PROTEASOME-LMP COMPLEX AND ANTIGEN PROCESSING

高等脊椎动物的细胞已经进化出一种机制， 在它们的表面上展示它们的细胞内内容物的样品， 与主要组织相容性复合体（MHC）结合的肽的形式 I类分子。 如此复杂。不仅需要 识别和破坏携带细胞内病原体的细胞， 或含有改变形式的自身蛋白质的细胞，如癌基因， 而且还用于T细胞在其免疫过程中的阳性和阴性选择。 胸腺的发育。 因此，重要的是确定如何 产生这些肽-MHC复合物。 此外，最近的数据显示， 不是给定抗原的所有肽都可以结合特定的 MHC I类分子实际上是在正常情况下产生的，并且 抗原加工中的多态性可能会改变 在不同个体中呈递给T细胞的肽。 照经上所 重要的是要确定是否和在多大程度上的特异性， 潜在的多态性，它们的产生影响了 这些肽被呈递给T细胞。 尽管它们至关重要，但肽的作用机制 与呈递给T细胞相关的是在正常细胞中产生的， 目前未知。 然而，最近的证据表明， 在这个过程中，细胞内的结构称为LMP复合物。 虽然 间接证据是强有力的，没有直接证据证明这一功能 仍然存在 本提案中描述的实验旨在 从基因和功能上检验这个假设。 我们特别 将确定正常抗原是否需要LMP复合体基因 处理，以及纯化的LMP复合物是否能够产生 体外相关肽。 此外，已知的 （等位基因）结构变异在这个复杂的蛋白水解 将测定活性和/或特异性。 我们还将扩大 初步迹象表明，不同形式的复杂存在， 不同的组织，并测试这种结构的潜在关系， 变功能。 这些研究的结果可能具有重要意义。 免疫反应的个体差异的影响， MHC连锁疾病易感性的遗传基础，以及MHC I类 匹配和非匹配移植。

Cells of higher vertebrates have evolved mechanisms enabling them to display on their surfaces a sampling of their intracellular contents, in the form of peptides bound to major histocompatibility complex (MHC) class I molecules. Such complexes. are required not only for the recognition and destruction of cells harboring intracellular pathogens, or cells containing altered forms of self proteins, such as oncogenes, but also for the positive and negative selection of T cells during their development in the thymus. It is therefore important to determine how these peptide-MHC complexes are generated. Moreover, recent data suggest that not all peptides of a given antigen which can bind to a particular MHC class I molecule are in fact produced under normal circumstances, and that polymorphism in antigen processing may alter the repertoire of peptides presented to T cells in different individuals. Thus, it is important to determine whether and to what extent the specificity of, and potential polymorphism in, their generation affects the repertoire of peptides that are presented to T cells. Despite their critical importance, the mechanisms by which peptides relevant to presentation to T cells are produced in normal cells are currently unknown. However, recent evidence implicates a large intracellular structure called the LMP complex in this process. Although the circumstantial evidence is strong, no direct proof for this function yet exists. The experiments described in this proposal are designed to test this hypothesis both genetically and functionally. Specifically, we will determine whether LMP complex genes are required for normal antigen processing, and whether purified LMP complex is capable of producing relevant peptides in vitro. Furthermore, the effect of the known (allelic) structural variation in this complex on its proteolytic activity and/or specificity will be determined. We will also expand on the preliminary indications that different forms of the complex exist in different tissues, and test the potential relationship of this structural variation to function. The results of these studies may have important implications for individual differences in immune responsiveness, the genetic basis of MHC-linked predisposition to disease, and MHC-class I matched and non-matched transplantation.