RACK1, a PKC targeting protein, is exclusively localized to basal airway epithelial cells

Abstract

The novel isoform of protein kinase C (PKC), PKCε, is an important regulator of ciliated cell function in airway epithelial cells, including cilia motility and detachment of ciliated cells after environmental insult. However, the mechanism of PKCε signaling in the airways and the potential role of the PKCε-interacting protein, receptor for activated C kinase 1 (RACK1), has not been widely explored. We used immunohistochemistry and Western blot analysis to show that RACK1 is localized exclusively to basal, non-ciliated (and non-goblet) bovine and human bronchial epithelial cells. Our immunohistochemistry experiments used the basal body marker pericentrin, a marker for cilia, β-tubulin, and an airway goblet cell marker, MUC5AC, to confirm that RACK1 was excluded from differentiated airway cell subtypes and is only expressed in the basal cells. These results suggest that PKCε signaling in the basal airway cell may involve RACK1; however, PKCε regulation in ciliated cells uses RACK1-independent pathways. © The Histochemical Society, Inc.