The Angiopoietin-Like Protein 3 and 8 Complex Interacts with Lipoprotein Lipase and Induces LPL Cleavage

Area of Science:

• Biochemistry
• Molecular Biology
• Lipid Metabolism

Background:

• Lipoprotein lipase (LPL) is crucial for triglyceride hydrolysis.
• Angiopoietin-like proteins (ANGPTL) 3, 4, and 8 inhibit LPL.
• The ANGPTL3/8 complex is a potent LPL inhibitor, but its structural interaction with LPL is unclear.

Purpose of the Study:

• To investigate the structural and functional effects of the ANGPTL3/8 complex on LPL.
• To elucidate the mechanism by which ANGPTL3/8 inhibits LPL activity.

Main Methods:

• Hydrogen-deuterium exchange mass spectrometry (HDX-MS) to probe conformational changes in LPL.
• Enzymatic activity assays to measure LPL inhibition.
• Western blotting and siRNA to assess LPL cleavage and the role of furin.

Main Results:

• HDX-MS revealed significant conformational changes in LPL's lid, ApoC2 binding site, and furin cleavage region upon ANGPTL3/8 binding.
• ANGPTL3/8 strongly inhibited LPL activity and increased LPL cleavage compared to individual proteins.
• ANGPTL3/8-induced LPL cleavage was blocked by an ANGPTL3 antibody and a furin inhibitor, and reduced by furin knockdown.

Conclusions:

• The ANGPTL3/8 complex induces structural alterations in LPL, leading to potent inhibition of its activity.
• ANGPTL3/8 promotes furin-mediated cleavage of LPL, representing a novel regulatory pathway.
• Targeting the ANGPTL3/8-furin interaction may offer therapeutic strategies for lipid disorders.