Pla2g12b is Essential for Expansion of Nascent Lipoprotein Particles

SUMMARYTriglyceride-rich lipoproteins (TRLs) are micelle-like particles that enable efficient transport of lipids throughout the bloodstream, but also promote atherosclerotic cardiovascular disease. Despite this central relevance to cardiovascular disease, very little is known about how lipids are loaded onto nascent TRLs prior to secretion. Here we show that Pla2g12b, a gene with no previously described function, concentrates components of the TRL biogenesis machinery along the ER membrane to ensure efficient delivery of lipids to nascent TRLs. We find that the lipid-poor TRLs secreted in PLA2G12B-/- mice and zebrafish support surprisingly normal growth and physiology while conferring profound resistance to atherosclerosis, and demonstrate that these same processes are conserved in human cells. Together these findings shed new light on the poorly understood process of TRL expansion, ascribe function to the previously uncharacterized gene Pla2g12b, and reveal a promising new strategy to remodel serum lipoproteins to prevent cardiovascular disease.