PKA and PKC Balance in Synapse Elimination during Neuromuscular Junction Development

Abstract

During the development of the nervous system, synaptogenesis occurs in excess though only the appropriate connections consolidate. At the neuromuscular junction, competition between several motor nerve terminals results in the maturation of a single axon and the elimination of the others. The activity-dependent release of transmitter, cotransmitters, and neurotrophic factors allows the direct mutual influence between motor axon terminals through receptors such as presynaptic muscarinic ACh autoreceptors and the tropomyosin-related kinase B neurotrophin receptor. In previous studies, we investigated the synergistic and antagonistic relations between these receptors and their downstream coupling to PKA and PKC pathways and observed a metabotropic receptor-driven balance between PKA (stabilizes multinnervation) and PKC (promotes developmental axonal loss). However, how much does each kinase contribute in the developmental synapse elimination process? A detailed statistical analysis of the differences between the PKA and PKC effects in the synapse elimination could help to explore this point. The present short communication provides this analysis and results show that a similar level of PKA inhibition and PKC potentiation would be required during development to promote synapse loss.

Keywords

• motor end-plate
• postnatal synapse elimination
• axonal competition
• acetylcholine release
• nicotinic acetylcholine receptor clusters
• protein kinases