ACSL4-Mediated Ferroptosis and Its Potential Role in Central Nervous System Diseases and Injuries

Abstract

As an iron-dependent regulated form of cell death, ferroptosis is characterized by iron-dependent lipid peroxidation and has been implicated in the occurrence and development of various diseases, including nervous system diseases and injuries. Ferroptosis has become a potential target for intervention in these diseases or injuries in relevant preclinical models. As a member of the Acyl-CoA synthetase long-chain family (ACSLs) that can convert saturated and unsaturated fatty acids, Acyl—CoA synthetase long-chain familymember4 (ACSL4) is involved in the regulation of arachidonic acid and eicosapentaenoic acid, thus leading to ferroptosis. The underlying molecular mechanisms of ACSL4-mediated ferroptosis will promote additional treatment strategies for these diseases or injury conditions. Our review article provides a current view of ACSL4-mediated ferroptosis, mainly including the structure and function of ACSL4, as well as the role of ACSL4 in ferroptosis. We also summarize the latest research progress of ACSL4-mediated ferroptosis in central nervous system injuries and diseases, further proving that ACSL4-medicated ferroptosis is an important target for intervention in these diseases or injuries.

Full text

Citation: Jia, B.; Li, J.; Song, Y.; Luo,
C. ACSL4-Mediated Ferroptosis and
Its Potential Role in Central Nervous
System Diseases and Injuries. Int. J.
Mol. Sci. 2023,24, 10021. https://
doi.org/10.3390/ijms241210021
Academic Editors: Hari
Shanker Sharma and Anna Atlante
Received: 12 April 2023
Revised: 1 June 2023
Accepted: 6 June 2023
Published: 12 June 2023
Copyright: © 2023 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
International Journal of
Molecular Sciences
Review
ACSL4-Mediated Ferroptosis and Its Potential Role in Central
Nervous System Diseases and Injuries
Bowen Jia, Jing Li, Yiting Song and Chengliang Luo *
Department of Forensic Medicine, School of Basic Medicine and Biological Sciences, Soochow University,
Suzhou 215123, China
*Correspondence: clluo@suda.edu.cn
Abstract:
As an iron-dependent regulated form of cell death, ferroptosis is characterized by iron-
dependent lipid peroxidation and has been implicated in the occurrence and development of various
diseases, including nervous system diseases and injuries. Ferroptosis has become a potential target for
intervention in these diseases or injuries in relevant preclinical models. As a member of the Acyl-CoA
synthetase long-chain family (ACSLs) that can convert saturated and unsaturated fatty acids, Acyl—
CoA synthetase long-chain familymember4 (ACSL4) is involved in the regulation of arachidonic
acid and eicosapentaenoic acid, thus leading to ferroptosis. The underlying molecular mechanisms
of ACSL4-mediated ferroptosis will promote additional treatment strategies for these diseases or
injury conditions. Our review article provides a current view of ACSL4-mediated ferroptosis, mainly
including the structure and function of ACSL4, as well as the role of ACSL4 in ferroptosis. We also
summarize the latest research progress of ACSL4-mediated ferroptosis in central nervous system
injuries and diseases, further proving that ACSL4-medicated ferroptosis is an important target for
intervention in these diseases or injuries.
Keywords: ACSL4; ferroptosis; nervous system diseases; nervous system injuries
1. Introduction
Cell death is a common process in all living organisms, and diverse types of cell death
have been classified over time. According to the latest recommendations of the Cell Death
Nomenclature Committee in 2018, there are two types of cell death, that is, accidental cell
death (ACD) and regulated cell death (RCD) [
1
]. As a new form of regulated cell death
(RCD), ferroptosis is iron-dependent and characterized by the intracellular accumulation
of lipid peroxides to lethal levels [
2
]. However, ferroptosis is distinct from apoptosis,
various forms of necrosis, and autophagy in terms of morphology, biochemistry, and gene
expression. The typical symptoms of mitochondrial cristae reduction or disappearance and
outer membrane rupture differ from those of apoptotic cells, which are characterized by
membrane blistering and contraction [
3
]. ACSLs are a family of enzymes that can convert
saturated and unsaturated fatty acids with chain lengths of 8–22 to fatty acid acyl-CoA
esters [
4
]. ACSLs mediate fatty acid metabolism and are widely involved in endoplasmic
reticulum ER stress and ferroptosis. In particular, ACSL4 is a key enzyme in the production
of lipid peroxides, thus promoting ferroptosis in cells [
5
]. In this review, we will mainly
discuss the role of ACSL4 in the process of ferroptosis and investigate the effect of ACSL4
on nervous system diseases or injuries.
2. The Structure and Physiological Function of ACSL4
2.1. The Structure of ACSL4
ACSLs play a crucial role in activating long- and ultra-long-chain fatty acids to form
fatty acid acyl-CoA esters. It is made up of five members of the ACSLs family and can be
divided into two groups according to the composition of the homologous sequences. One is
Int. J. Mol. Sci. 2023,24, 10021. https://doi.org/10.3390/ijms241210021 https://www.mdpi.com/journal/ijms

Int. J. Mol. Sci. 2023,24, 10021 2 of 17
composed of ACSL1, ACSL5, and ACSL6, the other group consists of ACSL3 and ACSL4 [
6
].
The gene for ACSL4 is situated on the X chromosome of the human body, and the subcellular
localization of ACSL4 is mainly in the secretion pathway of endosome and peroxisome [
7
].
In addition, ACSL4 is transferred to the plasma membrane and the mitochondria-associated
membrane, which is responsible for fatty acid synthesis and beta-oxidation [
7
]. ACSL4 is
formed from five regions: an NH2 terminal, luciferase-like regions 1 and 2, the ligand that
connects two luciferase-like regions, and a C terminal [
8
]. ACSL4 is highly expressed in the
brain, adrenal glands, testes, and ovaries. In the ACSLs family, the luciferin-like region 2
and the C terminal amino acids sequence are identical, suggesting that the two regions are
the crux of the reaction catalyzed by ACSLs. The absence of 50 NH2-corresponding amino
acids may lead to differential responses of ACSLs to fatty acid preferences [
6
,
9
]. ACSL4
specifically exhibits preference for 20-carbon polyunsaturated fatty acid (PUFA) substrates,
including arachidonic acid (AA) and adrenic acid (AdA) [10].
2.2. The Physiological Function of ACSL4
Long-chain fatty acids (carbon chain length 14 to 24) are significant nutrients for the
formation and maintenance of cell membranes, energy supply with storage, membrane
anchoring of proteins in protein post-translational modification (PTM) pathways, transport
and localization pathways, and signal transduction, as well as protein interactions, etc. [
6
]
First phase fatty acid transporters (FATPs) bind and transport long-chain fatty acids to
target cells. ACSLs then catalyze the intracellular free long-chain fatty acids to acyl-CoA.
PUFA is an acronym for polyunsaturated fatty acids, which are a category of fatty acids
with multiple double bonds in their carbon chains. These fatty acids are divided into
two primary groups:
ω
-3 (n-3) and
ω
-6 (n-6) fatty acids, based on the location of the
first double bond from the methyl end of the fatty acid chain [
11
]. In the mammalian
ACSLs family [
12
], ACSL4 tends to catalyze several PUFAs to polyunsaturated fatty acid
coenzyme A (PUFAs-CoA), primarily including arachidonic acid 20:4 and adrenic acid
22:4. Following their formation, PUFAs-CoA are esterified into phospholipids by different
lysophosphatidylcholine acyltransferases (LPCATs). This process facilitates the incorpora-
tion of long-chain polyunsaturated fatty acids into cellular lipid membranes [
8
]. It enhances
membrane fluidity and facilitates the transportation of substances required for maintain-
ing normal cellular physiological functions. ACSL4 is involved in distinct biochemical
processes across different organelles. Within mitochondria, ACSL4 primarily contributes
to fatty acid synthesis and
β
-oxidation [
13
]. Among the peroxidases, ACSL4 is mainly
involved in
β
-oxidation and the synthesis of alkyl lipids. In the endoplasmic reticulum
(ER), it promotes glycerolipid synthesis and
ω
-oxidation, serving as the primary pathway
for catabolism of medium-chain fatty acids when
β
-oxidation is impaired [
14
,
15
]. The afore-
mentioned findings highlight the critical involvement of ACSL4 in fatty acid metabolism,
and it is the only subunit of the ACSLs family that plays an essential and direct role in
the process of ferroptosis. However, the influence of ACSL4 on the catalytic selectivity for
exogenous fatty acids can vary among different tissues and cell types, potentially owing
to variations in cell type and intracellular fatty acid composition [16,17]. For example, the
absence of ACSL4 in lipocytes reduces the incorporation of AA into phospholipids and
correspondingly reduces the level of 4-hydroxynonenal, the lipid peroxidation product
of AA [
6
]. ACSL4 deficiency plays a role in obesity-associated adipocyte dysfunction
because the ability of PUFA to synthesize phospholipids is abruptly diminished, resulting
in alterations in lipid composition and a high-fat diet and leading to fat accumulation
and adipocyte death [
18
]. The overexpression of ACSL4 in human arterial smooth muscle
cells stimulates the production of phosphatidylinositol (PI) and phosphatidylinositol (PE)
from exogenous AA, resulting in a decreased release of cytokine-dependent PGE2 [
19
,
20
].
Moreover, ACSL4 expression stimulates the generation of PE from exogenous AA and
oleic acid (OA) in fibroblast-like COS-7 cells. Dissociated AA is also implicated in the
synthesis of phosphatidylcholine (PC) in COS-7 cells, and steroidogenic cells regulate AA
release via the acyl-CoA thioesterase 2 (ACOT2) pathway [
21
]. In this pathway, ACSL4

Int. J. Mol. Sci. 2023,24, 10021 3 of 17
catalyzes the conversion of free intracellular AA into AA-CoA and provides it to ACOT2,
which subsequently transports AA to the mitochondria [
22
]. The released AA undergoes
progressive conversion through the lipoxygenase pathway, leading to the formation of the
steroidogenic acute regulatory (StAR) protein [
17
]. The StAR protein regulates the transport
of cholesterol into the inner mitochondrial membrane and serves as a critical rate-limiting
enzyme in steroid hormone biosynthesis [
23
]. AA and cyclic adenosine monophosphate
(cAMP) transduce signals from hormone receptors into the nucleus through two different
pathways and jointly regulate steroid production and STAR gene expression [6,24].
The overexpression of ACSL4 may result in false positive results by disrupting protein
distribution within cells. To investigate its physiological function, researchers commonly
use gene silencing or knockout experiments. For example, knockout of ACSL4 in rat fi-
broblast 3Y1 cells led to a reduction of AA-containing phospholipid levels following IL-1
β
stimulation, while AA-containing PC and PI levels were less affected [
6
,
25
]. In mouse em-
bryonic fibroblasts, ACSL4 knockout significantly decreased the level of polyunsaturated
fatty acid PE and inhibited ferroptosis [
26
]. Additionally, recombinant glutathione peroxidase
4 (GPX4)-ACSL4 double knockout cells showed significant resistance to ferroptosis. ACSL4
facilitates the esterification of CoA to free fatty acids in an ATP-dependent manner, thereby
activating fatty acid oxidation or lipid biosynthesis. This enzyme is also responsible for
the enrichment of long-chain unsaturated
ω
-6 fatty acids in the cell membrane [
27
,
28
].
However, ACSL4-KO cells exhibited increased sensitivity to ferroptosis upon supplemen-
tation with exogenous AA or AdA (along with other long-chain PUFAs), likely due to
the different kinetic properties of ACSL enzymes. ACSL4 prefers to use AA and AdA to
synthesize phospholipids at low concentrations in the presence of other fatty acids, while
other ACSL-like enzymes use other fatty acids. This concept is physiologically relevant
because the molar percentage of plasma AA levels is at least one to two orders of magnitude
lower than other fatty acids such as oleic acid, suggesting that ACSL4 is responsible for
activating AA at physiological concentrations while other ACSL-like enzymes may activate
AA when intracellular AA levels are elevated [26].
Thus, the regulation of PUFA by ACSL4 plays a crucial physiological role. Additionally,
ACSL4 serves other physiological functions apart from its role in lipid metabolism. A study
conducted by Cho revealed that ACSL4-deficient pure mice mostly perish during embryonic
development, while heterozygous female mice with ACSL4 deficiency experience decreased
fertility and compromised offspring quality [29,30].
2.3. The Regulation Mechanism of ACSL4
ACSL4 transcription is negatively regulated by miR-211-5p, miR-204A-5p, miR-34A-
5p, miR-424-5p, miR-205, and miR-34a [
5
], the expression of which is also inhibited by the
activation of integrin
α
6
β
4-mediated Src and signal transduction and transcription activator
3 (STAT3) or androgen receptors [
31
]. Furthermore, free AA may alter the levels of the
ACSL4 enzyme through the promotion of ubiquitination and proenzyme degradation [
32
].
Moreover, cyclic adenosine monophosphate (cAMP), special protein 1 (SP1), tyrosine
phosphatase SHP2 [
33
], and proto-oncogene transcriptional co-activator YAP were shown
to positively regulate ACSL4 expression [
5
]. ACSL4’s proximal promoter region contains
a cAMP response element binding site that initiates ACSL4 transcription by binding to
cAMP. The transcription of the ACSL4 gene can be triggered by the release of YAP activity
to enhance ferroptosis [
34
]. In addition, Zhang et al., found that the activation of PKC
β
II,
one of the isoforms of PKC (protein kinase C), amplified lipid peroxidation through the
phosphorylation and activation of ACSL4, which could directly phosphorylate ACSL4
Thr328. Furthermore, the lipid peroxidation PKC
β
II-ACSL4 positive feedback mechanism
could enhance the level of lipid peroxidation to induce ferroptosis [35].
3. ACSL4 in Ferroptosis
As a form of cell death driven by iron-dependent lipid peroxidation, ferroptosis was
proposed in 2012 by Drs. Brent R. Stockwell, Scott Dixon, and members of their labora-

Int. J. Mol. Sci. 2023,24, 10021 4 of 17
tory [
36
–
38
]. In general, ferroptosis has three essential features: (1) oxidation of PUFAs
(including membrane phospholipids); (2) redox activities related to iron utilization; (3) loss
of lipid hydrogen peroxide (LOOH) repair capacity [
8
]. Morphologically, ferroptosis cells
exhibit typical changes in mitochondrial membrane shrinkage, reduction or disappear-
ance of mitochondrial cristae, and rupture of the outer membrane, whereas mitochondria
usually show swelling in other forms of cell death [
39
–
41
]. Furthermore, treated with the
ferroptosis inducer erastin, the nuclei of cancer cells retained their structural integrity and
no nuclear pyknosis or chromatin edge clustering was observed [
42
]. These morphologic
features distinguish ferroptosis from apoptosis and necrosis [43].
Alterations in fatty acid metabolism serve as markers that indicate various patho-
logical conditions and metabolic disorders. Lipid metabolism disorders are observed in
ferroptosis and are heavily reliant on specific lipid metabolism proteins involved in the
metabolism of AA and AdA. To identify the major genes associated with lipid peroxida-
tion in ferroptosis, the research teams of Sebastian Doll and Bettina Proneth performed
two independent genetic experiments. By simultaneously analyzing a short palindromic
repeat-based genetic screen and another transcriptome microarray assay after comparing
ferroptosis-sensitive and resistant cells, ACSL4 gene expression was found to be indis-
pensable in the process of the oxidation of arachidonic acid-phosphatidylethanolamine
(AA-PE) and adrenal acid-phosphatidylethanolamine (AdA-PE) [
26
]. Among the ACSLs
family members, ACSL4 is the lipid metabolism enzyme which is most closely related to
ferroptosis. The overexpression of ACSL4 leads to the catalysis of diverse PUFAs, including
AA/AdA, thereby modifying the composition of cellular lipids and increasing cellular
susceptibility to ferroptosis [
44
]. In general, AdA and AA are first activated by ACSL4
during ferroptosis, followed by the formation of AdA-CoA and AA-CoA derivatives at
ER-associated oxidation centers. AdA-CoA and AA-CoA are then esterified by LPCAT3
to AdA-PE and AA-PE, which are then oxidized by 15-lipoxygenase (15-LOX) to produce
lipid hydroperoxide, giving rise to ferroptosis (Figure 1).
By cloning the mouse ACSL4 gene cDNA into a lentiviral vector, Yu Cui and Yan
Zhang demonstrated that cortical lentivirus administration injected into the left brain after
tMCAO surgery resulted in increased infarct size and decreased neurological function in
the ACSL4-overexpressing brain. Additionally, confocal microscopy revealed neuronal
death and heightened microglial activation in ACSL4-overexpressing mice, leading to
the release of substantial amounts of neurotoxic factors such as reactive oxygen species
(ROS) [
45
,
46
]. In the cerebral ischemia/reperfusion model, ACSL4 knockdown attenuates
ischemic brain injury while ACSL4 overexpression exacerbates ischemic brain injury [
26
].
Furthermore, ACSL4 contributes to neuronal death by promoting ferroptosis, and therefore,
inhibiting the esterification of AA/AdA to PE through pharmacological or genetic inhibi-
tion of ACSL4 has emerged as a specific approach to counteracting ferroptosis [
47
]. ACSL4
is also a potential target for tumor treatment, as studies have demonstrated its inhibitory
effect on glioma cell proliferation through the activation of the ferroptosis pathway [
48
].
Suppression of the thrombin-ACSL4 pathway may reduce neuronal ferroptosis following is-
chemic stroke [
49
]. Additionally, paeonol exhibits significant inhibition of ACSL4-mediated
neuronal ferroptosis induced by ferroptosis inducers [
50
]. In conclusion, ACSL4-mediated
fatty acid activation of AA/AdA is a key step in ferroptosis. The expression level or enzyme
activity of the ACSL4 protein is a vital biological factor for ferroptosis in cells and tissues,
which can be used as a biomarker for ferroptosis susceptibility and as a therapeutic target
for the treatment of ferroptosis-related diseases. Overall, the overexpression of ACSL4
promotes ferroptosis by regulating PUFAs, particularly when PUFAs reach hazardous
levels.

Int. J. Mol. Sci. 2023,24, 10021 5 of 17
Int.J.Mol.Sci.2023,24,xFORPEERREVIEW5of18



Figure1.Duringferroptosis,PKCβIIphosphorylatestheThr328siteofACSL4,directlyactivating
ACSL4andfacilitatingthebiosynthesisofPUFAlipids.PUFAs,primarilyAA20:4andAdA22:4,
areactivatedbyACSL4andthenformPUFA-CoAbybindingwithcoenzymeA(CoA)attheendo-
plasmicreticulumoxidationcenter,aprocessthatconsumesadenosinetriphosphate(ATP).PUFA-
CoAisesterifiedtoPUFA-PEthroughtheassistanceofLPCAT3.Subsequently,itundergoesoxida-
tionby15-lipoxygenase(15-LOX),resultingintheproductionoflipidhydroperoxidesthatcontrib-
utetoirondepletion.Additionally,Fe2+canbereleasedfromthelabileironpool,leadingtothe
generationofreactiveoxygenspecies(ROS)suchasHO·throughtheFentonreaction.Consequently,
lipidperoxides,includingLOOH,canaccumulateviaasimilarreactionmediatedbyFe,resulting
inachainreactionthatproducesasignificantnumberoflipidradicals.SystemXC−facilitatesthe
exchangeofcysteineandglutamate,enablinghighlyspecificcysteineuptake.Oncecysteineenters
thecytoplasm,itundergoesreductiontocysteine,followedbycatalysisbyγ-glutamylcysteinesyn-
thase(γ-GCS)andglutathionesynthase(GSS)toproduceglutathionefromcysteine.Twomolecules
ofreducedglutathione(GSH)serveaselectrondonors,reducingPE-AA-OOHandPE-AdA-OOH
totheirrespectivealcohols,PE-AA-OHandPE-AdA-OH,andgeneratingoxidizedglutathione.Fur-
thermore,ACSL4directlyinhibitsGPX4,leadingtoferroptosis.However,steroid-producingcells
regulatethereleaseofAAthroughtheACOT2pathway.Inthispathway,ACSL4catalyzesthecon-
versionofintracellularfreeAAtoAA-coenzymeAandsuppliesittoACOT2,whichsubsequently
releasesAAintothemitochondria.ThereleasedAAisprogressivelymetabolizedthroughthelipox-
ygenasepathway,inducingStAR,althoughitsroleinferroptosisremainsunclear.PUFAs,polyun-
saturatedfayacids;AA,ArachidonicAcid;AdA,AdrenalAcid;PUFA-CoA,PolyunsaturatedFay
Acid-CoenzymeA;AA-CoA,ArachidonicAcid-CoenzymeA;AdA-CoA,AdrenalAcid-Coenzyme
A;ATP ,AdenosineTriphosphate;LPCAT3,Lysophosphatidylcholineacyltransferase3;PE-AA,
Phosphatidylethanolamine-ArachidonicAcid;PE-AA,Phosphatidylethanolamine-AdrenalAcid;
15-LOX,15-lipoxygenase;PE-AA-OOH,Phosphatidylethanolamine-ArachidonicAcidHydroper-
oxide;PE-AdA-OOH,Phosphatidylethanolamine-AdrenalAcidHydroperoxide;PE-AA-OO.,Phos-
phatidylethanolamine-ArachidonicAcidPeroxylRadical;PE-AdA-OO.,Phosphatidylethanola-
mine-AdrenalAcidPeroxylRadical;PE-AA-OH,Phosphatidylethanolamine-ArachidonicAcidAl-
cohol;PE-AdA-OH,Phosphatidylethanolamine-AdrenalAcidAlcohol;Glu,GlutamicAcid;Cys,
Cysteine;GSH,Glutathione;GSSG,GlutathioneDisulfide;GPX4,GlutathionePeroxidase4;ACOT2,
acyl-CoAthioesterase2;StAR,steroidogenicacuteregulatory;PKCβII,proteinkinaseCβII.
BycloningthemouseACSL4genecDNAintoalentiviralvector,YuCuiandYa n 
Zhangdemonstratedthatcorticallentivirusadministrationinjectedintotheleftbrainafter
tMCAOsurgeryresultedinincreasedinfarctsizeanddecreasedneurologicalfunctionin
theACSL4-overexpressingbrain.Additionally,confocalmicroscopyrevealedneuronal
deathandheightenedmicroglialactivationinACSL4-overexpressingmice,leadingtothe
Figure 1.
During ferroptosis, PKC
β
II phosphorylates the Thr328 site of ACSL4, directly activat-
ing ACSL4 and facilitating the biosynthesis of PUFA lipids. PUFAs, primarily AA 20:4 and AdA
22:4, are activated by ACSL4 and then form PUFA-CoA by binding with coenzyme A (CoA) at the
endoplasmic reticulum oxidation center, a process that consumes adenosine triphosphate (ATP).
PUFA-CoA is esterified to PUFA-PE through the assistance of LPCAT3. Subsequently, it undergoes
oxidation by 15-lipoxygenase (15-LOX), resulting in the production of lipid hydroperoxides that
contribute to iron depletion. Additionally, Fe
2+
can be released from the labile iron pool, lead-
ing to the generation of reactive oxygen species (ROS) such as HO
·
through the Fenton reaction.
Consequently, lipid peroxides, including LOOH, can accumulate via a similar reaction mediated
by Fe, resulting in a chain reaction that produces a significant number of lipid radicals. System
X
C
−
facilitates the exchange of cysteine and glutamate, enabling highly specific cysteine uptake.
Once cysteine enters the cytoplasm, it undergoes reduction to cysteine, followed by catalysis by
γ
-glutamylcysteine synthase (
γ
-GCS) and glutathione synthase (GSS) to produce glutathione from
cysteine. Two molecules of reduced glutathione (GSH) serve as electron donors, reducing PE-AA-
OOH and PE-AdA-OOH to their respective alcohols, PE-AA-OH and PE-AdA-OH, and generating
oxidized glutathione. Furthermore, ACSL4 directly inhibits GPX4, leading to ferroptosis. However,
steroid-producing cells regulate the release of AA through the ACOT2 pathway. In this pathway,
ACSL4 catalyzes the conversion of intracellular free AA to AA-coenzyme A and supplies it to ACOT2,
which subsequently releases AA into the mitochondria. The released AA is progressively metabolized
through the lipoxygenase pathway, inducing StAR, although its role in ferroptosis remains unclear.
PUFAs, polyunsaturated fatty acids; AA, Arachidonic Acid; AdA, Adrenal Acid; PUFA-CoA, Polyun-
saturated Fatty Acid-Coenzyme A; AA-CoA, Arachidonic Acid-Coenzyme A; AdA-CoA, Adrenal
Acid-Coenzyme A; ATP, Adenosine Triphosphate; LPCAT3, Lysophosphatidylcholine acyltrans-
ferase 3; PE-AA, Phosphatidylethanolamine-Arachidonic Acid; PE-AA, Phosphatidylethanolamine-
Adrenal Acid; 15-LOX, 15-lipoxygenase; PE-AA-OOH, Phosphatidylethanolamine-Arachidonic
Acid Hydroperoxide; PE-AdA-OOH, Phosphatidylethanolamine-Adrenal Acid Hydroperox-
ide; PE-AA-OO
.
, Phosphatidylethanolamine-Arachidonic Acid Peroxyl Radical; PE-AdA-OO
.
,
Phosphatidylethanolamine-Adrenal Acid Peroxyl Radical; PE-AA-OH, Phosphatidylethanolamine-
Arachidonic Acid Alcohol; PE-AdA-OH, Phosphatidylethanolamine-Adrenal Acid Alcohol; Glu,
Glutamic Acid; Cys, Cysteine; GSH, Glutathione; GSSG, Glutathione Disulfide; GPX4, Glutathione
Peroxidase 4; ACOT2, acyl-CoA thioesterase 2; StAR, steroidogenic acute regulatory; PKC
β
II, protein
kinase C βII.

Int. J. Mol. Sci. 2023,24, 10021 6 of 17
Recently, Leslie Magtanong et al., discovered that ACSL4 serves as a context-specific
regulator of ferroptosis. Through an overview of previous studies, Magtanong high-
lighted ACSL4’s role in inducing ferroptosis, primarily attributed to its inhibitory effect
on GPX4 [
51
]. The relationship between ACSL4 and GPX4 has been a prominent area of
investigation in ferroptosis research. For instance, the team led by Bo Chu demonstrated
that ACSL4 is necessary in ferroptosis induced by erastin or GPX4 inhibitors, whereas it
is dispensable in P53-mediated ferroptosis [
52
]. Shui et al., also reported that lipids can
be directly generated through photodynamic therapy (PDT) with exogenous oxygen radi-
cals, initiating lipid peroxidation independent of ACSL4 and lipoxygenases (ALOXs) [53].
Furthermore, Pang et al., identified that edaravone can alleviate spinal cord injury by
modulating the GPX4/ACSL4/5-LOX pathway [
54
]. Li et al., discovered that baicalein
improves cerebral ischemia-reperfusion injury through the GPX4/ACSL4/ACSL3 axis [
55
].
Wang et al., demonstrated that Seco Lupan Triterpen Derivatives induce ferroptosis via
the GPX4/ACSL4 axis [
56
]. These findings provide a theoretical foundation for further
elucidating the mechanisms of ferroptosis.
4. ACSL4 in Neurological Diseases and Injuries
4.1. ACSL4 in Brain Injury
Traumatic Brain Injury (TBI) is one of the world’s most serious health problems
with high morbidity and mortality [
57
,
58
]. TBI and its complications place an enormous
economic burden on families and society [
59
–
62
], and an increasing number of studies
have shown that ACSL4 plays an important role in the process of ferroptosis induced
after TBI [
63
]. ACSL4 turns membrane phospholipids into AA/AdA-CoA, which is the
initial step to lipid peroxides [
64
]. Hogan discovered the elevated level of PUFAs in
TBI, and that the occurrence of lipid peroxidation-mediated injury is associated with
brain injury [
65
]. Xiao found that, 6 h after controlled cortical injury (CCI), the mRNA
level of ACSL4 increased [
66
], and a significant increase in ACSL4 was observed after
injury according to Kenny [
67
] (Table 1). However, as biomarkers related to ferroptosis,
GPX4 and ACSL4 [
68
,
69
] were differentially expressed only in the early post-TBI period,
suggesting that the most active stage of ferroptosis may occur early after injury. Using
baicalein could abate PE oxidation and provided histological and cognitive protection
in postinjury [
67
,
70
,
71
] (Table 1). Furthermore, the application of ferroptosis inhibitors
ferristatin-1 and ferristatin II in the TBI mouse model can inhibit iron deposition, neuronal
degeneration, and reduce brain injury of TBI [
72
], which testifies the existence of ferroptosis
in TBI. As previously discussed, the accumulation of oxidized AA- or AdA-containing PE
leads to ferroptosis. Therefore, inhibition of ACSL4 and thus the formation of AA- and
AdA-esterified PE may also protect against TBI.
Moreover, knockdown of ACSL4 by specific shRNA inhibited erastin-induced ferrop-
tosis in HepG2 and HL60 cells (ferroptosis-sensitive cells) [
69
]. The inhibition of ACSL4
expression by shRNA only reduced MDA production, thus reducing the final production
of lipid peroxidation, while Fe
2+
did not accumulate in HepG2 and HL60 cells after erastin
treatment. These findings suggest that ACSL4 induces neuronal ferroptosis by regulating
lipid peroxidation rather than iron accumulation.

Int. J. Mol. Sci. 2023,24, 10021 7 of 17
Table 1. Models of neurodegenerative diseases and outcomes after intervention.
Diseases Biological Model Intervention Measure Consequence Reference
Traumatic Brain Injury
Controlled cortical impact
(CCI) /ACSL4 expression level
increased [66]
CCI Baicalein Decreased ferroptotic PE
oxidation [67]
Ischemic stroke
Middle cerebral artery
occlusion (MCAO) /ACSL4 increased after
decreasing 1–3 h of ischemia [46]
MCAO liproxstatin-1/Rosiglitazo-
ne/
Lipid peroxidation index
was significantly inhibited in
comparison with untreated
group
[73]
Hemorrhagic stroke
Oxygen and glucose
deprivation (OGD) /ACSL4 mRNA expression
was significantly increased [46]
OGD Paeonol Paeonol inhibited the
expression of ACSL4 [50]
Alzheimer’s disease APPswe transgenic mice /
Aβaccumulates in brain
tissue due to lipid
peroxidation
[74]
APPswe/PSEN1dE9
(APP/PS1) double
transgene mice
tetrahydroxy stilbene
glycoside (TSG)
TSG inhibited the expression
of ACSL4 [75]
Parkinson’s disease PD mice model
1-methyl-4-phenyl-1,2,3,6-
tetrahydropyridine
(MPTP)
The expression of ACSL4
significantly increased [76]
PD mice model β-hydroxybutyrate (BHB) BHB inhibits ferroptosis in
PD model [77]
Spinal cord injury Spinal cord Edaravone Reduces ACSL4 levels [54]
contusion injury model
Multiple sclerosis Experimental autoimmune
encephalitis (EAE) model ACSL4-KO
Knocking down the ACSL4
gene considerably reduced
the severity of EAE and the
clinical score of EAE mice
[78]
4.2. ACSL4 in Stroke
4.2.1. ACSL4 in Ischemic Stroke
Ischemic stroke is currently one of the leading causes of human mortality, accounting
for 80% of all strokes [
79
]. Currently, the only treatment options for patients with ischemic
stroke are surgery or thrombolysis with tissue plasminogen activator, but the prognosis
remains poor [
80
]. Recent studies have found that ferroptosis is closely related to the onset
and development of stroke, which may be a potential direction for stroke treatment [81].
The ferroptosis inhibitors liproxstatin-1 and ferrostatin-1 could prevent cerebral is-
chemia reperfusion injury induced by stroke in mice [
82
]. To observe the temporal pattern
of ACSL4 expression after focal ischemia, Cui et al., subjected mice to transient middle cere-
bral artery occlusion (tMCAO) for 1 h followed by reperfusion. The expression of ACSL4 in
the ipsilateral cortex decreased significantly after 1 to 3 h of ischemia and was higher than
that in the contralateral cortex after 6 h of reoxygenation. This suggests that, in the early
stages of focal ischemia, the expression of ACSL4 is down-regulated [
46
]. Hypoxia-inducing
factor 1-alpha (HIF-1
α
) mediated decreased ACSL4 expression after oxygen and glucose
deprivation (OGD). Knockdown of ACSL4 can alleviate ischemic brain damage, and the
overexpression of ACSL4 can exacerbate ischemic brain damage [
83
,
84
]. Chen et al., estab-
lished a transient ischemic model in mice with middle cerebral artery occlusion (MCAO)
after intravenous administration of rosiglitazone 1 h before MCAO. After inhibition of
ACSL4 with rosiglitazone (RSG), the decrease of GPX4 was greatly attenuated (Table 1).
Neurological function was significantly improved at 72 h after stroke, and cerebral infarct
volume was reduced. This study demonstrated that inhibition of ACSL4 could promote
recovery of neurological function after stroke by inhibiting ferroptosis [
73
]. Tuo et al., found
that, during the period of I/R, reduction of ACSL4 could be the result of modification after
translation. They also discovered that ACSL4 can mediate thrombin cytotoxicity which can
be blocked by the ACSL4 inhibitor pioglitazone (PIO). These results suggest that thrombin

Int. J. Mol. Sci. 2023,24, 10021 8 of 17
may contribute to neuronal cell death through the promotion of ACSL4-dependent ferrop-
tosis, and that reduction of ACSL4 may contribute to the inhibition of thrombin-induced
ferroptosis [49].
4.2.2. ACSL4 in Hemorrhagic Stroke
Intracerebral hemorrhage (ICH) is one of the most common and refractory diseases
in the world [
85
]. The hematoma after intracerebral hemorrhage causes progressive brain
tissue damage [
86
], and it is closely associated with ferroptosis during its development [
87
].
ACSL4 mRNA expression was significantly increased in brain microvascular endothelial
cells (BMVECs) treated with the hypothermic oxygen–glucose deprivation intracerebral
hemorrhage model cells (OGD/H). ACSL4 inhibits miR-106b-5p, promoting ferroptosis.
Target gene analysis identified ACSL4 as a target gene of miR-106b-5p in OGD/H ICH
model cells [
46
] (Table 1). The overexpression of ACSL4 countered the effects of miR-
106b-5p, suppressed the viability of ICH cells, and stimulated ferroptosis. These results
suggest that ACSL4 promotes ferroptosis, decreasing the cellular function of BMVECs,
which is consistent with the findings of Xie et al. [
88
]. Furthermore, H19 acts as a competing
endogenous RNA ceRNA and regulates the proliferation and ferroptosis of BMVECs
through the miR-106b-5p/ACSL4 axis [
81
,
82
]. H19 knockdown may prevent ICH by
regulating miR-106b-5p/ACSL4, making this axis a potential therapeutic target for ICH
treatment.
Paeonol (PAN, 2
0
-hydroxy-4
0
-methoxy acetophenone) is a natural product isolated
from Paeoniflora [
89
]. Zheng’s team used hemin to mimic ICH in HT22 cells and found that
hemin significantly up-regulated ACSL4 expression in neuronal cells, while PAN partially
reversed this phenomenon. Additionally, RNA pull-down experiments identified UPF1 and
ACSL4 as downstream targets of HOTAIR in ICH, and PAN could inhibit ICH progression
by mediating the HOTAIR/UPF1/ACSL4 axis, which may serve as a new medicine for
cerebral hemorrhage [50,89] (Table 1).
In recent years, the role of ferroptosis in early brain injury (EBI) of subarachnoid
hemorrhage (SAH) has been highlighted. Ferroptosis is involved in the pathogenesis
of EBI after SAH through various pathways, including the activation of ACSL4, iron
metabolism disorders [
90
], and the down-regulation of GPX4 and ferroptosis suppressor
protein 1 (FSP1) [
91
]. Western blot and immunofluorescence experiments have confirmed
the expression level of ACSL4 in brain tissue after SAH, which increases and then decreases.
The immunofluorescence assay also revealed the colocalization of ACSL4 with the neuronal
marker NEUN in the brain, which significantly increased 24 h after SAH [
92
]. Using
siRNA technology to silence ACSL4 expression, inflammation, blood–brain barrier (BBB)
damage, oxidative stress, cerebral edema, behavioral and cognitive deficits, and neuronal
death were reduced, while the number of surviving neurons increased. Similar results
were obtained with ferroptosis inhibitors [
27
]. Therefore, early intervention to reduce the
oxidative response and ferroptosis may be an effective treatment for SAH. For example,
puerarin can activate SIRT1 or the AMPK/PGC1
α
/NRF2 pathway to alleviate oxidative
stress and reduce ferroptosis in EBI after SAH [93].
4.3. ACSL4 in Alzheimer’s Disease
Alzheimer’s disease (AD) is a degenerative disease of the central nervous system
that primarily affects people over the age of 65 [
94
]. Its clinical manifestations are mainly
the decline of memory, language, and other cognitive abilities. The main pathological
features are amyloid beta peptide (A
β
) [
95
,
96
] as the core component of senile plaques and
neurofibrillary tangles caused by tau hyperphosphorylation [97,98]. Under the increasing
aging trend, due to the unclear pathogenesis of Alzheimer’s disease and the lack of cost-
effective clinical treatment, Alzheimer’s disease places a heavy burden on patients and
medical social security [97,99].
Lipids constitute a vital component of the brain, comprising approximately 40% to 75%
of its dry weight and accounting for up to 80% of the myelin sheath. They play crucial roles

Int. J. Mol. Sci. 2023,24, 10021 9 of 17
in energy metabolism, signal transduction, and various other processes [
100
]. In the context
of AD, the elevated presence of free radicals leads to lipid peroxidation, which is closely
associated with the initial pathological changes observed in AD [
101
]. Furthermore, there is
evidence linking ROS to brain damage in AD [102]. Previous studies have shown that the
level of total free fatty acids in the hippocampus of AD patients is significantly decreased
and the level of ACSL4 is significantly increased. Furthermore, high levels of free MDA
and 4-hydroxynonenal (4-HNE) are detected in several brain regions, and GPX4 expression
is down-regulated, proving the existence of ferroptosis and lipid peroxidation in AD
brain [
103
]. The abnormal folding and aggregation of A
β
in the brain is one of the hallmark
pathological changes of Alzheimer’s disease [
104
]. It has been reported that A
β
oligomer
can cause long-term enhancement impairment in the hippocampus of experimental rats,
and abnormally activate microglia proinflammatory phenotype and complement system,
inducing neuroinflammation and synaptic loss. A
β
is potentially associated with lipid
peroxidation in ferroptosis [
104
], it has the ability to integrate into the lipid bilayer of
neurons, leading to the production of hydrogen peroxide. However, in the presence of
oxidation-reducing metal ions, such as Fe
2+
, a Fenton reaction can occur, resulting in the
generation of a substantial amount of ROS that further target unsaturated lipids. This
exacerbates oxidative damage to lipids, proteins, and DNA [
105
]. Praticòet al., observed
the accumulation of Aβthrough lipid peroxidation and oxidative stress in an APP mouse
model [
74
]. Gao et al., conducted experiments using tetrahydroxy stilbene glycoside (TSG)
on mouse models of AD and found that TSG reduced the formation and accumulation of
A
β
(Table 1). Furthermore, compared to the non-intervention group, the TSG-treated group
exhibited a certain reduction in indices associated with lipid peroxidation in ferroptosis [
75
].
4.4. ACSL4 in Parkinson’s Disease
Parkinson’s disease (PD) is a widespread chronic degenerative disorder that commonly
affects motor skills, language, and other functions of the central nervous system [
106
,
107
].
PD is characterized by the damage to dopamine (DA) neurons in the pars compactus
nigra (SNpc), which may result in muscle rigidity, static tremors, sleep disturbances, motor
retardation, abnormal postural reflexes, sensory disturbances, autonomic nervous system
dysfunction, and other clinical symptoms [76].
Through the assessment of PD patients, it has been observed that the iron content
in glial and dopaminergic neurons is abnormally elevated compared to that in healthy
individuals, and this elevation is positively associated with the severity of PD [
108
–
110
].
Research has identified the formation of Lewy bodies, composed mainly of
α
-synuclein
nucleoprotein [
111
,
112
], as a distinctive hallmark of PD, occurring within the cytoplasm
of substantia nigra neurons [
113
,
114
]. Notably,
α
-synuclein exhibits a strong affinity for
lipid binding. In addition,
α
-synuclein not only mediates the formation of membrane
PUFAs [115], but also regulate the metabolism of AA [77]. ACSL4 demonstrates a specific
preference for AA, and PUFA has the ability to induce α-synuclein aggregation [116,117].
Recent research has indicated that the inhibition of SP1 can confer neuroprotective
effects in PD models [
118
]. Additionally, Ma et al., demonstrated that SP1 has the abil-
ity to reverse the impact of repressor element-1 silencing transcription factor (REST) on
erastin-induced LUHMES cell viability, ROS production, ferroptosis, and neuronal damage,
implying that REST may alleviate PD by reducing SP1 activity [
118
]. Additionally, the
study revealed that the overexpression of REST down-regulates ACSL4 in erastin-induced
LUHMES cells [
118
]. The interaction between miR-494-3p and ACSL4, REST, or SP1 was ex-
amined using luciferin chromatin immunoprecipitation or EMSA. The results revealed that
the repression of miR-494-3p could prevent ferroptosis and neuronal damage by regulating
the SP1/ACSL4 axis in PD by targeting REST.REST is a downstream gene of miR-494-3p,
which can inhibit ferroptosis neuronal damage induced by SP1, ROS, and mitochondrial
damage in LUHMES cells [
118
]. Furthermore, Song et al., discovered that 1-methyl-4-
phenyl-1,2,3,6-tetrahydropyridine (MPTP) treatment significantly up-regulates ACSL4
expression and down-regulates GPX4 expression in PD mice (Table 1). Apoferritin [
119
]

Int. J. Mol. Sci. 2023,24, 10021 10 of 17
treatment leads to reduced ASCL4 expression and increased expression of ferroptosis sup-
pressor protein 1 (FSP1) [
76
]. Moreover, Yu et al., demonstrated that
β
-hydroxybutyrate
(BHB) directly affects the stability of ACSL4 mRNA through zinc finger protein 36 (ZFP36),
exerting inhibitory effects on ferroptosis [
77
] (Table 1). The aforementioned studies offer
insights for potential future PD treatments by targeting ACSL4 to inhibit ferroptosis [
109
].
4.5. ACSL4 in Spinal Cord Diseases
Spinal cord injury causes permanent or temporary changes in the function of the spinal
cord which can be divided into traumatic spinal cord injury (TSCI) and nontraumatic spinal
cord injury (NTSCI) [
120
]. The main symptoms include sensory–motor or autonomic nerve
dysfunction below the level of the spinal cord injury. TSCI is usually caused by external
physical shocks, such as car accidents, falls, sports, falling objects, or violent activities.
Globally, with the popularity of modern cars, the rise of various outdoor sports, and the
growth of the aging population, the incidence of TSCI presents an increasing and aging
trend.
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by
the progressive degeneration of motor neurons in the central nervous system, including
the brain and spinal cord. This degeneration leads to muscle paralysis, atrophy, and
functional impairment [
121
]. Although ALS and TSCI are distinct diseases, they share
certain similarities [
122
]. In rare cases, ALS can cause spinal cord injury, while TSCI can
result in motor neuron injury resembling ALS. Furthermore, both conditions are associated
with neurological damage and dysfunction, significantly impacting the affected individuals’
lives [
123
]. Edaravone shows promise as a potential therapeutic intervention by preventing
ferroptosis in ALS [124].
Edaravone, also known as 3-methyl-1-phenyl-2-pyrazolin-5-one, is a free radical
scavenger due to the lipophilicity of phenylmethyl, which allows edaravone to remain on
the membrane and scavenge lipid-reactive oxygen species [
125
,
126
]. By scavenging free
radicals, edaravone has the potential to mitigate oxidative stress and inhibit the activation of
ACSL4, and Yilin Pang and colleagues demonstrated that edaravone inhibits the ferroptosis
pathway following spinal cord injury in a contusion injury model [
54
]. 5-LOX and ACSL4
increased 2 days after injury, while edaravone significantly down-regulated their expression
and up-regulated GPX4/xCT in the acute phase of spinal cord injury [
54
]. There was no
significant change in the expression of 5-LOX and ACSL4 in each group 7 days after SCI,
suggesting that ferroptosis mainly occurred in the acute phase [
54
]. Edaravone regulates
GPX4/ ACSL4/5-LOX in the lower spinal segment of the lesion, and ACSL4 is expressed
in both the nucleus and cytoplasm of the injured spinal cord [54] (Table 1).
In addition, abnormalities in mitochondrial function and morphology have been ob-
served in ALS. In the context of neurodegenerative diseases, edaravone has demonstrated
a protective effect on mitochondria [
127
]. However, the precise mechanism underlying this
effect remains unclear. Considering that ACSL4 is localized to mitochondria-associated
membranes (MAMs), it is plausible that edaravone’s action on mitochondrial integrity
may prevent ACSL4 dysregulation or degradation [
128
]. Additionally, edaravone has been
shown to possess anti-inflammatory properties by inhibiting the production of inflam-
matory mediators. By attenuating the inflammatory response, edaravone may indirectly
modulate ACSL4 levels and potentially impact the pathogenesis of TSCI [129].
4.6. ACSL4 in Multiple Sclerosis
Multiple sclerosis (MS) is a disease characterized by inflammatory demyelination,
which involves the infiltration of immune cells into the central nervous system
(CNS)
[130,131]
, leading to recurrent demyelinating lesions with varying degrees of inflam-
mation, including inflammation throughout the entire lesion area, limited to the lesion
border or lack, and all of these were observed in MS patients [
132
]. Moreover, MS may cause
ongoing neurodegeneration (secondary progression), which leads to cumulative disability
over time [
133
]. To date, treatment of MS has reduced the frequency of relapses without

Int. J. Mol. Sci. 2023,24, 10021 11 of 17
affecting secondary progression. Iron acts as a co-factor for several enzymes that maintain
oligodendrocyte and myelin health, and may play a crucial role in remyelination [
134
].
Aberrant iron regulation in multiple sclerosis (MS) has been observed through magnetic
resonance imaging (MRI) and histological examinations, revealing iron deposition in gray
matter and a decrease in normal white matter [
132
]. These findings suggest a potential
association between MS and ferroptosis.
Given that MS is an immune-mediated disease with similarities to autoimmune dis-
orders, several drugs for MS have been developed using the experimental autoimmune
encephalitis (EAE) model. Genes implicated in ferroptosis were examined in the spinal cord
of EAE mice. The results indicated significant alterations in key ferroptosis-related genes,
including ACSL4 and GPX4. Furthermore, elevated levels of ACSL4 were detected prior to
the onset of clinical symptoms in EAE mice, and remained high in the chronic active areas
of MS patients. Notably, during the peak of EAE, the expression of ACSL4 was significantly
increased [
135
]. Knocking down the ACSL4 gene considerably reduced the severity of EAE
and the clinical score of EAE mice, indicating that ACSL4-mediated ferroptosis provoked
inflammation and promoted T-cell activation and CNS infiltration (Table 1). Therefore, the
inhibition of ACSL4 suppresses ferroptosis, which provides a potential therapeutic target
for the treatment of secondary neurodegeneration, but further clinical trials are needed to
test the efficacy of the drug [78,136].
5. Conclusions
Ferroptosis is an iron-dependent and novel form of regulated cell death in which lipid
peroxide levels accumulate to lethal levels. A variety of diseases, including nervous system
disorders and injuries, are associated with ferroptosis. According to reports on ferroptosis,
ACSL4 is one of the important enzymes in the ferroptosis pathway, which can be used as a
biomarker for ferroptosis and can promote ferroptosis. On the one hand, it can promote
tumor cell death; on the other hand, it also illustrates its role in disease-induced ferroptosis.
The pro-ferroptosis effect of ACSL4 was mainly due to its critical role in AA and AdA
metabolism and lipid peroxidation. Due to the different content and distribution of fatty
acids in different tumor cells and different tissue cells, as well as the different distribution
and content of ACSL4 and other related lipid metabolism enzymes, the sensitivity of
different tissues and different cells to ferroptosis varies greatly [
135
,
137
]. For example,
ACSL4 is highly expressed in patients with liver cancer and colon cancer, and the higher the
expression level is, the worse the prognosis is, while patients with gastric cancer [
138
] tend
to have a low expression of ACSL4. This is a very important clue for how to use ferroptosis
to inhibit tumor cells or inhibit ferroptosis to improve the prognosis of neurological diseases.
At present, it is urgent to accelerate the process of ferroptosis treatment of tumors without
toxic side effects on normal tissues through the pathological tissue analysis of tumors, or by
further exploring the time window of ACSL4 inhibitors or other ferroptosis inhibitors after
ischemia-reperfusion injury [
139
–
141
]. In addition, the possibility that ACSL4 plays a role
in genetic disorders cannot be ignored, as ACSL4 deletion mutations have been reported
in a family with Alport disease (also known as eye-ear-kidney syndrome). Moreover, the
specifics of ACSL4 deletion and complex disorders remain to be investigated. Finally, there
are still few studies on the lipid peroxidation pathway associated with ACSL4 in TBI. As a
type of injury with a high mortality rate, the role of ACSL4 in TBI needs to be further and
more widely explored.
Author Contributions:
B.J., J.L., Y.S. and C.L. carried out the studies of literature research and
performed the acquisition of data and writing in manuscript preparation. B.J., J.L. and Y.S. proofread
the manuscript and gave important comments from their area of expertise. C.L. supervised the
development of work, gave critical revisions, and edited the manuscript. All authors have read and
agreed to the published version of the manuscript.
Funding:
This work was supported by the National Natural Science Foundation of China (82271409,
81971163), the outstanding young backbone teacher of the “Blue Project” in Jiangsu Province

Int. J. Mol. Sci. 2023,24, 10021 12 of 17
(SR13450121), a Project Funded by the Priority Academic Program Development of Jiangsu Higher
Education Institutions (PAPD), the Key Program of Educational Commission of Anhui Province
(KJ2021A0826), and National Training Program of Innovation and Entrepreneurship for Undergradu-
ate (2021suda046).
Institutional Review Board Statement: Not applicable.
Informed Consent Statement: Not applicable.
Data Availability Statement:
Data sharing is not applicable to this article as no datasets were
generated or analyzed during the current study.
Conflicts of Interest: The authors declare that they have no competing interest.
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