PEPTIDES IDENTIFIED FROM THE TYPE I DIABETES ASSOCIATED MHC CLASS I-H2-KD

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。由主要组织相容性复合体（MHC）结合的肽库决定了重要生物学结果的命运，如细胞防御和对外来入侵者的免疫反应，或在某些异常情况下对自身抗原的反应。对I类和II类MHC分子的天然加工肽的详细分析揭示了某些一般特征，例如，由I类MHC分子选择的天然加工肽的长度通常限制在8-10米，而由II类MHC分子选择的肽更长，更多变，通常在14-24米之间。更重要的是，对天然加工肽的详细分析解决了密切相关的MHC分子中肽选择特异性的关键问题，这在先前涉及合成肽库的研究中并不明显。在本分析中，我们试图确定由I类MHC分子H-2Kd选择的肽的性质和基序。我们之所以选择H-2Kd，是因为它可能在几个疾病领域发挥重要作用，包括：对病毒和细菌病原体的应答、自身免疫性糖尿病、肿瘤免疫学和基于肽的肿瘤疫苗的功效。我们对H-2Kd选择的大量肽的分析结果已经牢固地建立了肽结合基序。虽然大部分自然选择的肽的长度为8至10个氨基酸，但也有相当一部分长度较长，有些长达18米。结合研究表明，短肽结合具有较高的亲和力并形成长寿命的肽- mhc复合物，而长肽结合较弱且解离速度快。修剪长肽不能改善结合相互作用，相反，延长9-mer自然加工的表位也不能降低结合。最后，研究了长肽的结合方式。这些实验结果表明，H-2Kd选择的天然加工肽的长度从8- 18-m不等。虽然大多数肽的长度为8-10个氨基酸，但长度为10个氨基酸的肽也占显著比例。这些肽的免疫学意义目前正在研究中。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The repertoire of peptides bound by major histocompatability complexes (MHC) determines the fate of important biological outcomes such as the cellular defense and immune responses to foreign invaders or in some aberrant cases reactivity to self antigens. Detailed analyses of naturally processed peptides from class I and II MHC molecules have revealed certain general features, for example the lengths of naturally processed peptides selected by class I MHC molecules are usually restricted to 8-10-mers whereas those selected by class II MHC molecules are longer and more variable, usually between 14-24-mer. More importantly, detailed analyses of naturally processed peptides have addressed key issues regarding the specificity of peptide-selection among closely related MHC molecules, which was not evident in prior studies involving synthetic peptide libraries. In this analyses, we sought to identify the nature and motif of peptides that are selected by the class I MHC molecule, H-2Kd. We selected H-2Kd because it may play a significant role in several areas of disease including: responses against viral and bacterial pathogens, autoimmune diabetes, tumor immunology, and the efficacy of peptide-based tumor vaccines. Results from our analyses of large numbers of peptides selected by H-2Kd have firmly established the peptide-binding motif. Although a large fraction of naturally selected peptides were 8 to 10 amino acids in length, there were a significant fraction that were of longer length, some as long as 18-mers. Binding studies demonstrated that while the short peptides bound with higher affinity and formed long-lived peptide-MHC complexes, the longer peptides bound weakly and had a fast dissociation rate. Trimming the long peptides did not improve binding interactions and conversely extending the 9-mer naturally processed epitopes did not decrease binding. Finally, the mode of binding of the longer peptides was investigated. Results from these experiments demonstrate that the Naturally processed peptides selected by H-2Kd varied in length from 8-mers to 18-mers ? although most peptides were 8-10 amino acids, there was a significant fraction that were 10 amino acids in length. The immunological significance of these peptides is currently under investigation.