In the kidney, the epithelial sodium channel (ENaC) regulates blood pressure through control of sodium and volume homeostasis, and in the lung, ENaC regulates the volume of airway and alveolar fluids. ENaC is a heterotrimer of homologous α-, β- and γ-subunits, and assembles in the endoplasmic reticulum (ER) before it traffics to and functions at the plasma membrane. Improperly folded or orphaned ENaC subunits are subject to ER quality control and targeted for ER-associated degradation (ERAD). We previously established that a conserved, ER lumenal, molecular chaperone, Lhs1/GRP170, selects αENaC, but not β- or γ-ENaC, for degradation when the ENaC subunits were individually expressed. We now find that when all three subunits are co-expressed, Lhs1-facilitated ERAD was blocked. To determine which domain–domain interactions between the ENaC subunits are critical for chaperone-dependent quality control, we employed a yeast model and expressed chimeric α/βENaC constructs in the context of the ENaC heterotrimer. We discovered that the βENaC transmembrane domain was sufficient to prevent the Lhs1-dependent degradation of the α-subunit in the context of the ENaC heterotrimer. Our work also found that Lhs1 delivers αENaC for proteasome-mediated degradation after the protein has become polyubiquitinated. These data indicate that the Lhs1 chaperone selectively recognizes an immature form of αENaC, one which has failed to correctly assemble with the other channel subunits via its transmembrane domain.
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February 2017
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The picture shows a fluorescence immunohistochemistry image identifying GFAP (green), actin (red) and nuclei (blue) in E15 derived primary mouse astrocytes. For more information please see pp. 333–355. Image provided by Dr. Christopher Ugbode.
Research Article|
January 20 2017
Interactions between intersubunit transmembrane domains regulate the chaperone-dependent degradation of an oligomeric membrane protein
Teresa M. Buck;
Teresa M. Buck
1Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, U.S.A.
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Alexa S. Jordahl;
Alexa S. Jordahl
1Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, U.S.A.
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Megan E. Yates;
Megan E. Yates
1Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, U.S.A.
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G. Michael Preston;
G. Michael Preston
1Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, U.S.A.
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Emily Cook;
Emily Cook
*
1Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, U.S.A.
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Thomas R. Kleyman;
Thomas R. Kleyman
2Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh, Pittsburgh, PA, U.S.A.
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Jeffrey L. Brodsky
Jeffrey L. Brodsky
1Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, U.S.A.
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Publisher: Portland Press Ltd
Received:
August 17 2016
Revision Received:
November 28 2016
Accepted:
November 30 2016
Accepted Manuscript online:
November 30 2016
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 2017 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society
2017
Biochem J (2017) 474 (3): 357–376.
Article history
Received:
August 17 2016
Revision Received:
November 28 2016
Accepted:
November 30 2016
Accepted Manuscript online:
November 30 2016
Citation
Teresa M. Buck, Alexa S. Jordahl, Megan E. Yates, G. Michael Preston, Emily Cook, Thomas R. Kleyman, Jeffrey L. Brodsky; Interactions between intersubunit transmembrane domains regulate the chaperone-dependent degradation of an oligomeric membrane protein. Biochem J 1 February 2017; 474 (3): 357–376. doi: https://doi.org/10.1042/BCJ20160760
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