Journal Article

NDFIP allows NEDD4/NEDD4L-induced AQP2 ubiquitination and degradation

de Groot, Theun, Cheval, Lydie, Doucet, Alain, van den Berg, Dennis T. M., Stagljar, Igor, Ariza, Carolina A., Deen, Peter M. T., Trimpert, Christiane, Wesche, Daniel, Pimentel Rodriguez, Martha M., Wong, Victoria

2017

Overview

Regulation of our water homeostasis is fine-tuned by dynamic translocation of Aquaporin-2 (AQP2)-bearing vesicles to and from the plasma membrane of renal principal cells. Whereas binding of vasopressin to its type-2 receptor initiates a cAMP-protein kinase A cascade and AQP2 translocation to the apical membrane, this is counteracted by protein kinase C-activating hormones, resulting in ubiquitination-dependent internalization of AQP2. The proteins targeting AQP2 for ubiquitin-mediated degradation are unknown. In collecting duct mpkCCD cells, siRNA knockdown of NEDD4 and NEDD4L E3 ligases yielded increased AQP2 abundance, but they did not bind AQP2. Membrane Yeast Two-Hybrid assays using full-length AQP2 as bait, identified NEDD4 family interacting protein 2 (NDFIP2) to bind AQP2. NDFIP2 and its homologue NDFIP1 have PY motifs by which they bind NEDD4 family members and bring them close to target proteins. In HEK293 cells, NDFIP1 and NDFIP2 bound AQP2 and were essential for NEDD4/NEDD4L-mediated ubiquitination and degradation of AQP2, an effect not observed with PY-lacking NDFIP1/2 proteins. In mpkCCD cells, downregulation of NDFIP1, NEDD4 and NEDD4L, but not NDFIP2, increased AQP2 abundance. In mouse kidney, Ndfip1 and Ndfip2 mRNA distribution was similar and high in proximal tubules and collecting ducts, which was also found for NDFIP1 proteins. Our results reveal that NEDD4/NEDD4L mediate ubiquitination and degradation of AQP2, but that NDFIP proteins are needed to connect NEDD4/NEDD4L to AQP2. As NDFIP1/2 bind many NEDD4 family E3 ligases, which are implicated in several cellular processes, NDFIP1/2 may be the missing link for AQP2 ubiquitination and degradation from different subcellular locations.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Abundance / Animals / Aquaporin 2 / Aquaporin 2 - metabolism / Aquaporins / Baits / Biochemistry / Biodegradation / Biology and life sciences / Carrier Proteins - genetics / Carrier Proteins - metabolism / Cell Line / Collecting duct / Degradation / Departments / Diabetes / Down-Regulation / Endosomal Sorting Complexes Required for Transport - antagonists & inhibitors / Endosomal Sorting Complexes Required for Transport - genetics / Endosomal Sorting Complexes Required for Transport - metabolism / Gene expression / Genetic aspects / HEK293 Cells / Homeostasis / Homology / Hormones / Humans / Immunoprecipitation / Internalization / Kidneys / Kinases / Life Sciences / Ligases / Male / Medicine and Health Sciences / Membrane Proteins - genetics / Membrane Proteins - metabolism / Mice / Mice, Inbred C57BL / mRNA / Nedd4 Ubiquitin Protein Ligases / Nephrons / Nephrons - metabolism / Phosphorylation / Physiological aspects / Physiology / Plasma / Protein Binding / Protein kinase A / Protein kinase C / Proteins / Proximal tubules / Research and Analysis Methods / RNA Interference / RNA, Messenger - metabolism / RNA, Small Interfering - metabolism / Rodents / siRNA / Sodium / Translocation / Transplants & implants / Two-Hybrid System Techniques / Ubiquitin / Ubiquitin-proteasome system / Ubiquitin-protein ligase / Ubiquitin-Protein Ligases - antagonists & inhibitors / Ubiquitin-Protein Ligases - genetics / Ubiquitin-Protein Ligases - metabolism / Ubiquitination / Urine / Vasopressin / Yeast