GENERATING ANTIGENIC PEPTIDE/MHC BY CRYPTIC TRANSLATION

该项目的长期目标是了解抗原处理机制如何通过非常规(隐蔽)翻译产生抗原肽/MHC I类复合体。最近，来自几个不同实验室的研究表明，肿瘤、病毒感染细胞和转基因细胞表面的MHC I类分子提供的自然加工的多肽可以来自信使RNA未被翻译的区域。细胞对这种神秘的抗原肽来源与代表蛋白质转化副产品的常规来源进行采样的机制尚不清楚。此外，这些隐匿的多肽在多大程度上有助于MHC分子呈现的多肽库，以及它们的免疫学作用仍有待确定。在这项提议中，我们将检验这些非常规的、隐蔽的多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学作用的假设。使用本实验室建立的独特试剂和方法，将通过(1)定义上下文规则来验证这些假设，这些上下文规则决定了隐藏的mRNA如何发生翻译并导致肽/MHC I类复合体的表达，(2)确定隐藏肽/MHC I类复合体在正常转基因小鼠中的免疫学作用，以及(3)分析隐藏肽/MHC I类复合体产生途径的不同步骤。对隐匿肽/MHC复合体产生机制的深入了解不仅将为疫苗设计提供新的抗原肽来源和方法，而且还将为蛋白质翻译和免疫监控机制提供新的见解。

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.