Angiopoietin-like 4 Is a Wnt Signaling Antagonist that Promotes LRP6 Turnover

Area of Science:

• Molecular biology
• Developmental biology
• Cell signaling

Background:

• Angiopoietin-like 4 (ANGPTL4) is a secreted protein involved in cardiovascular disease, metabolic disorders, and cancer.
• The precise signaling mechanisms of ANGPTL4 beyond lipid metabolism are not fully understood.

Purpose of the Study:

• To elucidate the molecular mechanisms underlying ANGPTL4 signaling.
• To identify novel interaction partners and pathways regulated by ANGPTL4.

Main Methods:

• Biochemical assays to detect protein-protein interactions.
• Cellular assays including endocytosis and degradation studies.
• In vivo studies using Xenopus embryos to assess developmental roles.

Main Results:

• ANGPTL4 was identified as a Wnt signaling antagonist.
• ANGPTL4 binds to syndecans and forms a ternary complex with LRP6.
• This complex undergoes clathrin-mediated endocytosis and lysosomal degradation, attenuating Wnt/β-catenin signaling.
• ANGPTL4 promotes notochord formation and inhibits muscle differentiation in Xenopus embryos.

Conclusions:

• ANGPTL4 functions as a Wnt signaling antagonist through a novel mechanism involving LRP6 complex formation and degradation.
• The role of ANGPTL4 in embryonic development highlights its broader physiological significance.
• Understanding ANGPTL4's interaction with Wnt signaling may offer new therapeutic strategies for diseases involving these pathways.