A new tool to sense pH changes at the neuromuscular junction synaptic cleft

Area of Science:

• Neuroscience
• Biochemistry
• Molecular Biology

Background:

• Synaptic transmission causes transient acidification in the synaptic cleft.
• Postsynaptic channel opening is influenced by pH, necessitating tools to study these dynamics.

Purpose of the Study:

• To develop a novel biosensor for measuring synaptic cleft pH changes.
• To enable the study of postsynaptic pH dynamics without requiring animal transgenesis.

Main Methods:

• A pH-sensitive Green Fluorescent Protein (Super Ecliptic pHluorin) was fused with alpha-bungarotoxin.
• The recombinant protein was expressed in Pichia pastoris.
• The sensor was applied to mouse levator auris muscle to label the postsynaptic membrane.

Main Results:

• The recombinant sensor successfully labeled the postsynaptic membrane of the neuromuscular junction.
• Physiological alterations in postsynaptic pH were measured via changes in the fluorescent signal.
• A pH drop of 0.01–0.05 units near acetylcholine receptors was detected following nerve stimulation.

Conclusions:

• A novel, non-transgenic tool was created to measure synaptic cleft pH.
• This sensor allows for the real-time assessment of pH changes at the postsynaptic membrane.
• Further research will elucidate precise pH dynamics during synaptic activation.