Rapid Induction of Jak2 and Spl in T Cells by Phosphorothioate Oligonucleotides

Abstract

Phosphorothioate-modified ODNs ([S]ODNs) are known to exert a variety of sequence-independent effects that are mediated in part by rapid induction of the Sp1 transcription factor. An unidentified tyrosine kinase was implicated in this Sp1 induction. In the present study, antisense [S]ODNs, initially designed to target three signaling molecules in the prolactin (PRL)-responsive rat Nb2 T cell line rapidly elevated Jak2 tyrosine kinase and Sp1 protein levels. The [S]ODN-mediated elevation of Jak2 peaked (3-fold to 6.5-fold above controls) at 15 minutes and returned to basal levels by 1 hour, whereas elevation of Sp1 (about 2-fold above controls) peaked at 1 hour. The [S]ODN-mediated induction of Sp1, but not Jak2, was abrogated by AG 490, a Jak2-specific inhibitor. In the presence of submaximal doses of PRL (0.18-0.36 ng/ml), [S]ODN-mediated induction of Jak2 and Sp1 was sustained for 72 hours. Furthermore, the [S]ODNs alone significantly increased Nb2 cell growth and enhanced the growth stimulatory effects of PRL on these cells. In contrast, unmodified ODNs had no effect on Jak2 or Sp1 protein levels and did not stimulate Nb2 cell growth. In conclusion, [S]ODNs stimulate the coordinate induction of Jak2 and Sp1 and stimulate Nb2 T cell proliferation in a sequence-independent manner. The abrogation of Sp1 induction by AG 490 indicates that Jak2 tyrosine kinase is required for [S]ODN-mediated induction of Sp1 in these cells. These results may help to explain some of the nonspecific effects of [S]ODNs, particularly in cytokine-dependent immune cells.