GLUCOCORTICOIDS AND LYMPHOCYTE CATABOLISM

拟议研究的长期目标是了解 肾上腺类固醇激素（糖皮质激素）对淋巴细胞和免疫细胞的影响 系统一般。 我们将继续详细调查 糖皮质激素诱导的细胞机制，最终导致 淋巴细胞死亡，从而抑制免疫功能。 胸腺 肾上腺切除大鼠的淋巴细胞将是我们关注的焦点。 细胞非常适合这些调查，因为它们是 细胞周期阶段丰富、均匀。分化状态均匀， 在体外和体内对糖皮质激素有反应， 肾上腺类固醇的作用 三个重要的意见， 过去已经进行了糖皮质激素诱导的淋巴细胞溶解 授予期。 它们是：1）糖皮质激素诱导的淋巴细胞 DNA降解是死亡的先兆; 2）糖皮质激素诱导的DNA 降解不是随机的，这意味着特异性; 3）核 糖皮质激素“诱导的”核酸酶活性已被鉴定。 基于 根据这些观察，我们希望提出以下假设： 糖皮质激素诱导或激活脱氧核糖核酸酶， 改变基因组DNA的完整性并导致细胞死亡。 测试 根据这一假设，我们提出以下具体目标：1）评估 糖皮质激素诱导的DNA“断裂”是否发生在转录或 非转录基因组序列; 2）为了纯化至同质， 糖皮质激素“诱导”核酸酶并检测其体外特异性; 3） 克隆糖皮质激素诱导的核酸酶基因，并评估其在 糖皮质激素通过转染实验诱导细胞死亡; 4）最后， 通过选择性细胞分选评估糖皮质激素的发展 大鼠胸腺淋巴细胞向成熟T细胞分化过程中的阻力 细胞 总之，这些研究应该测试所提出的假设， 为糖皮质激素诱导的淋巴结转移提供分子基础数据。 细胞死亡

The long term goal of the proposed research is to understand the action of adrenal steroid hormones (glucocorticoids) on lymphocytes and the immune system in general. We will continue to investigate in detail the glucocorticoid induced cellular mechanisms which ultimately lead to lymphocyte death and thereby suppressed immune function. The thymic lymphocyte of the adrenalectomized rat will be the focus of our attention. The cells are well suited for these investigations because they are abundant, uniform in cell cycle stage. uniform in state of differentiation, responsive to glucocorticoids in vitro and in vivo and a well studied model for adrenal steroid action. Three seminal observations concerning glucocorticoid induced lymphocytolysis have been made during the past granting period. They are: 1) Glucocorticoid induced lymphocyte cell death is preceeded by DNA degradation; 2) Glucocorticoid induced DNA degradation is not random, implying specificity; 3) A nuclear glucocorticoid "induced" nuclease activity has been identified. Based on these observations, we wish to propose the following hypothesis: Glucocorticoids induce or activate a deoxyribonuclease which selectively alters the integrity of genomic DNA and causes the cells to die. To test this hypothesis, we propose the following Specific Aims: 1) To evaluate whether glucocorticoid induced "breaks" in DNA occur in transcribed or non-transcribed genomic sequences; 2) To purify to homogeneity the glucocorticoid "induced" nuclease and test its specificity in vitro; 3) To clone the glucocorticoid "induced" nuclease gene and evaluate its role in glucocorticoid induced cell death by transfection experiments; 4) Lastly, to evaluate via selective cell sorting the development of glucocorticoid resistance during the differentiation of rat thymic lymphocytes to mature T cells. Together, these studies should test the proposed hypothesis and provide data on the molecular basis for glucocorticoid induced lymphoid cell death.