SIRT3 Modulates Endothelial Mitochondrial Redox State during Insulin Resistance

Area of Science:

• Endocrinology and Metabolism
• Cellular Biology
• Oxidative Stress Research

Background:

• Sirtuin signaling defects are linked to impaired metabolism, insulin resistance (IR), and endothelial dysfunction.
• Palmitic acid (PA) is implicated in metabolic disturbances and cellular damage.

Purpose of the Study:

• To investigate the impact of PA on mitochondrial sirtuins (SIRT2-5) and oxidative balance in human endothelial cells (TeloHAEC).
• To explore the role of SIRT3 in PA-induced cellular dysfunction and the potential therapeutic effects of δ-valerobetaine (δVB).

Main Methods:

• Human endothelial cells (TeloHAEC) were treated with palmitic acid (PA).
• Sirtuin expression, cell viability, insulin signaling, oxidative status, autophagy, inflammation, and pyroptosis were assessed.
• SIRT3 levels were modulated using mimic transfection.
• The effects of the antioxidant δ-valerobetaine (δVB) were evaluated.

Main Results:

• PA treatment impaired cell viability, insulin signaling, and oxidative homeostasis, downregulating sirtuin expression, especially SIRT3.
• Restoring SIRT3 suppressed PA-induced autophagy, inflammation, and pyroptosis via the NLRP3/caspase-1 pathway.
• δVB counteracted PA-induced redox imbalance by upregulating sirtuins, reducing reactive oxygen species (ROS), and decreasing cell death.

Conclusions:

• SIRT3 plays a critical role in maintaining endothelial redox homeostasis under conditions of insulin resistance.
• The antioxidant δ-valerobetaine (δVB) demonstrates potential in mitigating IR-related endothelial injury by enhancing cellular defense mechanisms.