Dynamic control of Raf-ERK signaling modulates neuronal activity across biological scales

Area of Science:

• Neuroscience
• Molecular Biology
• Signaling Pathways

Background:

• Neuronal activity engages the extracellular signal-regulated kinase (ERK) pathway via Ca2+-dependent mechanisms.
• The acute and causal role of ERK in modulating ongoing neuronal activity is not fully understood due to complex regulation.
• Diverse subcellular functions of ERK present challenges in studying its real-time impact.

Purpose of the Study:

• To investigate whether ERK can acutely and causally modulate ongoing neuronal activity.
• To develop a tool for precise temporal and spatial control of ERK signaling.
• To explore ERK's function across different biological scales, from cell cultures to the intact brain.

Main Methods:

• Development and application of opto-miniRaf, an optogenetic ERK activator.
• Utilizing AAV-compatible systems for gene delivery.
• Employing calcium imaging and electrophysiology in cultured neurons, brain slices, and awake, behaving mice.

Main Results:

• Optogenetic activation of ERK significantly enhances synchronized network burst activity in cultured cortical neurons.
• Activation of ERK increases calcium activity in cortical pyramidal neurons of awake, moving mice.
• Demonstrated selective, rapid, graded, and reversible control of ERK signaling.

Conclusions:

• Extracellular signal-regulated kinase (ERK) signaling acts as an acute modulator of neuronal and network activity.
• Opto-miniRaf provides a versatile platform for precise spatiotemporal control of intracellular kinase signaling.
• Establishes a direct link between ERK activation and immediate changes in neuronal function.