Endoplasmic Reticulum Stress Mediates Axon Initial Segment Shortening: Implications for Diabetic Brain Complications

Area of Science:

• Neuroscience
• Metabolic Disorders
• Cellular Biology

Background:

• Type 2 Diabetes Mellitus (T2DM) is linked to neurodegeneration and cognitive impairment, even with glucose control.
• Endoplasmic reticulum (ER) stress and the protein kinase RNA-like ER kinase (PERK) pathway are implicated in T2DM pathophysiology.
• Previous work showed T2DM-associated cognitive deficits correlate with shorter axon initial segment (AIS) length in the prefrontal cortex.

Purpose of the Study:

• To investigate if ER stress mediates AIS shortening in diabetic conditions.
• To explore potential therapeutic targets for T2DM-related cognitive impairment.

Main Methods:

• Utilized primary mouse cortical cultures.
• Administered ER stress inhibitors (sodium 4-phenylbutyrate) and inducers (tunicamycin).
• Used a PERK-specific inhibitor (GSK2606414) to assess pathway involvement.

Main Results:

• Sodium 4-phenylbutyrate prevented AIS shortening and PERK activation induced by the T2DM factor methylglyoxal.
• Tunicamycin caused dose-dependent AIS shortening without affecting neuronal viability.
• A PERK inhibitor blocked tunicamycin-induced AIS shortening, demonstrating ER stress is sufficient and necessary for this effect in vitro.

Conclusions:

• ER stress is a key mediator of AIS shortening in diabetic conditions.
• Targeting ER stress and AIS shortening presents a potential therapeutic strategy for T2DM-related cognitive impairment.