Kruppel-like Factor 2 [KLF2, also called lung Kruppel-like factor (LKLF)] is a transcription factor shown to be necessary for the maintenance of naive T cells. KLF2 is expressed in both naive and memory cells, and is proposed to promote quiescence in these populations. During T cell stimulation, both KLF2 protein and mRNA are down-regulated, and loss of KLF2 appears to be critical for full T cell activation. It is unclear, however, how KLF2 expression is maintained in naive T cells. Recently it was proposed that IL-7, which is known to promote KLF2 re-expression in antigen-stimulated T cells, may also induce KLF2 expression in naive T cells. Here we address this issue by comparing the impact of IL-7 on KLF2 expression in naive and activated T cells. Use of bcl-2 transgenic T cells allowed us to uncouple the requirements for IL-7 in preserving naive T cell survival from its role in maintaining KLF2 expression. Our data demonstrates that IL-7 signals are not required for KLF2 maintenance in naive T cells, suggesting that this cytokine has distinct effects on KLF2 expression in naive versus activated T cells.
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We would like to thank Jeff Leiden for supplying the polyclonal anti-KLF2 antibody used for western blotting, and Matt Mescher for providing IL-12 and for advice with T cell purification and activation conditions. We also wish to thank other members of the Hogquist and Jameson laboratories for their support and input into this project. This work was supported in part by awards from the NIH (R01 AI38903) and ACS (RPG-99-264-01) to S. C. J. and through an NIH Immunology Training Grant (T32 AI07313) to B. T. E.
- T cell