Molecular biological investigation of interleukin-7 receptor gene expression in t lymphocytes

Official URL: http://risc01.sabanciuniv.edu/record=b1301342 (Table of Contents)

Interleukin-7 (IL-7) is an essential cytokine for the development and differentiation of lymphocytes in the mammalian immune system. IL-7 signaling requires the expression of IL-7 receptor (IL-7R) on the surface of B- and Tlymphocytes. IL-7R signaling initiates the transcription of various genes that control survival, proliferation and differentiation. Differentiation of immature thymocytes into mature T cells takes place in the thymus, where IL-7R is expressed starting from the CD4- CD8- double negative stage. However, IL-7R expression is suppressed in the CD4+ CD8+ double positive stage and is reexpressed in CD4+ CD8- and CD4- CD8+ single positive cells. IL-7R gene expression is tightly regulated in lymphocytes because of its importance in differentiation and survival. The transcription factors PU.1, GA binding protein (GABP) and Growth factor independence-1 (GFI-1), respectively upregulate and inhibit IL-7R gene expression in lymphocytes. We searched for the mechanisms of regulation of the IL-7R gene expression in T lymphocytes by deleting a putative suppressor-binding region in the IL-7Ralpha locus using bacterial artificial chromosome recombineering techniques. We attempted to downregulate the expression of various IL-7Ralpha activators using retroviral short hairpin RNA vectors targeting T lymphocyte cell lines. We analyzed IL-7R transcriptional activity and surface protein expression by flow cytometry and fluorescent microscopy.