Hepatocyte nuclear factor-4 alpha in noise-induced cochlear neuropathy.
Noise-induced hearing loss (NIHL) is a problem of profound clinical significance and growing magnitude. Alarmingly, even moderate noise levels, previously assumed to cause only temporary shifts in auditory thresholds ("temporary" NIHL), are now known to cause cochlear synaptopathy and subsequent neuropathy. To uncover molecular mechanisms of this neuropathy, a network analysis of genes reported to have significantly altered expression after temporary threshold shift-inducing noise exposure was performed. The transcription factor Hepatocyte Nuclear Factor-4 alpha (HNF4α), which had not previously been studied in the context of cochlear response to noise, was identified as a hub of a top-ranking network. Hnf4α expression and localization using quantitative RT-PCR and in situ hybridization, respectively, were described in adolescent and adult mice exposed to neuropathic noise levels in adolescence. Isoforms α3 and α12 in the cochlea were also identified. At every age examined, Hnf4α mRNA expression in the cochlear apex was similar to expression in the base. Hnf4α expression was evident in select cochlear cells, including spiral ganglion neurons (SGNs) and hair cells, and was significantly upregulated from 6 to 70 weeks of age, especially in SGNs. This age-related Hnf4α upregulation was inhibited by neuropathic noise exposure in adolescence. Hnf4α silencing with shRNA transfection into auditory neuroblast cells (VOT-33) reduced cell viability, as measured with the MTT assay, suggesting that Hnf4α may be involved in SGN survival. Our results motivate future studies of HNF4α in cochlear pathophysiology, especially because HNF4α mutations and polymorphisms are associated with human diseases that may include hearing loss. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 76: 1374-1386, 2016.
Eaton-Peabody Laboratories and Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, 02114.|Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts, 02115.|Department of Biomedical Sciences, University of Copenhagen, 2200, Copenhagen, Denmark.
Jane Bjerg
JB
Groth
Eaton-Peabody Laboratories and Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, 02114.
Shyan-Yuan
SY
Kao
Eaton-Peabody Laboratories and Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, 02114.|Department of Otorhinolaryngology, Leiden University Medical Center, 2333 ZA, Leiden, The Netherlands.
Martijn C
MC
Briët
Eaton-Peabody Laboratories and Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, 02114.|Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts, 02115.|Program in Speech and Hearing Bioscience and Technology, Harvard Medical School, Boston, Massachusetts, 02115.
Konstantina M
KM
Stankovic
D000818:Animals; D001309:Auditory Threshold / Q000502:physiology*; D003051:Cochlea / Q000502:physiology*; D016057:Evoked Potentials, Auditory, Brain Stem; D006198:Hair Cells, Auditory / Q000378:metabolism; D006317:Hearing Loss, Noise-Induced / Q000378:metabolism* / Q000503:physiopathology; D051557:Hepatocyte Nuclear Factor 4 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009622:Noise
D051557:Hepatocyte Nuclear Factor 4; C496593:Hnf4a protein, mouse
aging; cochlear neuropathy; gene expression; hepatocyte nuclear factor 4 alpha; molecular pathways; noise-induced hearing loss; temporary threshold shift