The Regulation of Th2 Cytokine Genes: Functional and Comparative Genomic Analysis
AuthorStrempel, Jannine M
Committee ChairVercelli, Donata
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractImmune responses to extracellular pathogens are mediated by the Th2 cytokines Interleukin (IL)-4, IL-5 and IL-13, which are typically expressed by T helper type-2 (Th2) cells. The genes for IL4, IL5 and IL13 are grouped together within 150 kb of human chromosome 5q31, and their expression is regulated at multiple levels to ensure these proteins are rapidly secreted together in response to antigenic stimulation. Indeed, co-expression of these cytokines is vital for effective Th2 immunity and pathogen expulsion. This dissertation combines comparative approaches with molecular experimentation to provide novel insights into the mechanisms that govern the co-expression of Th2 cytokine genes.Conserved non-coding sequence (CNS)-1 has been shown to coordinately regulate the expression of all three Th2 cytokines genes. Using reporter assays with CNS-1 deletion mutants, we mapped a potent, 68 bp T cell activation-dependent enhancer core within CNS-1, which drives transcription of both human IL13 and IL4. The CNS-1 core contained three CREB binding sites to which CREB and the coactivators CREB binding protein and p300 were recruited in vivo upon T cell activation. Furthermore, CBP and p300 were required for CNS-1 core activity. These data define the region within CNS-1 responsible for enhancement of both IL4 and IL13 transcription in response to T cell receptor signaling.Coordinated expression of Th2 cytokine genes is rooted in an extensive array of cis-regulatory regions. We performed a multi-species comparative analysis of the Th2 cytokine gene cluster to locate CNSs, which may represent cis-regulatory elements, and identify transcription factor binding sites shared among them, which may mediate coregulated expression. Sites for GATA transcription factors were the most prevalent and widely distributed throughout the Th2 cytokine locus, consistent with the known role of GATA3 as a Th2 master switch. Notably, binding motifs for ETS proteins were also predicted within several Th2 CNSs. The majority of these sites bound Ets-1 both in vitro and in vivo in murine Th2 cells. Importantly, IL-4, IL-5, and IL-13 expression was markedly decreased in Th2 cells from Ets-1-/-mice. These data suggest an important and novel role for Ets-1 in the concerted expression of Th2 cytokine genes.