRBC-induced osteoclast differentiation was independent of caspase activation and apoptosis induction activity; however, rRBC-induced osteoclastogenesis was dependent on activation of NF-κB, ERK1/2, and p38 MAP kinase. Thus, our data demonstrated that rRBC induced osteoclast differentiation through a non-apoptotic signaling pathway. In addition to triggering apoptosis, the rRBC also induced osteoclast differentiation. According to this study, a novel role is proposed for rRBC in regulating osteoclast differentiation and in osteoimmunology.