INSULIN STIMULATES HAPTOTACTIC MIGRATION OF HUMAN EPIDERMAL-KERATINOCYTES THROUGH ACTIVATION OF NF-KAPPA-B TRANSCRIPTION FACTOR

Insulin-mediated cell motility as well as the role of transcription fa ctors in insulin-activated intracellular signal events have not been e xtensively studied. In this report we have examined whether insulin co uld mediate haptotactic migration of cultured human epidermal keratino cytes through activation of transcription factor NF-kappa B, Insulin c aused a dose-dependent stimulation of keratinocyte migration that maxi mally reached 2-fold at 2 x 10(-7) M hormone, This phenomenon was inde pendent of the nature of the extracellular matrix component (collagen I or laminin5/nicein) on which the cells migrated, indicating that a s pecific integrin-ligand complex is not required. A 10(-7) M insulin tr eatment of keratinocytes resulted in activation of a major kappa B DNA binding complex within 15 to 30 minutes, which was identified as the p65/p50 NF-kappa B heterodimer by electrophoretic mobility shift assay s. The activation induced nuclear translocation of cytosolic pools of NF-KB factor, Pyrrolidine dithiocarbamate and N-acetyl-leucinyl-leucin yl-norleucinal H (two compounds that differentially inhibit I kappa B alpha degradation and, thus, NF-kappa B activation) reversed the insul in-stimulated keratinocyte haptotactic migration without affecting ins ulin receptor activation, These compounds inhibited the insulin-induce d nuclear translocation of NF-kappa B as detected by confocal laser sc anning microscopy, Taken together our experiments demonstrate that ins ulin stimulates haptotactic migration of human epidermal keratinocytes through activation of NF-kappa B transcription factor, They emphasize the ability of insulin to stimulate keratinocyte movement and provide a first clue to the mechanism of insulin-indued haptotactic signaling .