The α1 subunit of nicotinic acetylcholine receptors in the inner ear: transcriptional regulation by ATOH1 and co-expression with the γ subunit in hair cells.
Acetylcholine is a key neurotransmitter of the inner ear efferent system. In this study, we identify two novel nAChR subunits in the inner ear: α1 and γ, encoded by Chrna1 and Chrng, respectively. In situ hybridization shows that the messages of these two subunits are present in vestibular and cochlear hair cells during early development. Chrna1 and Chrng expression begin at embryonic stage E13.5 in the vestibular system and E17.5 in the organ of Corti. Chrna1 message continues through P7, whereas Chrng is undetectable at post-natal stage P6. The α1 and γ subunits are known as muscle-type nAChR subunits and are surprisingly expressed in hair cells which are sensory-neural cells. We also show that ATOH1/MATH1, a transcription factor essential for hair cell development, directly activates CHRNA1 transcription. Electrophoretic mobility-shift assays and supershift assays showed that ATOH1/E47 heterodimers selectively bind on two E boxes located in the proximal promoter of CHRNA1. Thus, Chrna1 could be the first transcriptional target of ATOH1 in the inner ear. Co-expression in Xenopus oocytes of the α1 subunit does not change the electrophysiological properties of the α9α10 receptor. We suggest that hair cells transiently express α1γ-containing nAChRs in addition to α9α10, and that these may have a role during development of the inner ear innervation.
Scheffer
Deborah
D
INSERM, Equipe Avenir, Unité 841, Creteil, France.
Sage
Cyrille
C
Plazas
Paola V
PV
Huang
Mingqian
M
Wedemeyer
Carolina
C
Zhang
Duan-Sun
DS
Chen
Zheng-Yi
ZY
Elgoyhen
A Belen
AB
Corey
David P
DP
Pingault
Veronique
V
D000595:Amino Acid Sequence; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000502:physiology*; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D007758:Ear, Inner / Q000196:embryology / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D055724:Electrophysiological Phenomena; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D006199:Hair Cells, Auditory, Inner / Q000378:metabolism*; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010957:Plasmids / Q000235:genetics; D011247:Pregnancy; D012313:RNA / Q000096:biosynthesis / Q000235:genetics; D011978:Receptors, Nicotinic / Q000096:biosynthesis* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D014982:Xenopus laevis
D051792:Basic Helix-Loop-Helix Proteins; D008156:Luciferases; D012313:RNA; D011978:Receptors, Nicotinic; C500943:Atoh1 protein, mouse; C555576:CHRNA1 protein, mouse; C559497:acetylcholine receptor gamma, mouse