Design and synthesis of acetaminophen probe APAP-P1 for identification of the toxicity targets thioredoxin reductase-1 in HepaRG cells

Article abstract of DOI:10.1039/c9ra00483a

Drug-induced liver injury is one of the main causes of drug non-approval and drug withdrawal by the Food and Drug Administration (FDA). Acetaminophen (APAP) is a widely used non-steroidal anti-inflammatory drug for treating fever and headache. APAP is con

Full text of DOI:10.1039/c9ra00483a

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PAPER
Design and synthesis of acetaminophen probe
APAP-P1 for identification of the toxicity targets
thioredoxin reductase-1 in HepaRG cells†
abcde
Cite this: RSC Adv., 2019, 9, 15224
Shan Wang,
‡
Yu Tian,‡abcde Shan Lu,abcde Ruiying Wang,abcde Hai Shang,abcde
abcde
abcde
Xuelian Zhang,abcde Chenyang Zhang,abcde Guibo Sun,
Xudong Xu
*
*
abcde
*
and Xiaobo Sun
Drug-induced liver injury is one of the main causes of drug non-approval and drug withdrawal by the Food
and Drug Administration (FDA). Acetaminophen (APAP) is a widely used non-steroidal anti-inflammatory
drug for treating fever and headache. APAP is considered safe at therapeutic doses; however, there have
been reports of acute liver injury following the administration of APAP. To explore APAP hepatotoxicity
and its mechanisms, we designed and synthesized a new click chemistry probe, APAP-P1, in our current
study. We introduced the PEG-azide probe linker into the acetyl group of acetaminophen. First, we
evaluated the probe toxicity in HepaRG cells and found that it still retained hepatotoxicity. We also found
that this probe APAP-P1 can be metabolized by HepaRG cells. This demonstrated that the APAP-P1
probe still kept its metabolism characteristics. Using this probe, we pulled down its potential targets in
vivo and in vitro. APAP can directly target TrxR1; thus, we tested for this interaction by Western blotting
of pull-down proteins. The results showed that APAP-P1 can pull down TrxR1 in vivo and in vitro.
Received 20th January 2019
Accepted 21st April 2019
DOI: 10.1039/c9ra00483a
rsc.li/rsc-advances
metabolism to form the reactive electrophile N-acetyl-p-benzo-
quinone imine (NAPQI), which causes extensive and rapid
Introduction
glutathione depletion, mitochondrial dysfunction, oxidant stress,
peroxynitrite formation and nuclear DNA fragmentation in
hepatocytes.1,7–9 Its molecular toxicology was proposed to be
initiated by reactive oxygen species (ROS) formation in the
mitochondria, leading to the subsequent activation of apoptosis
signalling-regulating kinase 1 (ASK1) and the c-Jun N-terminal
kinase (JNK) pathway.10,11 Thioredoxin reductase-1 (TrxR1),
encoded by the Txnrd1 gene, is a NADPH-dependent enzyme and
is known to be related to oxidative stress and the regulation of
cell growth and development. Some studies have found that the
GSH- or TrxR1-dependent redox pathway can independently
support hepatocyte proliferation during liver growth.12 Previous
research has found that NAPQI directly inactivates TrxR1, which
may be associated with enhanced Nrf2 activity.13,14 TrxR1 is
important for attenuating the activation of apoptosis signaling-
regulating kinase 1 (ASK1) and the c-JunN-terminal kinase
(JNK) pathway, which is caused by high doses of APAP.15 The Trx
system impacts bioenergetics and drug metabolism, and some
studies have indicated it to be a potential marker of DILI, as in
the case of anti-tuberculosis drugs.16,17
Drug-induced liver injury (DILI) is an unpredictable adverse drug
reaction that affects only a small subset of treated patients and
remains an increasingly recognized cause of hepatotoxicity and
liver failure worldwide.1–3 Acetaminophen (APAP) is a widely used
agent for the treatment of pain and fever around the world and is
considered safe at therapeutic doses; however, overdose can
cause severe hepatotoxicity leading to acute liver failure, which is
the most common cause of drug-induced liver damage in the
world.4,5 APAP causes potentially fatal hepatocellular necrosis
when taken in nontherapeutic doses.6 APAP can undergo
aBeijing Key Laboratory of Innovative Drug Discovery of Traditional Chinese Medicine
(Natural Medicine) and Translational Medicine, Institute of Medicinal Plant
Development, Chinese Academy of Medical Sciences
& Peking Union Medical
College, Beijing 100193, P. R. China. E-mail: sun_xiaobo163@163.com
bKey Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal
Medicine, Ministry of Education, Beijing 100193, P. R. China
cKey Laboratory of Efficacy Evaluation of Chinese Medicine against Glycolipid
Metabolic Disorders, State Administration of Traditional Chinese Medicine, Beijing
100193, P. R. China
dZhong guan cun Open Laboratory of the Research and Development of Natural
Medicine and Health Products, Beijing 100193, P. R. China
eKey Laboratory of New Drug Discovery Based on Classic Chinese Medicine
Prescription, Beijing 100193, P. R. China
HepaRG cells express most of the enzymes and transcription
factors involved in xenobiotic biotransformation and transport
and have been shown to be a valuable model for studying the
mechanism of hepatotoxicity induced by drugs and toxins.18
Research has demonstrated that HepaRG cells can be used to
explore the mechanisms of APAP hepatotoxicity.19 APAP is
† Electronic supplementary information (ESI) available. See DOI:
10.1039/c9ra00483a
‡ These two authors contributed equally to this paper.
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converted to the reactive intermediate NAPQI in HepaRG cells, experiments. First, to investigate the cytotoxic effects of various
which has been thought to be the toxin for hepatotoxicity.20 In concentrations of APAP and APAP-P1 in the HepaRG cell line,
our research, we chose the HepaRG cell line as our in vitro we performed MTT assays aer 24 h of treatment, and the
model to evaluate the liver damage caused by APAP.
results showed that both APAP and APAP-P1 inhibited cell
Chemical proteomics is a growing area of chemical biology viability in a dose-dependent manner (Fig. 1). The results
that seeks to design small molecule probes to understand showed that APAP-P1 cytotoxicity was lower than that of APAP at
protein function.21 Activity-based protein proling (ABPP) has the same concentration; however, APAP-P1 had similar effects
emerged as a powerful functional chemical proteomic strategy as APAP. This demonstrated that APAP-P1 can still maintain
that enables global proling of proteome reactivity toward cytotoxicity aer inducing the PEG-azide probe linker into the
bioactive small molecules in complex biological and/or patho- acetyl group of APAP. With this probe generated, we moved
logical processes.22 Activity-based probes (ABPs) usually consist forward to APAP-P1 cytotoxicity target identication.
of three fundamental building blocks with distinct functions:
Metabolism of APAP-P1. A previous study demonstrated that
(1) an active warhead (WH) that contains reactive groups that APAP can be metabolized to NAPQI in HepaRG cells,20 NAPQI
target the conserved mechanistic or structural feature of a set of was the main hepatotoxic intermediate. To explore whether
proteins; (2) a reporter tag for identication and purication of APAP-P1 can be metabolized to NAPQI analogue by HepaRG
modied proteins; and (3) a linker region that can modulate the cells, we incubated 5 mM APAP-P1 with HepaRG cells for 24 h
reactivity and specicity of the reactive group and binding and then collected the cells and medium for UPLC-Q-TOF/MS
group while providing enough space between the reporter and analysis. Our results showed that the APAP-P1 (3) probe was
the reactive or binding group.23,24 In this study, we designed and metabolized to the toxic metabolite APAP-P1 (4) (Scheme 2).
synthesized a new ABPP probe, APAP-P1, for the identication This also demonstrated that the APAP-P1 probe retained toxic
of APAP toxicity targets in HepaRG cells.
characteristics aer introduction of the PEG-azide probe linker.
So these above results demonstrated APAP-P1 can be used for
hepatotoxic targets shing and identication.
Gel-based CC-ABPP proling of APAP-interacting proteins in
cell lysate and living cells. With the APAP-P1 probe in hand, we
then evaluated its labelling efficiency in cell lysate and living
cells by silver staining. The workow in Fig. 2A lists the APAP-P1
CC-ABPP experiment step-by-step in HepaRG cell lysate. Hep-
aRG cell lysates were treated with different concentrations of
APAP-P1 (1.25, 2.5, 5 mM) for 1 h to form the probe–protein
complex. The labelled cell lysates were conjugated with biotin-
alkynyl via CuAAC and separated by SDS-PAGE. The results
revealed clear and distinct labelling protein proling for
different concentration probes (Fig. 2C), which suggested that
the APAP-P1 probe could pull down the proteomes in a dose-
dependent manner. APAP can be converted to the reactive
Results and discussion
Chemistry
As illustrated in Scheme 1, commercially available p-amino-
phenol (1) was treated with tert-butyldimethylsilyl chloride
(TBSCl) and imidazole in dry tetrahydrofuran (THF) to obtain
a good yield of intermediate 2. Intermediate 2 reacted with
succinic anhydride (SAA) in organic alkali conditions with
dimethylaminopyridine (DMAP) to provide compound 3, which
was subjected to an acylation reaction to obtain compound 4 in
the presence of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide
hydrochloride (EDCI) and DMAP. Then, APAP-P1 was obtained
via the deprotection reaction of intermediate 4 with tetrabuty-
lammonium uoride in THF solution.
Cytotoxicity of APAP-P1 Administered to HepaRG cell line.
To study the mechanism of APAP hepatotoxicity in humans, the
cell line HepaRG is a useful human model for the study of APAP-
induced liver injury.19 Aer the probe design, we needed to
evaluate its associated activities to ensure that this linker didn't
change its hepatotoxicity, so the probe could be used for further
Fig. 1 Evaluation of the cytotoxicity of APAP and APAP-P1 in HepaRG
cells. Cell viability of HepaRG cells incubated with different concen-
trations (1.25, 2.5, 5 mM) of APAP and the same concentrations (1.25,
Scheme 1 The synthesis of toxic probe APAP-P1. Reagents and 2.5, 5 mM) of APAP-P1 for 24 h. The data are expressed as the mean ꢀ
conditions: (a) TBSCl, imidazole, THF; (b) succinic anhydride (SAA), SD from three independent experiments. ##P < 0.01 versus the same
DMAP, DCM; (c) EDCI, DMAP, DCM; (d) TBAF, THF.
concentration group, **P < 0.01 versus control group.
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binding model. APAP-P1 was docked into the active pocket of
3QFA. The most reasonable binding mode was chosen based on
the compatibility with the reported protein structure and
binding data, as well as energetic considerations. The in silico-
predicted data showed that APAP-P1 was located in the pocket
of the TrxR1 3D structure (Fig. 3B), and the position of APAP-P1
in the pocket of TrxR1 is depicted. The surface of APAP-P1
possesses the same orientation, which could exactly map the
pocket. Hydrogen bonds were formed at Ser-22, Asp-42, Thr-58,
Cys-64, and Gly-132 in TrxR1 (Fig. 3C), which might be the key
residues in the interaction between APAP-P1 and TrxR1.
Scheme 2 APAP and APAP-P1 metabolism pathway.
Experimental
Chemistry
Procedure for the synthesis of intermediate 2. To a solution
of p-aminophenol (1) (3.0 g, 27.5 mmol) in dry DCM (20 mL),
TBSCl (5.4 g, 36.1 mmol) and imidazole (2.96 g, 43.5 mmol) were
ꢁ
added at 0 C. Then the reaction mixture was stirred at room
temperature for 3 h. Reaction was monitored by TLC. The crude
mixture was separated and the water layer was extracted with
DCM (3 ꢂ 20 mL). The combined organic layer was evaporated
and puried through column chromatography (eluent : PE-
EtOAc, 1 : 1) to offer pure white solid compound 2, 93% yield;
1H-NMR (600 MHz, CDCl3) d: 6.69–6.68 (m, 2H, Ph-H), 6.58–6.56
(m, 2H, Ph-H), 3.45 (s, 2H, NH2), 1.01 (s, 9H, C-(CH3)3), 0.19 (m,
6H, Si-(CH3)2); 13C-NMR (150 MHz, CDCl3) d: 148.0, 140.4, 120.6,
116.3, 25.8, 18.2, ꢃ4.48; HRMS (ESI): calcd for [M + H]+
C12H22NOSi: 224.1471, found 224.1484.
Procedure for the synthesis of intermediate 3. To a solution
of compound 2 (0.5 g, 2.25 mmol) in dry DCM (10 mL), and
succinic anhydride (0.25 g, 2.48 mmol), catalytic amount of
DMAP (27.5 mg, 0.225 mmol) and triethylamine (0.62 mL, 4.5
mmol) were added. Reaction was monitored by TLC. Then the
reaction mixture was stirred at room temperature for 12 h until
its completion. The crude mixture was evaporated and puried
through column chromatography (eluent : EtOAc) to offer pure
white solid compound 3, 81% yield; 1H-NMR (600 MHz, CDCl3)
d: 8.29 (s, 1H, NH), 7.32–7.31 (m, 2H, Ph-H), 6.72–6.70 (m, 2H,
Ph-H), 2.63 (m, 2H, CH2COOH), 2.53 (m, 2H, CH2CONH), 0.95
(s, 9H, C-(CH3)3), 0.14 (m, 6H, Si-(CH3)2); 13C-NMR (150 MHz,
Fig. 2 Gel-based CC-ABPP profiling of APAP-interacting proteins in cell
lysate and living cells. (A) Workflow for the gel-based CC-ABPP profiling
of APAP-P1 in HepaRG cell lysate. (B) Workflow for the gel-based CC-
ABPP profiling of APAP-P1 in living HepaRG cells. (C) Protein profiling of
the APAP-P1 probe in HepaRG cell lysates was separated by SDS-PAGE
and stained by silver staining. (D) Protein profiling of the APAP-P1 probe
in living HepaRG cells was separated by SDS-PAGE and stained by silver
staining. Identification of TrxR1 as the APAP potential toxicity target.
intermediate NAPQI. To explore its protein proling in cells, we
also designed a CC-ABPP experiment in living HepaRG cells, as
shown in Fig. 2B. We rst incubated the probe with HepaRG
cells for 24 h, then the labelled protein–probe complex were
conjugated with biotin-alkynyl via CuAAC and the proteins were
pulled down and separated by SDS-PAGE. Finally, we found that
5 mM APAP-P1 pulled down a specic 42–55 kDa band.
From our results, we found that APAP-P1 has a similar
protein proling in HepaRG cell lysates and in HepaRG cells.
APAP-P1 can pull down 42–55 kDa bands; however, there are
obvious differences. For the cell lysate, the probe mainly pulled
down the 100 kDa protein bands, but 42–55 kDa bands were
more obvious in cells. These results demonstrated that aer
APAP-P1 metabolism, its interaction protein prole was
changed. This suggests that we should focus more on the APAP
metabolism for hepatotoxicity. With this useful probe, we will
perform additional in vivo research in the future.
Identication of TrxR1 as the APAP potential toxicity target.
Previous studies have shown that TrxR1 is a potential target for
Fig. 3 Identification of Txnrd1 as the APAP potential toxicity target. (A)
NAPQI.15,25 To explore whether the probe could be used for Western blotting validation of the APAP-P1 target TrxR1 in cell lysates
and in cells after performing a pull-down assay. (B) Binding mode of
APAP-P1 in the 3D structure of TrxR1. (C) Ser-22, Asp-42, Thr-58, Cys-
64, and Gly-132 may be the key residues in the interaction between
APAP-P1 and TrxR1.
further in vivo research, we tested the APAP-P1 pull-down
proteins TrxR1. APAP-P1 pulled down TrxR1 both in cells and
in cell lysate (Fig. 3A). We used the docking assay to predict the
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CDCl3) d: 177.9, 170.9, 152.5, 131.5, 122.0, 120.4, 31.8, 30.1, alignment of peak intensities, and a list of m/z and retention times
25.8, 18.3, ꢃ4.35; HRMS (ESI): calcd for [M + Na]+ C16H25- with corresponding peaks was provided for all metabolites in every
NNaO4Si: 346.1451, found 346.1476.
sample in the data set.
Procedure for the synthesis of intermediate 4. A mixture of
Docking research. Docking experiment was employed to
compound 3 (0.23 g, 0.68 mmol), DMAP (8.3 mg, 0.068 mmol) explore the binding modes of APAP-P1 with TrxR1 by MOE so-
and EDCI (0.19 g, 1 mmol) was stirred in dry DCM 10 mL, then ware (Chemical Computing Group, Inc). The 3D structure of APAP-
198 mL amine (1 mmol) was dropped, and stirred under N2 until P1 was energy minimized by MOE using the MMFF94x force eld,
completion. The mixture was evaporated and puried through and the protein TrxR1 was energy minimized by MOE using the
column chromatography (eluent : DCM-MeOH, 20 : 1) to offer Amber 10 EHT force eld. The interactive forces between the
1
pure white solid compound 4, 65% yield; H-NMR (600 MHz, ligand and receptor primarily included hydrogen bonding,
CDCl3) d: 8.66 (s, 1H, CONHPh), 7.37–7.35 (m, 2H, Ph-H), 6.75– aromatic interactions and hydrophobic interactions. The residues
˚
6.73 (m, 2H, Ph-H), 6.67 (t, J ¼ 5.7 Hz, 1H, CH2CONH), 3.66–3.57 within eight A from the ligand were set to be exible. No explicit
(m, 10H, CH2(OCH2CH2)2), 3.53–3.51 (m, 2H, CH2O), 3.44–3.42 water molecules were added during the docking simulation, and
(m, 2H, CH2N3), 3.38–3.37 (m, 2H, CONHCH2), 2.67–2.65 (m, the solvation and entropic effects were not taken into account.
2H, CONHCH2), 2.61–2.59 (m, 2H, CH2CONH), 0.95 (s, 9H, C-
(CH3)3), 0.15 (m, 6H, Si-(CH3)2); 13C-NMR (150 MHz, CDCl3) d:
172.7, 170.5, 152.0, 132.2, 121.3, 120.3, 70.7, 70.7, 70.6, 70.3,
Biological studies
70.1, 69.8, 50.7, 39.5, 32.9, 31.7, 25.8, 18.3, ꢃ4.38; HRMS (ESI):
Cell culture and treatment. HepaRG cells were obtained
calcd for [M + Na]+ C24H41N5NaO6Si: 546.2724, found 546.2753. from Guan Dao Biotechnology (Shanghai, China) and cultured
Procedure for the synthesis of intermediate APAP-P1. To in RPMI-1640 medium supplemented with 10% (v/v) fetal
a solution of compound 4 (0.24 g, 0.47 mmol) in dry tetrahydrofuran bovine serum (FBS) (Gibco, Thermo Fisher Scientic, Waltham,
(THF) 5 mL, TBAF (321 mL, 1.17 mmol) was slowly dropped at 0 ꢁC MA, USA), 100 U mLꢃ1 penicillin and 100 mg mLꢃ1 strepto-
and reacted for 2 h. When complete, the crude product was evap- mycin. The media and supplements were purchased from Gibco
orated and subjected to column chromatography (eluent : EtOAc), containing 5% CO2 at 37 ꢁC. APAP and APAP-P1 were dissolved
1
to offer pure white solid APAP-P1, 90% yield; H-NMR (600 MHz, in DMSO and incubated in FBS-free complete medium with
CDCl3) d: 8.68 (s, 1H, Ph-OH), 7.92 (s, 1H, CONHPh), 7.20–7.19 (m, a nal DMSO concentration of 1%.
2H, Ph-H), 6.74 (t, J ¼ 5.3 Hz, 1H, CH2CONH), 6.69–6.68 (m, 2H, Ph-
Cell viability. Cell viability was determined using the MTT (3-
H), 3.63–3.55 (m, 10H, CH2(OCH2CH2)2), 3.48–3.47 (m, 2H, CH2O), (4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium, Amresco,
3.38–3.33 (m, 4H, CH2N3, CONHCH2), 2.64–2.62 (m, 2H, 0973) assay as previously described.27 Briey, HepaRG cells were
CONHCH2), 2.56–2.54 (m, 2H, CH2CONH); 13C-NMR (150 MHz, plated on 96-well plates at a density of 8 ꢂ 104 cells per well and
CDCl3) d: 172.9, 170.9, 153.4, 130.5, 122.5, 115.7, 70.7, 70.7, 70.6, then grown at 37 ꢁC for 24 h. The cells were pre-treated with
70.3, 70.1, 69.7, 50.8, 39.6, 32.5, 31.5; HRMS (ESI): calcd for [M + APAP or APAP-P1 with different concentrations for 24 h. Twenty
Na]+ C18H27N5NaO6: 432.1859, found 432.1875.
microliters of MTT (5 mg mLꢃ1) was added to each well and
Metabolism research by UPLC-Q-TOF/MS analysis. To incubated for 4 h. The medium was removed, and the formazan
explore the metabolism of APAP-P1 in HepaRG cells, we incubated crystals were dissolved with dimethyl sulfoxide (DMSO). The
DMSO or 5 mM APAP-P1 with HepaRG cells for 24 h, then collected absorbance was measured at 570 nm on a microplate reader
the cells and medium.20 All of the in vitro incubation samples were (TECAN Innite M1000, Grodig, Austria).
¨
prepared by the same methods as follows. To a 200 mL aliquot of
Probe labelling of HepaRG cell lysate for biotin–streptavidin
the in vitro incubations, 200 mL of ethanol was added. This sample pull-down assay. HepaRG at 100% conuence were lysed in PBS
was vortex-mixed and centrifuged at 14 000g for 5 min. The buffer, and the protein concentration was adjusted to 2 mg mLꢃ1
.
supernatant was transferred into a glass tube, evaporated to The experimental and control samples were incubated with 5 mL
dryness under a stream of nitrogen.26 Then the dried metabolites of 125, 250, 500 mmol Lꢃ1 APAP-P1 or 5 mL DMSO into 500 mL
extract was dissolved in 300 mL of methanol, and an aliquot of 2 mL proteomes at room temperature for 1 h. Then, the proteomes
was injected for UPLC/MS analysis. The lysate and cell samples were labelled with biotin-alkynyl (100 mM), TCEP (1 mM), TBTA
were analysed on a Waters Acquity™ Ultra Performance LC system (100 mM), and CuSO4$5H2O (1 mM) for 2 h. Seven hundred y
(Waters Corporation, Milford, MA, USA) equipped with a BEH C18 microliters of cold MeOH were added and sonicated for 3–4 s
column (100 mm ꢂ 2.1 mm, 1.7 mm). The autosampler tempera- using a probe sonicator (30% power level) at 4 ꢁC to re-suspend
ture was kept at 4 ꢁC and the column compartment was set at the protein. The samples were then centrifuged for 10 min at
40 ꢁC. The mobile phase was composed of solvents A (2 mM 6500 ꢂ g at 4 C and the supernatant was removed. The pellets
ꢁ
ammonium acetate in 95% H2O/5% acetonitrile + 0.1% acetic were dissolved in PBS containing 1.2% SDS via sonication and
acid) and B (2 mM ammonium acetate in 95% acetonitrile/5% H2O then diluted with PBS containing 0.2% SDS. The samples were
+ 0.1% acetic acid). A Waters SYNAPT G2 HDMS (Waters Corp., incubated with streptavidin beads for 2 h at room temperature
Manchester, UK) was used to carry out the mass spectrometry with and washed with PBS several times. Samples were denatured by
an electrospray ionization source (ESI) operating in positive ion heating in 2 ꢂ SDS-loading buffer and analysed by SDS-PAGE.
modes. The UPLC-Q-TOF/MS raw data were processed by Mar- The resulting bands were visualized by silver staining.
kerLynx Applications Manager version 4.1 (Waters, Manchester,
Probe labelling in HepaRG cells for biotin–streptavidin pull-
UK). The procedure included integration, normalization, and down assay. HepaRG at 80% conuence were treated with 0,
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1.25, 2.5, 5 mmol Lꢃ1 APAP-P1 for 24 h. Then the cells were lysed
in PBS buffer, and the concentration was adjusted to 2 mg mLꢃ1
for biotin–streptavidin pull-down assay just like cell lysate.
Western blotting. Proteomes from pull-down assay were
used for Western blot experiment. 10 mL samples were sub-
jected to SDS-PAGE electrophoresis and transferred to NC
membranes. The membranes were blocked with 5% (w/v)
non-fat dried milk for 2 h and incubated with various
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In conclusion, we designed and synthesized one new powerful
probe APAP-P1, introducing the PEG-azide probe linker into the
acetyl group of acetaminophen. This probe maintained hepato-
toxicity in HepaRG cells by MTT assay, and demonstrated that the
PEG-azide probe linker does not change APAP hepatotoxicity.
Metabolite of APAP-P1 by HepaRG cells showed this probe still can
be metabolised to hepatotoxic intermediate. Results above proved
APAP-P1 worked well in HepaRG cells, so we can use this probe for
target shing and identication. By CC-ABPP pull-down assays in
both cell lysate and cells, we identied their protein proles. There
was some difference under the two conditions. This change is due
to the metabolism of APAP-P1. This is similar to the process of
APAP in vivo. TrxR1 has been proved NAPQI hepatotoxicity target in
previous research, nally, we also identied that APAP-P1 can
target TrxR1 by pull-down protein Western blot assay and thus
APAP-P1 can be used for further research in vivo.
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Conflicts of interest
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The authors conrm that there are no conicts of interest.
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Acknowledgements
This work was supported by the National Science and Technology
Major Project (Grant No. 2015ZX09501004-001-003), the Special
Research Project for TCM (Grant No. 201507004), and the CAMS
Innovation Fund for Medical Science (CIFMS) (Grant No. 2016-I2M-
1-012), Beijing Natural Science Foundation (Grant No. 7192129).
Notes and references
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15228 | RSC Adv., 2019, 9, 15224–15228
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