Phosphorylation of mitogen-activated protein kinase cascade during early embryo development in the mouse.
The mitogen-activated protein kinase (MAPK) cascade is one of the most important signal transduction pathways that regulate the cell cycle in somatic cells. The present study examined the phosphorylation states of components in the MAPK cascade, Raf-1, MEK-1, and extracellular signal regulated kinases (ERKs), which are activated by mitogens, throughout early mouse embryo development and in cultured somatic cells generally. In somatic cells, Raf-1 and MEK-1 were phosphorylated at M-phase and dephosphorylated during interphase. ERKs were not phosphorylated at any stage during the cell cycle. These results were similar to previous findings for the first and second cell cycles of early mouse embryos. In contrast, after the four-cell stage, not only ERKs, but also Raf-1 and MEK-1, were not phosphorylated at any stage during the cell cycle in mouse early embryos. These results suggest that the MAPK cascade in mouse embryos is regulated by the same mechanism as in somatic cells before the two-cell stage, and that regulation is changed to an embryo-specific mechanism after the four-cell stage.
Iwamori
N
N
Laboratory of Applied Genetics, Graduate School of Agricultural and Life Sciences, University of Tokyo, Japan. aa07157@mail.ecc.u-tokyo.ac.jp
Naito
K
K
Sugiura
K
K
Kagii
H
H
Yamashita
M
M
Ohashi
S
S
Goto
S
S
Yamanouch
K
K
Tojo
H
H
D016475:3T3 Cells; D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D005314:Embryonic and Fetal Development / Q000502:physiology*; D005260:Female; D048369:MAP Kinase Kinase 1; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008938:Mitosis / Q000502:physiology; D010766:Phosphorylation; D011247:Pregnancy; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D015398:Signal Transduction
D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; C482127:Map2k1 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases