STRUCTURE AND FUNCTION OF THE SV40 SMALL T ANTIGEN

SV40小T抗原促进病毒大T-T抗原转化 这就需要至少两个Small-t整环的函数。这个 首先落在氨基酸97-103范围内，并影响小T细胞 抑制蛋白磷酸酶2A。PP2A抑制与 Small-t激活多种细胞激酶(MAPK，MEK， JNK1)，并刺激AP1DNA结合活性。AP1的增加 活性导致包含细胞周期蛋白D1的构建体的转录激活 小写T启动子。拟议中的实验将确定这些机制 AP1活性增加和Small-t在调节细胞周期蛋白D1中的作用 自然感染中的表达(目标1)。第二个领域，42-47 区域域，对于小t依赖的变换也是必需的 系统。初步结果表明，该域对于以下各项是必需的 Small-T激活细胞周期蛋白。瞬变中的推动者 检测并增强内源性细胞周期蛋白A基因的表达。42- 将对47个区域进行基因探测，以确定是否会发生转化 和激活功能是可以分开的，无论小t和 大T抗原在提供42-47区功能方面起到同样的作用 (目标2)。拟议的实验将探索细胞周期蛋白A的序列 启动子是小T反式激活所必需的，并定义片段 在放置时足以产生小T反应的启动子 转化为最低限度的报告构建(目标3)。部分基于以下结果 细胞周期蛋白A启动子的几种可能机制的研究 将测试小t可能会起作用(目标4)。小T的潜在影响 鉴于最近有报道称，在 限制性生长条件，如没有锚定，细胞可能 由于阻止了Cyclin A表达式，因此无法增长。因此，最终的目标是 目的是探讨Small-t抗原对细胞周期蛋白A表达的影响。 因此，最终目标是探索小T抗原对细胞周期蛋白的影响。 细胞周期蛋白A表达受到限制的细胞中的A水平。结果： 这些研究可以解释为什么对小t抗原的需求最多。 经常在生长受阻的细胞和化验中观察到 需要转化细胞的非锚定生长。

The SV40 small-t antigen enhances transformation by viral large-T-T antigen and this requires the functions of at least two domains of small-t. The first falls within amino acids 97-103 and affects the ability of small-t to inhibit protein phosphatase 2A. PP2A inhibition correlates with the ability of small-t to activate a variety of cellular kinases (MAPK, MEK, JNK1) and to stimulate AP1 DNA binding activity. The increased AP1 activity results in transactivation of constructs that contain a cyclin D1 promoter by small-t. Proposed experiments will determine the mechanisms for increased AP1 activity and the role of small-t in regulating cyclin D1 expression in natural infections (aim 1). The second domain, the 42-47 region domain, is also required for transformation in small-t dependent systems. Preliminary results have shown that this domain is required for small-t to transactivate the cellular cyclin. A promoter in transient assays and to enhance expression of the endogenous cyclin A gene. The 42- 47 region will be probed genetically to determine whether transformation and transactivation functions can be separated and whether small-t and large-T antigens contribute equally in providing the 42-47 region function (aim 2). Proposed experiments will explore sequences in the cyclin A promoter that are required for small-t transactivation, and define segments of the promoter that are sufficient for small-t responsiveness when placed into minimal reporter constructs (aim 3). Based in part on results of studies of the cyclin A promoter, several possible mechanisms through which small-t may act will be tested (aim 4). The potential effect of small-t on cyclin A is of even greater interest given recent reports that, under restrictive growth conditions such as the absence of anchorage, cells may fail to grow because of a block to cyclin A expression. Thus, a final goal is to explore the effects of small -t antigen on cyclin A expression. Thus, a final goal is to explore the effects of small-t antigen on cyclin A levels in cells in which cyclin A expression is restricted. Results of these studies may explain why a requirement for small-t antigen has most frequently been observed in growth-arrested cells and in assays that require the anchorage-independent growth of transformed cells.