Entire mitogen activated protein kinase (MAPK) pathway is present in preimplantation mouse embryos
Article first published online: 29 JUN 2004
Copyright © 2004 Wiley-Liss, Inc.
Volume 231, Issue 1, pages 72–87, September 2004
How to Cite
Wang, Y., Wang, F., Sun, T., Trostinskaia, A., Wygle, D., Puscheck, E. and Rappolee, D. A. (2004), Entire mitogen activated protein kinase (MAPK) pathway is present in preimplantation mouse embryos. Dev. Dyn., 231: 72–87. doi: 10.1002/dvdy.20114
- Issue published online: 4 AUG 2004
- Article first published online: 29 JUN 2004
- Manuscript Accepted: 22 MAR 2004
- Manuscript Revised: 15 MAR 2004
- Manuscript Received: 19 DEC 2003
- National Institute of Child Health and Human Development. Grant Number: R01 HD40972A
- NASA. Grant Number: NAG1503-2
- growth factor;
- signal transduction;
To understand how mitogenic signals are transduced into the trophoblasts in preimplantation embryos, the expression of mitogen-activated protein kinase (MAPK) pathway molecules was tested. We used immunocytochemical means and reverse transcriptase-polymerase chain reaction to test whether MAPK pathway molecule gene products exist at the protein and phosphoprotein level in the zygote and the RNA level in the egg and zygote. In addition, all antibodies detected the correct-sized major band in Westerns of placental cell lines representing the most prevalent cell type in preimplantation embryos. A majority of mRNA transcripts of MAPK pathway genes were detected in unfertilized eggs, and all were expressed in the zygote. We found that the MAPK pathway protein set consisting of the following gene products was present: FRS2α, GRB2, GAB1, SOS1, Ha-ras, Raf1/RafB, MEK1,2,5, MAPK/ERK1,2, MAPK/ERK5, and RSK1,2,3 (see abbreviations). These proteins were detected in trophoblasts in embryonic day (E) 3.5 embryos when they could mediate mitogenic fibroblast growth factor signals from the embryo or colony stimulating factor-1 signals from the uterus. The phosphorylation state and position of the phosphoproteins in the cells suggested that they might function in mediating mitogenic signals. Interestingly, a subtle transition from maternal MAPK function to zygotic function was suggested by the localization for three MAPK pathway enzymes between E2.5 and E3.5, Raf1 phospho is largely cell membrane-localized at E2.5 and E3.5, and MEK1,2 phospho accumulates in the nucleus on E2.5 and E3.5. However, MAPK phospho shifts from nuclear accumulation at E2.5 to cytoplasmic accumulation at E3.5. This finding is similar to the cytoplasmic MAPK phospho localization reported in fibroblast growth factor signaling fields in postimplantation embryos (Corson et al.  Development 130:4527–4537). This spatial and temporal expression study lays a foundation to plan and analyze perturbation studies aimed at understanding the role of the major mitogenic pathway in preimplantation mouse embryos. Developmental Dynamics 231:72–87, 2004. © 2004 Wiley-Liss, Inc.