GKLF in thymus epithelium as a developmentally regulated element of thymocyte-stroma cross-talk

Gut-enriched Kruppel-like factor (GKLF) is a transcriptional regulator expr essed in differentiated epithelia. We identified GKLF transcript as a regul ated element in thymic epithelium of recombinase-deficient mice during thym us development induced by anti-CD3 antibody injection. This treatment recap itulates the organogenetic process depending on productive rearrangement of T cell receptor (TCR) beta gene with thymocytes expansion and acquisition of the CD4(+)8(+) double positive phenotype. In wildtype mice, GKLF is expr essed very early in embryogenesis and becomes intensely up-regulated in thy mus epithelium at day 18 of gestation when TCR beta expressing cells have s electively expanded and express both CD4 and CD8. The results presented her e suggest that thymocytes may regulate GKLF transcriptionally in the cortic al epithelium at the developmental check-point controlled by TCR beta gene rearrangement. Furthermore, GKLF expression in hematopoietic stroma might s uggest the thus far uncharacterised participation of this factor in hematop oiesis. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.