Abstract
O-GlcNAcylation is an essential post-translational modification that occurs on nuclear and cytoplasmic proteins, regulating their function in response to cellular stress and altered nutrient availability. O-GlcNAc transferase (OGT) is the enzyme that catalyzes this reaction and represents a potential therapeutic target, whose biological role is still not fully understood. To support this research field, a series of cell-permeable, low-nanomolar OGT inhibitors were recently reported. In this study, we resynthesized the most potent OGT inhibitor of the library, OSMI-4, and we used it to investigate OGT inhibition in different human cell lines. The compound features an ethyl ester moiety that is supposed to be cleaved by carboxylesterases to generate its active metabolite. Our LC-HRMS analysis of the cell lysates shows that this is not always the case and that, even in the cell lines where hydrolysis does not occur, OGT activity is inhibited.
Highlights
O-GlcNAc transferase (OGT) is a ubiquitous cellular enzyme responsible for one of the most important post-translational protein modifications: the transfer of GlcNAc moiety to serine or threonine residues [1]
In contrast to numerous kinases, O-GlcNAcylation is catalyzed by one enzyme only: OGT, which exists in three isoforms differing in the tetratricopeptide region that influences the protein substrate specificity [5]
We analyzed the presence of OSMI-4b and its derivatives in lysates of different human cell lines, using HPLC coupled to High-Resolution Mass Spectrometry
Summary
O-GlcNAc transferase (OGT) is a ubiquitous cellular enzyme responsible for one of the most important post-translational protein modifications: the transfer of GlcNAc moiety to serine or threonine residues [1]. As UDP-GlcNAc level depends mostly on the intracellular concentration of glucose that fuels hexosamine biosynthetic pathway, OGT activity reflects the cell nutritional status and influences many critical cellular processes, including lipid droplet remodeling, mitochondrial functioning, epigenetic control of gene expression, and proteostasis [2]. It shares the same substrates as kinases and, interferes with kinase-dependent signaling [3,4]. Despite the evident importance of O-GlcNAcylation in shaping cellular protein activity, the phenotypic cell response upon OGT modulation is still not entirely understood.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
