Activation of PKC-beta(I) in glomerular mesangial cells is associated withspecific NF-kappa B subunit translocation

Changes in expression and activity of protein kinase C (PKC) isoforms and e arly transcription factors may account for alterations in cell behavior see n in diabetes. We studied the expression of PKC-beta (I) in rat glomerular mesangial cells (MCs) cultured in normal or high glucose and compared it wi th the temporal and spatial expression of dimeric transcription factor (NF- kappaB) p50 and p65. The results show that in unstimulated cells PKC-beta ( I) and NF-kappaB p50 are distributed in the cytosol and, on stimulation, th eir distribution is perinuclear and they are localized to the membrane. Ser um-starved MCs cultured in high-glucose medium exhibit a predominantly cyto solic localization of PKC-beta (I) and both p50 and p65 NF-kappaB. However, phorbol 12-myristate 13-acetate (PMA) stimulation of cells grown in the pr esence of high glucose resulted in membrane translocation of PKC-beta (I) t hat was associated with nuclear translocation of NF-kappaB p65, but not NF- kappaB p50. Moreover, the translocation to the nucleus for NF-kappaB p65 wa s significantly higher in MCs exposed to high glucose compared with those e xposed to normal glucose. These observations indicate that the NF-kappaB p6 5, but not NF-kappaB p50, expression and translocation pattern mirrors that of PKC-beta (I), which may be one important pathway by which signaling is enhanced in the high-glucose state.