Polarity Establishment Mechanisms in Candida albicans

白念珠菌菌丝尖端极性建立和维持的分子机制 增长在很大程度上仍是未知的，这种知识差距限制了模型的开发 菌丝侵入组织是如何防止的。与这项研究计划相关的长期目标 是了解菌丝尖端的极性是如何建立的(菌丝引导)以及菌丝引导是如何建立的 蛋白质介导白色念珠菌的接触感觉(亲水性)和侵袭行为。这些目标将是 通过追求以下三个具体目标在本提案中实现：1)确定重要的蛋白质 用于菌丝顶端的极性建立；2)确定顶端局部化的极性建立的程度 蛋白质参与趋趋性和侵袭性；以及3)建立已知的 菌丝导向GTP酶，Rsrlp，控制菌丝导向。在第一个目标下，前向基因筛查将 用于识别皮质定位的极性建立蛋白，(通过GFP融合的定位)和 缺乏这些末端定位候选蛋白的菌株的极性建立表型分析。在……下面 第二个目标是菌丝引导蛋白对菌脊的反应，能够调节菌丝的重定向。 而上皮细胞的损伤将被确定。在第三个目标下，遗传和生化相互作用 Rsrlp和菌丝顶端独特的极性蛋白之间的关系将由TIP的定位决定 缺乏Rsrlp活性菌株的极性结构(极化体和Spitzenkorper)，b)免疫共沉淀 Rsrlp和TIP极性蛋白之间的物理相互作用分析，以及c)上位性分析 缺乏Rsrlp和第二极性建立蛋白的菌株的趋性和侵袭能力。 这项拟议的研究意义重大，因为它将提供所需的知识来理解菌丝如何 以定向的方式生长，以及这与临床上相关的过程-宿主组织侵袭的关系。在… 同时，对菌丝体极性建立的基础性新知识进行了展望 在其他丝状真菌和其他极化真核生物中推进极性响应的一般场 细胞系统。这是白念珠菌生物学的一个重要且未被充分研究的领域，适用于 了解系统性白念珠菌感染时组织侵袭的发病机制 免疫功能受损的病人。

The molecular mechanism by which polarity is established and maintained during Candida albicans hyphal tip growth remains largely unknown and this gap in knowledge has limited the development of models for how hyphae invade tissues how this can be prevented. The long-term goal associated with this research program is to understand how polarity is established at hyphal tips (hyphal guidance) and how hyphal guidance proteins mediate C. albicans contact sensing (thigmotropic) and invasive behavior. These objectives will be achieved in this proposal by pursuing the following three Specific Aims: 1) Identify proteins that are important for polarity establishment at hyphal tips; 2) Determine the extent to which tip-localized polarity establishment proteins are involved in thigmotropism and invasion; and 3) Establish the mechanism by which the known hyphal guidance GTPase, Rsrlp, controls hyphal guidance. Under the first aim, a forward genetic screen will be used to identify cortically-localized polarity establishment proteins, (by localization of GFP fusions) and by analysis of polarity establishment phenotypes in strains lacking these tip-localized candidate proteins. Under the second aim, the ability of hyphal guidance proteins to mediate hyphal re-orientation in response to a ridge and epithelial cell damage will be determined. Under the third aim, genetic and biochemical interactions between Rsrlp and unique polarity proteins at the hyphal tip will be determined by a) localization of tip polarity structures (polarisome and Spitzenkorper) in strains lacking Rsrlp activity, b) co-immunoprecipitation analysis of physical interactions among Rsrlp and tip polarity proteins, and c) epistasis analysis of thigmotropic and invasive ability of strains lacking both Rsrlp and a second polarity establishment protein. The proposed research is significant because it will provide the knowledge needed to understand how hyphae grow in a directional manner and how this is related to a clinically relevant process - host tissue invasion. At the same time, the fundamental new knowledge obtained about polarity establishment in hyphae is expected to advance the general field of polarity responses in other filamentous fungi and in other polarized eukaryotic cell systems. This is an important and under-investigated area of C. albicans biology that has applicability to understanding the pathogenesis of tissue invasion during systemic C. albicans infections in immunocompromised patients.