FGF IS AN ESSENTIAL REGULATOR OF THE 5TH CELL-DIVISION IN PREIMPLANTATION MOUSE EMBRYOS

Citation
N. Chai et al., FGF IS AN ESSENTIAL REGULATOR OF THE 5TH CELL-DIVISION IN PREIMPLANTATION MOUSE EMBRYOS, Developmental biology (Print), 198(1), 1998, pp. 105-115
Citations number
43
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Developmental Biology
Journal title
ISSN journal
0012-1606
Volume
198
Issue
1
Year of publication
1998
Pages
105 - 115
Database
ISI
SICI code
0012-1606(1998)198:1<105:FIAERO>2.0.ZU;2-B
Abstract
Fibroblast growth factor (FGF) signaling is required prior to gastrula tion in the mouse embryo. To test for the spatial and temporal require ments of FGF signaling, a dominant negative FGF receptor (dnFGFR) was used to make transgenic mouse embryos. In mosaic embryos, cell divisio n ceased at the fifth cell division in all cells that expressed the mu tant receptor, but cell death did not increase. lifter the fifth cell division, the progeny of unaltered cells and cells expressing lacZ con tinued to accumulate at the same rate, suggesting that the FGF require ment is cell autonomous. In mosaic embryos, lacZ, but not dnFGFR expre ssion was detected in mitotic trophoblasts adjacent to the ICM. Conver sely, dnFGFR-expressing extraembryonic ectoderm cells were detected at the abembryonic pole in postmitotic cells. In blastocysts expressing the dnFGFR in all cells, the morphology appeared normal and inner cell masses (ICMs) formed, but resultant embryos had only one-third the nu mber of cells as control embryos. In these blastocysts, cell division had also ceased at the fifth cell division, but cavitation, a concurre nt morphogenetic event, initiated and progressed normally. To test for the continuing requirement of FGF, FGFR-3 was overexpressed in all ce lls and resulted in an increase in cell numbers after the fifth cell c ycle. In a model for postimplantation development, addition of FGF-4 t o blastocyst outgrowths increased the number of extraembryonic ectoder m cells, suggesting a continuing role for FGF. Thus, FGF signaling ind uces the cell division of embryonic and extraembryonic cells in the pr eimplantation mouse embryo starting at the fifth cell division. The si gnal requirement for FGF is cell autonomous, but is not required to pr event cell death. This provides the first evidence for the necessity o f a growth factor before implantation. (C) 1998 Academic Press.