RRC ID 4131
Author Tanaka H, Maeda R, Shoji W, Wada H, Masai I, Shiraki T, Kobayashi M, Nakayama R, Okamoto H.
Title Novel mutations affecting axon guidance in zebrafish and a role for plexin signalling in the guidance of trigeminal and facial nerve axons.
Journal Development
Abstract In zebrafish embryos, the axons of the posterior trigeminal (Vp) and facial (VII) motoneurons project stereotypically to a small number of target muscles derived from the first and second branchial arches (BA1, BA2). Use of the Islet1 (Isl1)-GFP transgenic line enabled precise real-time observations of the growth cone behaviour of the Vp and VII motoneurons within BA1 and BA2. Screening for N-ethyl-N-nitrosourea-induced mutants identified seven distinct mutations affecting different steps in the axonal pathfinding of these motoneurons. The class 1 mutations caused severe defasciculation and abnormal pathfinding in both Vp and VII motor axons before they reached their target muscles in BA1. The class 2 mutations caused impaired axonal outgrowth of the Vp motoneurons at the BA1-BA2 boundary. The class 3 mutation caused impaired axonal outgrowth of the Vp motoneurons within the target muscles derived from BA1 and BA2. The class 4 mutation caused retraction of the Vp motor axons in BA1 and abnormal invasion of the VII motor axons in BA1 beyond the BA1-BA2 boundary. Time-lapse observations of the class 1 mutant, vermicelli (vmc), which has a defect in the plexin A3 (plxna3) gene, revealed that Plxna3 acts with its ligand Sema3a1 for fasciculation and correct target selection of the Vp and VII motor axons after separation from the common pathways shared with the sensory axons in BA1 and BA2, and for the proper exit and outgrowth of the axons of the primary motoneurons from the spinal cord.
Volume 134(18)
Pages 3259-69
Published 2007-9
DOI 10.1242/dev.004267
PII dev.004267
PMID 17699608
MeSH Animals Axons / physiology* Embryonic Development / genetics* Facial Nerve / embryology* Motor Neurons / physiology Mutation Receptors, Cell Surface / genetics Receptors, Cell Surface / physiology* Semaphorins / physiology Trigeminal Nerve / embryology* Zebrafish / embryology* Zebrafish / genetics Zebrafish Proteins / genetics Zebrafish Proteins / physiology*
IF 5.763
Times Cited 26
Zebrafish rw0 (Tg(CM-isl1:GFP)) Tg(alpha-actin:GFP) RIKEN WT (RW)