Usp9X Controls Ankyrin-Repeat Domain Protein Homeostasis during Dendritic Spine Development
- Neuron. 2020 Feb 5;105(3):506-521.e7. doi: 10.1016/j.neuron.2019.11.003.
- 1. Department of Physiology, Northwestern University Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
- 2. Griffith Institute for Drug Discovery, Griffith University, Brisbane, QLD 4111, Australia; The School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072 Australia.
- 3. Griffith Institute for Drug Discovery, Griffith University, Brisbane, QLD 4111, Australia.
- 4. Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
- 5. The School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072 Australia; Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
- 6. Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia; Queensland Centre for Mental Health Research, The Park Centre for Mental Health, Wacol, QLD 4076, Australia.
- 7. Robinson Research Institute, School of Medicine, University of Adelaide, Adelaide, SA 5005, Australia.
- 8. Department of Physiology, Northwestern University Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA. Electronic address: [email protected].
Variants in the ANK3 gene encoding ankyrin-G are associated with neurodevelopmental disorders, including intellectual disability, autism, schizophrenia, and bipolar disorder. However, no upstream regulators of ankyrin-G at synapses are known. Here, we show that ankyrin-G interacts with Usp9X, a neurodevelopmental-disorder-associated Deubiquitinase (DUB). Usp9X phosphorylation enhances their interaction, decreases ankyrin-G polyubiquitination, and stabilizes ankyrin-G to maintain dendritic spine development. In forebrain-specific Usp9X knockout mice (Usp9X-/Y), ankyrin-G as well as multiple ankyrin-repeat domain (ANKRD)-containing proteins are transiently reduced at 2 but recovered at 12 weeks postnatally. However, reduced cortical spine density in knockouts persists into adulthood. Usp9X-/Y mice display increase of ankyrin-G ubiquitination and aggregation and hyperactivity. USP9X mutations in patients with intellectual disability and autism ablate its catalytic activity or ankyrin-G interaction. Our data reveal a DUB-dependent mechanism of ANKRD protein homeostasis, the impairment of which only transiently affects ANKRD protein levels but leads to persistent neuronal, behavioral, and clinical abnormalities.