Unique Regulation of Human Na+/H+ Exchanger 3 (NHE3) by Nedd4-2 Ligase That Differs from Non-primate NHE3

• Authors: Yi Ran No, Emory University; Peijian He, Emory University; Byong Kwon Yoo, Emory University; Chris Yun, Emory University
• Journal Title: Journal of Biological Chemistry
• Volume: Volume 289, Number 26
• Publisher: American Society for Biochemistry and Molecular Biology | 2014-06-27, Pages 18360-18372
• Type of Work: Article | Final Publisher PDF
• Publisher DOI: http://doi.org/10.1074/jbc.M113.541706
• Subjects: Chemistry, Biochemistry; Biology, Molecular
• Keywords: Science & Technology; Life Sciences & Biomedicine; Biochemistry & Molecular Biology; CELL-SURFACE; UBIQUITIN LIGASES; PROXIMAL TUBULE; BLOOD-PRESSURE; ISOFORM NHE3; WW DOMAINS; ACTIVATION; PHOSPHORYLATION; HYPERTENSION; DEGRADATION

Abstract

Na+/H+ exchanger NHE3 expressed in the intestine and kidney plays a major role in NaCl and HCO3T absorption that is closely linked to fluid absorption and blood pressure regulation. The Nedd4 family of E3 ubiquitin ligases interacts with a number of transporters and channels via PY motifs. A comparison of NHE3 sequences revealed the presence of PY motifs in NHE3s from human and several non-human primates but not in non-primate NHE3s. In this study we evaluated the differences between human and non-primate NHE3s in ubiquitination and interaction with Nedd4-2. We found that Nedd4-2 ubiquitinated human NHE3 (hNHE3) and altered its expression and activity. Surprisingly, rat NHE3 coimmunoprecipitated Nedd4-2, but its expression and activity were not altered by silencing of Nedd4-2. Ubiquitination by Nedd4-2 rendered hNHE3 to undergo internalization at a significantly greater rate than non-primate NHE3s without altering protein stability. Insertion of a PY motif in rabbit NHE3 recapitulated the interaction with Nedd4-2 and enhanced internalization. Thus, we propose a new model where disruption of Nedd4-2 interaction elevates hNHE3 expression and activity.