Deoxysphingolipids: Atypical Skeletal Muscle Lipids Related to Insulin Resistance in Humans That Decrease Insulin...

Area of Science:

• Metabolic research
• Endocrinology
• Molecular biology

Background:

• Sphingolipids are implicated in skeletal muscle insulin resistance.
• Deoxysphingolipids (dSLs), atypical sphingolipids, are elevated in type 2 diabetes plasma and impair beta-cell function.
• The role of dSLs in human skeletal muscle insulin resistance remains unexplored.

Purpose of the Study:

• To investigate the role of deoxysphingolipids (dSLs) in human skeletal muscle insulin resistance.
• To determine if dSL levels change with obesity, type 2 diabetes, and insulin-sensitizing interventions.
• To explore the effects of increased dSLs on primary human myotubes.

Main Methods:

• Quantification of dSL species in skeletal muscle biopsies from lean, obese, and type 2 diabetic individuals.
• Analysis of muscle dSL content before and after a weight loss and exercise intervention.
• In vitro studies using primary human myotubes with manipulated dSL synthesis.

Main Results:

• dSL species were significantly elevated in the muscle of individuals with obesity and type 2 diabetes compared to athletes and lean controls.
• Muscle dSL content was inversely correlated with insulin sensitivity.
• A significant reduction in muscle dSL content was observed after a combined weight loss and exercise intervention.
• Increased dSL content in human myotubes led to decreased insulin sensitivity, increased inflammation, reduced AMPK phosphorylation, and altered insulin signaling.

Conclusions:

• Deoxysphingolipids (dSLs) play a significant role in human skeletal muscle insulin resistance.
• dSLs are elevated in muscle of individuals with obesity and type 2 diabetes and decrease with successful interventions.
• dSLs represent a potential therapeutic target for preventing and treating type 2 diabetes.