Identification of the mechanisms controlling TLR9 localization

描述(申请人提供)：Toll样受体(TLRs)已进化为识别微生物病原体的保守特征。几个TLR家族成员认为核酸是病毒感染的标志。例如，TLR9识别存在于许多DNA病毒中的未甲基化的CpG DNA基序。在确保检测病原体的同时，核酸的这种特异性也使宿主暴露于由于对自身核酸的不适当识别而产生的潜在自身免疫。因此，必须存在防止自我识别的机制，同时仍然允许检测外源核酸。在这种情况下，令人惊讶的是，所有参与核酸检测的TLRs都保留在细胞内，而其他TLRs表达在细胞表面。我们假设TLR9的细胞内区隔阻止了对自身DNA的识别。这项提案的总体目标是确定建立和维持TLR9贩运和本地化的机制。在目标1中，我们将定义TLR9中的基序/S，它通过截短TLR9和具有选定突变的全长TLR9来调控转运到内溶酶体。在目标2中，我们将使用候选基因方法和siRNA筛选来确定控制TLR9内溶酶体定位的细胞因素。这一建议的完成将导致对TLR9细胞生物学的更好理解，并将对该受体的自我/非自我辨别产生影响。

DESCRIPTION (provided by applicant): Toll-like receptors (TLRs) have evolved to recognize conserved features of microbial pathogens. Several TLR family members recognize nucleic acids as signatures of viral infection. For example, TLR9 recognizes unmethylated CpG DNA motifs present in many DNA viruses. While ensuring the detection of pathogens, this specificity for nucleic acids also exposes the host to potential autoimmunity due to inappropriate recognition of self nucleic acid. Thus, mechanisms must exist that prevent self- recognition while still allowing detection of foreign nucleic acid. In this context, it is striking that all the TLRs involved in nucleic acid sensing are retained intracellulariy, while other TLRs are expressed at the cell surface. We hypothesize that the intracellular compartmentalization of TLR9 prevents the recognition of self-DNA. The overall goal of this proposal is to define the mechanisms that establish and maintain TLR9 trafficking and localization. In Aim 1, we will define the motif/s within TLR9 that govern trafficking to the endolysosome using truncations of TLR9 as well as full-length TLR9 with selected mutations. In Aim 2, we will identify cellular factors that control endolysosomal localization of TLR9 using a candidate gene approach as well as an siRNA screen. The completion of this proposal will result in a better understanding of TLR9 cell biology and will have implications for self/non-self discrimination by this receptor.