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]

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Summary

Introduction

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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