The E3 ligase Ubr3 regulates Usher syndrome and MYH9 disorder proteins in the auditory organs of Drosophila and mammals

Elife. 2016 Jun 22;5:e15258. doi: 10.7554/eLife.15258.


Myosins play essential roles in the development and function of auditory organs and multiple myosin genes are associated with hereditary forms of deafness. Using a forward genetic screen in Drosophila, we identified an E3 ligase, Ubr3, as an essential gene for auditory organ development. Ubr3 negatively regulates the mono-ubiquitination of non-muscle Myosin II, a protein associated with hearing loss in humans. The mono-ubiquitination of Myosin II promotes its physical interaction with Myosin VIIa, a protein responsible for Usher syndrome type IB. We show that ubr3 mutants phenocopy pathogenic variants of Myosin II and that Ubr3 interacts genetically and physically with three Usher syndrome proteins. The interactions between Myosin VIIa and Myosin IIa are conserved in the mammalian cochlea and in human retinal pigment epithelium cells. Our work reveals a novel mechanism that regulates protein complexes affected in two forms of syndromic deafness and suggests a molecular function for Myosin IIa in auditory organs.

Keywords: D. melanogaster; MYH9 disorder; Myosin; Usher syndrome; cell biology; developmental biology; hearing; human; mouse; stem cells; ubiquitination.

MeSH terms

  • Animals
  • Cell Line
  • Cochlea / embryology*
  • Drosophila
  • Drosophila Proteins / genetics
  • Drosophila Proteins / metabolism*
  • Genetic Testing
  • Humans
  • Myosin VIIa
  • Myosins / metabolism*
  • Nonmuscle Myosin Type IIA / metabolism*
  • Ubiquitin-Protein Ligases / genetics
  • Ubiquitin-Protein Ligases / metabolism*


  • Drosophila Proteins
  • MYO7A protein, human
  • Myo7a protein, mouse
  • Myosin VIIa
  • myosin 7a, Drosophila
  • Ubiquitin-Protein Ligases
  • Nonmuscle Myosin Type IIA
  • Myosins
  • Ubr3 protein, Drosophila