Neurobiol Dis. 2013 Apr 19. pii: S0969-9961(13)00122-8. doi: 10.1016/j.nbd.2013.04.008. [Epub ahead of print]
Loss of osteoprotegerin expression in the inner ear causes degeneration of the cochlear nerve and sensorineural hearing loss.

Kao SY, Kempfle JS, Jensen JB, Perez-Fernandez D, Lysaght AC, Edge AS, Stankovic KM.

Eaton-Peabody Laboratories, Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA 02114; Department of Otology and Laryngology, Harvard Medical School, Boston, MA 02114.


Osteoprotegerin (OPG) is a key regulator of bone remodeling. Mutations and variations in the OPG gene cause many human diseases that are characterized by not only skeletal abnormalities but also poorly understood hearing loss: Paget's disease, osteoporosis, and celiac disease. To gain insight into mechanisms of hearing loss in OPG deficiency, we studied OPG knockout (Opg -/-) mice. We show that they develop sensorineural hearing loss, in addition to conductive hearing loss due to abnormal middle-ear bones. OPG deficiency caused demyelination and degeneration of the cochlear nerve in vivo. It also activated ERK, sensitized spiral ganglion cells (SGC) to apoptosis, and inhibited proliferation and survival of cochlear stem cells in vitro, which could be rescued by treatment with exogenous OPG, an ERK inhibitor, or bisphosphonate. Our results demonstrate a novel role for OPG in the regulation of SGC survival, and suggest a mechanism for sensorineural hearing loss in OPG deficiency.
Copyright 2013. Published by Elsevier Inc.