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Sci Rep. 2016 Jun 17;6:27703. doi: 10.1038/srep27703.

The polyglutamine-expanded androgen receptor responsible for spinal and bulbar muscular atrophy inhibits the APC/C(Cdh1) ubiquitin ligase complex.

Author information

1
Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm 17177, Sweden.
2
National Institute of Neurological Disorders and Stroke, Neurogenetics Branch, Bethesda, MD 20892, USA.
3
Flow Cytometry Core Facility, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA.
4
Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA.

Abstract

Polyglutamine expansion in the androgen receptor (AR) causes spinal and bulbar muscular atrophy (SBMA), an X-linked neuromuscular disease that is fully manifest only in males. It has been suggested that proteins with expanded polyglutamine tracts impair ubiquitin-dependent proteolysis due to their propensity to aggregate, but recent studies indicate that the overall activity of the ubiquitin-proteasome system is preserved in SBMA models. Here we report that AR selectively interferes with the function of the ubiquitin ligase anaphase-promoting complex/cyclosome (APC/C), which, together with its substrate adaptor Cdh1, is critical for cell cycle arrest and neuronal architecture. We show that both wild-type and mutant AR physically interact with the APC/C(Cdh1) complex in a ligand-dependent fashion without being targeted for proteasomal degradation. Inhibition of APC/C(Cdh1) by mutant but not wild-type AR in PC12 cells results in enhanced neurite outgrowth which is typically followed by rapid neurite retraction and mitotic entry. Our data indicate a role of AR in neuronal differentiation through regulation of APC/C(Cdh1) and suggest abnormal cell cycle reactivation as a pathogenic mechanism in SBMA.

PMID:
27312068
PMCID:
PMC4911547
DOI:
10.1038/srep27703
[Indexed for MEDLINE]
Free PMC Article

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