Candida albicans secreted protease Sap6 engages epithelial protease-activated receptors PAR2 and NLRP3

白念珠菌致病性与其由酵母菌转化为 丝状菌丝的生产。菌丝专一性蛋白的分泌，特别是天冬氨酸 蛋白水解酶Sap6是其从共生状态向毒力状态转变的关键标志。SAP6包含 在其催化区附近有一个蛋白酶域和一个RGDRGD整合素结合基序。 我们发现，rSap6加入到原代口腔上皮细胞(OEC)中，可以诱导典型的口腔黏膜上皮细胞(OEC)分泌IL1β。 NLRP3信号转导还产生IL-8。嗅鞘细胞中加入SAP6诱导p38和p38的磷酸化 通过蛋白水解酶激活受体(PAR2)产生IL-8。PAR2信号在受热时丢失 Sap6失活，而NLRP信号在Sap6 RGD结合位点缺失后减少， 从而导致我们的假设，即Sap6蛋白降解和RGD介导的机制都参与了 嗅鞘细胞检测这种真菌分泌的蛋白质水平。我们将通过确定 Sap6激活Aim1中OECs中PAR2 MAPKinase信号的蛋白分解机制 评估Sap6整合素结合RGD基序在NLRP3炎症体中的作用 AIM 2的激活和凋亡。这项工作将建立PAR2和整合素/NLRP3作为细胞表面 白念珠菌Sap6受体及其在调节宿主炎症反应中的作用 嗅鞘细胞中的真菌蛋白。该项目长期目标将是激活/停用PAR2 受体或NLRP3信号作为调节宿主炎症的一种手段 念珠菌病的治疗。

Candida albicans pathogenicity is associated with its morphological transformation from yeast to production of filamentous hyphae. Secretion of hyphal-specific proteins, particularly the aspartyl protease Sap6, is a key marker of its transition from commensalism to virulence. Sap6 contains both a proteinase domain and an RGDRGD integrin-binding motif adjacent to its catalytic domain. We found that rSap6 added to primary oral epithelial cells (OECs) elicited IL1β secretion typical of NLRP3 signaling but also produced IL-8. Sap6 added to OECs induced phosphorylation of p38 and IL-8 production through the protease- activated receptor (PAR2). PAR2 signaling was lost upon heat inactivation of Sap6, while NLRP signaling was reduced upon deletion of Sap6 RGD-binding sites, leading to our hypothesis that both Sap6 proteolytic and RGD-mediated mechanisms are involved in sensing levels of this fungal secreted protein by OECs. We will test this hypothesis by identifying the proteolytic mechanism for Sap6 activated PAR2 MAPKinase signaling in OECs in Aim1, and assessing the contribution of the Sap6 integrin-binding RGD motif in NLRP3 inflammasome activation and apoptosis in Aim 2. This work will establish PAR2 and integrin/NLRP3 as cell surface receptors for C. albicans Sap6 and define their role in modulating host inflammatory responses to fungal proteins in OECs. The long-range goal of this project will be to activate/deactivate PAR2 receptors or NLRP3 signaling as a means of modulating host inflammation as an avenue for treatment of candidiasis.