The induction of neurotrophin and TRK receptor mRNA expression during early avian embryogenesis.
Nerve growth factor, brain-derived neurotrophic factor and neurotrophin-3, designated neurotrophins, are a family of neurotrophic factors, having important functions in the survival of embryonic and adult neuronal subpopulations. Through the trk family of receptors, these neurotrophins utilize phosphotyrosine-mediated signal transduction. We have used RT-PCR to detect the expression of mRNA for the above neurotrophins and their respective receptors, namely trkA, trkB and trkC in embryonic stages 1-8 of chicken development. While trkA and trkC mRNAs were expressed from stage 1 onwards, NGF and NT-3 mRNAs were expressed only at stages 3 and 5, respectively. In contrast, BDNF mRNA was expressed at stage 1, being the only neurotrophin expressed prior to expression of its respective receptor trkB. However, the latter was not expressed until stage 8. These results indicate an earlier expression of some but not all trk proto-oncogenes, suggesting that the two different receptor mRNAs expressed i.e. trkA and trkC in conjunction with BDNF, at stage 1, may act in aspects of very early embryonic development, such as gastrulation. Thereafter, mRNAs for trkB, NGF and NT-3 are expressed reflecting their later action in early embryonic development.
Baig
M A
MA
Department of Anatomy and Cell Biology, State University of New York, Brooklyn 11203, USA.
Khan
M A
MA
D000818:Animals; D001483:Base Sequence; D019208:Brain-Derived Neurotrophic Factor; D002642:Chick Embryo; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D006133:Growth Substances / Q000235:genetics; D008969:Molecular Sequence Data; D009414:Nerve Growth Factors / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000235:genetics; D020933:Neurotrophin 3; D016133:Polymerase Chain Reaction; D011134:Polysaccharides / Q000235:genetics*; D011518:Proto-Oncogene Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics*; D020917:Receptor, trkA; D020813:Receptor, trkB; D020812:Receptor, trkC; D017475:Receptors, Nerve Growth Factor / Q000235:genetics*
D019208:Brain-Derived Neurotrophic Factor; D006133:Growth Substances; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D020933:Neurotrophin 3; D011134:Polysaccharides; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D017475:Receptors, Nerve Growth Factor; C010491:neurotropin; D020794:Receptor Protein-Tyrosine Kinases; D020917:Receptor, trkA; D020813:Receptor, trkB; D020812:Receptor, trkC