MULTIPLE TRANSCRIPTION FACTORS ARE REQUIRED FOR ACTIVATION OF HUMAN INTERLEUKIN-9 GENE IN T-CELLS

The genetic elements and regulatory mechanisms responsible for human i nterleukin 9 (IL-9) gene expression in a human T cell leukemia virus t ype I-transformed human T cell line, C5MJ2, were investigated. We demo nstrated that IL-9 gene expression is controlled, at least in part, by transcriptional activation. Transient expression of the luciferase re porter gene Linked to serially deleted sequences of the 5'-flanking re gion of the IL-9 gene has revealed several positive and negative regul atory elements involved in the basal and inducible expression of the I L-9 gene in C5MJ2 cells. An AP-1 site at -146 to -140 was shown to be involved in the expression of the IL-9 gene. A proximal region between -46 and -80 was identified as the minimum sequence for the basal and inducible expression of the IL-9 gene in C5MJ2 cells. Within this regi on, an NF-kappa B site at -59 to -50 and its adjacent 20-base pair ups tream sequence were demonstrated to play a critical role for the IL-9 promoter activity. DNA-protein binding studies indicated that NF-kappa B, c-Jun, and potentially novel proteins (around 35 kDa) can bind to this important sequence. Mutations at different sites within this prox imal promoter region abolished the promoter activity as well as the DN A binding. Taken together, these results suggest that the cooperation of different transcription factors is essential for IL-9 gene expressi on in T cells.