The role of vasodilator-stimulated phosphoprotein (VASP) in the control of hepatic gluconeogenic gene expression

PLoS One. 2019 Apr 24;14(4):e0215601. doi: 10.1371/journal.pone.0215601. eCollection 2019.

Abstract

During periods in which glucose absorption from the gastrointestinal (GI) tract is insufficient to meet body requirements, hepatic gluconeogenesis plays a key role to maintain normal blood glucose levels. The current studies investigated the role in this process played by vasodilatory-associated phosphoprotein (VASP), a protein that is phosphorylated in hepatocytes by cAMP/protein kinase A (PKA), a key mediator of the action of glucagon. We report that following stimulation of hepatocytes with 8Br-cAMP, phosphorylation of VASP preceded induction of genes encoding key gluconeogenic enzymes, glucose-6-phosphatase (G6p) and phosphoenolpyruvate carboxykinase (Pck1), and that VASP overexpression enhanced this gene induction. Conversely, hepatocytes from mice lacking VASP (Vasp-/-) displayed blunted induction of gluconeogenic enzymes in response to cAMP, and Vasp-/- mice exhibited both greater fasting hypoglycemia and blunted hepatic gluconeogenic enzyme gene expression in response to fasting in vivo. These effects of VASP deficiency were associated with reduced phosphorylation of both CREB (a key transcription factor for gluconeogenesis that lies downstream of PKA) and histone deacetylase 4 (HDAC4), a combination of effects that inhibit transcription of gluconeogenic genes. These data support a model in which VASP functions as a molecular bridge linking the two key signal transduction pathways governing hepatic gluconeogenic gene expression.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blood Glucose / metabolism
  • Cell Adhesion Molecules / deficiency
  • Cell Adhesion Molecules / genetics
  • Cell Adhesion Molecules / metabolism*
  • Cells, Cultured
  • Cyclic AMP-Dependent Protein Kinases / metabolism
  • Fasting / metabolism
  • Gene Expression Regulation
  • Gluconeogenesis / genetics*
  • Glucose-6-Phosphatase / genetics
  • Hepatocytes / metabolism
  • Liver / metabolism*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Microfilament Proteins / deficiency
  • Microfilament Proteins / genetics
  • Microfilament Proteins / metabolism*
  • Models, Biological
  • Phosphoenolpyruvate Carboxykinase (GTP) / genetics
  • Phosphoproteins / deficiency
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism*
  • Phosphorylation
  • Signal Transduction

Substances

  • Blood Glucose
  • Cell Adhesion Molecules
  • Microfilament Proteins
  • Phosphoproteins
  • vasodilator-stimulated phosphoprotein
  • Cyclic AMP-Dependent Protein Kinases
  • Glucose-6-Phosphatase
  • Phosphoenolpyruvate Carboxykinase (GTP)