An anti-ANGPTL3/8 antibody decreases circulating triglycerides by binding to a LPL-inhibitory leucine zipper-like motif

• Main Authors: Austin, A.K (Author), Balasubramaniam, D. (Author), Beyer, T.P (Author), Chen, Y.Q (Author), Davies, J. (Author), Day, J.W (Author), Ehsani, M. (Author), Fitchett, J.R (Author), Glaesner, W. (Author), Heng, A.R (Author), Jones, B.E (Author), Konrad, R.J (Author), Qian, Y.-W (Author), Russell, A.M (Author), Schroeder, O. (Author), Siegel, R.W (Author), Zhen, E.Y (Author)
• Format: Article
• Language: English
• Published: American Society for Biochemistry and Molecular Biology Inc. 2022
• Subjects: angiopoietin-like protein (ANGPTL); apolipoprotein (Apo); epitopes; hydrogen-deuterium exchange mass spectrometry (HDXMS); leucine zipper; lipoprotein lipase (LPL); molecular modeling; nano-imaging; transmission electron microscopy (TEM); triglycerides (TG)
• Online Access: View Fulltext in Publisher

 Triglycerides (TG) are required for fatty acid transport and storage and are essential for human health. Angiopoietin-like-protein 8 (ANGPTL8) has previously been shown to form a complex with ANGPTL3 that increases circulating TG by potently inhibiting LPL. We also recently showed that the TG-lowering apolipoprotein A5 (ApoA5) decreases TG levels by suppressing ANGPTL3/8-mediated LPL inhibition. To understand how LPL binds ANGPTL3/8 and ApoA5 blocks this interaction, we used hydrogen-deuterium exchange mass-spectrometry and molecular modeling to map binding sites of LPL and ApoA5 on ANGPTL3/8. Remarkably, we found that LPL and ApoA5 both bound a unique ANGPTL3/8 epitope consisting of N-terminal regions of ANGPTL3 and ANGPTL8 that are unmasked upon formation of the ANGPTL3/8 complex. We further used ANGPTL3/8 as an immunogen to develop an antibody targeting this same epitope. After refocusing on antibodies that bound ANGPTL3/8, as opposed to ANGPTL3 or ANGPTL8 alone, we utilized bio-layer interferometry to select an antibody exhibiting high-affinity binding to the desired epitope. We revealed an ANGPTL3/8 leucine zipper-like motif within the anti-ANGPTL3/8 epitope, the LPL-inhibitory region, and the ApoA5-interacting region, suggesting the mechanism by which ApoA5 lowers TG is via competition with LPL for the same ANGPTL3/8-binding site. Supporting this hypothesis, we demonstrate that the antiANGPTL3/8 antibody potently blocked ANGPTL3/8-mediated LPL inhibition in vitro and dramatically lowered TG levels in vivo. Together, these data show that an anti-ANGPTL3/8 antibody targeting the same leucine zipper-containing epitope recognized by LPL and ApoA5 markedly decreases TG by suppressing ANGPTL3/8-mediated LPL inhibition. © 2022 THE AUTHORS