title: Heterozygous expression of the oncogenic Pik3ca(H1047R) mutation during murine development results in fatal embryonic and extraembryonic defects.
abstract: The phosphoinositide 3-kinase (PI3K)/AKT signalling pathway regulates many cellular functions including proliferation, migration, survival and protein synthesis. Somatic mutations in PIK3CA, the gene encoding the p110α catalytic subunit of PI3K enzyme, are commonly associated with many human cancers as well as recently being implicated in human overgrowth syndromes. However, it is not clear if such mutations can be inherited through the germline. We have used a novel mouse model with Cre recombinase (Cre)-conditional knock-in of the common H1047R mutation into the endogenous Pik3ca gene. Heterozygous expression of the Pik3ca(H1047R) mutation in the developing mouse embryo resulted in failed 'turning' of the embryo and disrupted vascular remodelling within the embryonic and extraembryonic tissues, leading to lethality prior to E10. As vascular endothelial growth factor A (VEGF-A) signalling was disrupted in these embryos, we used Cre under the control of the Tie2 promoter to target the Pik3ca(H1047R) mutation specifically to endothelial cells. In these embryos turning occurred normally but the vascular remodelling defects and embryonic lethality remained, likely as a result of endothelial hyperproliferation. Our results confirm the lethality associated with heterozygous expression of the Pik3ca(H1047R) mutation during development and likely explain the lack of inherited germline PIK3CA mutations in humans.
authors.affiliation: Cancer Biology and Surgical Oncology Research Laboratory, Peter MacCallum Cancer Centre, St. Andrew's Place, Melbourne, Victoria 3002, Australia; Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, Victoria 3800, Australia.
authors.forename: Lauren M
authors.initials: LM
authors.lastname: Hare
authors.affiliation: Department of Human Immunology, Centre for Cancer Biology, University of South Australia, Frome Road, Adelaide, South Australia 5000, Australia.
authors.forename: Quenten
authors.initials: Q
authors.lastname: Schwarz
authors.affiliation: Department of Human Immunology, Centre for Cancer Biology, University of South Australia, Frome Road, Adelaide, South Australia 5000, Australia.
authors.forename: Sophie
authors.initials: S
authors.lastname: Wiszniak
authors.affiliation: Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, Victoria 3800, Australia.
authors.forename: Rajendra
authors.initials: R
authors.lastname: Gurung
authors.affiliation: Cancer Biology and Surgical Oncology Research Laboratory, Peter MacCallum Cancer Centre, St. Andrew's Place, Melbourne, Victoria 3002, Australia.
authors.forename: Karen G
authors.initials: KG
authors.lastname: Montgomery
authors.affiliation: Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, Victoria 3800, Australia.
authors.forename: Christina A
authors.initials: CA
authors.lastname: Mitchell
authors.affiliation: Cancer Biology and Surgical Oncology Research Laboratory, Peter MacCallum Cancer Centre, St. Andrew's Place, Melbourne, Victoria 3002, Australia; Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, Victoria 3800, Australia; The Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria 3010, Australia. Electronic address: wayne.phillips@petermac.org.
authors.forename: Wayne A
authors.initials: WA
authors.lastname: Phillips
mesh_terms: D000818:Animals; D018376:Cardiovascular Abnormalities / Q000235:genetics*; D058534:Class I Phosphatidylinositol 3-Kinases; D004622:Embryo, Mammalian / Q000378:metabolism; D042783:Endothelial Cells / Q000378:metabolism; D055879:Gene Knock-In Techniques; D005804:Genes, Lethal; D006579:Heterozygote; D051379:Mice; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics* / Q000378:metabolism*
chemical_list: D058534:Class I Phosphatidylinositol 3-Kinases; D019869:Phosphatidylinositol 3-Kinases; C546639:Pik3ca protein, mouse
keywords: Angiogenesis; Cardiovascular system; Development; Embryogenesis; PI3K; Pik3ca