JAK-STAT SIGNALING INDUCED BY THE V-ABL ONCOGENE

The effect of the v-abl oncogene of the Abelson murine leukemia virus (A-MuLV) on the Jak-STAT pathway of cytokine signal transduction was i nvestigated. In murine pre-B lymphocytes transformed with A-MuLV, the Janus kinases (Jaks) Jak1 and Jak3 exhibited constitutive tyrosine kin ase activity, acid the STAT proteins (signal transducers and activator s of transcription) normally activated by interleukin-4, and interleuk in-7 were tyrosine-phosphorylated in the absence of these cytokines. C oimmunoprecipitation experiments revealed that in these cells v-Abl wa s physically associated with Jak1 and Jak3. Inactivation of v-Abl tyro sine kinase in a pre-B cell line transformed with a temperature-sensit ive mutant of v-abl resulted in abrogation of constitutive Jak-STAT si gnaling. A direct link may exist between transformation by v-abl and c ytokine signal transduction.