Antigen processing in the secretory pathway

描述（由申请人提供）：我们研究的长期目标是了解和操纵免疫监视途径。抗原加工机制在细胞表面产生数千种肽/MHC I类复合物（pMHC I）作为CD 8 T细胞的潜在配体。与教科书中描述的抗原肽在细胞质中生成的模型相反，最近的研究结果表明，抗原加工在内质网（ER）中继续进行。在ER中修剪抗原前体的蛋白酶被称为ERAAP（或ERAP 1），用于与抗原加工相关的ER氨肽酶。在ERAAP缺陷型小鼠中，ER中肽修剪的缺乏破坏了由经典（MHC Ia）和令人惊讶的非经典（MHC Ib）呈递的正常肽库：许多pMHC I缺失，伴随着许多新的，高免疫原性的pMHC I出现在ERAAP缺陷型细胞的表面上。独特肽的丢失和获得导致野生型与ERAAP缺陷型小鼠中强烈的相互免疫应答。在这里，我们建议测试ERAAP缺陷细胞中呈现的新肽在结构上不同的假设，因为它们代表正常修剪肽或被ERAAP破坏的肽的未编辑版本。我们将通过质谱和基于T细胞的测定来确定独特免疫原性肽的结构和来源。此外，由于ERAP 1的多态性与自身免疫性疾病（强直性脊柱炎和银屑病）相关，我们将检验以下假设：肽库的组成不仅受多态性MHC分子本身的影响，而且受ERAAP多态性的影响。我们预计这一建议的结果，以提供更深入的了解抗原加工途径，以及如何可以操纵的途径，以调节免疫原性。

DESCRIPTION (provided by applicant): The long term goal of our research is to understand and manipulate immune surveillance pathways. The antigen processing mechanisms yields thousands of peptide/MHC class I complexes (pMHC I) on the cell surface as potential ligands for CD8 T cells. Contrary to text book models which often depict the final antigenic peptide being generated in the cytoplasm itself, recent findings have shown that antigen processing continues in the endoplasmic reticulum (ER). The protease that trims antigenic precursors in the ER is called ERAAP (or ERAP1), for the ER aminopeptidase associated with antigen processing. In ERAAP-deficient mice, lack of peptide trimming in the ER disrupts the normal peptide repertoire presented by the classical (MHC Ia) and surprisingly, non-classical (MHC Ib) as well: many pMHC I go missing and concomitantly many novel, highly immunogenic pMHC I emerge on the surface of ERAAP-deficient cells. The loss and gain of unique peptides results in vigorous reciprocal immune responses in wild-type versus ERAAP-deficient mice. Here we propose to test the hypothesis that the novel peptides presented in ERAAP-deficient cells are structurally distinct because they represent unedited versions of normally trimmed peptides or those that were destroyed by ERAAP. We will determine the structure and origin of the unique immunogenic peptides by mass spectrometry and T-cell based assays. In addition, because polymorphisms in ERAP1 have been associated with autoimmune diseases (ankylosing spondylitis and psoriasis) we will test the hypothesis that the composition of the peptide repertoire is influenced not only by polymorphic MHC molecules themselves, but also by polymorphisms in ERAAP. We anticipate the results of this proposal to provide a deeper understanding of the antigen processing pathway and how the pathway can be manipulated to regulate immunogenicity.