Retrograde transport of transcription factor NF-kappa B in living neurons

The mechanism by which signals such as those produced by glutamate are tran sferred to the nucleus may involve direct transport of an activated transcr iption factor to trigger long-term transcriptional changes. Ionotropic glut amate receptor activation or depolarization activates transcription factor NF-kappaB and leads to translocation of NF-kappaB from the cytoplasm to the nucleus. We investigated the dynamics of NF-kappaB translocation in living neurons by tracing the NF-kappaB subunit RelA (p65) with jellyfish green f luorescent protein. We found that green fluorescent protein-RelA was locate d in either the nucleus or cytoplasm and neurites, depending on the coexpre ssion of the cognate inhibitor of NF-kappaB, I kappaB-alpha. Stimulation wi th glutamate, kainate, or potassium chloride resulted in a redistribution o f NF-kappaB from neurites to the nucleus. This transport depended on an int act nuclear localization signal on RelA. Thus, in addition to its role as a transcription factor, NF-kappaB may be a signal transducer, transmitting t ransient glutamatergic signals from distant sites to the nucleus.