title: Distinct cellular distributions of Kv4 pore-forming and auxiliary subunits in rat dorsal root ganglion neurons.
abstract: OBJECTIVE
  Dorsal root ganglia contain heterogeneous populations of primary afferent neurons that transmit various sensory stimuli. This functional diversity may be correlated with differential expression of voltage-gated K(+) (Kv) channels. Here, we examine cellular distributions of Kv4 pore-forming and ancillary subunits that are responsible for fast-inactivating A-type K(+) current.
  
  
  METHODS
  Expression pattern of Kv α-subunit, β-subunit and auxiliary subunit was investigated using immunohistochemistry, in situ hybridization and RT-PCR technique.
  
  
  RESULTS
  The two pore-forming subunits Kv4.1 and Kv4.3 show distinct cellular distributions: Kv4.3 is predominantly in small-sized C-fiber neurons, whereas Kv4.1 is seen in DRG neurons in various sizes. Furthermore, the two classes of Kv4 channel auxiliary subunits are also distributed in different-sized cells. KChIP3 is the only significantly expressed Ca(2+)-binding cytosolic ancillary subunit in DRGs and present in medium to large-sized neurons. The membrane-spanning auxiliary subunit DPP6 is seen in a large number of DRG neurons in various sizes, whereas DPP10 is restricted in small-sized neurons.
  
  
  CONCLUSIONS
  Distinct combinations of Kv4 pore-forming and auxiliary subunits may constitute A-type channels in DRG neurons with different physiological roles. Kv4.1 subunit, in combination with KChIP3 and/or DPP6, form A-type K(+) channels in medium to large-sized A-fiber DRG neurons. In contrast, Kv4.3 and DPP10 may contribute to A-type K(+) current in non-peptidergic, C-fiber somatic afferent neurons.
authors: Department of Physiology II, Nara Medical University, Kashihara, Nara, Japan.
authors: Hiroko
authors: H
authors: Matsuyoshi
authors: Koichi
authors: K
authors: Takimoto
authors: Takakazu
authors: T
authors: Yunoki
authors: Vickie L
authors: VL
authors: Erickson
authors: Pradeep
authors: P
authors: Tyagi
authors: Yoshihiko
authors: Y
authors: Hirao
authors: Akio
authors: A
authors: Wanaka
authors: Naoki
authors: N
authors: Yoshimura
mesh_terms: D000818:Animals; D005260:Female; D005727:Ganglia, Spinal / Q000378:metabolism*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D016133:Polymerase Chain Reaction; D051381:Rats; D017207:Rats, Sprague-Dawley; D051672:Shal Potassium Channels / Q000378:metabolism*
chemical_list: D051672:Shal Potassium Channels