Functional characterization of CARD9 genetic variants in fungal immunity

摘要 真菌是皮肤和粘膜表面普遍存在的定植者。虽然许多人表现出轻微的真菌生长，但数百万人经历了危及生命的全身感染。许多基因的多态性与个体对真菌病原体产生炎症反应的能力有关。在许多这些基因中，已经观察到罕见的高等位基因，这些等位基因强烈破坏基因功能，导致原发性免疫缺陷和感染性疾病易感性增加。此外，在这些基因中已经报道了常见的遗传变异，其通过将基因产物的活性或表达改变到小但显著的程度来增加疾病的风险。这些基因提供了一个独特的机会，了解如何调整对病原体的免疫反应，以达到适当的免疫反应水平。这一假设通过与CARD9的不同遗传变体相关的各种表型得到了很好的说明。CARD9是在许多C型凝集素受体（CLR）下游起作用的信号传导蛋白，所述C型凝集素受体识别真菌和其他病原体上的碳水化合物部分。了解这些与人类疾病相关的CARD9突变如何影响CARD9功能将促进我们对真菌免疫的理解。在本提案的目标1中，我们研究了Card9泛素化在树突状细胞检测真菌中的作用。在目标2中，我们将确定控制Card9磷酸化的分子机制及其对真菌检测的影响。在目标3中，我们比较了Card9遗传变异如何影响念珠菌感染和结肠炎的发展。总之，这些目标将破译CARD9调控的机制基础，并表征CARD9遗传变异，以确定在真菌防御和炎症中具有重要作用的新分子机制。

ABSTRACT Fungi are ubiquitous colonizers of skin and mucosal surfaces. While many individuals exhibit minor fungal outgrowth, millions of others experience systemic infections with life-threatening consequences. Polymorphisms in numerous genes have been associated with the ability of an individual to generate an inflammatory response to fungal pathogens. In many of these genes, rare high-penetrance alleles have been observed that strongly disrupt gene function, resulting in primary immunodeficiencies and an increase in infectious disease susceptibility. Additionally, common genetic variants have been reported in these genes that increase the risk of disease by modifying the activity or expression of the gene product to a small but significant degree. These genes offer a unique opportunity to understand how immune responses to pathogens are tuned to achieve an appropriate level of immune response. This hypothesis is well illustrated by the various phenotypes associated with different genetic variants of CARD9. CARD9 is a signaling protein that functions downstream of many C type lectin receptors (CLRs), which recognize carbohydrate moieties on fungi and other pathogens. Understanding how these human disease-related CARD9 mutations affect CARD9 functions will advance our understanding of fungal immunity. In Aim 1 of this proposal, we examine the role of Card9 ubiquitination on fungal detection by dendritic cells. In Aim 2, we will identify the molecular mechanisms controlling Card9 phosphorylation and their consequences for fungal detection. In Aim 3, we compare how Card9 genetic variants affect Candida infection and the development of colitis. Together, these aims will decipher the mechanistic basis of CARD9 regulation and characterize CARD9 genetic variants to identify novel molecular mechanisms with important roles in fungal defense and inflammation.