Regulation of Cellular Proliferation and Migration by Palmitoylation of the Na+‐H+ Exchanger Isoform 1 (NHE1)

Abstract

The Na+‐H+ Exchanger Isoform 1 (NHE1) is an important factor in cellular proliferation and migration of cells in both healthy and diseased tissues. NHE1 has been extensively studied in cancer biology, as activation of NHE1 contributes to the inversion of the pH gradient that is characteristic of the transformation from healthy function to a tumorigenic state. NHE1 is a 12‐pass transmembrane protein consisting of 815 amino acids. The N‐terminal transport domain resides in the plasma membrane and exchanges a single extracellular sodium ion for one intracellular hydrogen ion. NHE1 also has an extended C‐terminal cytoplasmic tail that function as the transporters regulatory domain. The cytoplasmic regulatory domain includes an extensive series of binding motifs for proteins and lipids as well as numerous phosphorylation sites. Recently, it was recognized that NHE1 also undergoes reversible palmitoylation. We hypothesize that this palmitoylation may be utilized to regulate NHE1 activation, thereby regulating cell proliferation and migration. In order to evaluate the role of palmitoylation, 2‐bromopalmitate (2BP), an inhibitor for palmitoylation, along with ethyl‐isopropyl‐amiloride (EIPA), which acts as an inhibitor for NHE1, will be employed in migration and proliferation assays in Human Embryonic Kidney cells (HEK293). CRISPR‐Cas9 technology will also be used to create a knock‐out version of this cell line (HEK293NHE1KO). Further analysis with then be performed to assess effects of palmitoylation in the absence of NHE1. We hypothesize that inhibition of endogenous NHE1 activity and lack of cellular palmitoylation will decrease the potential for growth and migration.