AIDS Opportunistic Infectious: Virulence of C. glabrata

描述（由申请人提供）：HIV阳性人群发生粘膜念珠菌病的风险增加，在艾滋病晚期，发生播散性念珠菌病的风险增加。在HIV阳性人群中，白色念珠菌和光滑念珠菌是阴道和食管念珠菌病的第一和第二常见病原体。在HIV阳性人群中，C. glabrata是第二个最常见的分离的真菌物种（在C.白色念珠菌）在美国的ICU中。关于C的相互作用知之甚少。与人类宿主接触这一延续的目的是建立在我们最近在C. glabrata的一个大家庭的假定的粘附素，有证明的作用，毒力。 C. glabrata编码至少20种与EPA1同源的细胞壁蛋白，EPA1是一种介导体外粘附上皮细胞的凝集素。这些基因中的大多数是端粒和转录沉默。我们已经发现，这种抑制是由基于表观遗传染色质的沉默引起的，并且已经鉴定了介导这种抑制的一些反式作用因子中的突变体。这些表观遗传调节因子中的突变体显示EPA基因表达增加和对毒力的显著影响。这一发现意义重大，因为它首次在真菌物种中将表观遗传基因调控与毒力联系起来。 该基金建议研究基因表达的表观遗传控制如何影响C.光滑的将在相关动物模型中检测已证明可改变毒力的沉默机制组分突变体。由于知之甚少，即使在S。为了了解酿酒酵母中用于启动端粒沉默的顺式作用序列，将对四个EPA簇绘制EPA沉默所需的沉默元件。EPA基因表达的其他表观遗传调节因子将使用遗传学和生物信息学方法进行鉴定。IVET方法将用于监测沉默的体内变化，以确定通常被亚端粒沉默抑制的EPA基因在何处和何时表达。 这一分析将导致对表观遗传调控如何改变C。glabrata基因，特别是粘附素基因，以及该调节如何影响宿主的定殖和感染。

DESCRIPTION (provided by applicant): The HIV positive population is at increased risk for mucosal candidiasis and, in late stage AIDS, for disseminated candidiasis. In the HIV positive population, Candida albicans and Candida glabrata are the first and second most frequent causative agents of vaginal and esophageal candidiasis. Mirroring what is seen in the HIV positive population, C. glabrata is the second most frequently isolated fungal species (after C. albicans) in ICUs in the United States. Little is understood about the interaction of C. glabrata with the human host. The objective of this continuation is to build on our recent discoveries in C. glabrata of a large family of putative adhesins, that have a demonstrated role in virulence. C. glabrata encodes at least 20 cell wall proteins with homology to EPA1, a lectin mediating in vitro adherence to epithelial cells. Most of these genes are telomeric and transcriptionally silent. We have found that this repression is brought about by epigenetic chromatin based silencing and have identified mutants in some of the trans acting factors that mediate this repression. Mutants in these epigenetic regulators show increased EPA gene expression and significant effects on virulence. This finding is significant in as much as it links epigenetic gene regulation with virulence for the first time in a fungal species. This grant proposes to examine how epigenetic control of gene expression impacts virulence in C. glabrata. Mutants in components of the silencing machinery that have been demonstrated to alter virulence will be tested in relevant animal models. Since little is known, even in S. cerevisiae about the cis-acting sequences that serve to initiate silencing at telomeres, the silencer elements required for EPA silencing will be mapped for four EPA clusters. Additional epigenetic regulators of EPA gene expression will be identified using genetic and bioinformatic approaches. IVET approaches will be used to monitor in vivo changes in silencing to determine where and when EPA genes normally repressed by sub telomeric silencing are expressed. This analysis will lead to a much increased understanding of how epigenetic regulation can alter expression of C. glabrata genes, in particular adhesin genes, and how that regulation impacts on colonization and infection of the host.