Fig. 4.

Altered early thymocyte development in ThPOK^const mice. (A) FACS analysis of thymocytes from ThPOK^const and control non-Tg mice at different stages in ontogeny, as indicated, showing expression of CD4, CD8, and TCRβ. Note prominent TCRβ⁻ SP CD4 subset in embryonic ThPOK^const mice, which diminishes progressively in neonates and adults. Also, note that the CD8⁺ immature single positive (ISP) subset is absent in ThPOK^const mice at e17 (0.6% SP CD8 cells, compared with 4.9% in WT control). (B) RT-PCR analysis of ThPOK and Runx3 mRNA expression in indicated sorted thymic subsets from ThPOK^const MHC class II^−/− mice, compared with MHC class II^−/− and β2m^−/− mice. Note that ThPOK is expressed constitutively in all subsets from ThPOK^const MHC class II^−/− mice, whereas Runx3 is severely repressed in these mice. INT refers to CD4⁺8^low subset intermediate between DP and SP stages.