Il-2r¦Á Gene Negative Regulatory Element (nre / Nirs) Study Combined With Screening Of Protein Function

The magnitude and duration of T-cell immune response are critically regulated by the interaction of interleukin-2 (IL-2) and its high-affinity receptor (IL-2R) on the surface of the cell. The high-affinity IL-2R is composed of three subunits, α,β and γ . Among them, IL-2Rα is the only component that can be specifically induced in activated lymphocytes and binds to IL-2, the growth signal for T cell proliferation. While IL-2Rβ and IL-2Rγ are crucial for IL-2 signaling, induction of IL-2Rα to form high-affinity receptor is a prerequisite for the cell to be fully responsive to physiological concentrations of IL-2.The transcription of the IL-2Rα gene is tightly regulated in vivo. It was reported that human IL-2Rα gene contained at least four positive regulatory regions: PRR I, PRR II, PRR III, and PRR IV. Each regulatory region appears to play a well-defined and complementary role. Despite the negative regulatory element (NRE) within the upstream regulatory region of human IL-2 receptor α (IL-2Rα) gene has been identified for two decades, mechanisms of the NRE function on the gene is hetero unknown. The negative regulatory element (NRE) mapped at -390/-380 bp (5' -TTCATCCCAGG-3' ) of the IL-2Rα gene with 82% homologues to NRE sequence of HIV LTR, and the same kind of 50kD non-tissue specific expressed protein can bind to NRE either of IL-2Rα or HIV gene . In addition, an imperfect inverse repeated sequence of the NRE (NIRS) between -153 bp and -143 bp (5' -CCTGGTTTGAA-3') homologous to NRE has been found. It was also found that both NRE and NIRS are required simultaneously for activation or repression of IL-2R α gene transcription in Jurkat cells by enzyme activity assay of the luciferase reporter gene. In Jurkat and HeLa cells, there is one kind of protein that can bind to both NRE and NIRS sequence by using UV cross-linking experiments.They're some similarity in regulatory mechanism between IL-2R α gene and HIV gene. The activation of lymphocytes can activate expression of IL-2R α gene, and HIV replicated only in activated lymphocytes. In HeLa cell and lymphocytes, constant...