Reductive stress promotes protein aggregation and impairs neurogenesis

Area of Science:

• Neuroscience
• Cellular Biology
• Biochemistry

Background:

• Redox homeostasis is critical for cellular signaling in health and disease.
• While oxidative stress is well-studied, the role of reductive stress (RS) in neurodegenerative diseases remains unclear.
• This study investigates the impact of RS on neuronal health and neurogenesis.

Purpose of the Study:

• To determine if a shift towards reductive redox state damages neurons.
• To elucidate the mechanisms by which reductive stress impairs neurogenesis.
• To explore the role of Nrf2 signaling and Tau pathology in reductive stress-induced neurotoxicity.

Main Methods:

• Utilized neuroblastoma (Neuro 2a/N2a) cells treated with sulforaphane to induce Nrf2 activation and reductive stress.
• Assessed antioxidant production, reactive oxygen species (ROS) levels, endoplasmic reticulum (ER) stress, and protein aggregation.
• Evaluated neurogenesis markers, including neurite outgrowth, differentiation, and axon formation.
• Investigated the GSK3β/Tau signaling pathway and Tau phosphorylation under reductive stress conditions.

Main Results:

• Sulforaphane-induced Nrf2 activation led to a reductive redox state with decreased ROS and increased glutathione (GSH).
• Reductive stress caused ER stress, protein aggregation (including Tau and α-synuclein), and proteotoxicity.
• Acute reductive stress impaired neurite outgrowth, while chronic exposure severely reduced differentiation and axon formation.
• Reductive stress activated the GSK3β/Tau cascade, promoting Tau phosphorylation and contributing to proteotoxicity.

Conclusions:

• Both acute and chronic reductive stress can impair neurogenesis through GSK3β/TAU signaling and proteotoxicity.
• Nrf2-mediated reductive stress poses a significant threat to neuronal health and neurogenesis.
• Targeting redox mechanisms and proteostasis pathways is crucial for preserving neuronal function in neurodegenerative conditions.