Discovery of pan‐deubiquitinating enzyme inhibitors

Abstract

The ubiquitin system is the linchpin in maintenance of cellular fitness. While many studies have focused on the ubiquitylation pathways, comparatively little is known about the deubquitination proteins (DUBs). Recent research suggests that DUB inhibition is a promising strategy to treat diseases such as cancer, Alzheimer's, and Creutzfeldt‐Jakob disease. Thus development of new methods to improve understanding of deubiquitylation pathways is paramount for basic science and drug development. Known pan‐DUB inhibitors G5 and NSC632839 contain 2–3 highly reactive electrophillic groups that suggest these compounds may be non‐specific cross linkers. G5 and NSC632839 cause an accumulation of high molecular weight ubiquitin species as previously reported by others, but also cause the formation of large protein aggregates in vitro. We observe a similar pattern of accumulation of high molecular weight ubiquitin species, and protein aggregates, with non‐specific cross linkers such as phthalaldehyde and glutaraldehyde in vitro. Thus many pan DUB inhibitors may act through a random cross linking mechanism. We identified several compounds that cause the accumulation of high molecular weight ubiquitin species but not the formation of protein aggregates. These compounds do not contain highly reactive electrophiles. We suggest that these compounds represent a new class of pan DUB inhibitors.