Modest cortex and promiscuous medulla for thymic repertoire formation

Yousuke Takahama1, Keiji Tanaka, Shigeo Murata

  • 1Division of Experimental Immunology, Institute for Genome Research, University of Tokushima, Tokushima 770-8503, Japan. takahama@genome.tokushima-u.ac.jp <takahama@genome.tokushima-u.ac.jp>

Recent advances in the understanding of medullary thymic epithelial cell biology, and especially of their promiscuous gene expression, have highlighted the indispensable role of thymic medulla in shaping a self-tolerant T-cell repertoire. Additionally, our recent results have shown that cortical thymic epithelial cells possess a unique proteasome (the so-called thymoproteasome), which seems to possess limited protein degradation capability for generating peptides that are loaded onto class I major histocompatibility complex molecules. We discuss here the unique role of thymoproteasomes in the development and repertoire formation of CD8+ T cells, focusing on the stepwise and contrasting roles of cortical epithelial cells and medullary epithelial cells. These results could offer fundamental new insights into the molecular mechanisms of T-cell repertoire selection.

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