Sodium hydrogen exchanger (NHE1) palmitoylation and potential functional regulation

Aims: Determine the effect of palmitoylation on the sodium hydrogen exchanger isoform 1 (NHE1), a member of the SLC9 family. Main methods: NHE1 expressed in native rat tissues or in heterologous cells was assessed for palmitoylation by acyl-biotinyl exchange (ABE) and metabolic labeling with [H-3]palmitate. Cellular palmitoylation was inhibited using 2-bromopalmitate (2BP) followed by determination of NHE1 palmitoylation status, intracellular pH, stress fiber formation, and cell migration. In addition, NHE1 was activated with LPA treatment followed by determination of NHE1 palmitoylation status and LPA-induced change in intracellular pH was determined in the presence and absence of preincubation with 2BP. Key findings: In this study we demonstrate for the first time that NHE1 is palmitoylated in both cells and rat tissue, and that processes controlled by NHE1 including intracellular pH (pH(i)), stress fiber formation, and cell migration, are regulated in concert with NHE1 palmitoylation status. Importantly, LPA stimulates NHE1 palmitoylation, and 2BP pretreatment dampens LPA-induced increased pH(i) which is dependent on the presence of NHE1. Significance: Palmitoylation is a reversible lipid modification that regulates an array of critical protein functions including activity, trafficking, membrane microlocalization and protein-protein interactions. Our results suggest that palmitoylation of NHE1 and other control/signaling proteins play a major role in NHE1 regulation that could significantly impact multiple critical cellular functions.

Automated summary

This study demonstrates for the first time that NHE1 is palmitoylated in both cells and rat tissue, and that its palmitoylation status is associated with the regulation of intracellular pH, stress fiber formation, and cell migration. Furthermore, it is shown that LPA stimulates NHE1 palmitoylation, and pretreatment with 2BP inhibits LPA-induced increase in intracellular pH. These findings highlight the significance of palmitoylation in the regulation of NHE1 and other control/signaling proteins.