title: The small molecule inhibitor PR-619 of deubiquitinating enzymes affects the microtubule network and causes protein aggregate formation in neural cells: implications for neurodegenerative diseases.
abstract: A pathological hallmark of many neurodegenerative diseases is the aggregation of proteins. Protein aggregate formation may be linked to a failure of the ubiquitin proteasome system (UPS) and/or the autophagy pathway. The UPS involves the ubiquitination of proteins followed by proteasomal degradation. Deubiquitination of target proteins is performed by proteases called deubiquitinating proteins (DUBs). Inhibition of DUBs may lead to the dysregulation of homeostasis and have pathological consequences. To assess the effects of DUB-inhibition, we have used the oligodendroglial cell line, OLN-t40, stably expressing the longest human tau isoform. Cells were incubated with PR-619, a broad-range, reversible inhibitor of ubiquitin isopeptidases. Incubation with PR-619 led to morphological changes, the upregulation of heat shock proteins (HSP), including HSP70 and αB-crystallin, and to protein aggregates near the MTOC, containing ubiquitin, HSPs, and the ubiquitin binding protein p62, which may provide a link between the UPS and autophagy. Thus, inhibition of DUB activity caused stress responses and the formation of protein aggregates resembling pathological inclusions observed in aggregopathies. Furthermore, PR-619 led to the stabilization of the microtubule network, possibly through the modulation of tau phosphorylation, and small tau deposits assembled near the MTOC. Hence, organization and integrity of the cytoskeleton were affected, which is particularly important for the maintenance of the cellular architecture and intracellular transport processes, and essential for the functionality and survival of neural cells. Our data demonstrate that DUB inhibitors provide a useful tool to elucidate the manifold mechanisms of DUB functions in cells and their dysregulation in neurodegenerative diseases. This article is part of a Special Issue entitled: Ubiquitin Drug Discovery and Diagnostics.
authors.affiliation: Department of Biology, Molecular Neurobiology, University of Oldenburg, Oldenburg, Germany.
authors.forename: Veronika
authors.initials: V
authors.lastname: Seiberlich
authors.forename: Olaf
authors.initials: O
authors.lastname: Goldbaum
authors.forename: Victoria
authors.initials: V
authors.lastname: Zhukareva
authors.forename: Christiane
authors.initials: C
authors.lastname: Richter-Landsberg
mesh_terms: D000631:Aminopyridines / Q000494:pharmacology*; D015153:Blotting, Western; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D019084:Fluorescent Antibody Technique, Indirect; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D022101:Microtubule-Organizing Center / Q000187:drug effects*; D008870:Microtubules / Q000187:drug effects* / Q000378:metabolism; D009836:Oligodendroglia / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D046988:Proteasome Endopeptidase Complex / Q000187:drug effects*; D055503:Protein Multimerization / Q000187:drug effects*; D013861:Thiocyanates / Q000494:pharmacology*; D025801:Ubiquitin / Q000378:metabolism; D043222:Ubiquitin Thiolesterase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D054875:Ubiquitination / Q000187:drug effects; D016875:tau Proteins / Q000378:metabolism
chemical_list: C570894:2,6-diaminopyridine-3,5-bis(thiocyanate); D000631:Aminopyridines; D018840:HSP70 Heat-Shock Proteins; D013861:Thiocyanates; C501066:USP36 protein, human; D025801:Ubiquitin; D016875:tau Proteins; D043222:Ubiquitin Thiolesterase; D046988:Proteasome Endopeptidase Complex