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Schmilovich A, Ramello F, Malicki M, Berra NC, Rojo S, Davila G, Binner V, Barrionuevo H, Capria J, Poggio M, Arca R, Tabares D, Vicente D, Santillan D, Burre J, Vazquez M. Comorbidities (CM) and potential impact in outcomes of advanced colorectal cancer patients (ACC) in Argentina: EVIREPRO real life program - Trial in progress. Ann Oncol 2018. [DOI: 10.1093/annonc/mdy151.292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Ho PY, Li H, Pavlov TS, Tuerk RD, Tabares D, Brunisholz R, Neumann D, Staruschenko A, Hallows KR. β 1Pix exchange factor stabilizes the ubiquitin ligase Nedd4-2 and plays a critical role in ENaC regulation by AMPK in kidney epithelial cells. J Biol Chem 2018; 293:11612-11624. [PMID: 29858246 DOI: 10.1074/jbc.ra118.003082] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 05/22/2018] [Indexed: 12/22/2022] Open
Abstract
Our previous work has established that the metabolic sensor AMP-activated protein kinase (AMPK) inhibits the epithelial Na+ channel (ENaC) by promoting its binding to neural precursor cell-expressed, developmentally down-regulated 4-2, E3 ubiquitin protein ligase (Nedd4-2). Here, using MS analysis and in vitro phosphorylation, we show that AMPK phosphorylates Nedd4-2 at the Ser-444 (Xenopus Nedd4-2) site critical for Nedd4-2 stability. We further demonstrate that the Pak-interacting exchange factor β1Pix is required for AMPK-mediated inhibition of ENaC-dependent currents in both CHO and murine kidney cortical collecting duct (CCD) cells. Short hairpin RNA-mediated knockdown of β1Pix expression in CCD cells attenuated the inhibitory effect of AMPK activators on ENaC currents. Moreover, overexpression of a β1Pix dimerization-deficient mutant unable to bind 14-3-3 proteins (Δ602-611) increased ENaC currents in CCD cells, whereas overexpression of WT β1Pix had the opposite effect. Using additional immunoblotting and co-immunoprecipitation experiments, we found that treatment with AMPK activators promoted the binding of β1Pix to 14-3-3 proteins in CCD cells. However, the association between Nedd4-2 and 14-3-3 proteins was not consistently affected by AMPK activation, β1Pix knockdown, or overexpression of WT β1Pix or the β1Pix-Δ602-611 mutant. Moreover, we found that β1Pix is important for phosphorylation of the aforementioned Nedd4-2 site critical for its stability. Overall, these findings elucidate novel molecular mechanisms by which AMPK regulates ENaC. Specifically, they indicate that AMPK promotes the assembly of β1Pix, 14-3-3 proteins, and Nedd4-2 into a complex that inhibits ENaC by enhancing Nedd4-2 binding to ENaC and its degradation.
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Affiliation(s)
- Pei-Yin Ho
- Division of Nephrology and Hypertension, Department of Medicine and USC/UKRO Kidney Research Center, Keck School of Medicine, University of Southern California, Los Angeles, California 90033
| | - Hui Li
- Division of Nephrology and Hypertension, Department of Medicine and USC/UKRO Kidney Research Center, Keck School of Medicine, University of Southern California, Los Angeles, California 90033
| | - Tengis S Pavlov
- the Division of Hypertension and Vascular Research, Henry Ford Health System, Detroit, Michigan 48202; Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Roland D Tuerk
- Department of Biology, Institute of Cell Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Diego Tabares
- Division of Nephrology and Hypertension, Department of Medicine and USC/UKRO Kidney Research Center, Keck School of Medicine, University of Southern California, Los Angeles, California 90033
| | - René Brunisholz
- Functional Genomics Center, ETH Zurich, 8097 Zurich, Switzerland
| | - Dietbert Neumann
- Department of Biology, Institute of Cell Biology, ETH Zurich, 8093 Zurich, Switzerland; Department of Pathology, School for Cardiovascular Diseases, Maastricht University, 6200 MD Maastricht, The Netherlands
| | | | - Kenneth R Hallows
- Division of Nephrology and Hypertension, Department of Medicine and USC/UKRO Kidney Research Center, Keck School of Medicine, University of Southern California, Los Angeles, California 90033.
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