Stage-selective differential expression of kinesin (Kif) genes in cortical and medullary epithelial cells of the murine thymus.

The thymus is an organ with immunologic functions conserved from mouse to man (1). Both fetal and mammalian thymuses exist (1). The processes of negative and positive selection (2) both occur in the thymus and are thought to be conducted in an anatomically distinct fashion, across development. We performed global differential gene expression profiling using a microarray dataset (6) of the murine cortical epithelial cell (cTEC) and medullary epithelial cell (mTEC) transcriptome at months 1, 3, and 6. This analysis revealed that multiple members of the kinesin (Kif) gene family were differentially expressed by cTECs and by mTEC that express high levels of the class II major histocompatibility complex, in a stage-selective manner, but not by mTEC that express low levels of the class II major histocompatibility complex. The products of Kif genes may serve some important motor or transport function in the cortical or medullary epithelium of the mammalian thymus.