Hormone-sensitive lipase modulates adipose metabolism through PPARγ

Area of Science:

• Metabolic research
• Adipose tissue biology
• Lipid metabolism

Background:

• Hormone-sensitive lipase (HSL) is a key enzyme in lipolysis, regulating diacylglycerol and cholesteryl ester hydrolysis in adipose tissue.
• Previous studies suggest HSL's role in adipogenesis and adipose metabolism modulation.
• The necessity of HSL for supplying intrinsic ligands for PPARγ activation in adipogenesis remains unclear.

Purpose of the Study:

• To investigate whether HSL is required for providing intrinsic ligands for PPARγ activation during normal adipose differentiation.
• To evaluate the therapeutic potential of rosiglitazone in HSL-deficient mice.

Main Methods:

• Comparison of HSL knockout (HSL-/-) and wild-type (WT) littermates fed normal chow (NC) or high-fat (HF) diets with or without rosiglitazone for 16 weeks.
• Analysis of body weight, adipose depots, serum parameters (glucose, cholesterol, FFA, adiponectin), gene expression, and in vitro adipocyte function.
• Assessment of glucose tolerance and white adipose tissue (WAT) gene expression in response to HF diet and rosiglitazone.

Main Results:

• Rosiglitazone supplementation normalized body weight, adipose depots, and serum parameters in HSL-/- mice on an NC diet.
• Rosiglitazone treatment restored the expression of adipocyte differentiation genes and enzymes involved in lipid metabolism in HSL-/- mice.
• In vitro, HSL-/- adipocytes showed attenuated PPARγ activation compared to WT adipocytes, with no response to lipolytic stimulation.

Conclusions:

• HSL plays a critical role in providing intrinsic ligands or pro-ligands for PPARγ activation, thereby modulating adipose metabolism.
• Pharmacological activation of PPARγ with rosiglitazone can rescue metabolic deficits in HSL-deficient mice.
• These findings highlight a novel mechanism linking HSL activity to PPARγ signaling in adipose tissue regulation.