Reduced Expression of P2Y2 Receptor and Acetylcholinesterase at Neuromuscular Junction of P2Y1 Receptor Knock-out Mice

Abstract

ATP is co-stored and co-released with acetylcholine (ACh) at the pre-synaptic vesicles in vertebrate neuromuscular junction (nmj). Several lines of studies demonstrated that binding of ATP to its corresponding P2Y1 and P2Y2 receptors in the muscle regulated post-synaptic gene expressions. To further support the notion that P2Y receptors are playing indispensable role in formation of post-synaptic specifications at the nmj, the knock-out mice of P2Y1 receptor (P2Y1R (-/-)) were employed here for analyses. In P2Y1R (-/-) mice, the expression of P2Y2 receptor in muscle was reduced by over 50 %, as compared to P2Y1R (+/+) mice. In parallel, the expression of acetylcholinesterase (AChE) in muscle was markedly decreased. In the analysis of the expression of anchoring subunits of AChE in P2Y1R (-/-) mice, the proline-rich membrane anchor (PRiMA) subunit was reduced by 60 %; while the collagen tail (ColQ) subunit was reduced by 50 %. AChE molecular forms in the muscle were not changed, except the amount of enzyme was reduced. Immuno-staining of P2Y1R (-/-) mice nmj, both AChE and AChR were still co-localized at the nmj, and the staining was diminished. Taken together our data demonstrated that P2Y1 receptor regulated the nmj gene expression.

Activity-induced Ca2+ signaling in perisynaptic Schwann cells of the early postnatal mouse is mediated by P2Y1 receptors and regulates muscle fatigue

“…We found no difference in the total number of NMJs, the size of NMJs, the percentage of innervated NMJs, or the apposition of perisynaptic Schwann cells in P2ry1 mutant or WT mice ( Figure 3—figure supplement 1 ; data not shown). Next, we examined NMJs for AChE immunoreactivity, as previous reports of adult NMJs in P2ry1 mutants showed a reduction in the level of expression of this cholinesterase ( Xu et al, 2015 ). Using a highly specific antibody that fails to detect expression of this enzyme in AChE mutant mice, we were unable to observe any difference in its expression or synaptic localization ( Figure 3—figure supplement 1 ).…”

Activity-induced Ca2+signaling in perisynaptic Schwann cells is mediated by P2Y1receptors and regulates muscle fatigue

“…We found no difference in the total number of NMJs, the size of NMJs, the percentage of innervated NMJs, or the apposition of perisynaptic Schwann cells in P2ry1 mutant or WT mice ( Supplemental Figure 1A,B ; data not shown). Next, we examined NMJs for AChE immunoreactivity, as previous reports of adult NMJs in P2ry1 mutants showed a reduction in the level of expression of this cholinesterase (Xu et al, 2015). Using a highly specific antibody that fails to detect expression of this enzyme in AChE mutant mice, we were unable to observe any difference in its expression or synaptic localization ( Supplemental Figure 1C ).…”

Sepsis decreases the activity of acetylcholinesterase by reducing its expression at the neuromuscular junction

“…This process phosphorylates extracellular signal-regulated kinases (Erk) by triggering a mitogen-activated protein kinase signaling cascade. Phosphorylated Erk can then activate ELK1, ETS transcription factor, which increases the transcriptional activity of the AChE gene by binding to the AChE promoter (18,19). However, sepsis-induced mitochondrial dysfunction may impair the generation of ATP in motor neurons (20).…”