Project description:Tissue fibrosis is induced by chronic inflammation accompanied by repeated injuries. Chronic inflammation alters fibroblasts and stellate cells, maintaining the tissues in myofibroblasts and activating stellate cells. This activation promotes the augmentation of these cells and the abundant production of extracellular matrices, such as collagen. Fibrotic tissue dysfunction is eventually induced by expelling parenchymal cells with these abundant collagen depositions. To recover from tissue fibrosis, the activation of myofibroblasts and stellate cells is suppressed by selectively targeting these cells. Here we show that O-N-acetylglucosamine (GlcNAc)-modified proteins leaked from dead cells and GlcNAc-bearing polymers mimicking the GlcNAc moiety of these proteins suppress the activation of these cells; administration of the GlcNAc-bearing polymer into carbon tetrachloride-treated mice can improve liver fibrosis. We found that a multivalent GlcNAc moiety structure elicited antifibrotic activities in myofibroblasts by interacting with cell surface vimentin and desmin. Therefore, since these cells highly express cytoskeletal proteins, vimentin and desmin, on the cell surface and have GlcNAc-binding activity, we suggest that O-GlcNAc-modified proteins leaked from dead cells can function as suppressors of fibrosis and hyperplasia in spontaneous recovery. Moreover, we anticipate that GlcNAc-bearing polymers mimicked by O-GlcNAc-modified proteins will be useful as new therapeutic tools for fibrosis and hyperplasia.
Project description:We report that Oct4 is modified by O-GlcNAc in stem cells. To find O-GlcNAc-Oct4 target genes, we ChIPed Oct4 with Flag(Oct4) antibody and then O-GlcNAc modified proteins are enriched by sWGA beads (succinylated wheat germ agglutinin (sWGA), which specifically binds O-GlcNAc). Results show that several genes implicated in pluripotency regulation are bound by O-GlcNAc-Oct4 in their gene region.
Project description:We report that Oct4 is modified by O-GlcNAc in stem cells. To find O-GlcNAc-Oct4 target genes, we ChIPed Oct4 with Flag(Oct4) antibody and then O-GlcNAc modified proteins are enriched by sWGA beads (succinylated wheat germ agglutinin (sWGA), which specifically binds O-GlcNAc). Results show that several genes implicated in pluripotency regulation are bound by O-GlcNAc-Oct4 in their gene region. 2 samples examined: Control (ChIP with anti-Flag(Oct4) and then reChIP with IgG), O-GlcNAc-Oct4 (ChIP with anti-Flag (Oct4) and then reChIP with sWGA)
Project description:We applied the chemical reporter-based metabolic labeling method to acquire O-GlcNAc modified proteins chromatin loci. Human breast cancer cell line MCF-7, as well as the genotoxic stress (Adriamycin) adapted cells MCF-7/ADR, were fed with 1 mM GalNAz. Metabolic labeled O-GlcNAz chromatin were crosslinked, sonicated and enriched by bioorthogonal chemistry. Then, the genomic DNA fragments bounded by O-GlcNAc mark were de-crosslinked, and constructed into libraries following by next-generation sequencing (Chemoselective O-GlcNAc chromatin sequencing, COGC-seq). To verify the robustness of this chemical reporter-based metabolic labeling method, we compared the results in MCF-7 and MCF-7/ADR cells with classical lectin succinylated wheat germ agglutinin (sWGA) ChIP-seq strategy. We also analyzed gene expression MCF-7 and MCF-7/ADR cells by RNA-seq.
Project description:N6-methyladenosine (m6A) is the most abundant internal mRNA nucleotide modification in mammals, regulating critical aspects of cell physiology and differentiation. The YTHDF proteins are the primary readers of m6A modifications and exert physiological functions of m6A in the cytosol. Elucidating the regulatory mechanisms of YTHDF proteins is critical to understanding m6A biology. Here, we report a mechanism that protein post-translational modifications control the biological functions of the YTHDF proteins. We find that YTHDF1 and YTHDF3, but not YTHDF2, carry high levels of nutrient-sensing O-GlcNAc modifications. O-GlcNAc modification attenuates the translation promoting function of YTHDF1 and YTHDF3 by blocking their interactions with proteins associated with mRNA translation. We further demonstrate that O-GlcNAc modifications on YTHDF1 and YTHDF2 regulate the assembly, stability, and disassembly of stress granule, facilitating rapid exchange of m6A-modified mRNAs in stress granules for recovery from stress. Therefore, our results discover an important regulatory pathway of YTHDF functions, adding an additional layer of complexity to the post-transcriptional regulation function of mRNA m6A.
Project description:We developed a strategy to map GlcNAc modified proteins based on a chemical chromatin precipitation strategy. Drosophila S2 cells, as well as wild type (wt) and sxc null pupae, were fed with 100 uM Ac4GalNAz and the resulting DNA was cross-linked, sonicated, and purified. DNA strands cross-linked to GlcNAz proteins were isolated by congugating with alkyn-biotin by Staudinger ligation followed by streptavidin purification. The resulting DNA was constructed into libraries for sequencing. To asses the robustness of our strategy, we compared GalNAz ChIP-seq results in S2 cells with two other GlcNAc ChIP-seq strategies, using a mutant β-1,4-galactosyltransferase (GalT) and the lecting wheat germ agglutinin (WGA). Briefly, GalT was incubated with cross-linked, sonicated and purified DNA along with UDP-GalNAz. Ligation to biotin with click chemistry followed by streptavidin purification resulted in library ready material. For WGA and Pho ChIP-seq, cross-linked and purified DNA was incubated with pho antibody or WGA resin and purified followed by library preperation.
Project description:O-linked N-acetylglucosamine (O-GlcNAc) is a necessary protein modification installed onto hundreds of nucleocytoplasmic proteins by O-GlcNAc transferase (OGT). Recently, we developed an antibody-free metabolic feeding approach that enables unbiased mapping of O-GlcNAcylated proteins in a genome-wide manner, providing insight into the regulation of genes by O-GlcNAcylated proteins within Drosophila. Here we apply this O-GlcNAc chemical mapping strategy to a time course (TC) feeding experiment within Drosophila larvae, generated the first ever TC ChIP-seq experiment performed on both a protein modification and within a living organism. TC metabolic labeling experiments were performed in wild-type and O-GlcNAc hydrolase (OGA) deficient Drosophila. Analysis of the resulting sequencing data revealed that a loss of OGA causes a global increase in the retention of O-GlcNAc modification on proteins bound to the genome, suggesting most nuclear proteins are sensitive to effects of O-GlcNAc cycling. Interestingly, some loci are more sensitive to the impacts of a loss of OGA compared to others. This study will present an improved understanding of the regulation of gene expression by O-GlcNAc while providing the broader community with experimental methods for time-resolved analysis of genome-wide binding by proteins.
Project description:Antibodies against post-translational modifications (PTMs) such as lysine acetylation, ubiquitnation, or phospho-tyrosine have enabled significant advances in our understanding the fundamental roles of PTMs in biology. However, a number of PTM spaces remain unexplored due to the lack of robust enrichment reagents. The addition of N-acetylglucosamine to serine and threonine residues (O-GlcNAc) is a PTM implicated in numerous biological processes and disease states, and has limited techniques for its study. Here, we evaluate a new mixture of anti-O-GlcNAc monoclonal antibodies for the immunoprecipitation of native O-GlcNAcylated peptides from cells and tissues. The anti-O-GlcNAc antibodies display good sensitivity and excellent specificity toward O-GlcNAc, and not O-GalNAc or GlcNAc in extended glycans. Applying these antibodies to tissue samples, we achieved an in-depth characterization of O-GlcNAcylation from mouse synaptosomes, identifying over 1,300 unique O-GlcNAc-modified peptides and over 1,000 sites, using a fraction of sample preparation and instrument time of other landmark investigations. This rapid and robust method greatly simplifies the analysis of O-GlcNAc signaling and will help to elucidate the role of this challenging PTM in health and disease.
Project description:Dysfunctional mitochondria and generation of reactive oxygen species (ROS) promote chronic diseases, which have spurred interest in the molecular mechanisms underlying these conditions. Previously, we have demonstrated that disruption of post-translational modification of proteins with β-linked N-acetylglucosamine (O- glcnAcylation) via overexpression of the O-glcnAc–regulating enzymes O- glcnAc transferase (OGT) or O- glcnAcase (OGA) impairs mitochondrial function. Here, we report that sustained alterations in O- glcnAcylation either by pharmacological or genetic manipulation also alters metabolic function. Sustained O-glcnAc elevation in SH-SY5Y neuroblastoma cells increased OGA expression and reduced cellular respiration and ROS generation. Cells with elevated O-glcnAc levels had elongated mitochondria and increased mitochondrial membrane potential, and RNA-Seq in SH-SY5Y cells indicated transcriptome reprogramming and down regulation of the NRF2-mediated antioxidant response. Sustained O-glcnAcylation in mice brain and liver validated the metabolic phenotypes observed in the cells, and OGT knockdown in the liver elevated ROS levels, impaired respiration, and increased the NRF2 antioxidant response. Moreover, elevated O-glcnAc levels promoted weight loss and lowered respiration in mice and skewed the mice toward carbohydrate-dependent metabolism as determined by indirect calorimetry. In summary, sustained elevation in O-glcnAcylation coupled with increased OGA expression reprograms energy metabolism, a finding that has potential implications for the etiology, development, and management of metabolic diseases.