Nerve growth factor modulates tubulin transcript levels in pheochromocytoma PC12 cells

We report that nerve growth factor (NGF) can elevate tubulin transcript levels in cultured rat pheochromocytoma PC12 cells in a manner which correlates with its capacity to enhance neurite formation. The elevation is due, at least in part, to transcript stabilization. We have previously shown that insulin and its homologs can similarly enhance neurite outgrowth and tubulin mRNA levels in human neuroblastoma cells. Insulin by itself can neither induce neurite formation nor increase tubulin transcript levels in PC12 cells. However, both responses are potentiated in cells treated with the combination of insulin and NGF. The results together support the generalization that tubulin transcript levels are specifically elevated whenever neurite elongation is initiated by polypeptide neuritogenic factors.