Selective expression of the chicken platelet-derived growth factor alpha (PDGF alpha) receptor during limb bud...

Platelet-derived growth factor (PDGF) affects proliferation and differentiation of chicken limb bud mesoderm in vitro. However, no PDGF receptor has been characterized in the chicken wing bud in vivo. In this study, we used reverse transcription PCR (rtPCR), Northern blot analysis, and Western blot analysis to identify a molecule, in the developing wing bud, which represents the chicken homolog of the PDGF alpha receptor. The chicken PDGF alpha receptor mRNA was present in both mesoderm and ectoderm and all stages of the developing limb bud examined. Cultured limb bud mesoderm also expressed the PDGF alpha receptor transcript. In addition, the PDGF alpha receptor protein was present in whole limb buds and cultured limb bud mesoderm. Expression of the PDGF alpha receptor in cultured mesoderm was independent of the presence of ectoderm cells. The relative sizes of both the mRNA and protein for the PDGF alpha receptor in the chicken limb bud were similar to mammalian counterparts. Using similar approaches, neither the mRNA nor protein representing the chicken homolog of the PDGF beta receptor was detected. These data demonstrate for the first time that a PDGF alpha receptor is present in the embryonic chicken limb bud and may help regulate growth and differentiation of the embryonic limb.