O-GlcNAcylation mediates the control of cytosolic phosphoenolpyruvate carboxykinase activity via Pgc1α

PLoS One. 2017 Jun 23;12(6):e0179988. doi: 10.1371/journal.pone.0179988. eCollection 2017.

Abstract

PGC1α is a coactivator of many transcription factors and cytosolic phosphoenolpyruvate carboxykinase (PCK1) is a key enzyme for gluconeogenesis. PGC1α interacts with the transcription factor PPARγ to stimulate PCK1 expression and thus de novo glucose synthesis. These proteins are not only important for central energy metabolism but also for supplying intermediates for other metabolic pathways, including lipidogenesis and protein synthesis and might therefore be important factors in the ethiopathogenesis of metabolic disorders like diabetes but also in other pathologies like cancer. Since polymorphisms in these proteins have been related to some phenotypic traits in animals like pigs and PGC1α G482S polymorphism increases fat deposition in humans, we have investigated the molecular basis of such effects focusing on a commonly studied polymorphism in pig Pgc1α, which changes a cysteine at position 430 (WT) of the protein to a serine (C430S). Biochemical analyses show that Pgc1α WT stimulates higher expression of human PCK1 in HEK293T and HepG2 cells. Paradoxically, Pgc1α WT is less stable than Pgc1α p.C430S in HEK293T cells. However, the study of different post-translational modifications shows a higher O-GlcNAcylation level of Pgc1α p.C430S. This higher O-GlcNAcylation level significantly decreases the interaction between Pgc1α and PPARγ demonstrating the importance of post-translational glycosylation of PGC1α in the regulation of PCK1 activity. This, furthermore, could explain at least in part the observed epistatic effects between PGC1α and PCK1 in pigs.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Epistasis, Genetic
  • Glucose / metabolism
  • Glycosylation
  • HEK293 Cells
  • Hep G2 Cells
  • Humans
  • PPAR gamma / metabolism
  • Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha / genetics
  • Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha / metabolism*
  • Phenotype
  • Phosphoenolpyruvate Carboxykinase (GTP) / genetics
  • Phosphoenolpyruvate Carboxykinase (GTP) / metabolism*
  • Protein Processing, Post-Translational
  • Protein Stability
  • RNA, Messenger / metabolism
  • Sequence Homology, Amino Acid
  • Swine

Substances

  • PPAR gamma
  • Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha
  • RNA, Messenger
  • Phosphoenolpyruvate Carboxykinase (GTP)
  • Glucose

Grants and funding

This work has been funded by grants AGL2015-66177 to P.L.B. and J.A.C. from Ministerio de Economia, Industria y Competitividad (http://www.mineco.gob.es/portal/site/mineco/), UZ 2014-CIE-03 to P.L.B. and UZ-2015-BIO-01 to J.A.C. from University of Zaragoza (http://www.unizar.es). Funders' role has been limited to financial support. P.L. is supported by a predoctoral fellowship from ‘la Caixa’ Foundation (https://www.fundacionbancarialacaixa.org/corporate/home_es.html).