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Merck

Tumor necrosis factor alpha mediates neuromuscular synapse elimination.

Cell discovery (2020-03-07)
Xiu-Qing Fu, Jian Peng, Ai-Hua Wang, Zhen-Ge Luo
ABSTRACT

During the development of mammalian neuromuscular junction (NMJ), the original supernumerary axon inputs are gradually eliminated, finally leaving each muscle fiber innervated by a single axon terminal. However, the molecular cues that mediate the elimination of redundant axon inputs remain unclear. Here we show that tumor necrosis factor-α (TNFα) expressed in postsynaptic muscle cells plays an important role in presynaptic axonal elimination at the NMJ. We found that intramuscular injection of TNFα into the levator auris longus (LAL) muscles caused disassociation of presynaptic nerve terminals from the postsynaptic acetylcholine receptor (AChR) clusters. By contrast, genetic ablation of TNFα globally or specifically in skeletal muscle cells, but not in motoneurons or Schwann cells, delayed the synaptic elimination. Moreover, ablation of TNFα in muscle cells attenuated the tendency of activity-dependent competition in a motoneuron-muscle coculture system. These results suggest a role of postsynaptic TNFα in the elimination of redundant synaptic inputs.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Agrin Human, Recombinant, cell culture tested, expressed in HEK 293 cells
Sigma-Aldrich
2-Phenylindole, technical grade, 95%
Millipore
Protease Inhibitor Cocktail Set III, EDTA-Free, Protease inhibitor cocktail III, EDTA-free for inhibiting aspartic, cysteine, and serine proteases as well as aminopeptidases in mammalian cells and tissues.