Neuromuscular synapses mediate motor axon branching and motoneuron survival during the embryonic period of programmed cell death

Banks, G. B., Choy, P. T., Lavidis, N. A. and Noakes, P. G. (2003) Neuromuscular synapses mediate motor axon branching and motoneuron survival during the embryonic period of programmed cell death. Developmental Biology, 257 1: 71-84. doi:10.1016/S0012-1606(03)00056-3


Author Banks, G. B.
Choy, P. T.
Lavidis, N. A.
Noakes, P. G.
Title Neuromuscular synapses mediate motor axon branching and motoneuron survival during the embryonic period of programmed cell death
Journal name Developmental Biology   Check publisher's open access policy
ISSN 0012-1606
Publication date 2003-01-01
Sub-type Article (original research)
DOI 10.1016/S0012-1606(03)00056-3
Open Access Status
Volume 257
Issue 1
Start page 71
End page 84
Total pages 14
Place of publication San Diego
Publisher Elsvier
Language eng
Subject C1
730104 Nervous system and disorders
320704 Cellular Nervous System
06 Biological Sciences
Abstract The embryonic period of motoneuron programmed cell death (PCD) is marked by transient motor axon branching, but the role of neuromuscular synapses in regulating motoneuron number and axonal branching is not known. Here, we test whether neuromuscular synapses are required for the quantitative association between reduced skeletal muscle contraction, increased motor neurite branching, and increased motoneuron survival. We achieved this by comparing agrin and rapsyn mutant mice that lack acetylcholine receptor (AChR) clusters. There were significant reductions in nerve-evoked skeletal muscle contraction, increases in intramuscular axonal branching, and increases in spinal motoneuron survival in agrin and rapsyn mutant mice compared with their wild-type littermates at embryonic day 18.5 (E18.5). The maximum nerve-evoked skeletal muscle contraction was reduced a further 17% in agrin mutants than in rapsyn mutants. This correlated to an increase in motor axon branch extension and number that was 38% more in agrin mutants than in rapsyn mutants. This suggests that specializations of the neuromuscular synapse that ensure efficient synaptic transmission and muscle contraction are also vital mediators of motor axon branching. However, these increases in motor axon branching did not correlate with increases in motoneuron survival when comparing agrin and rapsyn mutants. Thus, agrin-induced synaptic specializations are required for skeletal muscle to effectively control motoneuron numbers during embryonic development. (C) 2003 Elsevier Science (USA). All rights reserved.
Keyword Developmental Biology
Motor Neuron
Agrin
Rapsyn
Neuromuscular
Cell Death
Synapse Formation
Acetylcholine Receptor
Rapsyn-deficient Mice
Skeletal-muscle
Spinal-cord
Neurotrophic Factors
Polysialic Acid
Chick-embryo
Mutant Mice
Acetylcholine-receptors
Junction Formation
Diaphragm Muscle
Q-Index Code C1

 
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Created: Wed, 15 Aug 2007, 12:31:43 EST