Loss of Usp9x disrupts cortical architecture, hippocampal development and TGFβ-mediated axonogenesis

PLoS One. 2013 Jul 5;8(7):e68287. doi: 10.1371/journal.pone.0068287. Print 2013.


The deubiquitylating enzyme Usp9x is highly expressed in the developing mouse brain, and increased Usp9x expression enhances the self-renewal of neural progenitors in vitro. USP9X is a candidate gene for human neurodevelopmental disorders, including lissencephaly, epilepsy and X-linked intellectual disability. To determine if Usp9x is critical to mammalian brain development we conditionally deleted the gene from neural progenitors, and their subsequent progeny. Mating Usp9x(loxP/loxP) mice with mice expressing Cre recombinase from the Nestin promoter deleted Usp9x throughout the entire brain, and resulted in early postnatal lethality. Although the overall brain architecture was intact, loss of Usp9x disrupted the cellular organization of the ventricular and sub-ventricular zones, and cortical plate. Usp9x absence also led to dramatic reductions in axonal length, in vivo and in vitro, which could in part be explained by a failure in Tgf-β signaling. Deletion of Usp9x from the dorsal telencephalon only, by mating with Emx1-cre mice, was compatible with survival to adulthood but resulted in reduction or loss of the corpus callosum, a dramatic decrease in hippocampal size, and disorganization of the hippocampal CA3 region. This latter phenotypic aspect resembled that observed in Doublecortin knock-out mice, which is an Usp9x interacting protein. This study establishes that Usp9x is critical for several aspects of CNS development, and suggests that its regulation of Tgf-β signaling extends to neurons.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Astrocytes / metabolism
  • Astrocytes / pathology
  • Axons / metabolism*
  • Axons / pathology
  • Central Nervous System / metabolism
  • Cerebellar Cortex / metabolism*
  • Cerebellar Cortex / pathology*
  • Doublecortin Protein
  • Endopeptidases / genetics*
  • Female
  • Gene Deletion
  • Genes, Lethal
  • Hippocampus / metabolism*
  • Hippocampus / pathology
  • Male
  • Mice
  • Mice, Knockout
  • Neurogenesis / genetics*
  • Neurons / metabolism
  • Neurons / pathology
  • Organ Size
  • Signal Transduction
  • Transforming Growth Factor beta / metabolism*
  • Ubiquitin Thiolesterase


  • Dcx protein, mouse
  • Doublecortin Protein
  • Transforming Growth Factor beta
  • Endopeptidases
  • Ubiquitin Thiolesterase
  • Usp9x protein, mouse

Grants and funding

This work was supported by a grant from the National Health and Medical Research Council of Australia APP1009248 to SAW, APP628952 and APP250340 to JG, a grant from the Women’s and Children’s Hospital Foundation to LAJ, and a grant to AMS from the Australian Government Department of Health and Ageing. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.