REGULATION AND FUNCTION OF THE PUTATIVE TRANSCRIPTION FACTOR GADD153

GADD153是一个高度保守的哺乳动物基因，它的表达增加 应对各种压力，包括生长停滞和DNA 损坏。它是CCAAT/增强子结合蛋白(C/EBP)的成员 转录激活因子家族，可与其他C/EBPs二聚化 通过亮氨酸拉链区域。然而，与其他C/EBPS相比，它 缺乏与CCAAT DNA序列结合的能力，因此 建议作为这个家族其他成员的负面调节器 (由于它能够与它们异源二聚并抑制它们的 与DNA结合)。这个项目的研究主要集中在监管方面 以及GADD153表达在应激反应中的作用。这些方法 所采取的措施包括(1)Gadd153表达的特征(以及 其他C/EBPs)对不同的生长抑制和代谢反应 刺激包括PGA/2介导的生长停滞、葡萄糖剥夺、DNA 体内和体外急性时相反应的损伤和诱导物； 使用酵母杂交蛋白系统来检查 GADD153蛋白和C/EBP家族的其他成员，以及(3)发育 转基因模型研究GADD153的表达和作用 在体内发育和对应激的反应。特别值得关注的是 我们的发现GADD153蛋白提供了一种功能性的反式激活 当结构域与酵母GAL4转录因子DNA结合位点融合时， 这表明GADD153可以直接行动(而不是作为主导者 负抑制物)可能会影响转录 穿过尚未确定的地点。使用酵母双杂交系统，我们 研究发现，与其他C/EBP家族成员相比，GADD153 不能形成同源二聚体，这表明它必须与 其他影响基因表达或起作用的转录因子 作为单体。

GADD153 is a highly conserved mammalian gene whose expression is increased in response to a variety of stresses including growth arrest and DNA damage. It is a member of the CCAAT/enhancer-binding protein (C/EBP) family of transcriptional activators and can dimerize with other C/EBPs through a leucine zipper domain. However, in contrast to other C/EBPs, it lacks the ability to bind to CCAAT DNA sequences and has therefore been proposed to serve as a negative regulator of other members of this family (by virtue of its ability to heterodimerize with them and inhibit their binding to DNA). Studies in this project have focused on the regulation and function of GADD153 expression in response to stress. The approaches taken have included (1) characterization of Gadd153 expression (and that of other C/EBPs) in response to diverse growth inhibitory and metabolic stimuli including PGA/2-mediated growth arrest, glucose deprivation, DNA damage, and inducers of the acute phase response in vivo and in vitro; (2) use of yeast hybrid protein systems to examine the interaction between the GADD153 protein and other members of the C/EBP family, and (3) development of transgenic models to address the expression and role of GADD153 during development and in response to stress in vivo. Of particular interest is our finding that the GADD153 protein provides a functional transactivation domain when fused to a yeast GAL4 transcription factor DNA binding site, suggesting that GADD153 can act directly (rather than as a dominant negative inhibitor as suggested above) to influence transcription perhaps through as yet unidentified sites. Using the yeast two hybrid system, we have found that in contrast to other C/EBP family members, GADD153 appears to be unable to form homodimers, suggesting that it must interact with other transcription factors to influence gene expression, or be functional as a monomer.