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Biochemistry Research International
Volume 2012 (2012), Article ID 837015, 12 pages
http://dx.doi.org/10.1155/2012/837015
Review Article

The Ubiquitin-Proteasome System in Huntington’s Disease: Are Proteasomes Impaired, Initiators of Disease, or Coming to the Rescue?

Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands

Received 31 May 2012; Revised 14 August 2012; Accepted 19 August 2012

Academic Editor: Shoshana Bar-Nun

Copyright © 2012 Sabine Schipper-Krom et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Huntington’s disease is a progressive neurodegenerative disease, caused by a polyglutamine expansion in the huntingtin protein. A prominent hallmark of the disease is the presence of intracellular aggregates initiated by N-terminal huntingtin fragments containing the polyglutamine repeat, which recruit components of the ubiquitin-proteasome system. While it is commonly thought that proteasomes are irreversibly sequestered into these aggregates leading to impairment of the ubiquitin-proteasome system, the data on proteasomal impairment in Huntington’s disease is contradictory. In addition, it has been suggested that proteasomes are unable to actually cleave polyglutamine sequences in vitro, thereby releasing aggregation-prone polyglutamine peptides in cells. Here, we discuss how the proteasome is involved in the various stages of polyglutamine aggregation in Huntington’s disease, and how alterations in activity may improve clearance of mutant huntingtin fragments.