Adipocyte triglyceride lipase expression in human obesity

Area of Science:

• Biochemistry
• Molecular Biology
• Human Physiology

Background:

• Adipose triglyceride lipase (ATGL) is crucial for lipolysis.
• Obesity is associated with altered lipid metabolism.
• Understanding ATGL regulation in obesity is vital.

Purpose of the Study:

• To investigate ATGL gene and protein expression and triglyceride (TG) lipase activity in lean and obese subjects.
• To compare lipolytic enzyme expression in subcutaneous and visceral adipose tissue.
• To explore the relationship between ATGL expression, activity, and obesity.

Main Methods:

• Obtained subcutaneous and visceral adipose tissue from lean and obese subjects.
• Analyzed mRNA expression of lipolytic enzymes using real-time quantitative PCR.
• Assessed ATGL protein content via Western blot and TG lipase activity radiometrically.

Main Results:

• Obese subjects showed elevated mRNA for ATGL (PNPLA2) and other lipases in adipose tissue.
• Surprisingly, ATGL protein expression and TG lipase activity were reduced in obese subcutaneous adipose tissue.
• ATGL immunoprecipitation significantly reduced TG lipase activity in both lean and obese subjects.

Conclusions:

• ATGL is essential for efficient TG lipase activity in humans.
• Obesity is characterized by reduced ATGL protein and TG lipase activity despite increased ATGL mRNA.
• Post-translational modifications, rather than expression levels, may influence ATGL activity in obesity.