A role for ubiquitin in the pathogenesis of human diseases was first suggested some two decades ago, from studies that localized the protein to intracellular protein aggregates, which are a feature of the major human neurodegenerative disorders. Although several different mechanisms have been proposed to connect impairment of the UPS (ubiquitin–proteasome system) to the presence of these ‘ubiquitin inclusions’ within diseased neurones, their significance in the disease process remains to be fully clarified. Ubiquitin inclusions also contain ubiquitin-binding proteins, such as the p62 protein [also known as SQSTM1 (sequestosome 1)], which non-covalently interacts with the ubiquitinated protein aggregates and may serve to mediate their autophagic clearance. p62 is a multifunctional protein and, in the context of bone-resorbing osteoclasts, is an important scaffold in the RANK [receptor activator of NF-κB (nuclear factor κB)]–NF-κB signalling pathway. Further, mutations affecting the UBA domain (ubiquitin-associated domain) of p62 are commonly found in patients with the skeletal disorder PDB (Paget's disease of bone). These mutations impair the ability of p62 to bind to ubiquitin and result in disordered osteoclast NF-κB signalling that may underlie the disease aetiology. Recent structural insights into the unusual mechanism of ubiquitin recognition by the p62 UBA domain have helped rationalize the mechanisms by which different PDB mutations exert their negative effects on ubiquitin binding by p62, as well as providing an indication of the ubiquitin-binding selectivity of p62 and, by extension, its normal biological functions.
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June 2008
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Conference Article|
May 21 2008
Disruption of ubiquitin-mediated processes in diseases of the brain and bone
Robert Layfield;
Robert Layfield
1
*School of Biomedical Sciences, University of Nottingham Medical School, Nottingham NG7 2UH, U.K.
1To whom correspondence should be addressed (email robert.layfield@nottingham.ac.uk).
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Mark S. Searle
Mark S. Searle
†Centre for Biomolecular Sciences, School of Chemistry, University of Nottingham, Nottingham NG7 2RD, U.K.
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Biochem Soc Trans (2008) 36 (3): 469–471.
Article history
Received:
December 20 2007
Citation
Robert Layfield, Mark S. Searle; Disruption of ubiquitin-mediated processes in diseases of the brain and bone. Biochem Soc Trans 1 June 2008; 36 (3): 469–471. doi: https://doi.org/10.1042/BST0360469
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