PKC isotype that affects the interaction of HRF with Na,K-ATPase

IgE-dependent histamine releasing factor (HRF), previously known as P23/P21 or translationally controlled tumor protein (TCTP), induces the degranulation of histamine in mast cell and basophil. Yeast two hybrid results showed that HRF interacts with the alpha subunit of Na,K-ATPase, suggesting that HRF is a regulator for governing the activity of Na,K-ATPase. In this study, we examined the interaction of HRF and Na,K-ATPase after treatments of various PKC isotype inhibitors. Membrane fractionation, pull-down assay and immunoprecipitation results showed that PKC α, PKC β, PKC δ subunits are involved in the phosphorylation of HRF. However, these results did not correlate with the results of histmamine release assay since histamine release assay results suggested that some PKC isotype inhibitors induced the histamine release in RBL-2H3 cell.