mTOR is essential for growth and proliferation in early mouse embryos and embryonic stem cells.
TOR is a serine-threonine kinase that was originally identified as a target of rapamycin in Saccharomyces cerevisiae and then found to be highly conserved among eukaryotes. In Drosophila melanogaster, inactivation of TOR or its substrate, S6 kinase, results in reduced cell size and embryonic lethality, indicating a critical role for the TOR pathway in cell growth control. However, the in vivo functions of mammalian TOR (mTOR) remain unclear. In this study, we disrupted the kinase domain of mouse mTOR by homologous recombination. While heterozygous mutant mice were normal and fertile, homozygous mutant embryos died shortly after implantation due to impaired cell proliferation in both embryonic and extraembryonic compartments. Homozygous blastocysts looked normal, but their inner cell mass and trophoblast failed to proliferate in vitro. Deletion of the C-terminal six amino acids of mTOR, which are essential for kinase activity, resulted in reduced cell size and proliferation arrest in embryonic stem cells. These data show that mTOR controls both cell size and proliferation in early mouse embryos and embryonic stem cells.
Murakami
Mirei
M
Research and Education Center for Genetic Information, Nara Institute of Science and Technology, Nara 630-0192, Japan.
Ichisaka
Tomoko
T
Maeda
Mitsuyo
M
Oshiro
Noriko
N
Hara
Kenta
K
Edenhofer
Frank
F
Kiyama
Hiroshi
H
Yonezawa
Kazuyoshi
K
Yamanaka
Shinya
S
D000818:Animals; D001755:Blastocyst / Q000378:metabolism; D015139:Blotting, Southern; D002453:Cell Cycle; D002455:Cell Division; D004622:Embryo, Mammalian / Q000166:cytology*; D005434:Flow Cytometry; D017353:Gene Deletion; D005838:Genotype; D006579:Heterozygote; D051379:Mice; D018345:Mice, Knockout; D008957:Models, Genetic; D009154:Mutation; D011494:Protein Kinases / Q000378:metabolism / Q000502:physiology*; D017434:Protein Structure, Tertiary; D011995:Recombination, Genetic; D019893:Ribosomal Protein S6 Kinases / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology; D013234:Stem Cells / Q000378:metabolism / Q000502:physiology*; D058570:TOR Serine-Threonine Kinases; D013997:Time Factors; D014018:Tissue Distribution
D011494:Protein Kinases; C546843:mTOR protein, mouse; D019893:Ribosomal Protein S6 Kinases; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus