The Property-Based Practical Applications and Solutions of Genetically Encoded Acetylcholine and Monoamine Sensors

Abstract

Neuromodulatory communication among various neurons and non-neuronal cells mediates myriad physiological and pathologic processes, yet defining regulatory and functional features of neuromodulatory transmission remains challenging because of limitations of available monitoring tools. Recently developed genetically encoded neuromodulatory transmitter sensors, when combined with superresolution and/or deconvolution microscopy, allow the first visualization of neuromodulatory transmission with nanoscale or microscale spatiotemporal resolution. In vitro and in vivo experiments have validated several high-performing sensors to have the qualities necessary for demarcating fundamental synaptic properties of neuromodulatory transmission, and initial analysis has unveiled unexpected fine control and precision of neuromodulation. These new findings underscore the importance of synaptic dynamics in synapse-, subcellular-, and circuit-specific neuromodulation, as well as the prospect of genetically encoded transmitter sensors in expanding our knowledge of various behaviors and diseases, including Alzheimer's disease, sleeping disorders, tumorigenesis, and many others.

Comparison of fluorescence biosensors and whole-cell patch clamp recording in detecting ACh, NE, and 5-HT

“…Furthermore, combined with super-resolution and deconvolution microscopy, the genetically encoded sensors enabled the investigation of the fundamental properties of neurotransmission, such as the transmitter diffusion range and found that acetylcholine and monoamines employed spatially restricted transmission mode and diffused at individual release sites with a spread length constant of ∼0.75 µm (Zhu et al, 2020). When combined with high-resolution imaging and analysis algorithms, the genetically encoded sensors will unveil more properties of neurotransmitters such as the number of release sites, release pool size, release probability, quantal size, and refilling rate, that are crucial for comprehending the underlying mechanisms of behaviors and neurological diseases (Zhu et al, 2020;Chen et al, 2021;Lin et al, 2021;Zheng et al, 2022).…”

“…The classical patch clamp recording has remarkable sensitivity and temporal resolution and is a powerful tool to study the transmission properties of glutamatergic and gammaaminobutyric acidergic transmitters (Jackman and Regehr, 2017;Chen et al, 2021). This is no doubt that patch-clamp recording is still the most direct and effective way of studying electrical signals in the brain (Reyes, 2019).…”

“…Over the last decade, two major groups of genetically encoded neurotransmitter sensors have been developed, including G-protein-coupled receptor (GPCR) and bacterial periplasmic binding protein (PBP) sensors for glutamate (Marvin et al, 2013), GABA (Marvin et al, 2019), dopamine (Patriarchi et al, 2018;Sun et al, 2018Sun et al, , 2020, acetylcholine (Jing et al, 2018;Borden et al, 2020), norepinephrine (Feng et al, 2019), and serotonin (Unger et al, 2020;Wan et al, 2021). These sensors have been shown to effectively and specifically detect endogenous neurotransmitters in neuronal and non-neuronal tissue preparations in vitro, ex vivo, and in vivo (Zhu et al, 2020;Chen et al, 2021;Dong et al, 2022;Swanson et al, 2022).…”

Real-Time Monitoring of Neurotransmitters in the Brain of Living Animals

“…The ligand-binding protein changes the fluorescence of cpGFP by inducing a conformational change when it binds to the transmitter. According to the type of neurotransmitter binding protein, these sensors are usually divided into periplasmic binding protein (PBP)-based sensors and G protein coupled receptor (GPCR)-based sensors . Bacterial periplasmic binding protein (PBP) is composed of a large and diverse protein superfamily, which can bind a variety of chemical molecules including neurotransmitters.…”

“…According to the type of neurotransmitter binding protein, these sensors are usually divided into periplasmic binding protein (PBP)-based sensors and G protein coupled receptor (GPCR)-based sensors. 138 Bacterial periplasmic binding protein (PBP) is composed of a large and diverse protein superfamily, which can bind a variety of chemical molecules including neurotransmitters. Fast dynamics and large dynamic range are the main advantages of PBP sensors.…”