Regulation of HSF1 and HSF2 by SUMO-1 Modification

描述(申请人提供)：本申请的长期目标是阐明调节应激诱导和热休克蛋白(HSP)结构性表达的机制(S)，这不仅对细胞在应激条件下生存的能力至关重要，而且对非应激细胞中正常的蛋白质折叠也至关重要。转录调节蛋白HSF1和HSF2的应激诱导活性与结构性活性对于这种应激激活和基础HSP基因的表达是至关重要的，但它们的差异调节活性是如何控制的尚不清楚。在对这一机制的探索中，我们已经确定了HSF1和HSF2的SUMO-1修饰分别导致应力诱导和结构性激活的不同调控。我们认为，HSFs的SUMO-1修饰是其与HSP基因启动子相互作用的转录活性(DNA结合活性)、与这些启动子上的其他因子组装转录复合体(反式激活潜力)以及保护其免受降解的先决条件。在这一应用中，我们将1)确定SUMO-1修饰对HSF1和HSF2的DNA结合和反式激活活性的功能后果，2)表征这种修饰在调节HSF1和HSF2周转中的作用，以及3)确定介导应激诱导的HSF1和HSF2的相扑1修饰与结构性相扑1修饰的差异调节的机制(S)，确定HSF相扑甲基化对体内蛋白质错误折叠的意义，以及确定HSFs的相扑甲基化是否因细胞老化而改变。这项研究的结果将确定HSF1和HSF2的差异调控导致热休克蛋白的应激诱导和结构性表达的基础，并可能为操纵细胞热休克蛋白的表达提供一种策略，有望成为治疗由蛋白质错误折叠/聚集引起的疾病，如帕金森氏症、亨廷顿病和阿尔茨海默病的潜在方法。

DESCRIPTION (provided by applicant): The long-term goal of this application is to elucidate the mechanism(s) that regulate stress-induced and constitutive expression of heat shock proteins (hsps), which are critical not only for the cell's ability to survive exposure to stress conditions but also for normal protein folding in non-stressed cells. The stress-inducible vs. constitutive activities of the transcriptional regulatory proteins HSF1 and HSF2 are critical for this stress-activated and basal hsp gene expression, but how their differentially-regulated activities are controlled is unknown. In the search for this mechanism, we have identified differential regulation of SUMO-1 modification of HSF 1 and HSF2 leading to stress-induced and constitutive activation, respectively. We propose that SUMO-1 modification of HSFs is pre-requisite for their transcriptional activities at the levels of their ability to interact with promoters of hsp genes (DNA-binding activities), for assembly of transcription complexes with other factors on these promoters (transactivation potential), and for their protection against degradation. In this application we will 1) determine the functional consequences of SUMO-1 modification for the DNA-binding and transactivation activities of HSF 1 and HSF2, 2) characterize the role of this modification in regulating the turnover of HSF1 and HSF2, and 3) identify the mechanism(s) which mediate the differential regulation of stress-induced vs. constitutive SUMO-1 modification of HSF1 and HSF2, determine the significance of HSF sumoylation for protein misfolding in vivo, and determine whether sumoylation of HSFs is altered by cellular aging. Results from the proposed studies will define the basis of the differential regulation of HSF 1 and HSF2 leading to stress-induced and constitutive expression of heat shock proteins, and may provide a strategy for manipulating cellular heat shock protein expression, a promising potential treatment of diseases caused by protein misfolding/aggregation such as Parkinson's, Huntington's, and Alzheimer's Disease.