Linked Life Data

12139396

Source:http://linkedlifedata.com/resource/pubmed/id/12139396

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2-3
pubmed:dateCreated
2002-7-25
pubmed:abstractText
Mouse mandibular salivary duct cells contain an amiloride-sensitive Na+ current and express all three subunits of the epithelial Na+ channel, ENaC. This amiloride-sensitive Na+ current is subject to feedback regulation by intracellular Na+ and we have previously demonstrated that this regulation is mediated by an ubiquitin-protein ligase, which we identified as Nedd4. The evidence supporting this identification is as follows: (1) antibodies raised against murine Nedd4 block Na+ feedback inhibition; (2) a mutant of murine Nedd4 containing the WW domains but no HECT domain (ubiquitin-protein ligase) blocks Na+ feedback inhibition; and (3) Nedd4 is expressed in mouse mandibular salivary duct cells. In the present studies, we have used whole-cell patch-clamp methods to further investigate the mechanisms by which ubiquitin-protein ligases regulate the amiloride-sensitive Na+ conductance in mouse salivary duct cells. In particular, we have examined the possibility that the ubiquitin-protein ligase, KIAA0439, which is closely related to Nedd4, may mediate Na+ feedback control of amiloride-sensitive Na+ channels. Furthermore, we have attempted to define the mechanism by which ubiquitin-protein ligases inhibit Na+ channels. We have found that KIAA0439 is expressed in mouse mandibular ducts and interacts with the PY motifs of the alpha-, beta-, and gamma-subunits of ENaC in vitro. Furthermore, in whole-cell patch-clamp studies, a glutathione-S-transferase (GST)-fusion protein containing the WW motifs of human KIAA0439 was able to inhibit feedback regulation of the amiloride-sensitive Na+ current by intracellular Na+. We also examined whether GST-fusion proteins containing the C-termini of the alpha-, beta-, and gamma-subunits of ENaC are able to interrupt Na+ feedback regulation of the amiloride-sensitive Na+ current. We found that the C-termini of the beta- and gamma-subunits were able to do so, whereas the C-terminus of the alpha-subunit was not. We conclude that KIAA0439 is, together with Nedd4, a potential mediator of the control of epithelial Na+ channels in salivary duct cells by intracellular Na+. We further conclude that ubiquitin-protein ligases interact with the Na+ channels through the C-termini of the beta- and gamma-subunits of the Na+ channels.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
1085-9195
pubmed:author
pubmed:issnType
Print
pubmed:volume
36
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
105-13
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed:year
2002
pubmed:articleTitle
Patch-clamp studies on epithelial sodium channels in salivary duct cells.
pubmed:affiliation
Department of Physiology, University of Sydney, NSW, Australia. davidc@physiol.usyd.edu.au
pubmed:publicationType
Journal Article, Review