Localization of bFGF-like proteins as punctate inclusions in the preseptation myocardium of the chicken embryo.
Immunocytochemistry has been employed to map the appearance of bFGF-like proteins in precardiac and preseptation myocardial cells between stages 6 and 15 of chicken embryogenesis. Stage 6 embryos exhibited no staining, with the exception of a subtle signal in endoderm cells. At subsequent stages, staining was observed only in cells of the developing myocardium, first appearing at the time of heart tube fusion (stage 9+) as punctate cytoplasmic aggregates. While the expression of bFGF-like antigen was temporally similar to that of myosin heavy chain, their staining patterns differed in that bFGF-like proteins were nonsarcomeric and did not extend into the inflow or outflow tracts. Western blotting of heparin agarose affinity-isolated proteins from stage 15 hearts revealed an antigen migrating at approximately 19 kDa. In contrast with the unique localization of bFGF-like proteins in myocardial cells, FGF receptor (FGFR) staining was widely distributed in the embryo; however, concentrated deposits of FGFR were detected in endothelial and myocardial cells, which diminished in the myocardium but not in the endothelium by stage 15. These results suggest that FGF-like proteins may have autocrine and/or paracrine functions during early cardiac morphogenesis.
Parlow
M H
MH
Department of Cellular Biology and Anatomy, Medical College of Wisconsin, Milwaukee 53226.
Bolender
D L
DL
Kokan-Moore
N P
NP
Lough
J
J
D000818:Animals; D002642:Chick Embryo; D004730:Endothelium, Vascular / Q000737:chemistry / Q000196:embryology; D016222:Fibroblast Growth Factor 2 / Q000032:analysis / Q000378:metabolism* / Q000502:physiology; D006321:Heart / Q000196:embryology*; D002479:Inclusion Bodies / Q000737:chemistry / Q000378:metabolism*; D008970:Molecular Weight; D009206:Myocardium / Q000737:chemistry / Q000378:metabolism*; D009218:Myosins / Q000276:immunology
D016222:Fibroblast Growth Factor 2; D009218:Myosins