Mechanisms of positive and negative thymic selection of CD8 T cells

描述(由申请人提供)：胸腺中TCR与自体多肽-MHC复合体的相互作用控制着正选择、谱系承诺和负选择的关键发育步骤，这些步骤对于产生功能性CD8T细胞库是必不可少的。这个 这项资助的基本假设是，为了成功通过积极和消极的选择，大多数胸腺细胞必须顺序地与不同胸腺细胞元件上呈现的不同多肽相互作用。我们推测，cTECs中的特化蛋白酶体(胸腺蛋白酶体)会产生为正选择而优化的多肽。我们进一步假设，为了产生一个广泛的、非自身反应性的CD8 T细胞谱系，通常有必要将mTECs和DC中用于否定选择的多肽转换为不同于用于正选择的多肽(“蛋白酶体/肽转换假说”)。为了验证这些假设，我们建立了一个新的小鼠模型，该模型在遗传上缺乏所有4个免疫和胸腺蛋白酶体亚基，因此只在所有细胞中表达构成蛋白酶体。我们建议结合最新的遗传模型、培养系统和质谱学来阐明胸腺选择的潜在机制。

DESCRIPTION (provided by applicant): TCR interactions with self peptide-MHC complexes in the thymus control the key developmental steps of positive selection, lineage commitment and negative selection that are essential for the generation of a functional CD8 T cell repertoire. The underlying hypothesis of this grant is that to successfully pass through positive and negative selection, most thymocytes must interact sequentially with distinct sets of peptides that are presented on different thymic cellular elements. We postulate that specialized proteasomes (thymoproteasomes) in cTECs make peptides that are optimized for positive selection. We further hypothesize that to generate a broad and non-autoreactive CD8 T cell repertoire, it is generally necessary to switch the peptides used for negative selection in mTECs and DCs to ones that are different than used for positive selection (the "proteasome/peptide switching hypothesis). To test these hypotheses, we have generated a novel mouse model that genetically lacks all 4 immuno- and thymo-proteasome subunits and therefore only expresses constitutive proteasomes in all cells. We propose to use this model together with state of the art genetic models, culture systems, and mass spectrometry to elucidate the underlying mechanisms of thymic selection.