Hepatocellular carcinoma (HCC) is a malignant tumor originating in the liver. Previous studies have indicated that O-GlcNAc transferase (OGT) and histone deacetylase-1 (HDAC1) play important roles in the pathogenesis of HCC. In the present study, we investigated the physical link between OGT and HDAC1. The O-GlcNAcylation of HDAC1 is overexpressed in HCC. We found that HDAC1 has two major sites of O-GlcNAcylation in its histone deacetylase domain. HDAC1 O-GlcNAcylation increases the activated phosphorylation of HDAC1, which enhances its enzyme activity. HDAC1 O-GlcNAc mutants promote the p21 transcription regulation through affecting the acetylation levels of histones from chromosome, and then influence the proliferation of HCC cells. We also found that mutants of O-GlcNAcylation site of HDAC1 affect invasion and migration of HepG2 cells. E-cadherin level is highly up-regulated in HDAC1 O-GlcNAc mutant-treated liver cancer cells, which inhibit the occurrence and development of HCC. Our findings suggest that OGT promotes the O-GlcNAc modification of HDAC1in the development of HCC. Therefore, inhibiting O-GlcNAcylation of HDAC1 may repress the progression of HCC.
Accumulating evidences demonstrated that microglia activation and the autocrine loop of tumor necrosis factor-α (TNFα) greatly contribute to the pathogenesis of several CNS diseases. TNFα exerts its biological effects by interacting with two different receptors: TNF receptor 1 (TNFR1) and TNFR2. The classic proinflammatory activity of TNFα is mainly mediated by TNFR1. In the present study, we found that TNFR1 was modificated by N-glycosylation on Asn151 and Asn202 in microglia. The N-glycosylation of TNFR1 could facilitate its capability of binding to TNFα and further promote the formation of TNFα autocrine loop in microglia stimulated by TNFα, resulting in excessive microglia activation and CNS inflammation. All these processes were related to TNFR1-mediated NF-κB pathways. Elimination of N-glycosylation did not affect the subcellular transportation and cell surface localization of TNFR1, but suppressed ligand-binding affinity. These findings indicated that the N-glycosylation of TNFR1 played an important role during microglia activation in CNS inflammation. By this study, we aimed to provide some valuable experimental evidence for a better understanding of the significance of protein glycosylation in microglia inflammatory activation and CNS disease.
Protein ubiquitination is a dynamic two-way process that can be reversed or regulated by deubiquitinating enzymes (DUB). USP11, located on the X chromosome, 6 is a member of USP subclass of the DUB family. Here, we demonstrate that USP11 may be involved in neuronal apoptosis in the processes of intracerebral hemorrhage (ICH). From the results of Western blot, immunohistochemistry, and immunofluorescence, we obtained a significant up-regulation of USP11 in neurons adjacent to the hematoma following ICH. Increasing USP11 level was found to be accompanied by the up-regulation of active caspase-3, Fas receptor (Fas), Fas ligand (FasL), and active caspase-8. Besides, USP11 co-localized well with active caspase-3 in neurons, indicating its potential role in neuronal apoptosis. What is more, knocking down USP11 by RNA-interference in PC12 cells reduced active caspase-3 expression. Thus, USP11 may play a role in promoting the brain secondary damage following ICH.
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