Ezrin is required for the functional regulation of the epithelial sodium proton exchanger, NHE3.
The sodium hydrogen exchanger isoform 3 (NHE3) mediates absorption of sodium, bicarbonate and water from renal and intestinal lumina. This activity is fundamental to the maintenance of a physiological plasma pH and blood pressure. To perform this function NHE3 must be present in the apical membrane...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Public Library of Science (PLoS)
2013-01-01
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| Series: | PLoS ONE |
| Online Access: | http://europepmc.org/articles/PMC3566197?pdf=render |
| _version_ | 1811319664146382848 |
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| author | Hisayoshi Hayashi Atsushi Tamura Devishree Krishnan Sachiko Tsukita Yuichi Suzuki Hetal S Kocinsky Peter S Aronson John Orlowski Sergio Grinstein R Todd Alexander |
| author_facet | Hisayoshi Hayashi Atsushi Tamura Devishree Krishnan Sachiko Tsukita Yuichi Suzuki Hetal S Kocinsky Peter S Aronson John Orlowski Sergio Grinstein R Todd Alexander |
| author_sort | Hisayoshi Hayashi |
| collection | DOAJ |
| description | The sodium hydrogen exchanger isoform 3 (NHE3) mediates absorption of sodium, bicarbonate and water from renal and intestinal lumina. This activity is fundamental to the maintenance of a physiological plasma pH and blood pressure. To perform this function NHE3 must be present in the apical membrane of renal tubular and intestinal epithelia. The molecular determinants of this localization have not been conclusively determined, although linkage to the apical actin cytoskeleton through ezrin has been proposed. We set out to evaluate this hypothesis. Functional studies of NHE3 activity were performed on ezrin knockdown mice (Vil2(kd/kd)) and NHE3 activity similar to wild-type animals detected. Interpretation of this finding was difficult as other ERM (ezrin/radixin/moesin) proteins were present. We therefore generated an epithelial cell culture model where ezrin was the only detectable ERM. After knockdown of ezrin expression with siRNA, radixin and moesin expression remained undetectable. Consistent with the animal ultrastructural data, cells lacking ezrin retained an epithelial phenotype but had shortened and thicker microvilli. NHE3 localization was identical to cells transfected with non-targeting siRNA. The attachment of NHE3 to the apical cytoskeleton was unaltered as assessed by fluorescent recovery after photobleaching (FRAP) and the solubility of NHE3 in Triton X-100. Baseline NHE3 activity was unaltered, however, cAMP-dependent inhibition of NHE3 was largely lost even though NHE3 was phosphorylated at serines 552 and 605. Thus, ezrin is not necessary for the apical localization, attachment to the cytoskeleton, baseline activity or cAMP induced phosphrylation of NHE3, but instead is required for cAMP mediated inhibition. |
| first_indexed | 2024-04-13T12:46:41Z |
| format | Article |
| id | doaj.art-83c1e622d852423babcdaab0f3d77368 |
| institution | Directory Open Access Journal |
| issn | 1932-6203 |
| language | English |
| last_indexed | 2024-04-13T12:46:41Z |
| publishDate | 2013-01-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS ONE |
| spelling | doaj.art-83c1e622d852423babcdaab0f3d773682022-12-22T02:46:21ZengPublic Library of Science (PLoS)PLoS ONE1932-62032013-01-0182e5562310.1371/journal.pone.0055623Ezrin is required for the functional regulation of the epithelial sodium proton exchanger, NHE3.Hisayoshi HayashiAtsushi TamuraDevishree KrishnanSachiko TsukitaYuichi SuzukiHetal S KocinskyPeter S AronsonJohn OrlowskiSergio GrinsteinR Todd AlexanderThe sodium hydrogen exchanger isoform 3 (NHE3) mediates absorption of sodium, bicarbonate and water from renal and intestinal lumina. This activity is fundamental to the maintenance of a physiological plasma pH and blood pressure. To perform this function NHE3 must be present in the apical membrane of renal tubular and intestinal epithelia. The molecular determinants of this localization have not been conclusively determined, although linkage to the apical actin cytoskeleton through ezrin has been proposed. We set out to evaluate this hypothesis. Functional studies of NHE3 activity were performed on ezrin knockdown mice (Vil2(kd/kd)) and NHE3 activity similar to wild-type animals detected. Interpretation of this finding was difficult as other ERM (ezrin/radixin/moesin) proteins were present. We therefore generated an epithelial cell culture model where ezrin was the only detectable ERM. After knockdown of ezrin expression with siRNA, radixin and moesin expression remained undetectable. Consistent with the animal ultrastructural data, cells lacking ezrin retained an epithelial phenotype but had shortened and thicker microvilli. NHE3 localization was identical to cells transfected with non-targeting siRNA. The attachment of NHE3 to the apical cytoskeleton was unaltered as assessed by fluorescent recovery after photobleaching (FRAP) and the solubility of NHE3 in Triton X-100. Baseline NHE3 activity was unaltered, however, cAMP-dependent inhibition of NHE3 was largely lost even though NHE3 was phosphorylated at serines 552 and 605. Thus, ezrin is not necessary for the apical localization, attachment to the cytoskeleton, baseline activity or cAMP induced phosphrylation of NHE3, but instead is required for cAMP mediated inhibition.http://europepmc.org/articles/PMC3566197?pdf=render |
| spellingShingle | Hisayoshi Hayashi Atsushi Tamura Devishree Krishnan Sachiko Tsukita Yuichi Suzuki Hetal S Kocinsky Peter S Aronson John Orlowski Sergio Grinstein R Todd Alexander Ezrin is required for the functional regulation of the epithelial sodium proton exchanger, NHE3. PLoS ONE |
| title | Ezrin is required for the functional regulation of the epithelial sodium proton exchanger, NHE3. |
| title_full | Ezrin is required for the functional regulation of the epithelial sodium proton exchanger, NHE3. |
| title_fullStr | Ezrin is required for the functional regulation of the epithelial sodium proton exchanger, NHE3. |
| title_full_unstemmed | Ezrin is required for the functional regulation of the epithelial sodium proton exchanger, NHE3. |
| title_short | Ezrin is required for the functional regulation of the epithelial sodium proton exchanger, NHE3. |
| title_sort | ezrin is required for the functional regulation of the epithelial sodium proton exchanger nhe3 |
| url | http://europepmc.org/articles/PMC3566197?pdf=render |
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