PROTEIN-TYROSINE KINASE SYK IS ASSOCIATED WITH AND ACTIVATED BY THE IL-2 RECEPTOR - POSSIBLE LINK WITH THE C-MYC INDUCTION PATHWAY

The IL-2 receptor (IL-2R) consists of three subunits, the IL-2R alpha, IL-2R beta, and IL-2R gamma chains. The IL-2-induced proliferative si gnals emanate from the cytoplasmic domains of IL-2R beta and IL-2R gam ma, but the nature and function of the signaling molecules that transm it these signals are not fully understood. Here, we report that Syk pr otein tyrosine kinase (PTK) is physically associated with IL-2R in per ipheral blood lymphocytes. cDNA expression studies further revealed th at this association is critical for the IL-2-induced activation of Syk PTK, which occurs primarily via the serinerich region of the IL-2R be ta chain, which is essential for proliferative signal transmission. Fu rthermore, we provide evidence that in the hematopoietic cell line, BA F-BO3, the activation of Syk PTK results in the induction of the c-myc gene, an event critical for the cell proliferation. Thus, Syk PTK may be a critical integral member of the signaling molecules engaged by t he IL-2R.