Abstract

The goal of this proposal is to understand the role of WW domain ubiquitin-protein ligases in the regulation of renal Na v absorption via the epithelial Na v channel, ENaC. ENaC forms the pathway for Na + absorption in the kidney collecting duct and other epithelia. Thus, this channel plays a critical role in Na+ homeostasis and blood pressure control. Mechanisms that control the expression of ENaC at the cell surface play an important role in the regulation of epithelial Na v absorption. A key sequence is the PY motif, located in the C-termini of ENaC subunits. Mutation or deletion of this sequence increases the number of ENaC channels at the cell surface, causing an inherited form of hypertension (Liddle's syndrome). PY motifs mediate protein interactions by binding to WW domains, implicating a critical role for WW domain proteins. Previous work found that a WW domain protein (Nedd4) decreased Na+ current by binding to ENaC and targeting the channel for degradation. However, the role of Nedd4 in the kidney collecting duct is unknown. Moreover, it is clear that Nedd4 is part of a large family of Nedd4-related proteins. This proposal will use a systematic approach to test the hypothesis that WW domain proteins regulate ENaC-mediated Na* absorption in the collecting duct.
Specific Aim 1 will identify the WW domain proteins that regulate ENaC, based on their expression patterns, their binding to ENaC subunits, and their ability to inhibit ENaC in heterologous expression systems and epithelial model systems.
Specific Aim 2 will extend these results to test the hypothesis that WW domain proteins are regulated by cellular messengers (vasopressin/cAMP and Ca2+). This work will provide novel insights in the mechanisms by which these signaling pathways regulate epithelial Na + transport.
Specific Aim 3 will test the hypothesis that polymorphisms in ENaC and WW domain proteins disrupt binding and/or channel regulation. By studying the functional consequences of naturally occurring genetic variation, these studies have potential to provide important new insights into the pathogenesis of renal diseases, including hypertension.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL072256-05
Application #
7252593
Study Section
General Medicine B Study Section (GMB)
Program Officer
Barouch, Winifred
Project Start
2003-07-15
Project End
2008-06-30
Budget Start
2007-07-01
Budget End
2008-06-30
Support Year
5
Fiscal Year
2007
Total Cost
$256,986
Indirect Cost

  Institution

Name
University of Iowa
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
062761671
City
Iowa City
State
IA
Country
United States
Zip Code
52242

  Publications

Butler, Phillip L; Staruschenko, Alexander; Snyder, Peter M (2015) Acetylation stimulates the epithelial sodium channel by reducing its ubiquitination and degradation. J Biol Chem 290:12497-503
Collier, Daniel M; Tomkovicz, Vivian R; Peterson, Zerubbabel J et al. (2014) Intersubunit conformational changes mediate epithelial sodium channel gating. J Gen Physiol 144:337-48
Zhou, Ruifeng; Tomkovicz, Vivian R; Butler, Phillip L et al. (2013) Ubiquitin-specific peptidase 8 (USP8) regulates endosomal trafficking of the epithelial Na+ channel. J Biol Chem 288:5389-97
Jing, Lan; Chu, Xiang-Ping; Jiang, Yu-Qing et al. (2012) N-glycosylation of acid-sensing ion channel 1a regulates its trafficking and acidosis-induced spine remodeling. J Neurosci 32:4080-91
Snyder, Peter M (2012) Intoxicated Na(+) channels. Focus on ""ethanol stimulates epithelial sodium channels by elevating reactive oxygen species"". Am J Physiol Cell Physiol 303:C1125-6
Collier, Daniel M; Snyder, Peter M (2011) Identification of epithelial Na+ channel (ENaC) intersubunit Cl- inhibitory residues suggests a trimeric alpha gamma beta channel architecture. J Biol Chem 286:6027-32
Wiemuth, Dominik; Lott, J Shaun; Ly, Kevin et al. (2010) Interaction of serum- and glucocorticoid regulated kinase 1 (SGK1) with the WW-domains of Nedd4-2 is required for epithelial sodium channel regulation. PLoS One 5:e12163
Collier, Daniel M; Snyder, Peter M (2009) Extracellular chloride regulates the epithelial sodium channel. J Biol Chem 284:29320-5
Yang, Tao; Gurrola 2nd, Jose G; Wu, Hao et al. (2009) Mutations of KCNJ10 together with mutations of SLC26A4 cause digenic nonsyndromic hearing loss associated with enlarged vestibular aqueduct syndrome. Am J Hum Genet 84:651-7
Zha, Xiang-ming; Wang, Runping; Collier, Dan M et al. (2009) Oxidant regulated inter-subunit disulfide bond formation between ASIC1a subunits. Proc Natl Acad Sci U S A 106:3573-8

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