Neuronal activity alters BDNF-TrkB signaling kinetics and downstream functions

Area of Science:

• Neuroscience
• Cellular Signaling
• Molecular Biology

Background:

• Signaling pathway kinetics can dictate distinct cellular responses.
• Brain-Derived Neurotrophic Factor (BDNF) signaling through Tropomyosin receptor kinase B (TrkB) typically exhibits transient activation.

Purpose of the Study:

• To investigate how neuronal activity modifies the temporal dynamics of BDNF-TrkB signaling.
• To determine the downstream consequences of altered TrkB signaling kinetics on neuronal function and survival.

Main Methods:

• Neuronal cultures subjected to depolarization (KCl) or specific stimulation patterns (theta-burst, low-frequency).
• Measurement of TrkB receptor activation and downstream signaling events.
• Assessment of dendritic branching and neuronal apoptosis following glutamate exposure.

Main Results:

• High-frequency neuronal activity (e.g., theta-burst stimulation) converts transient TrkB signaling to a sustained mode (>24 hours).
• Sustained TrkB activation enhances dendritic branching and protects neurons from glutamate-induced apoptosis.
• The kinetic shift is mediated by calcium (Ca2+) influx and CaMKII activation, increasing surface TrkB expression.

Conclusions:

• Neuronal activity dynamically regulates BDNF-TrkB signaling kinetics, impacting neuronal plasticity and resilience.
• Sustained TrkB signaling represents a crucial mechanism linking neuronal activity and BDNF effects.
• Physical exercise also influences TrkB signaling kinetics, suggesting broader physiological relevance.