Kv3.3 Channels Bind Hax-1 and Arp2/3 to Assemble a Stable Local Actin Network that Regulates Channel Gating

  • Cell. 2016 Apr 7;165(2):434-448. doi: 10.1016/j.cell.2016.02.009.
Yalan Zhang  #  1 ,  Xiao-Feng Zhang  #  2 ,  Matthew R Fleming  1 ,  Anahita Amiri  3 ,  Lynda El-Hassar  1 ,  Alexei A Surguchev  1 ,  Callen Hyland  2 ,  David P Jenkins  1 ,  Rooma Desai  1 ,  Maile R Brown  1 ,  Valeswara-Rao Gazula  1 ,  Michael F Waters  4 ,  Charles H Large  5 ,  Tamas L Horvath  6 ,  Dhasakumar Navaratnam  7 ,  Flora M Vaccarino  3 ,  Paul Forscher  2 ,  Leonard K Kaczmarek  1  8
Affiliations
  • 1. Department of Pharmacology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520.
  • 2. Department of Molecular, Cellular and Developmental Biology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520.
  • 3. Department of Child Study Center and Neurobiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520.
  • 4. Department of Neurology, University of Florida College of Medicine, HSC Box 100236, Gainesville, FL 32610-0236.
  • 5. Autifony Therapeutics Limited, Imperial College Incubator, Level 1 Bessemer Building, London, SW7 2AZ UK.
  • 6. Department of Comparative Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520.
  • 7. Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520.
  • 8. Department of Cellular and Molecular Physiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520.
  • # Contributed equally.
PMID: 26997484 DOI: 10.1016/j.cell.2016.02.009
Abstract

Mutations in the Kv3.3 Potassium Channel (KCNC3) cause cerebellar neurodegeneration and impair auditory processing. The cytoplasmic C terminus of Kv3.3 contains a proline-rich domain conserved in proteins that activate Actin nucleation through Arp2/3. We found that Kv3.3 recruits Arp2/3 to the plasma membrane, resulting in formation of a relatively stable cortical Actin filament network resistant to cytochalasin D that inhibits fast barbed end Actin assembly. These Kv3.3-associated Actin structures are required to prevent very rapid N-type channel inactivation during short depolarizations of the plasma membrane. The effects of Kv3.3 on the actin Cytoskeleton are mediated by the binding of the cytoplasmic C terminus of Kv3.3 to Hax-1, an anti-apoptotic protein that regulates Actin nucleation through Arp2/3. A human Kv3.3 mutation within a conserved proline-rich domain produces channels that bind Hax-1 but are impaired in recruiting Arp2/3 to the plasma membrane, resulting in growth cones with deficient Actin veils in stem cell-derived neurons.