Mechanisms of positive and negative thymic selection of CD8 T cells

描述（由申请方提供）：TCR与胸腺中自身肽-MHC复合物的相互作用控制着阳性选择、谱系定型和阴性选择的关键发育步骤，这些步骤对于功能性CD 8 T细胞库的产生至关重要。的 该授权的基本假设是，为了成功地通过阳性和阴性选择，大多数胸腺细胞必须顺序地与呈现在不同胸腺细胞元件上的不同肽组相互作用。我们假设，专门的蛋白酶体（胸腺蛋白酶体）在cTEC的肽，积极的选择是优化的。我们进一步假设，为了产生广泛的和非自身反应性的CD 8 T细胞库，通常需要将用于mTEC和DC中的阴性选择的肽转换为与用于阳性选择的肽不同的肽（“蛋白酶体/肽转换假说"）。为了验证这些假设，我们已经产生了一种新的小鼠模型，该模型在遗传上缺乏所有4种免疫和胸腺蛋白酶体亚基，因此在所有细胞中仅表达组成型蛋白酶体。我们建议使用这个模型与最先进的遗传模型，培养系统和质谱一起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.