Transactivation of the interleukin-1 alpha promoter by human T-cell leukemia virus.

The expression of interleukin-1 alpha (IL-1 alpha) appears to be tightly regulated, as the levels of constitutive expression in normal cells is extremely low. In contrast to normal hematopoietic cells, human T-cell leukemia virus type I (HTLV-I)-infected T-cell lines constitutively produce high levels of IL-1 alpha mRNA and secret this cytokine into the culture medium. IL-1-alpha mRNA is also expressed in fresh leukemic cells of adult T-cell leukemia/lymphoma (ATLL) patients. HTLV-I-induced IL-1 alpha might explain some symptoms observed in ATLL. In this regard, molecular dissection of the IL-1 alpha gene transcriptional regulation is of primary importance. In this review, the transcriptional regulation of IL-1 alpha gene expression and the possible role of the NF-kappaB pathway are discussed in the light of our current understanding of IL-1 alpha gene regulation by HTLV-I and HTLV-II Tax proteins, which are viral transcriptional transactivators.