AHNAK expression and subcellular localization in gastric surface epithelial cells

Abstract

We have previously demonstrated the expression of AHNAK protein in normal human organ donor stomach tissues. In order to identify the specific cells that express AHNAK in human stomach, we performed immunohistochemistry. We evaluated the subcellular localization and movement of AHNAK protein by immunohistochemistry, sucrose density gradient centrifugation, and Western blot analysis using specific AHNAK and subcellular marker antibodies. AHNAK immunoreactivity was localized to PAS, Alcian Blue, MUC5A positive gastric surface epithelial cells in normal human organ donor stomachs. Normal rat gastric mucosa (RGM1) cells demonstrated strong cytoplasmic staining for AHNAK. AHNAK protein was found predominately in the cytoplasmic fraction under standard culture conditions of RGM1 cells. AHNAK is often described as a nuclear phosphoprotein that translocates to the plasma membrane where it is involved in signal transduction, cell membrane differentiation, and repair. Further investigation and understanding of the potential recruitment of AHNAK to the plasma membrane may allow for novel strategies to regulate specific signaling cascades and induce membrane repair in gastric surface epithelial cells. This research was supported by an American Heart Association Predoctoral Fellowship and a Veterans Affairs Merit grant.