Molecular characterization of an inward rectifier channel (IKir) found in avian vestibular hair cells: Cloning and expression of pKir2.1

Manning J. Correia, Thomas Wood, Deborah Prusak, Tianxiang Weng, Katherine J. Rennie, Hui Qun Wang

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Abstract

A fast inwardly rectifying current has been observed in some of the sensory cells (hair cells) of the inner ear of several species. While the current was presumed to be an IKir current, contradictory evidence existed as to whether the cloned channel actually belonged to the Kir2.0 subfamily of potassium inward rectifiers. In this paper, we report for the first time converging evidence from electro physiological, biochemical, immunohistochemical, and genetic studies that show that the Kir2.1 channel carries the fast inwardly rectifying currents found in pigeon vestibular hair cells. Following cytoplasm extraction from single type II and multiple pigeon vestibular hair cells, mRNA was reverse transcribed, amplified, and sequenced. The open reading frame (ORF), consisting of a 1,284-bp nucleotide sequence, showed 94, 85, and 83% identity with Kir2.1 subunit sequences from chick lens, Kir2 sequences from human heart, and a mouse macrophage cell line, respectively. Phylogenetic analyses revealed that pKir2.1 formed an immediate node with hKir2.1 but not with hKir2.2-2.4. Hair cells (type I and type II) and supporting cells in the sensory epithelium reacted positively with a Kir2.1 antibody. The whole cell current recorded in oocytes and CHO cells, transfected with pigeon hair cell Kir2.1 (pKir2.1), demonstrated blockage by Ba2+ and sensitivity to changing K+ concentration. The mean single-channel linear slope conductance in transfected CHO cells was 29 pS. The open dwell time was long (∼300 ms at -100 mV), and the closed dwell time was short (∼34 ms at -100 mV). Multistates ranging from 3-6 were noted in some single-channel responses. All of the above features have been described for other Kir2.1 channels. Current clamp studies of native pigeon vestibular hair cells illustrated possible physiological roles of the channel and showed that blockage of the channel by Ba2+ depolarized the resting membrane potential by ∼30 mV. Negative currents hyperpolarized the membrane ∼20 mV before block but ∼60 mV following block. RT-PCR studies revealed that the pKir2.1 channels found in pigeon vestibular hair cells were also present in pigeon vestibular nerve, vestibular ganglion, lens, neck muscle, brain (brain stem, cerebellum and optic tectum), liver, and heart.

Original languageEnglish (US)
Pages (from-to)155-169
Number of pages15
JournalPhysiological Genomics
Volume19
DOIs
StatePublished - Jan 2005
Externally publishedYes

Fingerprint

Vestibular Hair Cells
Columbidae
Organism Cloning
CHO Cells
Lenses
Vestibular Nerve
Neck Muscles
Superior Colliculi
Inner Ear
Ganglia
Membrane Potentials
Cerebellum
Open Reading Frames
Brain Stem
Oocytes
Molecular Biology
Potassium
Cytoplasm
Epithelium
Macrophages

Keywords

  • Pigeon
  • Potassium channel

ASJC Scopus subject areas

  • Physiology
  • Genetics

Cite this

Molecular characterization of an inward rectifier channel (IKir) found in avian vestibular hair cells : Cloning and expression of pKir2.1. / Correia, Manning J.; Wood, Thomas; Prusak, Deborah; Weng, Tianxiang; Rennie, Katherine J.; Wang, Hui Qun.

In: Physiological Genomics, Vol. 19, 01.2005, p. 155-169.

Research output: Contribution to journalArticle

Correia, Manning J. ; Wood, Thomas ; Prusak, Deborah ; Weng, Tianxiang ; Rennie, Katherine J. ; Wang, Hui Qun. / Molecular characterization of an inward rectifier channel (IKir) found in avian vestibular hair cells : Cloning and expression of pKir2.1. In: Physiological Genomics. 2005 ; Vol. 19. pp. 155-169.
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