A MODEL OF MORPHOLOGIC SWITCHING IN CANDIDA ALBICANS

谢丽尔·A·盖尔博士是明尼苏达大学的新生儿专家。候选人的长期目标是追求主要致力于基础研究的学术生涯。在盖尔博士的儿科住院医生和新生儿团契培训期间，她接触到了新生儿重症监护病房早产儿中与系统性念珠菌病相关的高发病率和高死亡率。这一经历巩固了盖尔博士对了解真菌发病机制的兴趣，将其作为开发更有效治疗方法的一种手段。拟议的申请将为候选人提供必要的额外培训，使其具有独立资金的竞争力。明尼苏达大学丰富的学术和研究环境非常适合候选人的职业发展。在朱迪思·伯曼博士的直接指导下，盖尔博士将研究白念珠菌形态转换的分子机制。她将专注于在体内表征细胞骨架相关蛋白在形态转换过程中的定位，并确定细胞周期检查点在形态发生过程中的作用。形态转换被认为有助于白色念珠菌作为病原体的成功，因为它使真菌在面对不断变化的环境时具有多功能性。盖尔博士此前发现，白色念珠菌的INT1基因编码一种蛋白质，这种蛋白质对酵母形态向丝状形态的转变至关重要。INT1在通常不具致病性的酿酒酵母中的表达导致极长的芽体的形成，看起来类似于白色念珠菌的芽管。她最近对酿酒酵母中这些细长的芽的表征表明，Int1p的表达导致了细胞骨架相关蛋白(Septins)的新定位，这种定位模仿Int1p本身。她还发现，INT1的表达导致核细胞周期的延迟，部分原因是形态发生检查点蛋白Swe1p的激活。这项提案的具体目标将建立在这些初步结果的基础上，以直接确定在白念珠菌中，Int1p、Septins和细胞周期检查点在形态转换中的作用。盖尔博士将开发一种白念珠菌基因组表位标记技术，该技术将允许在白念珠菌的细胞周期和野生型和突变白念珠菌形态菌株(特定目标1和2)的形态转换期间在体内定位Int1p和Septins。候选人将破坏白色念珠菌的SWE1同源基因，并研究这种突变对菌株的生存能力和进行形态转换的能力的影响(特定目标3)。这些研究将使盖尔博士能够确定Int1p、Septins和细胞周期控制蛋白在形态转换过程中的关系，并可能确定抗真菌药物的新治疗靶点。

Dr. Cheryl A. Gale is a neonatologist at the University of Minnesota. The candidate's long-term goal is to pursue an academic career devoted primarily to basic research. During Dr. Gale's pediatric residency and neonatal fellowship training, she was exposed to the high morbidity and mortality associated with systemic candidiasis in her premature patients on the neonatal intensive care unit. This experience solidified Dr. Gale's interest in understanding fungal pathogenesis as a means toward developing more effective therapies. The proposed application will provide the candidate the additional training necessary to be competitive for independent funding. The rich academic and research environment at the University of Minnesota is extremely well suited for the candidate's career development. Under the direct mentorship of Dr. Judith Berman, Dr. Gale will study the molecular mechanism of morphologic switching in C. albicans. She will focus on characterizing in vivo the localization of cytoskeletal-associated proteins during morphologic switching and determining the role of cell cycle checkpoints during morphogenesis. Morphologic switching is postulated to contribute to the success of C. albicans as a pathogen because it gives the fungus versatility in the face of changing environments. Dr. Gale previously found that the C. albicans gene INT1 encodes a protein that is important for the morphologic switch from yeast-form to filamentous-form. Expression of INT1 in the usually non- pathogepic yeast, S. cerevisiae, results in the formation of extremely elongated buds that appear similar to C. albicans germ tubes. Her more recent characterization of these elongated buds in S. cerevisiae has shown that Int1p expression causes a novel localization of cytoskeletal-associated proteins (septins) that mimics that of Int1p itself. She also found that INT1 expression results in a delay in the nuclear cell cycle partially due to the activation of the morphogenesis checkpoint protein, Swe1p. The Specific Aims of this proposal will build on these preliminary results to directly determine, in C. albicans, the role of Int1p, septins, and cell cycle checkpoints in morphologic switching. Dr. Gale will develop a technique of genomic epitope tagging in C. albicans that will allow in vivo localization of Int1p and septins in C. albicans during the cell cycle and during morphologic switching in both wild-type and mutant C. albicans morphologic strains (Specific Aims 1 and 2). The candidate will disrupt the C. albicans SWE1 homolog and study the effect of such a mutation on the viability and ability of the strain to undergo morphologic switching (Specific Aim 3). These studies will allow Dr. Gale to determine the how Int1p, septins and cell cycle control proteins are related in the process of morphologic switching and may identify new therapeutic targets for anti- fungal agents.