Conditional Knock-out Reveals a Requirement for O-Linked N-Acetylglucosaminase (O-GlcNAcase) in Metabolic Homeostasis

Keembiyehetty, Chithra N.; Love, Dona C.; Harwood, Katryn R.; Гаврилова, Оксана; Comly, Marcella E.; Hanover, John A.

doi:10.1074/jbc.m114.617779

Cited by 129 publications

(158 citation statements)

References 86 publications

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“…Previous reports have shown that the loss of OGA in mice leads to defects in metabolic homeostasis, culminating in obesity and insulin resistance [26], and that the overexpression of OGA in db/db mice significantly improves the lipid profile in liver [45]. Consistently, we found impaired insulin signalling and glucose uptake capacity in myotubes after OGA knockdown or treatment with PUGNAc or D-GlcNAc, with concurrent increased O-GlcNAcylation and mitochondrial dysfunction.…”

Section: Discussionsupporting

confidence: 76%

“…Following the observation of OGT localisation to the mitochondria by Love et al [24], the presence of OGA was recently reported in cardiac mitochondria in rats [25]. Despite a recently identified association between OGA-mediated O-GlcNAcylation and diabetes progression [25,26], there have been no reports of the effects of OGA activity on mitochondrial regulation. In the current study in mice, we report that OGA deficiency promotes peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) degradation by increasing its O-GlcNAcylation, leading to suppressed mitochondrial biogenesis and myogenesis.…”

Section: Introductionmentioning

confidence: 99%

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O-GlcNAcase deficiency suppresses skeletal myogenesis and insulin sensitivity in mice through the modulation of mitochondrial homeostasis

et al. 2016

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Aims/hypothesis O-GlcNAcylation is implicated in modulating mitochondrial function, which is closely involved in regulating muscle metabolism. The presence of O-GlcNAcase (OGA), the enzyme involved in the removal of O-GlcNAc, in mitochondria was recently confirmed in rats. In the present study, we investigated the regulation of myogenesis and muscle insulin sensitivity to OGA in mice, with a focus on mitochondria. Methods C57BL/6J mice fed a high-fat diet for 4 months were used to observe mitochondrial density, activity and O-GlcNAcylation in muscle. Small interfering RNA and overexpression vectors were used to modulate protein content in vitro. Results High-fat feeding decreased the OGA level and largely increased mitochondrial O-GlcNAcylation in mouse skeletal muscle that was accompanied by decreased levels of peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), decreased mitochondrial density and disrupted mitochondrial complex activities. Knockdown of OGA in C2C12 myoblasts promoted PGC-1α degradation, resulting in the suppression of mitochondrial biogenesis and myogenesis, whereas neither knockdown of O-GlcNAc transferase nor overexpression of OGA had significant effects on myogenesis. Mitochondrial dysfunction as evidenced by decreased ATP content and increased reactive oxygen species production, and increased lipid and protein oxidation was observed in both myoblasts and myotubes after OGA knockdown. Meanwhile, elevated O-GlcNAcylation through either OGA knockdown or treatment with the OGA inhibitor PUGNAc and the O-GlcNAc transferase substrate D-GlcNAc suppressed myotube insulin signalling transduction and glucose uptake. OGA overexpression had no significant effect on insulin sensitivity but sufficiently improved the insulin resistance induced by D-GlcNAc treatment. Conclusions/interpretation These data suggest that OGA can modulate mitochondrial density via PGC-1α and mitochondrial function via protein O-GlcNAcylation. In this manner, OGA appears to play a key role in myogenesis and the development of muscle insulin resistance.

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Section: Discussionsupporting

confidence: 76%

Section: Introductionmentioning

confidence: 99%

O-GlcNAcase deficiency suppresses skeletal myogenesis and insulin sensitivity in mice through the modulation of mitochondrial homeostasis

et al. 2016

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“…Our findings are in accord with studies showing that reduced O‐GlcNAc lowers levels of Sp1 in cells6f, 13 and that OGT plays a pivitol role in fat tissues 14. Notably, these data also suggest that regulation of leptin by O‐GlcNAc is bidirectional in vivo as overexpression of OGT,3 knockout of OGA,15 and metabolic upregulation of UDP GlcNAc levels16 all increase leptin expression.…”

supporting

confidence: 91%

Metabolic Inhibitors of O‐GlcNAc Transferase That Act In Vivo Implicate Decreased O‐GlcNAc Levels in Leptin‐Mediated Nutrient Sensing

et al. 2018

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O‐Linked glycosylation of serine and threonine residues of nucleocytoplasmic proteins with N‐acetylglucosamine (O‐GlcNAc) residues is catalyzed by O‐GlcNAc transferase (OGT). O‐GlcNAc is conserved within mammals and is implicated in a wide range of physiological processes. Herein, we describe metabolic precursor inhibitors of OGT suitable for use both in cells and in vivo in mice. These 5‐thiosugar analogues of N‐acetylglucosamine are assimilated through a convergent metabolic pathway, most likely involving N‐acetylglucosamine‐6‐phosphate de‐N‐acetylase (NAGA), to generate a common OGT inhibitor within cells. We show that of these inhibitors, 2‐deoxy‐2‐N‐hexanamide‐5‐thio‐d‐glucopyranoside (5SGlcNHex) acts in vivo to induce dose‐ and time‐dependent decreases in O‐GlcNAc levels in various tissues. Decreased O‐GlcNAc correlates, both in vitro within adipocytes and in vivo within mice, with lower levels of the transcription factor Sp1 and the satiety‐inducing hormone leptin, thus revealing a link between decreased O‐GlcNAc levels and nutrient sensing in peripheral tissues of mammals.

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“…21,30 The loss of OGA led to almost complete perinatal lethality in these animals with a variety of developmental defects. 21,30 OGA -/-MEF (mouse embryonic fibroblast) demonstrated reduced growth rates, failure to resume cell cycle progression after serum starvation-reactivation, and these cells had an increase in polyploidy. 21 Interestingly, OGA knockdowns in colorectal cancer cells also had an increase in polyploidy.…”

Section: Discussionmentioning

confidence: 99%

Reduced O-GlcNAcase expression promotes mitotic errors and spindle defects

et al. 2016

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Alterations in O-GlcNAc cycling, the addition and removal of O-GlcNAc, lead to mitotic defects and increased aneuploidy. Herein, we generated stable O-GlcNAcase (OGA, the enzyme that removes OGlcNAc) knockdown HeLa cell lines and characterized the effect of the reduction in OGA activity on cell cycle progression. After release from G 1 /S, the OGA knockdown cells progressed normally through S phase but demonstrated mitotic exit defects. Cyclin A was increased in the knockdown cells while Cyclin B and D expression was reduced. Retinoblastoma protein (RB) phosphorylation was also increased in the knockdown compared to control. At M phase, the knockdown cells showed more compact spindle chromatids than control cells and had a greater percentage of cells with multipolar spindles. Furthermore, the timing of the inhibitory tyrosine phosphorylation of Cyclin Dependent Kinase 1 (CDK1) was altered in the OGA knockdown cells. Although expression and localization of the chromosomal passenger protein complex (CPC) was unchanged, histone H3 threonine 3 phosphorylation was decreased in one of the OGA knockdown cell lines. The Ewing Sarcoma Breakpoint Region 1 Protein (EWS) participates in organizing the CPC at the spindle and is a known substrate for O-GlcNAc transferase (OGT, the enzyme that adds OGlcNAc). EWS O-GlcNAcylation was significantly increased in the OGA knockdown cells promoting uneven localization of the mitotic midzone. Our data suggests that O-GlcNAc cycling is an essential mechanism for proper mitotic signaling and spindle formation, and alterations in the rate of O-GlcNAc cycling produces aberrant spindles and promotes aneuploidy.

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Conditional Knock-out Reveals a Requirement for O-Linked N-Acetylglucosaminase (O-GlcNAcase) in Metabolic Homeostasis

Cited by 129 publications

References 86 publications

O-GlcNAcase deficiency suppresses skeletal myogenesis and insulin sensitivity in mice through the modulation of mitochondrial homeostasis

O-GlcNAcase deficiency suppresses skeletal myogenesis and insulin sensitivity in mice through the modulation of mitochondrial homeostasis

Metabolic Inhibitors of O‐GlcNAc Transferase That Act In Vivo Implicate Decreased O‐GlcNAc Levels in Leptin‐Mediated Nutrient Sensing

Reduced O-GlcNAcase expression promotes mitotic errors and spindle defects

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