Restricted localization of proline‐rich membrane anchor (PRiMA) of globular form acetylcholinesterase at the neuromuscular junctions – contribution and expression from motor neurons

Abstract

The expression and localization of the proline‐rich membrane anchor (PRiMA), an anchoring protein of tetrameric globular form acetylcholinesterase (G4 AChE), were studied at vertebrate neuromuscular junctions. Both muscle and motor neuron contributed to this synaptic expression pattern. During the development of rat muscles, the expression of PRiMA and AChET and the enzymatic activity increased dramatically; however, the proportion of G4 AChE decreased. G4 AChE in muscle was recognized specifically by a PRiMA antibody, indicating the association of this enzyme with PRiMA. Using western blot and ELISA, both PRiMA protein and PRiMA‐linked G4 AChE were found to be present in large amounts in fast‐twitch muscle (e.g. tibialis), but in relatively low abundance in slow‐twitch muscle (e.g. soleus). These results indicate that the expression level of PRiMA‐linked G4 AChE depends on muscle fiber type. In parallel, the expression of PRiMA, AChET and G4 AChE also increased in the spinal cord during development. Such expression in motor neurons contributed to the synaptic localization of G4 AChE. After denervation, the expression of PRiMA, AChET and G4 AChE decreased markedly in the spinal cord, and in fast‐ and slow‐twitch muscles.

Effect of Sciatic Nerve Transection on acetylcholinesterase activity in spinal cord and skeletal muscles of the bullfrog Lithobates catesbeianus

“…Thus, it appears important to demonstrate the effect of SNT on distinct molecular forms of AChE in bullfrog spinal cord to better characterize this experimental model. In rat spinal cord, SNT induced a decrease in proline-rich membrane anchor (PRIMA) of the globular form of AChE (Leung et al, 2009). However, the effect of SNT on this molecular form of AChE in frog spinal cord is unknown.…”

Targeting Acetylcholinesterase to Membrane Rafts

“…However, there is no PDZ-binding site on the C terminus of PRiMA, which would imply an indirect interaction, if any (15). In addition, AChE may also be included in rafts at presynaptic sites, because PRiMAlinked AChE is expressed in presynaptic cholinergic neurons (supplemental material) (13,27).…”

“…Muscles, in particular the fast-twitch muscle in rat (11) or the slow twitch muscle in chicken (14), express PRiMA I in a tightly controlled manner during maturation. PRiMA-linked AChE was found to be located both pre-and post-synaptically at the vertebrate neuromuscular junctions (27,53) and may be associated with scaffold proteins.…”

“…1A). To establish the association of PRiMA with G 4 AChE in the cerebrum, the protein extract was immunoprecipitated by anti-PRiMA antibody, as reported previously (11,15,27). As shown in Fig.…”

Expression and Localization of PRiMA-Linked Globular Form Acetylcholinesterase in Vertebrate Neuromuscular Junctions

“…In accordance to the change of PRiMA expression, the proportion of PRiMA-linked G4 AChE is also decreased during the myogenic differentiation process in C2C12 muscle (Xie et al 2007). In addition, the level of G4 enzyme is different in muscle fiber types; fast-twitch muscles contain a high amount of G4 AChE, whereas slow-twitch muscles contain a much smaller amount (Bacou 1982;Leung et al 2009). Although PRiMA and G4 enzyme are shown to exist in muscle, the presence of PRiMA expression in spinal cord and/or motor neuron has not been revealed yet.…”