Kv2.1 voltage gated potassium channels

The voltage gated potassium channel Kv2.1 plays an important physiological role in numerous cell types and tissues. In particular, in the mammalian neurons, these channels have a protective function in response to stroke suppressing seizures which aggravate brain damage. This critical role is achieved by forming and regulating Kv2.1 surface clusters. We aim at revealing the mechanism of Kv2.1 channel cluster formation using single particle tracking with nanometer resolution in live mammalian cells. A greater understanding of how this channel is dynamically localized may lead to improved treatments for stroke, the third leading cause of death in the United States and a major cause of long term disability. By unraveling the mechanisms underlying surface protein localization and channel surface formation we will improve our knowledge of these molecular processes and advance human health.

We tackle the problem of cell surface domain maintenance using simple growth models and a Fokker-Planck formalism. Surprisingly, our results show that Kv2.1 domains are maintained by fluctuations in endocytosis/exocytosis without any type of feedback or additional regulation of domain size.

Using multicolor single-particle detection and tracking, we observe that Kv2.1 rapidly recycles between membrane and intracellular compartments and that intracellular Kv2.1-containing trafficking vesicles dock directly at Kv2.1 cell surface clusters. Surprisingly, Kv2.1 channels are not the only molecules that are endocytosed and exocytosed at these clusters, showing that the Kv2.1 clusters are specialized trafficking platforms. This study was the first to define stable cell surface sites for K+ channel delivery in mammalian cells.

 

Publications

A.V. Weigel, P.D. Fox, E.J. Akin, K.H. Ecklund, M.M. Tamkun, and D. Krapf, "Size of cell-surface Kv2.1 domains is governed by growth fluctuations", Biophys. J. 103, 1727 (2012)

E. Deutsch, A.V. Weigel, E.J. Akin, P. Fox, G. Hansen, C.J. Haberkorn, R. Loftus, D. Krapf, and M.M. Tamkun, "Kv2.1 cell surface clusters are insertion platforms for ion channel delivery to the plasma membrane", Mol. Biol. Cell 23, 2917 (2012)

P.D. Fox, C.J. Haberkorn, A.V. Weigel, J.L. Higgins, E.J. Akin, M.J. Kennedy, D. Krapf, and M.M. Tamkun, "Plasma membrane domains enriched in cortical endoplasmic reticulum function as membrane protein trafficking hubs", Mol. Biol. Cell 24, 2703 (2013)

A.V. Weigel, M.M. Tamkun, and D. Krapf, "Quantifying the dynamic interactions between a clathrin-coated pit and cargo molecules" Proc. Natl. Acad. Sci. USA 110, E4591 (2013)

P.D. Fox, C.J. Haberkorn, E.J. Akin, P.J. Seel, D. Krapf, and M.M. Tamkun, "Induction of stable endoplasmic reticulum/plasma membrane junctions by Kv2.1 potassium channels", J. Cell Sci. 128, 2096 (2015)

 

This project is supported by the National Science Foundation through grant 1401432.