ROLE OF HSP90 IN POLARIZED CELL MORPHOGENESIS IN SCEREVISIAE & C ALBICANS

这个子项目是许多利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 丰富的分子伴侣Hsp 90是至关重要的折叠和调节的一组特定的客户端蛋白参与细胞分裂和分化。 在过去的几年中，Hsp 90已经成为一个可行的抗癌药物靶标，因为许多致癌蛋白需要Hsp 90来发挥功能。 作为概念证明，Hsp 90抑制剂减缓肿瘤生长，目前正在进行II期临床试验。 除了在某些肿瘤的生长中发挥关键作用外，Hsp 90也是由白色念珠菌引起的耐药致病性酵母菌感染的发展所必需的，因为Hsp 90抑制剂减缓或防止耐药性。因此，Hsp 90可能是参与C.白念珠菌的致病性和对药物治疗的适应性。 本研究的总体目标是确定Hsp 90的功能如何根据C.白色念珠菌 驱动假说是，在向致病性生长阶段的转变期间或在耐药性的发展期间，Hsp 90的活性将集中于对这些专门功能至关重要的客户蛋白。 具体目标1。 表征导致白色念珠菌Hsp 90裂解的细胞事件。 全身感染C.白色念珠菌具有针对Hsp 90片段的循环抗体。 进一步的研究表明，抗C。Ablicans Hsp 90在治疗念珠菌病中具有保护性。 另一个实验室证实，当在S. cerevisiae，C.白色念珠菌进行切割以产生免疫原性片段。 我们将在酵母中使用遗传学方法来鉴定改变免疫原性片段产生的条件，目的是在C.以确定改变的蛋白水解切割对小鼠模型中的感染和免疫原性的影响。 具体目标2。 表征Hsp 90与Hbt 1的相互作用，Hbt 1是酿酒酵母中极化形态发生所需的蛋白质。 在菌丝转变过程中，C.白色念珠菌经历极化形态发生和细胞壁重组。 我们确定了Hbt 1和热休克蛋白90之间的相互作用，含有突变，导致缓慢的，温度敏感的生长伴随着改变形态。 我们的假设是，热休克蛋白90相互作用与Hbt 1在细胞中的限制生长条件下，或在细胞发生形态学变化。 这些研究将为Hsp 90和Hbt 1在细胞信号通路中的功能提供新的信息。 具体目标3。 了解Hsp 90与不同客户蛋白相互作用的相似性和差异性。 与辅伴侣蛋白结合，Hsp 90与数百种不同的蛋白质相互作用。 我们将确定不同的Hsp 90客户蛋白的活性是否同样受到Hsp 90和辅助分子伴侣突变的影响。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The abundant molecular chaperone Hsp90 is critical for the folding and regulation of a specific set of diverse client proteins involved in cell division and differentiation. In the last few years Hsp90 has emerged as a viable anti-cancer drug target since many oncogenic proteins require Hsp90 for function. As proof of concept, Hsp90 inhibitors slow tumor growth and are currently in Phase II clinical trials. In addition to playing a critical role in the growth of certain tumors, Hsp90 is also required for the development of drug-resistant pathogenic yeast infections caused by Candida albicans, since Hsp90 inhibitors slowed or prevented drug resistance. Thus it seems likely that Hsp90 is required for the function of key proteins involved in C. albicans pathogenicity and the adaptation to drug treatment. The overall goals of this proposal are to determine how Hsp90 function differs depending on the life stage of C. albicans. The driving hypothesis is that during the switch to the pathogenic growth phase or during development of drug resistance, activities of Hsp90 will be focused on client proteins essential for these specialized functions. Specific Aim 1. Characterize the cellular events that lead to cleavage of Candida albicans Hsp90. Patients that survive systemic infections of C. albicans have circulating antibodies against a fragment of Hsp90. Additional studies indicate that antibodies against C. ablicans Hsp90 are protective in treating candidiasis. Another laboratory established that when expressed in S. cerevisiae, C. albicans undergoes cleavage to generate the immunogenic fragments. We will use a genetic approach in yeast to identify conditions that alter production of the immunogenic fragments with the goal of making directed mutations in C. ablicans to determine the effect of altered proteolytic cleavage on infection and immunogenicity in mouse models. Specific Aim 2. Characterize the interaction of Hsp90 with Hbt1, a protein required for polarized morphogenesis in Saccharomyces cerevisiae. During the hyphal transition, C. albicans undergoes polarized morphogeneis and reorganization of the cell wall. We identified an interaction between Hbt1 and Hsp90 containing mutations that cause slow, temperature sensitive growth accompanied by altered morphology. Our hypothesis is that Hsp90 interacts with Hbt1 in cells under limiting growth conditions or in cells undergoing morphological changes. These studies will provide novel information about the functions of Hsp90 and Hbt1 in cellular signaling pathways. Specific Aim 3. Understanding the similarities and differences in how Hsp90 interacts with diverse client proteins. In conjunction with co-chaperone proteins, Hsp90 interacts with hundreds of diverse proteins. We will determine whether the activity of diverse Hsp90 client proteins is similarly affected by mutations in Hsp90 and co-chaperones.