[D816V mutation of KIT specifically induces phosphorylation of HNRNPL and HNRNPK in COS-1 cells].

Objective To study the regulation of D816V mutation of III tyrosine kinase receptor KIT on RNA binding proteins HNRNPL and HNRNPK. Methods In COS-1 cells, wild-type KIT or KIT D816V mutation were expressed alone or together with HNRNPL or HNRNPK. Activation of KIT and phosphorylation of HNRNPL and HNRNPK were detected by immunoprecipitation and Western blot analysis. The localization of KIT, HNRNPL and HNRNPK in COS-1 cells were examined by confocal microscopy. Results Wild-type KIT needs to bind its ligand stem cell factor (SCF) for phosphorylation, while KIT D816V could auto-phosphorylation without SCF stimulation. In addition, KIT D816V can induce phosphorylation of HNRNPL and HNRNPK, which is not possible in wild-type KIT. HNRNPL and HNRNPK are expressed in the nucleus, and wild-type KIT is expressed in cytosol and cell membrane, while KIT D816V is mainly found in cytosol. Conclusion Wild-type KIT needs SCF binding for activation, while KIT D816V can autoactivate without SCF stimulation, and induces phosphorylation of HNRNPL and HNRNPK specifically.