Therapeutic targeting of hepatic ACSL4 ameliorates NASH in mice

Duan, Jingjing; Wang, Zhuo; Duan, Ran; Yang, Chenxinhui; Zhao, Ruolin; Feng, Qi; Qin, Yuanyuan; Jiang, Jingwei; Gu, Shou-Yong; Lv, Kaiyan; Zhang, Libo; He, Bi-Xia; Birnbaumer, Lutz; Yang, Song; Chen, Zhen; Yang, Yong

doi:10.1002/hep.32148

Cited by 47 publications

(51 citation statements)

References 43 publications

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“…ACSL4 is the crucial metabolic enzyme responsible for esterifying long-chain polyunsaturated fatty acid (PUFA) to PUFA-CoA for phospholipid biosynthesis and is also an essential proferroptotic protein dominating cellular sensitivity to ferroptosis. 24,25 We first inhibited ACSL4 using Rosiglitazone (ROSI), a previously demonstrated inhibitor, and confirmed that it phenocopied the effect of SIL in protecting HepG2 cells from RSL3-induced ferroptosis (Figure 2E). Then, considering the multitarget nature of ROSI, we silenced ACSL4 using siRNA and confirmed that ACSL4 knockdown abolished the antiferroptotic function of SIL (Figure 2E and Figure S3A).…”

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confidence: 67%

Living Cell-Target Responsive Accessibility Profiling Reveals Silibinin Targeting ACSL4 for Combating Ferroptosis

et al. 2022

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We report a living cell-target responsive accessibility profiling (LC-TRAP) approach to identify the targetome of silibinin (SIL), a well-established hepatoprotective natural product (NP), in HepG2 cells. Proteins showing accessibility changes, probed by covalent lysine labeling reagents and leveraged by multiplexed quantitative proteomics, following the administration of SIL to the living cells were assigned as potential targets. Among the assigned targetome, ACSL4, an enzyme essential for ferroptosis induction, might be involved in the hepatoprotective effects of SIL and hence was intensively validated. We first demonstrated that SIL protected HepG2 cells from ferroptosis dependent on ACSL4. Then, we used biophysical assays and a SIL-derivatized chemical probe to corroborate that SIL can bind to ACSL4. The ensuing enzymatic assays showed that SIL inhibited ACSL4 enzymatic activity, thereby mitigating the ACSL4-mediated ferroptosis. As such, we revealed that ACSL4 inhibition, using SIL as a model compound, represents a promising hepatoprotective strategy. Further, since TRAP probes the accessibility changes of reactive proteinaceous lysines, it can pinpoint the proximal regions where the ligand engagement may occur. Thus, the LC-TRAP analysis of SIL, the newly discovered ligand of ACSL4, and arachidonic acid (AA), the substrate, intriguingly showed that SIL and AA both affected the conformation of the K536-proximal region of ACSL4, albeit through distinct binding patterns. Collectively, we describe a straightforward LC-TRAP workflow that does not involve ligand-derived probe synthesis and is widely applicable to target discovery of NPs.

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confidence: 67%

Living Cell-Target Responsive Accessibility Profiling Reveals Silibinin Targeting ACSL4 for Combating Ferroptosis

et al. 2022

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“…We herein confirm this crucial role of ACSL4 as mediator of ferroptotic cell death, specifically in mouse hepatocytes. In line with a disease-aggravating role of ferroptosis during chronic liver injury, hepatocyte-specific deletion of Acsl4 was recently shown to reduce disease severity, in particular liver steatosis and fibrosis, in two diet-based mouse models of NASH [ 45 ]. Similarly, we observed decreased liver fibrosis in a toxic injury model of HCC (i.e., DEN-CCl 4 ).…”

Section: Discussionmentioning

confidence: 99%

ACSL4-dependent ferroptosis does not represent a tumor-suppressive mechanism but ACSL4 rather promotes liver cancer progression

et al. 2022

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Ferroptosis is a novel type of programmed cell death that differs from apoptosis in that it involves iron-dependent peroxidation of membrane phospholipids. Its role in a variety of human disorders, including cancer has been hypothesized in recent years. While it may function as an endogenous tumor suppressor in a variety of cancers, its role during initiation and progression of liver cancer, particularly hepatocellular carcinoma (HCC), is yet unknown. Because HCC is most commonly found in chronically injured livers, we utilized two well-established mouse models of chronic injury-dependent HCC formation: Treatment with streptozotocin and high-fat diet as metabolic injury model, as well as treatment with diethylnitrosamine and carbon tetrachloride as toxic injury model. We used mice with hepatocyte-specific deletion of Acsl4, a key mediator of ferroptosis, to explore the significance of ferroptotic cell death in hepatocytes, the cell type of origin for HCC. Surprisingly, preventing ferroptotic cell death in hepatocytes by deleting Acsl4 does not increase the formation of HCC. Furthermore, Acsl4-deficient livers display less fibrosis and proliferation, especially in the HCC model of toxic damage. Intriguingly, in this model, the absence of ACSL4-dependent processes such as ferroptosis significantly slow down the growth of HCC. These findings suggest that during HCC formation in a chronically injured liver, ferroptotic cell death is not an endogenous tumor-suppressive mechanism. Instead, we find that ACSL4-dependent processes have an unanticipated cancer-promoting effect during HCC formation, which is most likely due to aggravated liver damage as demonstrated by increased hepatic fibrosis. Previous studies suggested that ferroptosis might have beneficial effects for patients during HCC therapy. As a result, during HCC progression and therapy, ferroptosis may have both cancer-promoting and cancer-inhibitory effects, respectively.

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“…However, this decrease in hepatic ACSL4 in NAFLD/NASH may be restricted to rodent models, as increased ACSL4 has been identified in human NAFLD (38, 39). And although we and others (36) observe decreased ACSL4 in rodent models of NAFLD/NASH, a recent report described that ACSL4 deletion or pharmacologic inhibition in mice protected from NASH primarily by enhancing fat oxidation (39). Thus, more studies are required to gain a better understanding of the importance of ACSL4 and arachidonoyl-CoA in both humans and rodent models of NASH.…”

Section: Discussionmentioning

confidence: 99%

“…Interestingly, free arachidonic acid causes ACSL4 to be ubiquitinated and degraded, leading to decreased ACSL4 protein expression (36, 37). However, this decrease in hepatic ACSL4 in NAFLD/NASH may be restricted to rodent models, as increased ACSL4 has been identified in human NAFLD (38, 39). And although we and others (36) observe decreased ACSL4 in rodent models of NAFLD/NASH, a recent report described that ACSL4 deletion or pharmacologic inhibition in mice protected from NASH primarily by enhancing fat oxidation (39).…”

Section: Discussionmentioning

confidence: 99%

Enhancing Hepatic MBOAT7 Expression Does Not Improve Nonalcoholic Steatohepatitis in Mice

Sharpe

Pyles

Hallcox

et al. 2022

Preprint

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Background & Aims Genetic analyses of human NASH have revealed polymorphisms near the membrane bound O-acyl transferase domain containing 7 (MBOAT7) gene associated with worsened liver injury. NAFLD/NASH also appears to decrease MBOAT7 expression or activity independent of these polymorphisms. Thus, we hypothesized that enhancing MBOAT7 function in NASH would improve pathology. Approach & Results Male C57BL6/J mice were infected with adeno-associated virus 8 (AAV8) expressing MBOAT7 under control of the hepatocyte-specific thyroid hormone-binding globulin promoter, or control virus expressing green fluorescent protein (GFP). Mice were infected after NASH induction with either choline-deficient high-fat diet or Gubra Amylin NASH diet and compared to low-fat fed control mice. Both NASH diets increased liver weights, liver triglycerides, and plasma alanine and aspartate aminotransferase (ALT and AST) markers of liver injury, which were modestly yet significantly improved by MBOAT7 overexpression. However, NASH liver histology assessed by categorical scoring was not substantially improved by MBOAT7 overexpression. MBOAT7 regulates the formation of phosphatidylinositol (PI) predominantly by arachidonoylation of lysophosphatidylinositol (LPI). Shotgun lipidomics of NASH GFP-control livers suggested decreased MBOAT7 activity in that LPI content was elevated, and both total and arachidonoylated-PI were reduced. Surprisingly, MBOAT7 overexpression did not rescue the content of most arachidonoylated PI species but did normalize or increase the abundance of several oleate and linoleate-containing PI species. Free arachidonic acid was elevated but the MBOAT7 substrate arachidonoyl-CoA was found to be low in all NASH livers compared to low-fat fed mice, likely due to decreased expression of both long-chain acyl-CoA synthetases (ACSL) 1 and 4 in NASH livers compared to controls. Conclusions These results suggest MBOAT7 overexpression fails to measurably improve NASH pathology potentially due to insufficient abundance of its arachidonoyl-CoA substrate in fatty livers.

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Therapeutic targeting of hepatic ACSL4 ameliorates NASH in mice

Cited by 47 publications

References 43 publications

Living Cell-Target Responsive Accessibility Profiling Reveals Silibinin Targeting ACSL4 for Combating Ferroptosis

Living Cell-Target Responsive Accessibility Profiling Reveals Silibinin Targeting ACSL4 for Combating Ferroptosis

ACSL4-dependent ferroptosis does not represent a tumor-suppressive mechanism but ACSL4 rather promotes liver cancer progression

Enhancing Hepatic MBOAT7 Expression Does Not Improve Nonalcoholic Steatohepatitis in Mice

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