Spermine synthase deficiency leads to deafness and a profound sensitivity to α-difluoromethylornithine

Xiaojing Wang, Snezana Levic, Michael Anne Gratton, Karen Jo Doyle, Ebenezer N. Yamoah, Anthony E. Pegg

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

Male gyro (Gy) mice, which have an X chromosomal deletion inactivating the SpmS and Phex genes, were found to be profoundly hearing impaired. This defect was due to alteration in polyamine content due to the absence of spermine synthase, the product of the SpmS gene. It was reversed by breeding the Gy strain with CAG/SpmS mice, a transgenic line that ubiquitously expresses spermine synthase under the control of a composite cytomegalovirus-IE enhancer/chicken β-actin promoter. There was an almost complete loss of the endocochlear potential in the Gy mice, which parallels the hearing deficiency, and this was also reversed by the production of spermine from the spermine synthase transgene. Gy mice showed a striking toxic response to treatment with the ornithine decarboxylase inhibitor α-diflu-oromethylornithine (DFMO). Within 2-3 days of exposure to DFMO in the drinking water, the Gy mice suffered a catastrophic loss of motor function resulting in death within 5 days. This effect was due to an inability to maintain normal balance and was also prevented by the transgenic expression of spermine synthase. DFMO treatment of control mice or Gy-CAG/SpmS had no effect on balance. The loss of balance in Gy mice treated with DFMO was due to inhibition of polyamine synthesis because it was prevented by administration of putrescine. Our results are consistent with a critical role for polyamines in regulation of Kir channels that maintain the endocochlear potential and emphasize the importance of normal spermidine:spermine ratio in the hearing and balance functions of the inner ear.

Original languageEnglish (US)
Pages (from-to)930-937
Number of pages8
JournalJournal of Biological Chemistry
Volume284
Issue number2
DOIs
StatePublished - Jan 9 2009
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

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