Stage-selective differential expression of eukaryotic initiation factor (Eif) genes in the medullary epithelial cells of the murine thymus.

The thymus is the site of positive and negative selection in mammals (1), the process by which developing lymphocytes are selected for or deleted based on their ability to encounter foreign or self antigen, respectively, with optimal binding affinity (2, 3). The thymus consists of a medulla and a cortex , with mTEC, or medullary thymic epithelial cells expressing high or low amounts of the class II major histocompatibility complex (mTEChi and mTEClo) (4, 5). To understand how the mTEC transcriptome changes over mammalian adult development, we performed global differential gene expression profiling using a public microarray dataset to compare the transcriptomes of mTEC at months 1, 3, and 6 (6). We found that multiple eukaryotic initiation factors, or Eif genes, were differentially expressed by mTEClo and mTEChi. These data suggest a unique requirement for specific eukaryotic initiation factors during translation of proteins in the mTEClo and mTEChi cell types of the thymus.