The neurons in our nervous system “talk” to one another by sending and receiving chemical messages known as neurotransmitters. This communication is facilitated by cell membrane proteins known as receptors, which decide up neurotransmitters and relay them throughout cells. In a latest research printed in Nature Communications, scientists from Japan report their findings on the dynamics of receptors, which can allow understanding of the processes of memory formation and learning.
The regulation of receptor motion and localization inside the neuron is vital for synaptic plasticity, an vital course of within the central nervous system. A selected sort of glutamate receptor, often called AMPA-type glutamate receptor (AMPAR), undergoes a continuing cycle of “trafficking,” being cycled in and out of the neuronal membrane. “A precise regulation of this ‘trafficking’ process is associated with learning, memory formation, and development in neural circuits,” says Professor Shigeki Kiyonaka from Nagoya University, Japan, who led the aforementioned research.
While strategies to investigate the trafficking of AMPARs can be found aplenty, every has its limitations. Biochemical approaches embrace “tagging” a receptor protein with biotin (a B vitamin). However, this requires purification of the proteins after tagging, hindering quantitative evaluation. Another methodology which includes producing “fusion” receptor proteins labelled with a fluorescent protein might intrude with the trafficking course of itself. “In most cases, these methods largely rely on the overexpression of target subunits. However, the overexpression of a single receptor subunit may interfere with the localization and/or trafficking of native receptors in neurons,” explains Prof. Kiyonaka.
To that finish, researchers from Nagoya University, Kyoto University, and Keio University developed an AMPAR-selective reagent (a chemical agent that causes reactions) that allowed them to label AMPARs with chemical probes in cultured neurons in a two-step method, combining affinity-based labeling with a biocompatible response. The new methodology, as anticipated by Prof. Kiyonaka, proved to be superior to the traditional ones: it allowed scientists to investigate receptor trafficking over each shorter in addition to for much longer durations (over 120 hours) and didn’t require additional purification steps after labeling.
The staff’s analyses confirmed a three-fold increased focus of AMPARs at synapses in contrast with dendrites in addition to a half-life of 33 hours in neurons. Additionally, scientists used this method to label and analyze the trafficking of NMDA-type glutamate receptors (NMDARs), and obtained a half-life of 22 hours in neurons. Interestingly, each half-life values have been considerably longer than these reported in HEK293T (a kidney cell line). The researchers attributed this to the formation of giant glutamate receptor protein complexes and — within the case of AMPARs — a distinction in phosphorylation ranges.
The staff is happy by potential implications of their findings. “Our method can contribute to our understanding of the physiological and pathophysiological roles of glutamate receptor trafficking in neurons. This, in turn, can help us understand the molecular mechanism underlying memory formation and the process of learning,” says Prof. Kiyonaka.
The research offers a better take a look at — and brings us a step nearer to deciphering — the processes of memory and learning on the molecular degree.
Materials offered by Nagoya University. Note: Content could also be edited for model and size.