CIS TRANSACTIVATION OF THE INTERLEUKIN-9 RECEPTOR GENE IN AN HTLV-I-TRANSFORMED HUMAN LYMPHOCYTIC CELL

The MT-2 cell-line, which had been established through in vitro cell t o cell transmission of human T-cell leukemia virus type T (HTLV-I) amo ng human primary lymphocytes, was shown to possess multiple copies of integrated proviruses, including defective proviral genomes. By analys ing a genomic clone, we identified the integration site of a single HT LV-I long terminal repeat (LTR) in the interleukin-9 (IL-9) receptor ( IL-9R) gene. The integrated HTLV-I-LTR was shown to be functional as a promoter and the integration site was located in an intron upstream o f the first coding exon of the IL-9R gene. Upon analysis of total cell ular RNA, specific expression of HTLV-I-LTR IL-9R chimeric mRNAs in MT -2 cells was demonstrated. Cloning and characterization of these cDNAs have identified HTLV-I-IL-9R chimeric splicing, using either intact o r alternative splice sites within the IL-9R gene. The potential roles of multiple interactions between IL-9, IL-9R and HTLV-I in the monoclo nal expansion and transformation of MT-2 cells are explored.