Fgf-8 expression in the post-gastrulation mouse suggests roles in the development of the face, limbs and central nervous system.
Fgf-8 is a member of the fibroblast growth factor (FGF) family that was initially identified as an androgen-inducible growth factor in a mammary carcinoma cell line. Alternative splicing of the primary Fgf-8 transcript results in three messenger RNAs which code for secreted FGF-8 protein isoforms that differ only in their mature amino termini. Fgf-8 RNA is present from day 10 through 12 of murine gestation when analyzed by northern blot analysis, suggesting that Fgf-8 normally functions during post-gastrulation development. To characterize the temporal, spatial and isoform-specific aspects of Fgf-8 expression during mouse development, we performed in situ hybridization and ribonuclease protection assays between the days 8 and 16 of gestation. Fgf-8 expression is first detected at day 9 of gestation in the surface ectoderm of the first branchial arches, the frontonasal process, the forebrain and the midbrain-hindbrain junction. At days 10-12 of gestation, Fgf-8 expression is detected in the surface ectoderm of the forelimb and hindlimb buds, in the nasal pits and nasopharynx, in the infundibulum and in the telencephalon, diencephalon and metencephalon. Fgf-8 expression continues in the developing hindlimbs through day 13 of gestation but is undetectable thereafter. Ribonuclease protection assays reveal that RNAs coding for all three FGF-8 isoforms are present at days 10-12 of gestation. These results reveal a unique temporal and spatial pattern of Fgf-8 expression in the developing mouse and suggest a role for this FGF in multiple regions of ectodermal differentiation in the post-gastrulation mouse embryo.
Heikinheimo
M
M
Department of Pediatrics, Washington University School of Medicine, St. Louis, MO 63110.
Lawshé
A
A
Shackleford
G M
GM
Wilson
D B
DB
MacArthur
C A
CA
D000818:Animals; D002490:Central Nervous System / Q000196:embryology*; D005121:Extremities / Q000196:embryology*; D005145:Face / Q000196:embryology*; D005346:Fibroblast Growth Factors / Q000235:genetics*; D005775:Gastrula / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D017403:In Situ Hybridization; D051379:Mice; D010614:Pharynx / Q000196:embryology; D012260:Ribonucleases
D005346:Fibroblast Growth Factors; D012260:Ribonucleases