Spying on neuromodulation by constructing new genetically-encoded flourescent sensors
Diverse neuromodulators in the brain, such as acetylcholine, monoamines, lipids and neuropeptides, play important roles in a plethora of physiological processes including reward, movement, attention, sleep, learning and memory. Dysfunction of the neuromodulatory system is associated with a range of diseases, such as epilepsy, addition, neurodegenerative and psychiatric diseases. A longstanding yet largely unmet goal is to measure the dynamics of different neuromodulators reliably and specifically with high spatiotemporal resolution, particularly in behaving animals. To achieve this goal, we develop a series of genetically encoded GPCR-activation-based (GRAB) sensors for the detection of acetylcholine, dopamine, norepinephrine, serotonin, histamine, endocannabinoids, adenosine, ATP and neuropeptides, and validate the performance of these sensors in multiple preparations in vitro and in vivo. The GRAB sensor toolbox provides new insights into the dynamics and mechanism of neuromodulatory signaling both in health and disease.
My group’s long-term goal is to understand neuromodulation in the nervous system under physiological and pathological conditions. To reach this goal, we develop and utilize genetically-encoded sensors for monitoring chemical and electricalsynapses.
For probing neuronal chemical modulation in vivo, our group has pioneered in developing a series of genetically-encoded neuromodulator sensors called GPCRActivation-Based (GRAB) sensors. Neuromodulators are bioactive molecules that dynamically and bio-directionally control neuron’s excitability and interneuronal synaptic transmission; despite their important roles, their dynamic properties in specific cells, tissues and live animals are poorly understood. We tapped into human GPCRs, coupling the ligand binding induced conformational change with the fluorescence increase of cpEGFP, and created GRAB biosensors for acetylcholine, dopamine, norepinephrine, serotonin, ATP, endocannabinoids, histamine, and neuropeptides such as CRF, CCK, NPY and oxytocin. We also expand the palette of GRAB sensors, for example, to detect dopamine, acetylcholine and serotonin in red. We and our collaborators showed that these GRAB sensors could be readily applied in broad model organisms in vivo, including fly, zebrafish, mouse and song bird. Importantly, they could reliably report physiological relevant dynamics of neuromodulators with sub-second temporal resolution, sub-cellular spatial resolution and excellent chemical specificity.
For probing electrical synapses in vivo, our group developed a system called “PARIS”, which could optogenetically map electrical synapses in vivo with subcellular resolution, providing a powerful tool to study gap junctional regulation non-invasively.
About the Wu Tsai Neuro MBCT Seminar Series The Stanford Center for Mind, Brain, Computation and Technology Seminars (MBCT) explores ways in which computational and technical approaches are being used to advance the frontiers of neuroscience. It features speakers from other institutions, Stanford faculty and senior training program trainees.
The MBCT Seminar Series is not offered via Zoom at this time. If given speaker permission, recordings will be available on our YouTube channel after the talk.