title: Prestin-Dependence of Outer Hair Cell Survival and Partial Rescue of Outer Hair Cell Loss in PrestinV499G/Y501H Knockin Mice.
abstract: A knockin (KI) mouse expressing mutated prestinV499G/Y501H (499 prestin) was created to study cochlear amplification. Recordings from isolated outer hair cells (OHC) in this mutant showed vastly reduced electromotility and, as a consequence, reduced hearing sensitivity. Although 499 prestin OHCs were normal in stiffness and longer than OHCs lacking prestin, accelerated OHC death was unexpectedly observed relative to that documented in prestin knockout (KO) mice. These observations imply an additional role of prestin in OHC maintenance besides its known requirement for mammalian cochlear amplification. In order to gain mechanistic insights into prestin-associated OHC loss, we implemented several interventions to improve survival. First, 499 prestin KI's were backcrossed to Bak KO mice, which lack the mitochondrial pro-apoptotic gene Bak. Because oxidative stress is implicated in OHC death, another group of 499 prestin KI mice was fed the antioxidant diet, Protandim. 499 KI mice were also backcrossed onto the FVB murine strain, which retains excellent high-frequency hearing well into adulthood, to reduce the compounding effect of age-related hearing loss associated with the original 499 prestin KIs. Finally, a compound heterozygous (chet) mouse expressing one copy of 499 prestin and one copy of KO prestin was also created to reduce quantities of 499 prestin protein. Results show reduction in OHC death in chets, and in 499 prestin KIs on the FVB background, but only a slight improvement in OHC survival for mice receiving Protandim. We also report that improved OHC survival in 499 prestin KIs had little effect on hearing phenotype, reaffirming the original contention about the essential role of prestin's motor function in cochlear amplification.
authors.affiliation: The Knowles Hearing Center, Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL, 60208, United States of America.
authors.forename: Mary Ann
authors.initials: MA
authors.lastname: Cheatham
authors.affiliation: The Knowles Hearing Center, Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL, 60208, United States of America.
authors.forename: Roxanne M
authors.initials: RM
authors.lastname: Edge
authors.affiliation: The Knowles Hearing Center, Department of Otolaryngology-Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, United States of America.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Homma
authors.affiliation: The Knowles Hearing Center, Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL, 60208, United States of America.
authors.forename: Emily L
authors.initials: EL
authors.lastname: Leserman
authors.affiliation: The Knowles Hearing Center, Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL, 60208, United States of America.|Department of Neurobiology, Northwestern University, Evanston, IL, 60208, United States of America.
authors.forename: Peter
authors.initials: P
authors.lastname: Dallos
authors.affiliation: The Knowles Hearing Center, Department of Otolaryngology-Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, United States of America.
authors.forename: Jing
authors.initials: J
authors.lastname: Zheng
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002470:Cell Survival; D004353:Drug Evaluation, Preclinical; D004365:Drugs, Chinese Herbal / Q000494:pharmacology; D055879:Gene Knock-In Techniques; D018072:Hair Cells, Auditory, Outer / Q000502:physiology*; D034381:Hearing Loss / Q000235:genetics; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D020409:Molecular Motor Proteins / Q000502:physiology*; D020125:Mutation, Missense
chemical_list: D000975:Antioxidants; D004365:Drugs, Chinese Herbal; D020409:Molecular Motor Proteins; C498720:Pres protein, mouse; C509374:Protandim