GENERATING ANTIGENIC PEPTIDE/MHC BY CRYPTIC TRANSLATION

该项目的长期目标是了解抗原加工机制如何通过非常规（隐式）翻译产生抗原肽/MHC I类复合物。最近来自几个不同实验室的研究表明，肿瘤、病毒感染细胞和转染细胞表面的MHC I类分子所呈现的天然加工肽可以产生于预期不会被翻译的信使RNA区域。细胞取样这种抗原肽的隐源与代表蛋白质周转副产物的传统来源的机制尚不清楚。此外，这些隐肽在多大程度上有助于MHC分子呈现的多样化肽库及其免疫学作用仍有待确定。在本提案中，我们将测试这些非常规的，隐肽可能是一种新的翻译机制的产物，并可能在正常动物中发挥重要的免疫作用的假设。使用本实验室建立的独特试剂和方法，这些假设将通过以下方式进行验证：(1)确定确定mRNA的隐翻译如何发生并导致肽/MHC I类复合物表达的上下文规则，(2)确定隐肽/MHC I类复合物在正常转基因小鼠中的免疫作用，以及(3)分析隐肽/MHC I类复合物生成途径中的不同步骤。预计对隐肽/MHC复合物生成机制的进一步了解不仅将为抗原肽和疫苗设计提供新的来源，而且还将对蛋白质翻译和免疫监测机制产生新的见解。

The long term goal of this project is to understand how the antigen processing mechanism generates antigenic peptide/MHC class I complexes by unconventional (cryptic) translation. Recent studies, from several different laboratories have demonstrated that naturally processed peptides presented by MHC class I molecules on the surface of tumors, virally infected cells, and transfected cells can arise from regions of messenger RNA that were not expected to be translated. The mechanism by which cells sample this cryptic source of antigenic peptides versus the conventional source representing by-products of protein turn-over is not known. In addition, to what extent these cryptic peptides contribute to the diverse pool of peptides presented by MHC molecules and their immunological role remains to be established. In this proposal we will test the hypotheses that these unconventional, cryptic peptides could be products of a novel translational mechanism and could play a significant immunological role in normal animals. Using unique reagents and methods established in this laboratory these hypotheses will be tested by, (1) defining the context rules which determine how cryptic translation of the mRNA occurs and results in expression of peptide/MHC class I complexes, (2) determining the immunological role of cryptic peptide/MHC class I complexes in normal transgenic mice, and, (3) analyzing the different steps in the pathway for generation of cryptic peptide/MHC class I complexes. It is expected that improved understanding of the mechanism for generation of cryptic peptide/MHC complexes will not only provide novel sources of antigenic peptides and approaches to vaccine design but will also yield new insights into protein translation and immunesurveillance mechanisms.