| Autor: |
Alli, Abdel A., Bao, Hui-Fang, Alli, Alia A., Aldrugh, Yasir, Song, John Z., Ma, He-Ping, Yu, Ling, Al-Khalili, Otor, Eaton, Douglas C. |
| Zdroj: |
American Journal of Physiology - Renal Physiology; September 2012, Vol. 303 Issue: 6 pF800-F811, 12p |
| Abstrakt: |
Phosphatidylinositol phosphates (PIPs) are known to regulate epithelial sodium channels (ENaC). Lipid binding assays and coimmunoprecipitation showed that the amino-terminal domain of the β- and γ-subunits of XenopusENaC can directly bind to phosphatidylinositol 4,5-bisphosphate (PIP2), phosphatidylinositol 3,4,5-trisphosphate (PIP3), and phosphatidic acid (PA). Similar assays demonstrated various PIPs can bind strongly to a native myristoylated alanine-rich C-kinase substrate (MARCKS), but weakly or not at all to a mutant form of MARCKS. Confocal microscopy demonstrated colocalization between MARCKS and PIP2. Confocal microscopy also showed that MARCKS redistributes from the apical membrane to the cytoplasm after PMA-induced MARCKS phosphorylation or ionomycin-induced intracellular calcium increases. Fluorescence resonance energy transfer studies revealed ENaC and MARCKS in close proximity in 2F3 cells when PKC activity and intracellular calcium concentrations are low. Transepithelial current measurements from Xenopus2F3 cells treated with PMA and single-channel patch-clamp studies of Xenopus2F3 cells treated with a PKC inhibitor altered XenopusENaC activity, which suggest an essential role for MARCKS in the regulation of XenopusENaC activity. |
| Databáze: |
Supplemental Index |
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