title: Optogenetic Control of Mouse Outer Hair Cells.
abstract: Normal hearing in mammals depends on sound amplification by outer hair cells (OHCs) presumably by their somatic motility and force production. However, the role of OHC force production in cochlear amplification and frequency tuning are not yet fully understood. Currently, available OHC manipulation techniques for physiological or clinical studies are limited by their invasive nature, lack of precision, and poor temporal-spatial resolution. To overcome these limitations, we explored an optogenetic approach based on channelrhodopsin 2 (ChR-2), a direct light-activated nonselective cation channel originally discovered in Chlamydomonas reinhardtii. Three approaches were compared: 1) adeno-associated virus-mediated in utero transfer of the ChR-2 gene into the developing murine otocyst, 2) expression of ChR-2(H134R) in an auditory cell line (HEI-OC1), and 3) expression of ChR-2 in the OHCs of a mouse line carrying a ChR-2 conditional allele. Whole cell recording showed that blue light (470 nm) elicited the typical nonselective cation current of ChR-2 with reversal potential around zero in both mouse OHCs and HEI-OC1 cells and generated depolarization in both cell types. In addition, pulsed light stimulation (10 Hz) elicited a 1:1 repetitive depolarization and ChR-2 currents in mouse OHCs and HEI-OC1 cells, respectively. The time constant of depolarization in OHCs, 1.45 ms, is 10 times faster than HEI-OC1 cells, which allowed light stimulation up to rates of 10/s to elicit corresponding membrane potential changes. Our study demonstrates that ChR-2 can successfully be expressed in mouse OHCs and HEI-OC1 cells and that these present a typical light-sensitive current and depolarization. However, the amount of ChR-2 current induced in our in vivo experiments was insufficient to result in measurable cochlear effects.
authors.affiliation: Oregon Hearing Research Center, NRC04, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon.
authors.forename: Tao
authors.initials: T
authors.lastname: Wu
authors.affiliation: Oregon Hearing Research Center, NRC04, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon.
authors.forename: Sripriya
authors.initials: S
authors.lastname: Ramamoorthy
authors.affiliation: Oregon Hearing Research Center, NRC04, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon.
authors.forename: Teresa
authors.initials: T
authors.lastname: Wilson
authors.affiliation: Oregon Hearing Research Center, NRC04, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon.
authors.forename: Fangyi
authors.initials: F
authors.lastname: Chen
authors.affiliation: Oregon Hearing Research Center, NRC04, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon.
authors.forename: Edward
authors.initials: E
authors.lastname: Porsov
authors.affiliation: Oregon Hearing Research Center, NRC04, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon.
authors.forename: Hrebesh
authors.initials: H
authors.lastname: Subhash
authors.affiliation: Oregon Hearing Research Center, NRC04, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon.
authors.forename: Sarah
authors.initials: S
authors.lastname: Foster
authors.affiliation: Oregon Hearing Research Center, NRC04, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Oregon Hearing Research Center, NRC04, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon.
authors.forename: Irina
authors.initials: I
authors.lastname: Omelchenko
authors.affiliation: Oregon Hearing Research Center, NRC04, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon.
authors.forename: Michael
authors.initials: M
authors.lastname: Bateschell
authors.affiliation: Oregon Hearing Research Center, NRC04, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon.
authors.forename: Lingyan
authors.initials: L
authors.lastname: Wang
authors.affiliation: Oregon Hearing Research Center, NRC04, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon.
authors.forename: John V
authors.initials: JV
authors.lastname: Brigande
authors.affiliation: Oregon Hearing Research Center, NRC04, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon.
authors.forename: Zhi-Gen
authors.initials: ZG
authors.lastname: Jiang
authors.affiliation: The Vollum Institute, Oregon Health & Science University, Portland, Oregon.
authors.forename: Tianyi
authors.initials: T
authors.lastname: Mao
authors.affiliation: Oregon Hearing Research Center, NRC04, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon; Kresge Hearing Research Institute, The University of Michigan, Ann Arbor, Michigan. Electronic address: nuttall@ohsu.edu.
authors.forename: Alfred L
authors.initials: AL
authors.lastname: Nuttall
mesh_terms: D000200:Action Potentials; D000818:Animals; D002460:Cell Line; D000075402:Channelrhodopsins; D018072:Hair Cells, Auditory, Outer / Q000378:metabolism* / Q000502:physiology; D051379:Mice; D062308:Optogenetics / Q000379:methods*
chemical_list: D000075402:Channelrhodopsins