Abstract 2150 Using System Biology Approaches to Understand the O-GlcNAc Rheostat

O-GlcNAcylation is a post-translational modification that plays an essential role in protein function, stability, localization, and interaction. However, ubiquitous and pleiotropic nature of O-GlcNAc makes understanding the complex role of this modification ambiguous. O-GlcNAc is processed by two key enzymes: a single O-GlcNAc transferase (OGT) that adds the modification, and a single O-GlcNAcase (OGA) that removes the modification. Together, the interplay between OGT and OGA maintains a homeostatic level of O-GlcNAc within the cell. Numerous studies found that upon environmental changes, O-GlcNAc levels within the cell are oscillated to modify signaling pathways. The oscillation of O-GlcNAc level is solely controlled by either a single enzyme OGT or OGA, and this allows the cell to harmonize all cellular function with fluctuating nutrient or growth signals. Though O-GlcNAc change provides minor impacts on the expression of a single protein; however, disruptions in the cells homeostatic O-GlcNAc levels can cause detrimental effects on cell development. For instance, the knockdown of either OGT or OGA causes abnormal cell division. As a result, the O-GlcNAcylation is crucial for multicellular eukaryotes to link cell cycle to nutrient availability. In order to fully understand how changes in O-GlcNAc affect a cell, we developed a systems view of O-GlcNAcylation to in mouse liver after pharmacologic and genetic manipulation of O-GlcNAc. On these liver, we performed Multi-omics analysis (transcriptomics, proteomics, phospho-proteomics, and metabolomics). Second, we developed a bioinformatics tool (AMEND) to align and process changes in Multi-omic data. When these methods were tested in OGT/OGA knockout liver or liver from mice treated with an OGA inhibitor for 1 or 2 weeks, substantial changes in metabolism and cell cycle regulation were observed. Bioinformatics predicted changes in cell cycle progression supporting previous findings, and in OGT KO liver, a propensity for aneuploidy was suggested. To test this outcome, we performed liver hepatectomy (PHX) on OGT KO livers. After 2-weeks, livers showed massive aneuploidy. This changes were driven by O-GlcNAc mediated effects on mitotic proteins, the Hippo signaling pathway, the mTOR signaling pathway, and heat-shock response. Together, a combinatorial Multi-omics approach with advancements in bioinformatics and animal models predicts the impacts of O-GlcNAc on cellular function at the cellular level. Furthermore, we argue that our systems biology approach will unlock new insights into how O-GlcNAc controls cellular function. This work was supported by NIH grant R01AAG064227 to CS.