PROMOTION OF CELL SURVIVAL BY ADENOVIRUS E1B 19K PROTEIN

调节性细胞死亡是消除特异性免疫缺陷的重要过程。 在正常发育过程中， 体内平衡细胞死亡失调会导致退行性疾病 例如阿尔茨海默氏症、帕金森氏症和艾滋病。抑制细胞 死亡也可导致肿瘤发生和对化疗药物的抵抗 治疗。人腺病毒（Ad）的E1B 19 kD蛋白是一种具有生物学活性的蛋白质。 参与细胞抑制的一类蛋白质的重要成员 死亡它促进被腺病毒感染的细胞的存活， 暴露于几种外部细胞死亡（凋亡）诱导刺激。的 19 kD蛋白在功能上类似于Bc1 - 2原癌蛋白， EB病毒BHRF1蛋白。19 kD和Bcl-2蛋白出现 共享抑制细胞死亡所必需的共同序列基序。 我们已经鉴定并克隆了四种细胞蛋白， 19 kD（19 kD相互作用蛋白，Nip 1至4）和Bc1 - 2蛋白 通过这些同源序列基序。为了阐明共同的 19 kD和Bc1 - 2蛋白抑制细胞死亡的机制，我们 建议在功能上表征各种Nips。这些的作用 细胞蛋白质在调节细胞死亡中的作用 将使用多个细胞死亡/存活测定来检查机制。 这些蛋白质的内源性表达和亚细胞定位， 将检查对暴露于各种细胞死亡刺激的反应。 这些细胞蛋白质中的一些含有有趣的序列同源性。 Nip1与某些人的催化结构域具有有限的同源性， 哺乳动物磷酸二酯酶。Nip2与（GT3）- 刺激蛋白RhoGAP。Nip3定位于线粒体中。nip2 和Nip4含有推测的Ca~（2+）结合基序。这些蛋白质将 其特征在于阐明其在信号转导和钙离子通道中的作用。 动员。由于腺病毒诱导的细胞死亡效应子 感染尚不清楚，我们建议使用无细胞体外细胞死亡 鉴定和克隆这种效应物的系统。由于灭活 19 kD和Bc1 - 2蛋白的存活促进活性将是 有利的，我们建议探索使用突变体的可能性， 作为显性负抑制剂的存活结构域缺陷。 类似地，对应于存活结构域的肽也将被修饰。 作为19 kD和Bc1 - 2蛋白的竞争性抑制剂进行了检测。因此，在本发明中， 我们的建议可以阐明19 kD和Bc1 - 2的机制， 蛋白质抑制细胞死亡，也揭示了干扰细胞死亡的策略。 他们的活动。

Regulated cell death is an important process for elimination of specific cells in multicellular organisms during normal development and homeostasis. Deregulated cell death can lead to degenerative diseases such as Alzheimer's and Parkinson's disease and AIDS. Inhibition of cell death can also lead to oncogenesis and resistance to chemotherapeutic treatments. The E1B 19 kD protein of human adenovirus (Ad) is an important member of a class of proteins involved in suppression of cell death. It promotes the survival of cells infected with adenovirus or exposed to several external cell death (apoptosis)-inducing stimuli. The 19 kD protein is functionally similar to the Bc1-2 protooncoprotein and the Epstein-Barr virus BHRF1 protein. The 19 kD and Bcl-2 proteins appear to share common sequence motifs essential for inhibition of cell death. We have identified and cloned four cellular proteins that interact with the 19 kD (19-kD-interacting proteins, Nip1 to 4) and the Bc1-2 proteins through these homologous sequence motifs. To elucidate the common mechanism of cell death inhibition by the 19 kD and Bc1-2 proteins, we propose to functionally characterize the various Nips. The role of these cellular proteins in regulating cell death induced by different mechanisms will be examined using multiple cell death/survival assays. Endogenous expression and subcellular localization of these proteins in response to exposure to various cell death stimuli will be examined. Some of these cellular proteins contain intriguing sequence homologies. Nip1 shares limited homology with the catalytic domain of certain mammalian phosphodiesterases. Nip2 shares homology with the (GTPase- stimulating protein RhoGAP. Nip3 is localized in the mitochondria. Nip2 and Nip4 contain putative Ca2+ -binding motifs. These proteins will be characterized to elucidate their role in signal transduction and calcium mobilization. Since the cell death effectors induced by adenovirus infection is not known, we propose to use a cell free in vitro cell death system to identify and clone such effector(s). Since inactivation of survival-promoting activities of the 19 kD and Bc1-2 proteins would be advantageous, we propose to explore the possibility of using mutants defective in the survival domains as dominant negative inhibitors. Similarly, peptides corresponding to the survival domains will also be examined as competitive inhibitors of the 19 kD and Bc1-2 proteins. Thus, our proposal may illuminate the mechanism by which the 19 kD and Bc1-2 proteins suppress cell death and also reveal strategies to interfere with their activities.