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Isolation of cDNAs encoding four mouse FGF family members and characterization of their expression patterns during
J M Hébert1, C Basilico, M Goldfarb
1Department of Anatomy, University of California, San Francisco 94134.
Abstract:
To initiate a study of the role of the fibroblast growth factor (FGF) family in mammalian development, we have isolated cDNAs encoding four mouse FGF family members, aFGF, bFGF, kFGF, and FGF-5. This was achieved by a process that circumvents the use of cDNA libraries: for each family member, a cDNA fragment containing the conserved portion of the coding region was amplified from a pool of embryonic and teratocarcinoma cell cDNAs using the polymerase chain reaction (PCR) and cloned; the remaining coding sequences 5' and 3' to the conserved region were cloned using the RACE method. The cDNA clones obtained were used as probes to analyze the expression of these genes at the RNA level in teratocarcinoma cells and embryos at 10.5 to 17.5 days of gestation. Fgfk appears to be specific to undifferentiated teratocarcinoma stem cells. Fgf5 transcripts were detected at every stage and in every tissue tested, but showed a dramatic 15-fold increase in abundance as teratocarcinoma stem cells differentiated to simple embryoid bodies. Fgfb expression showed the greatest tissue-specific variability in abundance, with the highest levels detected in the developing limbs and tail. Fgfa showed the least variable pattern of expression, with transcripts detected at roughly equivalent levels in almost all samples analyzed. On the basis of these data we speculate on some possible roles that the different FGF family members may play in the developing embryo.
Insights
This study isolated four mouse fibroblast growth factor (FGF) family member cDNAs to investigate their roles in mammalian development. FGF family members show distinct expression patterns in developing embryos and teratocarcinoma cells.
Area of Science:
- Developmental Biology
- Molecular Biology
- Genetics
Background:
- The fibroblast growth factor (FGF) family plays crucial roles in mammalian development.
- Understanding the specific functions of individual FGF members is essential for deciphering developmental processes.
Purpose of the Study:
- To isolate cDNAs encoding four mouse FGF family members: aFGF, bFGF, kFGF, and FGF-5.
- To analyze the expression patterns of these FGF genes in developing mouse embryos and teratocarcinoma cells.
Main Methods:
- Utilized polymerase chain reaction (PCR) and RACE (Rapid Amplification of cDNA Ends) to isolate FGF cDNAs, bypassing traditional cDNA libraries.
- Employed cDNA clones as probes for RNA-level expression analysis via Northern blotting or similar techniques.
- Examined gene expression in teratocarcinoma cells and mouse embryos at various gestational stages (10.5–17.5 days).
Main Results:
- Fgfk expression was specific to undifferentiated teratocarcinoma stem cells.
- Fgf5 transcripts showed a 15-fold increase during teratocarcinoma stem cell differentiation.
- Fgfb expression varied significantly by tissue, with high levels in developing limbs and tail.
- Fgfa exhibited the least variable expression pattern across most tissues analyzed.
Conclusions:
- The distinct expression patterns of FGF family members suggest specialized roles in mammalian embryonic development.
- FGF signaling likely contributes to stem cell differentiation and tissue-specific development.
- Further research is warranted to elucidate the precise functions of each FGF member during embryogenesis.