LPCAT3 Inhibitors Remodel the Polyunsaturated Phospholipid Content of Human Cells and Protect from Ferroptosis

Abstract

LPCAT3 is an integral membrane acyltransferase in the Lands cycle responsible for generating C20:4 phospholipids and has been implicated in key biological processes such as intestinal lipid absorption, lipoprotein assembly, and ferroptosis. Small-molecule inhibitors of LPCAT3 have not yet been described and would offer complementary tools to genetic models of LPCAT3 loss, which causes neonatal lethality in mice. Here, we report the discovery by high-throughput screening of a class of potent, selective, and cell-active inhibitors of LPCAT3. We provide evidence that these compounds inhibit LPCAT3 in a biphasic manner, possibly reflecting differential activity at each subunit of the LPCAT3 homodimer. LPCAT3 inhibitors cause rapid rewiring of polyunsaturated phospholipids in human cells that mirrors the changes observed in LPCAT3-null cells. Notably, these changes include not only the suppression of C20:4 phospholipids but also corresponding increases in C22:4 phospholipids, providing a potential mechanistic explanation for the partial but incomplete protection from ferroptosis observed in cells with pharmacological or genetic disruption of LPCAT3.

The structure, catalytic mechanism, and inhibitor identification of phosphatidylinositol remodeling MBOAT7

“…Although these compounds require further characterization and optimization, they provide a foundation for developing selective MBOAT7 inhibitors as therapeutic agents for diseases with increased MBOAT7 activity, such as cancers, with MBOAT7 dependency. Interestingly, similar to other MBOAT inhibitors 18,35,36 , the structures of Sevenin-1 and −2 contain two bulky aromatic groups connected by an amide bond. This could be a common scaffold for the MBOAT inhibitors, which may help guide the design of future MBOAT inhibitors.…”

“…Interestingly, similar to other MBOAT inhibitors 18,35,36 , the structures of Sevenin-1 and -2 contain two bulky aromatic groups connected by an amide bond. This could be a common scaffold for the MBOAT inhibitors, which may help guide the design of future MBOAT inhibitors.…”

TMEM164 is an acyltransferase that forms ferroptotic polyunsaturated ether phospholipids

“…One difference in this remodeling profile, however, was the very minor increase in C22:4 ePEs caused by TMEM164 disruption ( Fig. 2d, e and Supplementary Dataset 1 ), which contrasted with the more dramatic elevation in C22:4 Pes found in LPCAT3-null cells 25,26 . Unlike these ePE changes, the diester PE content of sgTMEM164 cells was largely unaltered ( Fig.…”

“…2a, d, e and Supplementary Dataset 1 ). These results pointed to a broad acyl-chain remodeling outcome associated with TMEM164 deletion that is reminiscent of the reshuffling of acyl chains in ester PLs that accompanies the genetic or pharmacological disruption of C20:4-preferring ester PL acyltransferases LPCAT3 or MBOAT7 22–25 . One difference in this remodeling profile, however, was the very minor increase in C22:4 ePEs caused by TMEM164 disruption ( Fig.…”

“…The remarkable specificity displayed by TMEM164 for transferring C20:4 acyl chains suggests that this enzyme has a specialized role in regulating PUFA ePL content, which is reminiscent of the roles that enzymes like LPCAT3 and MBOAT7 play in C20:4 phospholipid metabolism 22–25 . In each case, when the C20:4 acyltransferase is genetically disrupted, the decreases in direct C20:4 (e)PL products is accompanied by increases in (monoun)saturated (e)PLs, which may reflect an acyl-chain remodeling outcome that may serve to maintain a consistent amount of total e(PL) in the cell.…”