Kv2.1 Cell Surface Clusters are Insertion and Retrieval Platforms For Kv Channel Trafficking at the Plasma Membrane
| Autor: | Aubrey V. Weigel, Gentry Hansen, Philip D. Fox, Elizabeth J. Akin, Rob J. Loftus, Michael M. Tamkun, Emily Deutsch, Diego Krapf |
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| Rok vydání: | 2012 |
| Předmět: |
0303 health sciences
Total internal reflection fluorescence microscope Vesicle HEK 293 cells Biophysics Transfection Biology Endocytosis Cell biology 03 medical and health sciences chemistry.chemical_compound 0302 clinical medicine chemistry 030217 neurology & neurosurgery Actin Ion channel 030304 developmental biology Cytochalasin D |
| Zdroj: | Biophysical Journal. 102:105a-106a |
| ISSN: | 0006-3495 |
| DOI: | 10.1016/j.bpj.2011.11.595 |
| Popis: | The Kv2.1 delayed-rectifier K+ channel regulates electrical activity in neurons and plays a non-conducting role in SNARE-mediated protein fusion in neuroendocrine cells. Kv2.1 is unusual among voltage-gated K+ channels in that it localizes to micron-sized clusters on the cell-surface of neurons and transfected HEK cells. Within these clusters Kv2.1 is non-conducting. Here we demonstrate that these surface structures are specialized platforms involved in trafficking of Kv channels to and from the cell surface. TIRF-based studies indicated that GFP-Kv2.1 containing vesicles tether directly to and deliver cargo in a discrete fashion to the Kv2.1 surface clusters in both transfected HEK and cultured hippocampal neurons. Qdot-based single molecule experiments indicated that the delivery and surface retrieval of Kv2.1 occurs at the perimeter of the surface clusters. Overall, 85±8.4% of newly synthesized channels in HEK cells and 84.9±10.4% in hippocampal neurons were inserted at the cluster perimeter even though the Kv2.1 clusters represent only 21.4 ±3.8% of the basal cell surface. When 132 continuously recycling Kv2.1 channels in HEK cells were examined, 96.2% were also inserted at the cluster perimeter. The actin depolymerizing agents swinholide A and cytochalasin D reduced the cluster localized insertion to 5 and 0% of control, respectively. Unlike Kv2.1, the Kv1.4 K+ channel has a homogeneous cell-surface expression in transfected cells. Demonstrating that Kv2.1 clusters represent cell-surface platforms for more than just Kv2.1 insertion and retrieval, the non-clustering Kv1.4 K+ channel also inserted into the HEK cell plasma membrane at the Kv2.1 cluster perimeter. Kv1.4 endocytosis also occurred at this region. Together, these results indicate that a non-conducting function of Kv2.1 is to form specialized cell-surface microdomains which are involved in ion channel trafficking. These domains may also be involved in additional cellular processes. |
| Databáze: | OpenAIRE |
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