Abstract
Acyl-CoA synthetase long-chain family member 4 (ACSL4) activates polyunsaturated fatty acids (PUFAs) to produce PUFA-derived acyl-CoAs, which are utilised for the synthesis of various biological components, including phospholipids (PLs). Although the roles of ACSL4 in non-apoptotic programmed cell death ferroptosis are well-characterised, its role in the other types of cell death is not fully understood. In the present study, we investigated the effects of ACSL4 knockdown on the levels of acyl-CoA, PL, and ferroptosis in the human normal kidney proximal tubule epithelial (HK-2) cells. Liquid chromatography–tandem mass spectrometry (LC-MS/MS) analyses revealed that the knockdown of ACSL4 markedly reduced the levels of PUFA-derived acyl-CoA, but not those of other acyl-CoAs. In contrast with acyl-CoA levels, the docosahexaenoic acid (DHA)-containing PL levels were preferentially decreased in the ACSL4-knockdown cells compared with the control cells. Cell death induced by the ferroptosis inducers RSL3 and FIN56 was significantly suppressed by treatment with ferrostatin-1 or ACSL4 knockdown, and, unexpectedly, upon treating with a necroptosis inhibitor. In contrast, ACSL4 knockdown failed to suppress the other oxidative stress-induced cell deaths initiated by cadmium chloride and sodium arsenite. In conclusion, ACSL4 is involved in the biosynthesis of DHA-containing PLs in HK-2 cells and is specifically involved in the cell death induced by ferroptosis inducers.
Highlights
Accumulating evidence has revealed that the dietary intake of polyunsaturated fatty acids (PUFAs)2 may play positive and/or negative roles in human disease and health, including cardiovascular and kidney diseases [1,2]; the underlying biological mechanisms are still not completely understood
To evaluate the effects of Acyl-CoA synthetase long-chain family member 4 (ACSL4) knockdown on cell death induced by chemicals in human normal kidney proximal tubule epithelial (HK-2) cells, we investigated the levels of long-chain acyl-CoA and PL in ACSL4 knockdown cells compared with the control cells
Consistent with previous reports [6,7], knockdown of ACSL4 markedly reduced the levels of long-chain acyl-CoA derived from fatty acids with more than two double bonds, such as arachidonic acid (AA) (C20:4), and adrenic acid (C22:4). These results show the possibility that ACSL4 participates in the biosynthesis of long-chain PUFA-derived acyl-CoA in HK-2 cells, which is consistent with substrate selectivity of recombinant ACSL4 enzyme [7]
Summary
Accumulating evidence has revealed that the dietary intake of polyunsaturated fatty acids (PUFAs) may play positive and/or negative roles in human disease and health, including cardiovascular and kidney diseases [1,2]; the underlying biological mechanisms are still not completely understood. Recent studies have revealed that the biosynthesis of AA- and/or eicosapentaenoic acid-derived acyl-CoA, and those of several PUFA-derived acyl-CoAs were significantly decreased in cells obtained from Acsl4-deficient mice compared with those in wildtype mice [6,7]. Consistent with these observations, genetic deletion of Acsl significantly decreased in the levels of PUFA-containing phospholipids (PLs) in several cells, such as adipocytes [6], macrophages [7], and fibroblasts [8]. It has been shown that oxidised PLs are a key factor in regulating the non-apoptotic form of License 4.0 (CC BY)
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