Auditory pathology in a transgenic mtTFB1 mouse model of mitochondrial deafness

Sharen E. McKay, Wayne Yan, Jessica Nouws, Maximilian J. Thormann, Nuno Raimundo, Abdul Khan, Joseph Santos-Sacchi, Lei Song, Gerald S. Shadel

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

The A1555G mutation in the 12S rRNA gene of human mitochondrial DNA causes maternally inherited, nonsyndromic deafness, an extreme case of tissue-specific mitochondrial pathology. A transgenic mouse strain that robustly overexpresses the mitochondrial 12S ribosomal RNA methyltransferase TFB1M (Tg-mtTFB1 mice) exhibits progressive hearing loss that we proposed models aspects of A1555G-related pathology in humans. Although our previous studies of Tg-mtTFB1 mice implicated apoptosis in the spiral ganglion and stria vascularis because of mitochondrial reactive oxygen species-mediated activation of AMP kinase (AMPK) and the nuclear transcription factor E2F1, detailed auditory pathology was not delineated. Herein, we show that Tg-mtTFB1 mice have reduced endocochlear potential, indicative of significant stria vascularis dysfunction, but without obvious signs of strial atrophy. We also observed decreased auditory brainstem response peak 1 amplitude and prolonged wave I latency, consistent with apoptosis of spiral ganglion neurons. Although no major loss of hair cells was observed, there was a mild impairment of voltage-dependent electromotility of outer hair cells. On the basis of these results, we propose that these events conspire to produce the progressive hearing loss phenotype in Tg-mtTFB1 mice. Finally, genetically reducing AMPK α1 rescues hearing loss in Tg-mtTFB1 mice, confirming that aberrant up-regulation of AMPK signaling promotes the observed auditory pathology. The relevance of these findings to human A1555G patients and the potential therapeutic value of reducing AMPK activity are discussed.

Original languageEnglish (US)
Pages (from-to)3132-3140
Number of pages9
JournalAmerican Journal of Pathology
Volume185
Issue number12
DOIs
StatePublished - Dec 2015

All Science Journal Classification (ASJC) codes

  • Pathology and Forensic Medicine

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