Ubiquitous expression of the Pik3caH1047R mutation promotes hypoglycemia, hypoinsulinemia, and organomegaly

FASEB J. 2015 Apr;29(4):1426-34. doi: 10.1096/fj.14-262782. Epub 2014 Dec 30.


Mutations in PIK3CA, the gene encoding the p110α catalytic subunit of PI3K, are among the most common mutations found in human cancer and have also recently been implicated in a range of overgrowth syndromes in humans. We have used a novel inducible "exon-switch" approach to knock in the constitutively active Pik3ca(H1047R) mutation into the endogenous Pik3ca gene of the mouse. Ubiquitous expression of the Pik3ca(H1047R) mutation throughout the body resulted in a dramatic increase in body weight within 3 weeks of induction (mutant 150 ± 5%; wild-type 117 ± 3%, mean ± sem), which was associated with increased organ size rather than adiposity. Severe metabolic effects, including a reduction in blood glucose levels to 59 ± 4% of baseline (11 days postinduction) and undetectable insulin levels, were also observed. Pik3ca(H1047R) mutant mice died earlier (median survival 46.5 d post-mutation induction) than wild-type control mice (100% survival > 250 days). Although deletion of Akt2 increased median survival by 44%, neither organ overgrowth, nor hypoglycemia were rescued, indicating that both the growth and metabolic functions of constitutive PI3K activity can be Akt2 independent. This mouse model demonstrates the critical role of PI3K in the regulation of both organ size and glucose metabolism at the whole animal level.

Keywords: PI3K; glucose metabolism; mouse model; overgrowth syndrome; p110α.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Substitution
  • Animals
  • Class I Phosphatidylinositol 3-Kinases
  • Female
  • Gene Expression
  • Gene Knock-In Techniques
  • Glucose / metabolism
  • Humans
  • Hypoglycemia / enzymology*
  • Hypoglycemia / genetics*
  • Hypoglycemia / metabolism
  • Insulin / blood*
  • Mice
  • Mice, Knockout
  • Mice, Mutant Strains
  • Mice, Transgenic
  • Mutant Proteins / genetics
  • Mutant Proteins / metabolism
  • Mutation*
  • Organ Size / genetics
  • Organ Size / physiology
  • Phosphatidylinositol 3-Kinases / genetics*
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Proto-Oncogene Proteins c-akt / deficiency
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins c-akt / metabolism
  • Weight Gain


  • Insulin
  • Mutant Proteins
  • Class I Phosphatidylinositol 3-Kinases
  • Pik3ca protein, mouse
  • Akt2 protein, mouse
  • Proto-Oncogene Proteins c-akt
  • Glucose