Oxidative stress and autophagy: mediators of synapse growth?

Area of Science:

• Neuroscience
• Cell Biology
• Genetics

Background:

• Neurodegenerative diseases are often characterized by oxidative stress, an imbalance between reactive oxygen species (ROS) and antioxidant defenses.
• Oxidative stress can damage cells, but antioxidant responses, such as autophagy, can mitigate this damage.
• Jun-kinase (JNK) signaling, activated by ROS, plays a role in mediating antioxidant responses through the AP-1 transcription factor.

Purpose of the Study:

• To investigate the role of oxidative stress and JNK-AP-1 signaling in synaptic overgrowth observed in Drosophila mutants.
• To determine if reducing oxidative stress can reverse synaptic overgrowth.
• To explore the potential of ROS as a regulator of synapse size and function.

Main Methods:

• Examined Drosophila mutants with overgrown larval neuromuscular synapses exhibiting lysosomal storage disease (LSD) hallmarks.
• Assessed the impact of reducing oxidative stress on synaptic overgrowth.
• Studied animals deficient in oxidative stress protection and treated larvae with paraquat, a ROS-generating toxin.

Main Results:

• Synaptic overgrowth in Drosophila mutants was reversed by reducing oxidative stress.
• Synaptic overgrowth was found to be mediated by autophagy and JNK-AP-1 activity.
• Animals with impaired oxidative stress protection and paraquat-treated larvae exhibited similar synaptic overgrowth.

Conclusions:

• Oxidative stress responses, potentially involving autophagy, can promote synaptic growth.
• Reactive oxygen species (ROS) are potent regulators of synapse size and neuronal function.
• Findings have implications for aging, neurodegenerative diseases, and understanding metabolic demands in learning and memory.