RT Journal Article
SR Electronic
T1 Muscle Contractions Guide Rohon–Beard Peripheral Sensory Axons
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 13190
OP 13201
DO 10.1523/JNEUROSCI.2179-09.2009
VO 29
IS 42
A1 Jeremiah D. Paulus
A1 Gregory B. Willer
A1 Jason R. Willer
A1 Ronald G. Gregg
A1 Mary C. Halloran
YR 2009
UL http://www.jneurosci.org/content/29/42/13190.abstract
AB Multiple molecular cues guide neuronal axons to their targets during development. Previous studies in vitro have shown that mechanical stimulation also can affect axon growth; however, whether mechanical force contributes to axon guidance in vivo is unknown. We investigated the role of muscle contractions in the guidance of zebrafish peripheral Rohon–Beard (RB) sensory axons in vivo. We analyzed several mutants that affect muscle contraction through different molecular pathways, including a new mutant allele of the titin a (pik) gene, mutants that affect the hedgehog signaling pathway, and a nicotinic acetylcholine receptor mutant. We found RB axon defects in these mutants, the severity of which appeared to correlate with the extent of muscle contraction loss. These axons extend between the muscle and skin and normally have ventral trajectories and repel each other on contact. RB peripheral axons in muscle mutants extend longitudinally instead of ventrally, and the axons fail to repel one another on contact. In addition, we showed that limiting muscle movements by embedding embryos in agarose caused similar defects in peripheral RB axon guidance. This work suggests that the mechanical forces generated by muscle contractions are necessary for proper sensory axon pathfinding in vivo.