Proliferative defect and embryonic lethality in mice homozygous for a deletion in the p110alpha subunit of phosphoinositide 3-kinase.
Phosphatidylinositol 3,4,5-trisphosphate is a phospholipid signaling molecule involved in many cellular functions including growth factor receptor signaling, cytoskeletal organization, chemotaxis, apoptosis, and protein trafficking. Phosphorylation at the 3 position of the inositol ring is catalyzed by many different 3-kinases (classified as types IA, IB, II, and III), but the physiological roles played by each of the different 3-kinase isozymes during embryonic development and in homeostasis in animals is incompletely understood. Mammalian type IA kinase isozymes are heterodimers that are active at 37 degrees C when the catalytic 110-kDa subunit interacts through an amino-terminal binding domain with a regulatory 85- or 55-kDa subunit. Using gene targeting in embryonic stem cells, we deleted this binding domain in the gene encoding the alpha isoform of the 110-kDa catalytic subunit (Pik3ca) of the alpha isozyme of the type IA kinases, leading to loss of expression of the p110 catalytic subunit. We show that Pik3cadel/del embryos are developmentally delayed at embryonic day (E) 9.5 and die between E9.5 and E10.5. E9. 5 Pik3cadel/del embryos have a profound proliferative defect but no increase in apoptosis. A proliferative defect is supported by the observation that fibroblasts from Pik3cadel/del embryos fail to replicate in Dulbecco's modified Eagle's medium and fetal calf serum, even with supplemental growth factors.
Bi
L
L
Genetic Diseases Research Branch, NHGRI, National Institutes of Health, Bethesda, Maryland 20892, USA.
Okabe
I
I
Bernard
D J
DJ
Wynshaw-Boris
A
A
Nussbaum
R L
RL
D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002455:Cell Division / Q000235:genetics*; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D017931:DNA Primers; D004622:Embryo, Mammalian / Q000166:cytology; D018390:Gene Targeting; D005804:Genes, Lethal; D005822:Genetic Vectors; D006720:Homozygote; D020287:In Situ Nick-End Labeling; D051379:Mice; D010641:Phenotype; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D017384:Sequence Deletion
D017931:DNA Primers; D012333:RNA, Messenger; D019869:Phosphatidylinositol 3-Kinases