RNA helicase A is necessary for KIF1Bß tumor suppression in neuroblastoma

During development neuronal progenitors compete for growth factors such as nerve growth factor NGF and require the prolyl hydroxylase EglN3 and the kinesin KIF1Bß for developmental apoptosis. Inherited KIF1Bß loss-of-function mutations in neuroblastomas and pheochromocytomas implicate KIF1Bß as a 1p36.2 tumor suppressor, however the mechanism of tumor suppression is unknown. We found that KIF1Bß interacts with the RNA helicase A (DHX9) resulting in DHX9 nuclear accumulation to regulate apoptosis. KIF1Bß-dependent DHX9 nuclear localization leads to transcription of the apoptotic target XIAP-associated factor 1. DHX9 is induced when NGF is limiting and required for apoptosis in cells deprived of NGF. Overall design: NB1 cells were transduced to incorporate shRNA against DHX9 or a scrambled control, and transfected with a KIF1Bß expression vector or control, then transfected cells were isolated and lysed after 48h.