Regulation of ß(1,3)-glucan exposure in Candida albicans

白色念珠菌中α(1,3)-葡聚糖暴露的调节

基本信息

批准号：
10611957
负责人：
Todd B Reynolds
金额：
$ 50.89万
依托单位：
UNIVERSITY OF TENNESSEE KNOXVILLE
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-05-08 至 2025-04-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10611957
关键词：
ACE2 Address Alleles Antifungal Agents Antifungal Therapy Architecture Biology Candida Candida albicans Carbohydrates Caspofungin Cell Wall Cells Cellular biology Chitin Cytolysis Decision Making Detection Epitopes Exhibits Feedback Genes Genetic Genetic Epistasis Genetic Transcription Glucans Glycoproteins Goals Health Human Hyperactivity Immune Immune response Immune system Immunologic Receptors In Vitro Infection Life LoxP-flanked allele MAP Kinase Modules Macrophage Macrophage-1 Antigen Mammals Mannans Masks Mediating Mitogen-Activated Protein Kinases Molecular Mus Mycoses Overlapping Genes Pathway interactions Patient-Focused Outcomes Pharmaceutical Preparations Polymers Proteins Regulation Research Services Signal Pathway Signal Transduction Stress Systemic infection Techniques Technology Testing Transgenic Mice Virulence cell type dectin 1 experimental study fungus genetic approach glucan synthase improved mortality mutant neutrophil novel overexpression receptor tool trait transcription factor upstream kinase

项目摘要

Candida albicans and related Candida spp. are responsible for ~400,000 invasive infections/year, which have an ~50% mortality rate. A crucial virulence trait of C. albicans, and other fungi, is the ability to diminish their detection by their hosts. The cell wall carbohydrate ß(1,3)-glucan is an important epitope that the immune systems of humans and other mammals use to recognize and respond to fungal infections through receptors like Dectin-1 and complement receptor 3 (CR3). Fungi like C. albicans diminish their detection from immune cells through masking ß(1,3)-glucan under an outer layer of mannosylated glycoproteins (mannan). The virulence of C. albicans is compromised in conditions where ß(1,3)-glucan is more exposed (unmasked). For example, echinocandin antifungal drugs, like caspofungin, inhibit ß(1,3)-glucan synthase and cause cell lysis in vitro, but also induce exposure of ß(1,3)-glucan, even at sublethal concentrations. In addition, a number of mutants that exhibit increased exposure of ß(1,3)-glucan have decreased virulence. However, a major research challenge is to understand the impact of ß(1,3)-glucan exposure on virulence during caspofungin treatment. It has been difficult to differentiate between cidal effects of the drug and the impact of ß(1,3)-glucan exposure. A challenge closely related to this is that the mechanism by which caspofungin causes ß(1,3)-glucan exposure is unknown. We have found that we can decouple caspofungin's cidal effects from unmasking, which allows us to address both of these challenges. This can be done by activating caspofungin-responsive signaling pathways using a genetic approach rather than the drug, and we have discovered that at least one of these pathways causes unmasking. The Cek1 MAP kinase (MAPK) pathway is activated by caspofungin treatment, and we have discovered that genetic activation of this cascade causes unmasking when hyperactivated, even in the absence of caspofungin. However, unlike the drug, activation of this pathway does not compromise viability. Thus, we can meet the second challenge by using this pathway to dissect the mechanism through which unmasking occurs. Moreover, we can meet the first challenge by using the Cek1 pathway as tool to probe how the immune system responds to unmasking during mouse systemic infections because, unlike caspofungin, it is not cidal. We will address these challenges in three specific aims. In Aim 1 we will elucidate the mechanisms by which the Cek1 cascade regulates ß(1,3)-glucan exposure. There are two main transcription factors downstream of Cek1 and we will determine how the pathway chooses a particular one (Cph1) using a combination of genetic, epistasis, and cell biology techniques that will identify how Cek1- Cph1 is activated to cause unmasking. In Aim 2 we will determine how transcriptional targets of Cek1-Cph1 alter the cell wall to cause unmasking. In Aim 3, we will elucidate how exposure of ß(1,3)-glucan causes decreased virulence in mice. We will use transgenic mice to define how neutrophils, macrophages, Dectin-1 and/or CR3 participate to reduce the virulence of unmasked C. albicans.

白色念珠菌和相关的念珠菌属。负责约400,000个侵入性感染/年约50％的死亡率。白色念珠菌和其他真菌的关键病毒特征是减少其的能力他们的主人发现。细胞壁碳水化合物ß（1,3）-Glucan是免疫的重要发作人类和其他哺乳动物的系统用于识别和反应通过受体的真菌感染例如Dectin-1和补体受体3（CR3）。真菌像白色念珠菌一样减少免疫的检测细胞通过遮罩糖蛋白（Mannan）的外层下层下层（1,3） - 葡聚糖。在β（1,3）-Glucan更暴露（未掩盖）的条件下，白色念珠菌的毒力被损害。为了例如，像caspofungin这样的echinocandin抗真菌药物抑制ß（1,3） - 葡聚糖合酶，并引起细胞裂解体外，但也会引起ß（1,3） - 葡聚糖的暴露，即使是在亚致死浓度下也是如此。另外，许多暴露于增加ß（1,3） - 葡聚糖暴露的突变体降低了病毒。但是，一个专业研究挑战是了解ß（1,3） - 葡聚糖对Caspofungin期间病毒的影响治疗。很难区分药物的cidal效应和ß（1,3）-glucan的影响接触。与此密切相关的挑战是Caspofungin引起ß（1,3）-Glucan的机制暴露是未知的。我们发现，我们可以将Caspofungin的Cidal效应与揭露，这使我们能够解决这两个挑战。这可以通过激活caspofungin响应性来完成使用遗传方法而不是药物的信号传导途径，我们发现至少一个这些途径会导致揭露。 CEK1 MAP激酶（MAPK）途径被Caspofungin激活治疗，我们发现该级联反应的遗传激活会导致揭露即使没有caspofungin，过度活化也是如此。但是，与药物不同，该途径的激活确实不妥协的生存能力。那就是我们可以通过使用此途径来剖析第二个挑战发生透明的机制。此外，我们可以使用CEK1来应对第一个挑战途径是探测免疫系统如何响应鼠标全身感染期间透明的工具的途径因为，与Caspofungin不同，它不是Cidal。我们将以三个具体目标解决这些挑战。在目标1中我们将阐明CEK1级联调节ß（1,3） - 葡聚糖暴露的机制。有两个 CEK1下游的主要转录因子，我们将确定该途径如何选择特定一种（CPH1）结合了遗传，上毒和细胞生物学技术的组合，该技术将如何确定CEK1- CPH1被激活以引起卸载。在AIM 2中，我们将确定CEK1-CPH1的转录目标如何更改细胞壁以引起卸载。在AIM 3中，我们将阐明如何暴露于ß（1,3） - 葡聚糖原因小鼠病毒降低。我们将使用转基因小鼠定义中性粒细胞，巨噬细胞，dectin-1如何和/或CR3参与以减少未掩盖白色念珠菌的病毒。