We have studied the primary transcriptional response of human peripheral blood T cells to mitogenic activation. Previously we had constructed a subtractive cDNA library and used subtractive and differential screening methods to isolate genes which are induced early on in T cells stimulated with mitogens. The limited number of known inducible genes encode oncogenes, lymphokines and their receptors, i.e., genes with significant roles in proliferation and/or initiation of an immune response. To date we have isolated in excess of 69 induced genes, which include several of the known genes but which represent a much larger number than could have been expected from previous studies. We are pursuing both functional and regulatory aspects of the many induced genes. By using mitogenic antibodies to the CD2 and CD3 receptors as well as the co-mitogens anti-CD28, phorbol myristate acetate, DIC8 and ionomycin, we were able to determine that every mitogenic agent induces all genes checked to date but that the co-mitogens could easily distinguish these genes into many different groups with common regulatory elements. Two genes, 464 and 744, behaved similar to interleukin-2 (IL-2). Approximately 1/4 of the genes tested are not expressed in activated human lung fibroblasts, including 464 and 744. These genes are also among those which are very sensitive to the immunosuppressive drug cyclosporin A and among those which are constitutively expressed in human T lymphotrophic virus I transformed cells. That these genes possibly encode lymphokines was further supported by their primary sequence, which predicts encoded proteins with typical N-terminal leader sequences and with homologies to each other as well as to a group of so called inflammatory responses genes, a new family of factors which is just emerging. In cell lines permanently transfected with the human immunodeficiency virus orf-B protein the induction of some genes, including 464, appears t be negatively affected. In addition to these studies we have discovered several DNA binding proteins which interact with the mitogen-responsive region of the IL-2 gene. Some of these proteins bind DNA only upon prior activation of the cells. Also, we have delimited further the segment of the c-myc gene, which controls the downregulation of this gene during terminal differentiation. Lastly, we have continued to attempt indirect methods of cloning a B cell growth factor and its receptor.
| Leonardi, A; Chariot, A; Claudio, E et al. (2000) CIKS, a connection to Ikappa B kinase and stress-activated protein kinase. Proc Natl Acad Sci U S A 97:10494-9 |
| Ellinger-Ziegelbauer, H; Kelly, K; Siebenlist, U (1999) Cell cycle arrest and reversion of Ras-induced transformation by a conditionally activated form of mitogen-activated protein kinase kinase kinase 3. Mol Cell Biol 19:3857-68 |
