title: Pck1 gene silencing in the liver improves glycemia control, insulin sensitivity, and dyslipidemia in db/db mice.
abstract: OBJECTIVE
  Cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C; encoded by Pck1) catalyzes the first committed step in gluconeogenesis. Extensive evidence demonstrates a direct correlation between PEPCK-C activity and glycemia control. Therefore, we aimed to evaluate the metabolic impact and their underlying mechanisms of knocking down hepatic PEPCK-C in a type 2 diabetic model.
  
  
  METHODS
  PEPCK-C gene targeting was achieved using adenovirus-transduced RNAi. The study assessed several clinical symptoms of diabetes and insulin signaling in peripheral tissues, in addition to changes in gene expression, protein, and metabolites in the liver. Liver bioenergetics was also evaluated.
  
  
  RESULTS
  Treatment resulted in reduced PEPCK-C mRNA and protein. After treatment, improved glycemia and insulinemia, lower triglyceride, and higher total and HDL cholesterol were measured. Unsterified fatty acid accumulation was observed in the liver, in the absence of de novo lipogenesis. Despite hepatic lipidosis, treatment resulted in improved insulin signaling in the liver, muscle, and adipose tissue. O(2) consumption measurements in isolated hepatocytes demonstrated unaltered mitochondrial function and a consequent increased cellular energy charge. Key regulatory factors (FOXO1, hepatocyte nuclear factor-4alpha, and peroxisome proliferator-activated receptor-gamma coactivator [PGC]-1alpha) and enzymes (G6Pase) implicated in gluconeogenesis were downregulated after treatment. Finally, the levels of Sirt1, a redox-state sensor that modulates gluconeogenesis through PGC-1alpha, were diminished.
  
  
  CONCLUSIONS
  Our observations indicate that silencing PEPCK-C has direct impact on glycemia control and energy metabolism and provides new insights into the potential significance of the enzyme as a therapeutic target for the treatment of diabetes.
authors.affiliation: Biophysics Unit, Department de Ciències Fisiològuiques II, IDIBELL-University of Barcelona, Barcelona, Spain.
authors.forename: Alicia G
authors.initials: AG
authors.lastname: Gómez-Valadés
authors.forename: Andrés
authors.initials: A
authors.lastname: Méndez-Lucas
authors.forename: Anna
authors.initials: A
authors.lastname: Vidal-Alabró
authors.forename: Francese X
authors.initials: FX
authors.lastname: Blasco
authors.forename: Miguel
authors.initials: M
authors.lastname: Chillon
authors.forename: Ramon
authors.initials: R
authors.lastname: Bartrons
authors.forename: Jordi
authors.initials: J
authors.lastname: Bermúdez
authors.forename: José C
authors.initials: JC
authors.lastname: Perales
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D015153:Blotting, Western; D003600:Cytosol / Q000201:enzymology; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000235:genetics / Q000473:pathology*; D050171:Dyslipidemias / Q000097:blood / Q000235:genetics / Q000473:pathology*; D004734:Energy Metabolism / Q000235:genetics; D005455:Fluorescent Antibody Technique; D020868:Gene Silencing; D005943:Gluconeogenesis / Q000235:genetics; D005951:Glucose Tolerance Test; D007333:Insulin Resistance; D008099:Liver / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D001786:Blood Glucose; D010729:Phosphoenolpyruvate Carboxykinase (GTP)