An essential role for cortactin in the modulation of the potassium channel Kv1.2.

@article{citeulike:2795823, abstract = {Ion channels are key determinants of membrane excitability. The actin cytoskeleton has a central role in morphology, migration, intracellular transport, and signaling. In this article, we show that the actin-binding protein cortactin regulates the potassium channel Kv1.2 and thereby provides a direct link between actin dynamics and membrane excitability. In previous reports, we showed that the tyrosine phosphorylation-mediated suppression of Kv1.2 ionic current occurs by endocytosis of the channel protein. Pull-down assays using recombinant-purified cortactin and Kv1.2 demonstrated that their interaction is direct and reduced by tyrosine phosphorylation of Kv1.2. This finding suggests a link between cortactin and Kv1.2 endocytosis. Here, we confirm that relationship and identify the molecular mechanisms involved. We use FRET to demonstrate that Kv1.2 and cortactin interact in vivo. By manipulating the cortactin-binding site within Kv1.2, we confirm that cortactin proximity influences channel function. We used flow cytometry in conjunction with cortactin gene replacement to identify C-terminal tyrosines, the fourth repeat actin-binding domain, and the N-terminal Arp2/3-binding region, as critical to Kv1.2 regulation. Surprisingly, cortactin's dynamin-binding Src homology 3 domain is not required for Kv1.2 endocytosis, despite that process being dynamin-dependent. These findings predict that cortactin-mediated actin remodeling in excitable cells is not only important for cell structure, but may directly impact membrane excitability.}, address = {Department of Pharmacology and Anatomy, University of Vermont College of Medicine, 89 Beaumont Avenue, Burlington, VT 05405, USA.}, author = {Williams, M. R. and Markey, J. C. and Doczi, M. A. and Morielli, A. D. }, citeulike-article-id = {2795823}, doi = {10.1073/pnas.0703865104}, issn = {0027-8424}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, keywords = {actin, cytosqueleton, endocytosis, kv, surface\_expression}, month = {October}, number = {44}, pages = {17412--17417}, posted-at = {2008-05-13 19:17:11}, priority = {0}, title = {An essential role for cortactin in the modulation of the potassium channel Kv1.2.}, url = {http://dx.doi.org/10.1073/pnas.0703865104}, volume = {104}, year = {2007} }

TY - JOUR ID - citeulike:2795823 L3 - citeulike-article-id:2795823 TI - An essential role for cortactin in the modulation of the potassium channel Kv1.2. JF - Proceedings of the National Academy of Sciences of the United States of America VL - 104 IS - 44 SP - 17412 EP - 17417 AD - Department of Pharmacology and Anatomy, University of Vermont College of Medicine, 89 Beaumont Avenue, Burlington, VT 05405, USA. SN - 0027-8424 N2 - Ion channels are key determinants of membrane excitability. The actin cytoskeleton has a central role in morphology, migration, intracellular transport, and signaling. In this article, we show that the actin-binding protein cortactin regulates the potassium channel Kv1.2 and thereby provides a direct link between actin dynamics and membrane excitability. In previous reports, we showed that the tyrosine phosphorylation-mediated suppression of Kv1.2 ionic current occurs by endocytosis of the channel protein. Pull-down assays using recombinant-purified cortactin and Kv1.2 demonstrated that their interaction is direct and reduced by tyrosine phosphorylation of Kv1.2. This finding suggests a link between cortactin and Kv1.2 endocytosis. Here, we confirm that relationship and identify the molecular mechanisms involved. We use FRET to demonstrate that Kv1.2 and cortactin interact in vivo. By manipulating the cortactin-binding site within Kv1.2, we confirm that cortactin proximity influences channel function. We used flow cytometry in conjunction with cortactin gene replacement to identify C-terminal tyrosines, the fourth repeat actin-binding domain, and the N-terminal Arp2/3-binding region, as critical to Kv1.2 regulation. Surprisingly, cortactin's dynamin-binding Src homology 3 domain is not required for Kv1.2 endocytosis, despite that process being dynamin-dependent. These findings predict that cortactin-mediated actin remodeling in excitable cells is not only important for cell structure, but may directly impact membrane excitability. KW - actin KW - cytosqueleton KW - endocytosis KW - kv KW - surface_expression AU - Williams, MR AU - Markey, JC AU - Doczi, MA AU - Morielli, AD PY - 2007/10/30/ UR - http://dx.doi.org/10.1073/pnas.0703865104 ER -