O-GlcNAcylation of RIPK3 (TLR4 signaling)

Stable Identifier
R-HSA-9687828
Type
Reaction [transition]
Species
Homo sapiens
Compartment
ReviewStatus
5/5
Locations in the PathwayBrowser
General
SVG |   | PPTX  | SBGN
Click the image above or here to open this reaction in the Pathway Browser
The layout of this reaction may differ from that in the pathway view due to the constraints in pathway layout
Receptor-interacting serine/threonine-protein kinase 3 (RIPK3) plays an integral role in mediating a pro-inflammatory form of cell death, termed necroptosis. RIPK3-dependent signaling is tightly regulated by post-translational modifications, including proteolysis, phosphorylation and ubiquitylation. O-linked β-N-acetylglucosamine (O-GlcNAc) transferase (OGT), a key enzyme for protein O-GlcNAcylation, was found to limit RIPK3 kinase-mediated inflammation and necroptosis in lipopolysaccharide (LPS)-stimulated mouse bone marrow-derived macrophages (BMM) and human monocyte-like THP-1 cells (Li X et al. 2019). Genetic deletion of Ogt in myeloid cells markedly exacerbated cytokine storm and host mortality in experimental sepsis in mice (Li X et al. 2019). Further, impaired O-GlcNAc signaling in patients with liver cirrhosis and in mice with ethanol-induced liver injury exhibited a significant increase in the level of phosphorylated mixed lineage kinase domain-like (MLKL) (Zhang B et al. 2019). OGT utilizes uridine diphosphate (UDP)-GlcNAc to catalyze O-linked attachment of a single GlcNAc to serine or threonine residues in target proteins. Co-immunoprecipitation assay showed that RIPK3 directly interacts with OGT in human embryonic kidney 293T (HEK293T) cells that were transfected with the tagged RIPK3 and OGT proteins (Li X et al. 2019; Zhang B et al. 2019). Further, both RIPK3 O-GlcNAcylation and the association between RIPK3 and OGT increased upon LPS stimulation in mouse BMM cells, despite attenuated total protein O-GlcNAcylation, which suggests that OGT actively and specifically promotes RIPK3 O-GlcNAcylation in response to LPS. In addition, upon LPS challenge, Ogt-deficient BMMs produced significantly higher amounts of inflammatory mediators. Similarly, OGT-deficient human THP-1 cells increased cytokine production in response to TLR2 (Pam3Cys), TLR4 (LPS) or TLR9 (CpG) agonists, suggesting that OGT negatively regulates cytokine production both in mouse and human cells (Li X et al. 2019). Thiamet-G (TMG), that increased intracellular O-GlcNAc levels, effectively shortened the half-life of RIPK3 in human non-small cell lung carcinoma cell line derived from the lymph node (H1299) as compared with the vehicle control suggesting that O-GlcNAcylation of RIPK3 decreases its protein stability (Zhang B et al. 2019). Truncations of human RIPK3 in conjunction with mass spectrometry and subsequent site-directed mutagenesis pinpointed the site of O-GlcNAcylation as residue T467 within the RIP homotypic interaction motif (RHIM) domain of RIPK3 (Li X et al. 2019). Examination of a RIPK3 T467A mutant, which is resistant to O-GlcNAc modification, confirmed that this modification repressed LPS-induced RIPK3-mediated phosphorylation events, cytokine production, and necroptotic cell death in THP-1 and RIPK3-expressing HEK293T cells (Li X et al. 2019). It should be noted that T467 on human RIPK3 is only partially conserved among mammalian species, suggesting a possibility that additional functional O-GlcNAcylation site(s) could exist in other species (Li X et al. 2019). Further, the O-GlcNAcylation of RIPK3 diminished RIPK1:RIPK3 and RIPK3:RIPK3 RHIM interactions and downstream RIPK3 kinase activation in RIPK3-expressing HEK293T cells. These findings are supported by structural modeling showing that O-GlcNAc modification lies in close proximity to the conserved RHIM VQVG motif and likely perturbs RHIM-mediated protein interaction through steric hinderance. Collectively these data show that OGT targets residue T467 of RIPK3 for O-GlcNAcylation to prevent RIPK3 activation in human cells. These findings demonstrate an immuno-metabolic crosstalk linking the hexosamine biosynthesis pathway (HBP)-associated O-GlcNAc signaling and innate immune cell activation (Li X et al. 2019; Zhang B et al. 2019).
Literature References
PubMed ID Title Journal Year
30770249 O-GlcNAc Transferase Suppresses Inflammation and Necroptosis by Targeting Receptor-Interacting Serine/Threonine-Protein Kinase 3

Yin, G, Rodriguez, DA, Lewis, RE, Li, T, Attri, KS, Herring, LE, Green, DR, Lei, YL, Gong, W, Yang, X, Wen, H, Kalil, AC, Singh, PK, Wang, H, Yang, M, Powers, R, Bhinderwala, F, Asara, JM, Li, X

Immunity 2019
Participants
Participates
Catalyst Activity

protein O-acetylglucosaminyltransferase activity of OGT [cytosol]

Orthologous Events
Authored
Reviewed
Created
Cite Us!