HSP72 AND REGULATION OF STRESS KINASES IN TUMOR CELLS

热休克蛋白HSP72是一种分子伴侣 重新折叠受损的蛋白质，保护细胞免受各种压力。此外, HSP72被证明作为细胞的特定调节因子发挥了意想不到的作用 死亡计划。来自该实验室的研究结果表明， HSP72介导的细胞凋亡抑制是一种蛋白激酶JNK的抑制。 HSP72通过刺激一种未知的JNK磷酸酶抑制JNK。一个 细胞在暴露于应激时是经历细胞凋亡的决定，还是 因此，修复似乎依赖于HSP72诱导之间的微妙平衡 和JNK的激活。了解该细胞的详细机制 命运控制是本提案的重点。第一个目标是 建议的研究是建立HSP72介导的调控机制 JNK去磷酸化。这个实验室的发现导致了一个模型， 胞浆中产生的异常蛋白对HSP72的隔离作用 热休克和其他蛋白质损伤应激是JNK的主要事件 监管。将确定与HSP72的关联是否至关重要 对于异常多肽激活JNK的能力；是否JNK 异常多肽对JNK的抑制作用 去磷酸化；以及其他与之合作的热休克蛋白是否 蛋白质复性中的HSP72参与了JNK的调节。第二个目标是 受热休克调节的JNK磷酸酶的鉴定和性质研究 以及HSP72。磷酸酶SHP-2作为JNK磷酸酶的可能功能 将会被研究。JNK的另一项主要脱磷活性将是 纯净的。该酶将被鉴定和克隆。这种酶在体内的作用 在viva中去磷酸化jnk将通过各种方法来探索，例如 作为正常基因的异位过表达和显性负突变； 以及表达反义RNA以抑制磷酸酶翻译。监管 热休克和HSP72对该酶的影响将被研究。澄清 HSP72抑制JNK的机制是理解热的关键 细胞抵抗力是肿瘤热疗的重要因素 病人。此外，类似的机制可能在HSP72介导的 保护细胞免受基因毒性应激和抗癌药物的影响。结果： 这项研究可能表明JNK磷酸酶和HSP72是否具有吸引力 抗癌药物设计的新目标。

(adapted from abstract) The heat shock protein Hsp72 is a molecular chaperone that refolds damaged proteins and protects the cell from various stresses. In addition, Hsp72 was shown to play an unexpected role as a specific regulator of the cell death program. Findings from this Laboratory show that a critical event in the Hsp72-mediated prevention of apoptosis is suppression of a protein kinase JNK. Hsp72 inhibits JNK through stimulation of an unidentified JNK phosphatase. A cell's decision to either undergo apoptosis upon exposure to stresses, or to repair thus appears to depend on a fine balance between the induction of Hsp72 and the activation of JNK. Understanding the detailed mechanism of this cell fate control is the focus of the present proposal. The first goal of the proposed research is to establish the mechanism of Hsp72-mediated regulation of JNK dephosphorylation. Findings from this Laboratory led to a model that sequestering of Hsp72 by abnormal proteins generated in the cytosol as a result of heat shock and other protein damaging stresses is a primary event in JNK regulation. It will be established whether association with Hsp72 is critical for the ability of abnormal polypeptides to activate JNK; whether JNK activation induced by abnormal polypeptides proceeds via inhibition of JNK dephosphorylation; and whether other heat shock proteins which cooperate with Hsp72 in protein refolding are involved in JNK regulation. The second goal is to identify and characterize JNK phosphatase, which is regulated by heat shock and by Hsp72. The possible function of a phosphatase Shp-2 as a JNK phosphatase will be studied. An additional major JNK dephosphorylating activity will be purified. The enzyme will be identified and cloned. The role of this enzyme in dephosphorylating JNK in viva will be probed by a variety of approaches, such as ectopic overexpression of the normal gene and a dominant negative mutant; and expressing an antisense RNA to inhibit phosphatase translation. Regulation of this enzyme by heat shock and Hsp72 will be investigated. Elucidating the mechanisms of JNK suppression by Hsp72 is essential for understanding of heat resistance of cells, an important factor in hyperthermia treatment of cancer patients. Furthermore, similar mechanisms may function in Hsp72-mediated protection of cells from genotoxic stresses and anti-cancer drugs. Results of this research may suggest whether JNK phosphatase and Hsp72 could be attractive new targets for anticancer drug design.