Analysis of nucleocytoplasmic shuttling of NF kappa B proteins in human leukocytes.

Controlled nucleocytoplasmic localization regulates activity of NF kappa B as well as other transcription factors. Analysis of the nucleocytoplasmic protein shuttling has been greatly facilitated by the use of leptomycin B (LMB), an inhibitor of CRM1-dependent nuclear export. The authors have previously shown that LMB inhibits NF kappa B activity in human neutrophils by increasing the nuclear accumulation of NF kappa B inhibitor, I kappa B alpha. In this chapter, the authors describe a protocol that uses LMB to study the nucleocytoplasmic shuttling of I kappa B alpha in human macrophage-like U937 cells, thus inhibiting NF kappa B activity. This protocol should be readily adaptable to analyze the nucleocytoplasmic shuttling of other proteins in human leukocytes.