Zebrafish TrkC1 and TrkC2 receptors define two different cell populations in the nervous system during the period of axonogenesis.
We identified previously five distinct trk genes in the zebrafish. The structures of two of these, TrkC1 and TrkC2, are most similar to mammalian TrkC. Detailed sequence comparisons reported here indicate that although the similarities to TrkC are greatest in those regions of the extracellular domain implicated in ligand binding, the two sequences also differ significantly in these regions. Whole-mount in situ hybridization experiments in the early embryo revealed full-length trkC1 but no trkC2 transcripts in the cranial ganglia and in a subset of Rohon-Beard neurons. At the same time, full-length trkC2 but no trkC1 transcripts were detected laterally in the spinal cord, in the caudal hindbrain, in reticulospinal neurons of rhombomeres 4, 5, and 6, and in the midbrain. Both types of transcripts were expressed in clusters of cells in the dorsal telencephalon and the nucleus of the tract of the postoptic commissure. These results suggest distinct functions of trkC1 and trkC2 in nervous system development. The expression patterns define two different neuronal populations in the zebrafish.
Martin
S C
SC
Evans Department of Clinical Research and Medicine, Boston University Medical Center Hospital, Boston, Massachusetts.
Sandell
J H
JH
Heinrich
G
G
D000595:Amino Acid Sequence; D000818:Animals; D001369:Axons / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D008969:Molecular Sequence Data; D009024:Morphogenesis; D009420:Nervous System / Q000166:cytology / Q000196:embryology*; D009474:Neurons / Q000737:chemistry; D009928:Organ Specificity; D012333:RNA, Messenger / Q000032:analysis; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics*; D020812:Receptor, trkC; D017475:Receptors, Nerve Growth Factor / Q000235:genetics*; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D015027:Zebrafish
D012333:RNA, Messenger; D017475:Receptors, Nerve Growth Factor; D020794:Receptor Protein-Tyrosine Kinases; D020812:Receptor, trkC