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Induction of c-fos transcripts in early postimplantation mouse embryos by TGF-alpha, EGF, PDGF, and FGF
L L Nielsen1, Z Werb, R A Pedersen
1Laboratory of Radiobiology and Environmental Health, University of California, San Francisco.
Abstract:
The activity of growth factor receptors in the early postimplantation mouse embryo was studied by analyzing changes in expression of mRNA transcripts of an early response gene, c-fos, after binding of specific ligands. Reverse transcription of mRNA coupled with the polymerase chain reaction was used to detect gene transcription in single embryos after exposure to growth factors. Postimplantation embryos (at 7.5 days of gestation) had physiologically active receptors for transforming growth factor-alpha (TGF-alpha), epidermal growth factor (EGF), human platelet-derived growth factor (PDGF), recombinant PDGF-AA homodimer, and basic fibroblast growth factor (FGF), as indicated by induced expression of c-fos mRNA, c-fos expression was not induced in untreated embryos or in embryos incubated with active recombinant PDGF-BB homodimer. These results show that growth factor receptors are functional during early mammalian embryogenesis.
Insights
Early mouse embryos possess functional growth factor receptors, crucial for mammalian development. Researchers detected active receptors for transforming growth factor-alpha (TGF-α) and epidermal growth factor (EGF) using c-fos gene expression analysis.
Area of Science:
- Developmental Biology
- Molecular Embryology
- Genetics
Background:
- Growth factor signaling pathways are essential for embryonic development.
- Understanding receptor activity in early embryogenesis is key to deciphering developmental processes.
Purpose of the Study:
- To investigate the functionality of growth factor receptors in early postimplantation mouse embryos.
- To determine which specific growth factors bind to active receptors during this critical developmental stage.
Main Methods:
- Analysis of c-fos mRNA expression as an indicator of growth factor receptor activity.
- Utilizing reverse transcription-polymerase chain reaction (RT-PCR) for sensitive gene transcription detection in single embryos.
- Exposure of 7.5-day mouse embryos to various purified growth factors and their ligands.
Main Results:
- Physiologically active receptors for transforming growth factor-alpha (TGF-α), epidermal growth factor (EGF), human platelet-derived growth factor (PDGF), and basic fibroblast growth factor (FGF) were detected.
- c-fos mRNA expression was induced by specific growth factors, confirming receptor activation.
- No c-fos induction was observed in untreated embryos or those exposed to recombinant PDGF-BB homodimer, indicating receptor specificity.
Conclusions:
- Growth factor receptors are functionally active during early mammalian embryogenesis.
- This study provides evidence for the role of specific growth factor signaling in early embryonic development.
- The findings highlight the importance of TGF-α, EGF, PDGF, and FGF signaling in postimplantation mouse embryos.