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Autophagy essential for hearing in mice

Mechanism helps maintain auditory sensory cells’ morphology

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University Hospital
2017/07/13

© 2017 Chisato Fujimoto.Atg5-deficient hair cells show progressive damage after postnatal day 14 (P14). Scale bar represents 10 microns.

Scanning electron microscopy of Atg5-deficient hair cells
Atg5-deficient hair cells show progressive damage after postnatal day 14 (P14). Scale bar represents 10 microns.
© 2017 Chisato Fujimoto.

A group of researchers at the University of Tokyo has demonstrated that autophagy, a key mechanism by which cells break down their own components and which helps them maintain a state of internal stability known as homeostasis, plays an important role in the ability of mice to hear clearly. The current finding holds promise of leading to further research on the relationship between autophagy and hearing impairment.

Most often, when the sensory cells involved in hearing, called auditory hair cells, are impaired, the damage is irreversible—thus making it imperative to maintain cell function to preserve hearing.

The research group led by Assistant Professor Chisato Fujimoto and Professor Tatsuya Yamasoba of the Department of Otolaryngology and Head and Neck Surgery at the University of Tokyo Hospital produced mice deficient in a gene essential for autophagy, autophagy-related 5 (Atg5), in the hair cells, to investigate the effect of autophagy on hearing and on the form and structure of the cells. The group found that deleting Atg5 resulted in profound hearing loss at the time of birth. Also, they did not discover any obvious changes in the form and structure of autophagy-deficient hair cells in 5-day-old mice; but they observed damage in many auditory hairs and some loss in the body of hair cells on Day 14; and at 8 weeks, hair-cell degeneration had progressed further.

The current findings reveal that autophagy in the hair cells plays an important role in hearing and maintenance of their form and structure.

"In recent years, experts have pointed out autophagy’s association with various pathological conditions, but the role of autophagy in the inner-ear hair cells was unknown," says Fujimoto. He continues, "I hope this research will serve as an impetus and lead to the accumulation of new findings on the involvement of autophagy in the origin and development of hearing impairment."

Press release (Japanese)

Paper

Chisato Fujimoto, Shinichi Iwasaki, Shinji Urata, Hideaki Morishita, Yuriko Sakamaki, Masato Fujioka, Kenji Kondo, Noboru Mizushima and Tatsuya Yamasoba, "Autophagy is essential for hearing in mice", Cell Death and Disease Online Edition: 2017/05/11 (Japan time), doi: 10.1038/cddis.2017.194.
Article link (Publication)

Links

University of Tokyo Hospital

Department of Otolaryngology and Head and Neck Surgery, Graduate School of Medicine (Japanese)

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