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O-glcnAc reprograms cellular energetics

ABSTRACT: 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.

ORGANISM(S): Homo sapiens

PROVIDER: GSE101642 | GEO | 2017/07/20

SECONDARY ACCESSION(S): PRJNA395053

REPOSITORIES: GEO

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Project description:Drosophila development is a complex and dynamic process regulated, in part, by members of the Polycomb (Pc), Trithorax (Trx) and Compass chromatin modifier complexes. O-GlcNAc Transferase (OGT/SXC) is essential for Pc repression suggesting that the O-GlcNAcylation of proteins plays a key role in regulating development. OGT transfers N-acetyl-D-glucosamine (GlcNAc) onto hydroxyl groups of serine or threonine residues of key transcriptional regulators using the nutrient-derived UDP-GlcNAc as a substrate, which is dynamically removed by O-GlcNAcase (OGA). We performed ChIP-chip and microarray analysis after OGT or OGA RNAi knockdown in Drosophila S2 cells and found that O-GlcNAc was elevated genome wide particularly at genes related to mitosis and cell cycle in OGA RNAi cells, but not at sites co-occupied by Pc member Pleiohomeotic (Pho), such as the Hox and NK homeobox gene clusters. Microarray analysis suggested that altered O-GlcNAc cycling perturbed the expression of genes associated with morphogenesis and cell cycle regulation. To examine the in vivo consequences of disturbed O-GlcNAc cycling in the whole animal, we produced a null allele of oga (ogadel.1) in Drosophila. Epigenetic activators including Trx group members Trithorax (Trx), Absent small or homeotic discs 1 (Ash1) and Compass member Set1 histone methyltransferases are O-GlcNAc modified in ogadel.1 mutants. ogadel.1 mutants displayed altered expression of a distinct set of cell cycle related genes in ovaries. Our results suggest that the loss of OGA could affect epigenetic machinery by accumulating O-GlcNAc on numerous chromatin factors including Trx, Ash1 and Set1 in Drosophila. We performed affymetrix tilingarray analysis after OGT or OGA RNAi knockdown in Drosophila S2 cells to find if that O-GlcNAc was elevated genome wide particularly at genes related to mitosis and cell cycle in OGA RNAi cells, but not at sites co-occupied by Pc member Pleiohomeotic (Pho), ------------------------------- This represents the gene expression component only