USP4 deficiency exacerbates hepatic ischaemia/reperfusion injury via TAK1 signalling

Betaine-homocysteine methyltransferase attenuates liver ischemia-reperfusion injury by targeting TAK1

Liver ischemia-reperfusion (IR) injury is a common complication following liver surgery, significantly impacting the prognosis of liver transplantation and other liver surgeries. Betaine-homocysteine methyltransferase (BHMT), a crucial enzyme in the methionine cycle, has been previously confirmed the pivotal role in hepatocellular carcinoma, and it has also been demonstrated that BHMT inhibits inflammation, apoptosis, but its role in liver IR injury remains unknow. Following I/R injury, we found that BHMT expression was significantly upregulated in human liver transplant specimens, mice and hepatocytes. Utilizing BHMT knockout mice, we established an in vivo model of liver IR injury, and with BHMT knockout and overexpression AML12 cell lines, we created an in vitro hypoxia-reoxygenation model. Our findings reveal that BHMT deficiency exacerbates liver IR injury, leading to increased reactive oxygen species, apoptosis and inflammation, whereas BHMT overexpression mitigates these effects. We observed that BHMT inhibits the c-Jun N-terminal kinase (JNK)/p38 signaling pathway in liver IR injury by interacting with TAK1 and inhibiting its activity. The application of 5z-7-ox, a TAK1 inhibitor, reversed the worsening of liver IR injury and the activation of the JNK/p38 pathway associated with BHMT deficiency. These results demonstrate that BHMT protects against liver IR injury by targeting TAK1 and inhibiting the JNK/p38 signaling pathway. Our findings suggest that BHMT may be a promising therapeutic target for preventing liver IR injury.

Vialinin A alleviates oxidative stress and neuronal injuries after ischaemic stroke by accelerating Keap1 degradation through inhibiting USP4-mediated deubiquitination

BACKGROUND

Oxidative stress is known as a hallmark of cerebral ischaemia‒reperfusion injury and it exacerbates the pathologic progression of ischaemic brain damage. Vialinin A, derived from a Chinese edible mushroom, possesses multiple pharmacological activities in cancer, Kawasaki disease, asthma and pathological scarring. Notably, vialinin A is an inhibitor of ubiquitin-specific peptidase 4 (USP4) that shows anti-inflammatory and antioxidative properties. However, the precise effect of vialinin A in ischaemic stroke, as well as its underlying mechanisms, remains largely unexplored.

PURPOSE

The present research focuses on the impacts of vialinin A on oxidative stress and explores the underlying mechanisms involved while also examining its potentiality as a therapeutic candidate for ischaemic stroke.

METHODS

Mouse ischaemic stroke was conducted by MCAO surgery. Vialinin A was administered via lateral ventricular injection at a dose of 2 mg/kg after reperfusion. Subsequent experiments were meticulously conducted at the appropriate time points. Stroke outcomes were evaluated by TTC staining, neurological score, Nissl staining and behavioural analysis. Co-IP assays were operated to examine the protein-protein interactions. Immunoblot analysis, qRT-PCR, and luciferase reporter assays were conducted to further investigate its underlying mechanisms.

RESULTS

In this study, we initially showed that administration of vialinin A alleviated cerebral ischaemia‒reperfusion injury-induced neurological deficits and neuronal apoptosis. Furthermore, vialinin A, which is an antioxidant, reduced oxidative stress injury, promoted the activation of the Keap1-Nrf2-ARE signaling pathway and increased the protein degradation of Keap1. The substantial neuroprotective effects of vialinin A against ischaemic stroke were compromised by the overexpression of USP4. Mechanistically, vialinin A inhibited the deubiquitinating enzymatic activity of USP4, leading to enhanced ubiquitination of Keap1 and subsequently promoting its degradation. This cascade caused the activation of Nrf2-dependent antioxidant response, culminating in a reduction of neuronal apoptosis and the amelioration of neurological dysfunction following ischaemic stroke.

CONCLUSIONS

This study demonstrates that inhibition of USP4 to activate Keap1-Nrf2-ARE signaling pathway may represent a mechanism by which vialinin A conferred protection against cerebral ischaemia‒reperfusion injury and sheds light on its promising prospects as a therapeutic intervention for ischaemic stroke.

Hepatocellular SETDB1 Regulates Hepatic Ischemia-Reperfusion Injury through Targeting Lysine Methylation of ASK1 Signal

Background: Hepatic ischemia-reperfusion injury (HIRI) stands as an unavoidable complication arising from liver surgery, profoundly intertwined with its prognosis. The role of lysine methyltransferase SET domain bifurcated 1 (SETDB1) in HIRI remains elusive, despite its confirmation as a potential therapeutic target for diverse diseases. Here, we investigated the mechanism by which SETDB1 regulated HIRI. Methods: RNA sequencing data were used to identify the expression and potential targets of SETDB1 through bioinformatics analysis. To elucidate the impact of SETDB1 on HIRI, both an in vivo model of HIRI in mice and an in vitro model of hepatocyte hypoxia/reoxygenation were established. Biochemical and histological analyses were used to investigate the influence of SETDB1 on liver damage mediated by HIRI. Chromatin immunoprecipitation and coimmunoprecipitation were implemented to explore the in-depth mechanism of SETDB1 regulating HIRI. Results: We confirmed that hepatocellular SETDB1 was up-regulated during HIRI and had a close correlation with HIRI-related inflammation and apoptosis. Moreover, inhibition of SETDB1 could mitigate HIRI-induced liver damage, inflammation, and apoptosis. Through our comprehensive mechanistic investigation, we revealed that SETDB1 interacts with apoptosis-signal-regulating kinase 1 (ASK1) and facilitates the methylation of its lysine residues. Inhibition of SETDB1 resulted in reduced phosphorylation of ASK1, leading to a marked suppression of downstream c-Jun N-terminal kinase (JNK)/p38 signaling pathway activation. The therapeutic effect on inflammation and apoptosis achieved through SETDB1 inhibition was nullified by the restoration of JNK/p38 signaling activation through ASK1 overexpression. Conclusions: The findings from our study indicate that SETDB1 mediates lysine methylation of ASK1 and modulates the activation of the ASK1-JNK/p38 pathway, thus involved in HIRI-induced inflammation and apoptosis. These results suggest that SETDB1 holds promise as a potential therapeutic target for mitigating HIRI.

MAPK Signaling Pathways in Hepatic Ischemia/Reperfusion Injury

The mitogen-activated protein kinase signaling pathway can be activated by a variety of growth factors, cytokines, and hormones, and mediates numerous intracellular signals related to cellular activities, including cell proliferation, motility, and differentiation. It has been widely studied in the occurrence and development of inflammation and tumor. Hepatic ischemia-reperfusion injury (HIRI) is a common pathophysiological phenomenon that occurs in surgical procedures such as lobectomy and liver transplantation, which is characterized by severe inflammatory reaction after ischemia and reperfusion. In this review, we mainly discuss the role of p38, ERK1/2, JNK in MAPK family and TAK1 and ASK1 in MAPKKK family in HIRI, and try to find an effective treatment for HIRI.

miR-194 ameliorates hepatic ischemia/reperfusion injury via targeting PHLDA1 in a TRAF6-dependent manner

Hepatic ischemia/reperfusion injury (IRI) is an inevitable pathological process in liver resection, shock and transplantation. However, the internal mechanism of hepatic IRI, including inflammatory transduction of multiple signaling pathways, is not fully understood. In the present study, we identified pleckstrin homology-like domain family member 1 (PHLDA1), suppressed by microRNA (miR)-194, as a critical intersection of dual inflammatory signals in hepatic IRI. PHLDA1 was upregulated in hepatic IRI with a concomitant downregulation of miR-194. Overexpression of miR-194 diminished PHLDA1 and inhibitors of the nuclear factor kappa-B kinase (IKK) pathway, thus leading to remission of hepatic pathological injury, apoptosis and release of cytokines. Further enrichment of PHLDA1 reversed the function of miR-194 both in vivo and in vitro. For an in-depth query, we verified PHLDA1 as a direct target of miR-194. Notably, inflammatory signal transduction of PHLDA1 was induced by activating TNF receptor-associated factor 6 (TRAF6), sequentially initiating IKK and mitogen-activated protein kinase (MAPK), both of which aggravate stress and inflammation in hepatic IRI. In conclusion, the miR-194/PHLDA1 axis was a key upstream regulator of IKK and MAPK in hepatic IRI. Targeting PHLDA1 might be a potential strategy for hepatic IRI therapy.

DUSP12 protects against hepatic ischemia-reperfusion injury dependent on ASK1-JNK/p38 pathway in vitro and in vivo

Hepatic ischemia-reperfusion (I/R) injury is an important risk factor resulting in liver failure during liver surgery. However, there is still lack of effective therapeutic methods to treat hepatic I/R injury. DUSP12 is a member of the dual specific phosphatase (DUSP) family. Some DUSPs have been identified as being involved in the regulation of hepatic I/R injury. However, the role of DUSP12 during hepatic I/R injury is still unclear. In the present study, we observed a significant decrease in DUSP12 expression in a hepatic I/R injury mouse model in vivo and in hypoxia/reoxygenation (H/R) model in vitro. Using hepatocyte-specific DUSP12 knockout mice and DUSP12 transgenic mice, we demonstrated that DUSP12 apparently relieved I/R-induced liver injury. Moreover, DUSP12 inhibited hepatic inflammatory responses and alleviated apoptosis both in vitro and in vivo. Furthermore, we demonstrated that JNK and p38 activity, but not ERK1/2, was increased in the DUSP12-deficient mice and decreased in the DUSP12 transgenic mice under I/R condition. ASK1 was required for DUSP12 function in hepatic I/R injury and inhibition of ASK1 prevented inflammation and apoptosis in DUSP12-deficient hepatocytes and mice. In conclusion, DUSP12 protects against hepatic I/R injury and related inflammation and apoptosis. This regulatory role of DUSP12 is primarily through ASK1-JNK/p38 signaling pathway. Taken together, DUSP12 could be a potential therapeutic target for hepatic I/R injury.

Spotlight on USP4: Structure, Function, and Regulation

The deubiquitinating enzyme (DUB)–mediated cleavage of ubiquitin plays a critical role in balancing protein synthesis and degradation. Ubiquitin-specific protease 4 (USP4), a member of the largest subfamily of cysteine protease DUBs, removes monoubiquitinated and polyubiquitinated chains from its target proteins. USP4 contains a DUSP (domain in USP)–UBL (ubiquitin-like) domain and a UBL-insert catalytic domain, sharing a common domain organization with its paralogs USP11 and USP15. USP4 plays a critical role in multiple cellular and biological processes and is tightly regulated under normal physiological conditions. When its expression or activity is aberrant, USP4 is implicated in the progression of a wide range of pathologies, especially cancers. In this review, we comprehensively summarize the current knowledge of USP4 structure, biological functions, pathological roles, and cellular regulation, highlighting the importance of exploring effective therapeutic interventions to target USP4.

Ubiquitously specific protease 4 inhibitor-Vialinin A attenuates inflammation and fibrosis in S100-induced hepatitis mice through Rheb/mTOR signalling

Inflammation and fibrosis are major consequences of autoimmune hepatitis, however, the therapeutic mechanism remains to be investigated. USP4 is a deubiquitinating enzyme and plays an important role in tissue fibrosis and immune disease. Vialinin A is an extract from mushroom and is a specific USP4 inhibitor. However, there is lack of evidences that Vialinin A plays a role in autoimmune hepatitis. By employing S100-induced autoimmune hepatitis in mice and AML12 cell line, therapeutic mechanism of Vialinin A was examined. Inflammation was documented by liver histological staining and inflammatory cytokines. Fibrosis was demonstrated by Masson, Sirius red staining and fibrotic cytokines with western blot and real-time RT-PCR. In experimental animal, there were increases in inflammation and fibrosis as well as USP4, and which were reduced after treatment of Vialinin A. Vialinin A also reduced Rheb and phosphorylated mTOR. Moreover, in LPS-treated AML12 cells, LPS-induced USP4, inflammatory and fibrotic cytokines, phosphorylated mTOR and Rheb. Specific inhibitory siRNA of USP4 reduced USP4 level and the parameters mentioned above. In conclusion, USP4 was significantly elevated in autoimmune hepatitis mice and Vialinin A reduced USP4 level and attenuate inflammation and fibrosis in the liver. The mechanism may be related to regulation of Rheb/mTOR signalling.

Ubiquitin-specific protease 4 predicts an unfavorable prognosis and promotes malignant behaviors in vitro in pancreatic cancer

Ubiquitin-specific protease 4 (USP4), has been reported to participate in the progression of various cancers due to its role in post-translational modulation. However, the prognostic significance and mechanism of USP4 in pancreatic cancer (PC) have not been well elucidated before. In the present study, we found that USP4 expression was higher in PC tissues than that in adjacent normal tissues and PC patients with high level of USP4 expression have a poor prognosis via immunohistochemistry and bioinformatics analyses. In vitro study showed that knockdown of USP4 inhibited PC cells proliferation, migration and invasion. Mechanistically, USP4 can activate nuclear factor kappa-B signaling pathway via stabilizing TNF receptor associated factor 6 at its protein level to promote the ability of proliferation, migration and invasion of PC cells. The results of this study revealed that USP4 plays a tumor-promoting role in PC and can be used as a prognostic indicator and therapeutic target for patients with resected PC.

Ubiquitin-Specific Peptidase 10 Protects Against Hepatic Ischaemic/Reperfusion Injury via TAK1 Signalling

Ubiquitin-specific peptidase 10 (USP10) protein is a deubiquitination enzyme involved in many important biological processes. However, the function of USP10 in hepatic ischaemic/reperfusion (I/R) injury remains unknown. The aim of this study was to explore the role of USP10 in hepatic I/R injury. USP10 Heterozygote mice and primary hepatocytes were used to construct hepatic I/R models. The effect of USP10 on hepatic I/R injury was examined via pathological and molecular analyses. Our results indicated that USP10 was significantly downregulated in the livers of mice after hepatic I/R injury and in hepatocytes subjected to hypoxia/reoxygenation stimulation. USP10 Heterozygote mice exhibited exacerbated hepatic I/R injury, as evidenced by enhanced liver inflammation via the NF-κB signalling pathway and increased hepatocyte apoptosis. Additionally, USP10 overexpression inhibited hepatocyte inflammation and apoptosis in hepatic I/R injury in vitro and in vivo. Mechanistically, our study demonstrated that USP10 knockdown exerted its detrimental effects on hepatic I/R injury by inducing activation of the transforming growth factor β-activated kinase 1 (TAK1)-JNK/p38 signalling pathways. TAK1 was required for USP10 function in hepatic I/R injury as TAK1 inhibition abolished USP10 function in vitro. In conclusion, our study demonstrated that USP10 plays a protective role in hepatic I/R injury by inhibiting the activation of the TAK1-JNK/p38 signalling pathways. Modulation of USP10/TAK1 might be a promising strategy to prevent this pathological process.

USP4 function and multifaceted roles in cancer: a possible and potential therapeutic target

Cancer remains one of the major culprits causing disease-related deaths and leads to a high morbidity and similar mortality. Insidious onset, difficult early detection and a lack of broad-spectrum and effective multi-cancer therapeutic targets have limited the prolongation of cancer patients’ survival for decades. Therefore, a versatile therapeutic target which is involved in various cancer-related signaling pathways and different cancers may be more effective for cancer targeted therapy. USP4, one of the DUBs members which participates in deubiquitination, an inverse process of ubiquitination, can regulate various classical cancer-related signaling pathways, and thereby plays a vital role in some pathological and physiological processes including tumor initiation and progression. Recently, USP4 has been found to exert versatile influences on cells proliferation, migration and invasion, also apoptosis of various tumors. Moreover, USP4 can also act as a prognostic biomarker in several cancers. This review will give a comprehensive introduction of USP4 about its regulatory mechanisms, related signaling pathways, pathophysiological functions and the roles in various cancers which may help us better understand its biological functions and improve future studies to construct suitable USP4-targeted cancer therapy system.

IL-4 Alleviates Ischaemia-Reperfusion Injury by Inducing Kupffer Cells M2 Polarization via STAT6-JMJD3 Pathway after Rat Liver Transplantation

Background

Liver ischaemia-reperfusion injury (IRI) remains a problem in liver transplantation. Interleukin-4 (IL-4) has been found to reduce liver IRI, but the exact mechanism remains unclear.

Methods

Donor livers were infused with recombinant IL-4 or normal saline during cold storage, and the hepatocellular apoptosis and the inflammatory response were detected. The effect of IL-4 treatment on Kupffer cells (KCs) polarization and expression of the STAT6-JMJD3 pathway was evaluated in vivo and in vitro. KCs in donor livers were depleted by clodronate liposome treatment or JMJD3 was inhibited by GSK-J4 before liver transplantation to determine whether the protective effect of IL-4 treatment was dependent on KCs.

Results

IL-4 treatment decreased sALT and sAST levels and alleviated hepatocellular apoptosis and inflammation at 6 h after liver transplantation. IL-4 treatment induced KCs alternatively activated (M2) polarization in vitro. KCs in donor livers were depleted by clodronate liposome treatment or JMJD3 was inhibited by GSK-J4 before liver transplantation to determine whether the protective effect of IL-4 treatment was dependent on KCs. in vivo and in vitro. KCs in donor livers were depleted by clodronate liposome treatment or JMJD3 was inhibited by GSK-J4 before liver transplantation to determine whether the protective effect of IL-4 treatment was dependent on KCs.

Conclusions

IL-4 treatment-induced KCs M2 polarization was dependent on the STAT6-JMJD3 pathway and protected liver grafts from IRI after liver transplantation.

Epigenetic Silencing of Ubiquitin Specific Protease 4 by Snail1 Contributes to Macrophage-Dependent Inflammation and Therapeutic Resistance in Lung Cancer

There is a positive feedback loop driving tumorigenesis and tumor growth through coordinated regulation of epigenetics, inflammation, and stemness. Nevertheless, the molecular mechanism linking these processes is not well understood. In this study, we analyzed the correlation of de-ubiquitinases (DUBs) expression with survival data from the OncoLnc database. Among the DUBs analyzed, ubiquitin specific protease 4 (USP4) had the lowest negative Cox coefficient. Low expression of USP4 was associated with poor survival among lung cancer patients and was inversely correlated with expression of stemness and inflammation markers. Expression of USP4 were reduced at more advanced stages of lung cancer. Mechanistically, expression of USP4 was downregulated in snail1-overexpressing and stemness-enriched lung cancer cells. Snail1 was induced in lung cancer cells by interaction with macrophages, and epigenetically suppressed USP4 expression by promoter methylation. Stable knockdown of USP4 in lung cancer cells enhanced inflammatory responses, stemness properties, chemotherapy resistance, and the expression of molecules allowing escape from immunosurveillance. Further, mice injected with USP4 knockdown lung cancer cells demonstrated enhanced tumorigenesis and tumor growth. These results reveal that the Snail1-mediated suppression of USP4 is a potential mechanism to orchestrate epigenetic regulation, inflammation and stemness for macrophage-promoted tumor progression.

Tripartite Motif 8 Deficiency Relieves Hepatic Ischaemia/reperfusion Injury via TAK1-dependent Signalling Pathways

Tripartite motif (Trim) 8 is an E3 ubiquitin ligase, interacting with and ubiquitinating diverse substrates, and is closely involved in innate immunity. However, the function of Trim8 in hepatic ischaemia/reperfusion (I/R) injury remains largely unknown. The aim of this study is to explore the role of Trim8 in hepatic I/R injury. Trim8 gene knockout mice and primary hepatocytes were used to construct hepatic I/R models. The effect of Trim8 on hepatic I/R injury was analysed via pathological and molecular analyses. The results indicated that Trim8 was significantly upregulated in liver of mice subjected to hepatic I/R injury. Trim8 knockout relieved hepatocyte injury triggered by I/R. Silencing of Trim8 expression alleviated hepatic inflammation responses and inhibited apoptosis in vitro and in vivo. Mechanistically, our study suggests that Trim8 deficiency may elicit hepatic protective effects by inhibiting the activation of transforming growth factor β-activated kinase 1 (TAK1)-p38/JNK signalling pathways. TAK1 was required for Trim8 function in hepatic I/R injury as TAK1 activation abolished Trim8 function in vitro. In conclusion, our study demonstrates that Trim8 deficiency plays a protective role in hepatic I/R injury by inhibiting the activation of TAK1-dependent signalling pathways.

Retracted Article: Elevation of USP4 antagonizes oxygen glucose deprivation/reoxygenation-evoked microglia activation and neuroinflammation-mediated neurotoxicity via the TRAF6-NF-κB signaling

An ischemic stroke is a devastating neurological disease with the typical occurrence of brain ischemia/reperfusion (I/R) injury, and it has high mortality and disability globally. Microglia activation after a stroke results in the release of pro-inflammatory cytokines that can further aggravate brain damage. A recent study confirmed the potential role of ubiquitin-specific peptidase 4 (USP4) in the injury process. Nevertheless, the role and mechanism of USP4 during an ischemic stroke remain elusive. In this research, we simulated an I/R injury by oxygen glucose deprivation/reoxygenation (OGD/R) in vitro and confirmed the obvious down-regulation of USP4 in microglia under OGD/R conditions. Moreover, USP4 elevation antagonized the OGD/R-induced microglia proliferation and activation by suppressing the NO levels and the expression of the microglial marker IBA-1. Additionally, the overexpression of USP4 suppressed the release of microglia activation-induced pro-inflammatory cytokines, including IL-1β, IL-6, and TNF-α. Intriguingly, incubation with the conditioned medium from the microglia under OGD/R conditions induced neurotoxicity by inhibiting cell viability and increasing the LDH release, apoptosis, and caspase-3 activity, which were reversed following USP4 overexpression. Mechanism analysis corroborated that USP4 up-regulation repressed the OGD/R-induced activation of TRAF6-NF-κB signaling. Notably, restoring the TRAF6 signaling ameliorated the suppressive effects of USP4 elevation on microglia activation, inflammation, and the subsequent neuron injury. These findings suggest that USP4 may alleviate ischemic stroke by restraining microglia-mediated neuro-inflammation and neurotoxicity via the TRAF6-NF-κB pathway, due to which it is a promising therapeutic agent against strokes.

An ischemic stroke is a devastating neurological disease with the typical occurrence of brain ischemia/reperfusion (I/R) injury, and it has high mortality and disability globally.