RRC ID 12094
Author Sato-Maeda M, Obinata M, Shoji W.
Title Position fine-tuning of caudal primary motoneurons in the zebrafish spinal cord.
Journal Development
Abstract In zebrafish embryos, each myotome is typically innervated by three primary motoneurons (PMNs): the caudal primary (CaP), middle primary (MiP) and rostral primary (RoP). PMN axons first exit the spinal cord through a single exit point located at the midpoint of the overlying somite, which is formed beneath the CaP cell body and is pioneered by the CaP axon. However, the placement of CaP cell bodies with respect to corresponding somites is poorly understood. Here, we determined the early events in CaP cell positioning using neuropilin 1a (nrp1a):gfp transgenic embryos in which CaPs were specifically labeled with GFP. CaP cell bodies first exhibit an irregular pattern in presence of newly formed corresponding somites and then migrate to achieve their proper positions by axonogenesis stages. CaPs are generated in excess compared with the number of somites, and two CaPs often overlap at the same position through this process. Next, we showed that CaP cell bodies remain in the initial irregular positions after knockdown of Neuropilin1a, a component of the class III semaphorin receptor. Irregular CaP position frequently results in aberrant double exit points of motor axons, and secondary motor axons form aberrant exit points following CaP axons. Its expression pattern suggests that sema3ab regulates the CaP position. Indeed, irregular CaP positions and exit points are induced by Sema3ab knockdown, whose ectopic expression can alter the position of CaP cell bodies. Results suggest that Semaphorin-Neuropilin signaling plays an important role in position fine-tuning of CaP cell bodies to ensure proper exit points of motor axons.
Volume 135(2)
Pages 323-32
Published 2008-1-1
DOI 10.1242/dev.007559
PII dev.007559
PMID 18077593
MeSH Animals Axons / metabolism Body Patterning* Embryo, Nonmammalian / cytology Models, Biological Motor Neurons / cytology Motor Neurons / metabolism* Nerve Growth Factors / metabolism Neuropilin-1 / metabolism Organogenesis Phenotype RNA, Antisense / metabolism Somites / cytology Somites / embryology Spinal Cord / cytology* Spinal Cord / embryology* Zebrafish / embryology* Zebrafish Proteins / metabolism
IF 5.611
Times Cited 19
Zebrafish Tg(nrp1a:GFP)