IL-7 receptor pathway in Xenopus laevis

Abstract

Abstract IL7/IL7 receptor signaling is essential for development of mammalian B and T cells, in particular γδ T cells. The IL7 receptor is a heterodimer comprised of the IL7R α chain and the γ common chain that is shared by other IL2 family cytokines that signal through the JAK-STAT pathway. Since the SCID-like phenotype observed in IL7-knockout mice is less severe than that seen in IL7R knockout mice, there may be other cytokines that signal through the IL7R. In fact, thymic stromal lymphopoietin (TSLP) can substitute for IL7 and signal through the IL7R, at least in mice and humans. We have begun to address the role of IL7/IL7R signaling in Xenopus laevis, in which γδ T cells are abundant, particularly at the larval stages. Although an IL7R α ortholog is present in frogs, BLAST searches of the Xenopus tropicalis genome and gene synteny analyses strongly suggest the absence of IL7. To better understand the function of the IL7 heterodimer receptor in frogs, we have created protein models of both IL7R and the γ common chain (γc). We identified regions of the predicted X. tropicalis IL-7R cDNA that are well-conserved among lower organisms and created primers for use in PCR analyses of cDNA products from oligo-dT primed RNA isolated from the Xenopus laevis thymus. Analysis of the PCR products is currently underway.