CHARACTERIZATION OF CELL SURFACE MOLECULES IMPORTANT FOR IMMUNE FUNCTION

对免疫功能重要的细胞表面分子的表征

• 批准号: 6288835
• 负责人: JOHN COLIGAN
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6288835
• 关键词: CD antigens; cell differentiation; cell mediated lymphocytolysis test; extracellular matrix; human tissue; integrins; natural killer cells; thymus; tissue /cell culture

Although integrin receptors have been shown to function as costimulatory molecules on mature thymocytes and T cells, it was not known whether these receptors could function as costimulatory molecules on immature thymocytes. Previous studies have shown that the expression of alpha 4 and alpha 5 integrins were significantly higher on immature, adult CD4- CD8- thymocytes than on either mature thymocytes or T cells, suggesting that these receptors are involved in early thymocyte development. We have shown that day 16 fetal thymocytes express levels of alpha 4 and alpha 5 equivalent to those of adult CD4- CD8- thymocytes. Immobilized fibronectin, a ligand for alpha 4 and alpha 5 integrins, was found to enhance the CD3-dependent proliferation of these fetal thymocytes. In the presence of IL-7, the magnitude of the proliferative response increased with time of incubation, resulting in a dramatic increase in the percentage of gamma delta thymocytes. The enhancement of proliferation by fibronectin was abrogated by soluble antibodies against alpha 4 and alpha 5, whereas immobilized mAb to alpha 4 and alpha 5 substituted for fibronectin in enhancing CD3- dependent proliferation, demonstrating that alpha 4 and alpha 5 integrins were responsible for the enhanced proliferation by fibronectin. Anti-alpha 4 mAb enhanced proliferation of fetal thymocytes by 100%, whereas anti-alpha 5 mAb and anti-CD28 mAb enhanced proliferation by 25%. Other costimulatory molecules, such as CD2, FcR gamma, and Thy-1, had no effect on the CD3 dependent proliferation of day 16 fetal thymocytes.In another study, several protein-nucleic acid complexes were observed when nuclear extracts from hepatoma cells were assayed for binding to the cAMP response element found in the phosphenolpyruvate carboxykinase-cytosolic (PEPCK-C) promoter. Although cAMP response element-binding protein and CCAAT/enhancer binding proteins alpha and beta have been identified as liver factors that bind this motif, an uncharacterized, slower migrating complex was also observed. We identified activating transcription factor-2 (ATF-2) as the factor in this complex and showed that ATF-2 stimulates expression from the PEPCK-C promoter. ATF-2 is a basic-leucine zipper transcription factor and a target for stress-activated protein kinases. We demonstrated that p38 beta mitogen-activated protein (MAP) kinase augments ATF-2 transactivation activity on the PEPCK-C promoter, which is consistent with the interpretation that PEPCK-C promoter activity is maintained under stress through a p38 MAP kinase dependent pathway. In this regard, we showed that treatment with sodium arsenite, a known activator of p38 MAP kinases, also stimulates expression from the PEPCK promoter. - Integrins, costimulatory molecules, cell adhesion, transcription factors, gene regulation, thymic differentiation, fibronectin

尽管已显示整联蛋白受体在成熟的胸腺细胞和T细胞上充当共刺激分子，但尚不清楚这些受体是否可以充当未成熟胸腺细胞的共刺激分子。先前的研究表明，未成熟，成人CD4- CD8-胸腺细胞的α4和α5整合素的表达显着高于成熟的胸腺细胞或T细胞，这表明这些受体参与早期胸腺细胞的发育。我们已经表明，第16天的胎儿胸腺细胞表达α4和α5等于成年CD4- CD8-胸腺细胞的水平。发现固定的纤连蛋白是α4和α5整合素的配体，可增强这些胎儿胸腺细胞的CD3依赖性增殖。在存在IL-7的情况下，随着孵育时间的增殖反应的大小增加，导致γ三角洲胸腺细胞百分比急剧增加。纤连蛋白通过对α4和α5的溶质抗体消除了纤连蛋白增殖的增强，而将固定的mAb固定在α4和α4中，用alpha 5代替纤连蛋白来增强CD3-依赖性的增殖，表明Alpha 4和Alpha 5整合蛋白是对fflpha 5的整合素的负责人，该蛋白质是由Fiperins phlppha ranped Ullanced ruplanced rupparted ruptication ratection richonection richonection。抗α4mAb可增强胎儿胸腺细胞的增殖100％，而抗α5mAb和抗CD28 mAb的增殖可增强25％。 Other costimulatory molecules, such as CD2, FcR gamma, and Thy-1, had no effect on the CD3 dependent proliferation of day 16 fetal thymocytes.In another study, several protein-nucleic acid complexes were observed when nuclear extracts from hepatoma cells were assayed for binding to the cAMP response element found in the phosphenolpyruvate carboxykinase-cytosolic (PEPCK-C)发起人。尽管CAMP反应元件结合蛋白和CCAAT/增强子结合蛋白α和β已被确定为结合该基序的肝脏因子，但也观察到了一个未表征，较慢的迁移复合物。我们将激活因子2（ATF-2）识别为该复合物的因子，并表明ATF-2刺激了PEPCK-C启动子的表达。 ATF-2是基本的亮氨酸拉链转录因子，也是应激激活蛋白激酶的靶标。我们证明了p38β有丝分裂原激活的蛋白（MAP）激酶增强PEPCK-C启动子上的ATF-2反式激活活性，这与PEPCK-C启动子活性通过p38 MAP MAP激酶依赖途径保持在应激下的解释是一致的。在这方面，我们表明，已知的p38 MAP激酶激活剂砷酸钠的处理也刺激了PEPCK启动子的表达。 - 整合素，共刺激分子，细胞粘附，转录因子，基因调节，胸腺分化，纤连蛋白