SHP-1 inhibits renal ischemia reperfusion injury via dephosphorylating ASK1 and suppressing apoptosis

The Dual-specificity Phosphatase 3 (DUSP3): A Potential Target Against Renal Ischemia/Reperfusion Injury

Renal ischemia/reperfusion (I/R) injury is a common clinical challenge faced by clinicians in kidney transplantation. I/R is the leading cause of acute kidney injury, and it occurs when blood flow to the kidney is interrupted and subsequently restored. I/R impairs renal function in both short and long terms. Renal ischemic preconditioning refers to all maneuvers intended to prevent or attenuate ischemic damage. In this context, the present review focuses on the dual-specificity phosphatase 3 (DUSP3), also known as vaccinia H1-related phosphatase, an uncommon regulator of mitogen-activated protein kinase (MAPK) phosphorylation. DUSP3 has different biological functions: (1) it acts as a tumor modulator and (2) it is involved in the regulation of immune response, thrombosis, hemostasis, angiogenesis, and genomic stability. These functions occur either through MAPK-dependent or MAPK-independent mechanisms. DUSP3 genetic deletion dampens kidney damage and inflammation caused by I/R in mice, suggesting DUSP3 as a potential target for preventing renal I/R injury. Here, we discuss the putative role of DUSP3 in ischemic preconditioning and the potential mechanisms of such an attenuated inflammatory response via improved kidney perfusion and adequate innate immune response.

Biochanin A-mediated anti-ferroptosis is associated with reduction of septic kidney injury

AIMS

This study aimed to investigate the therapeutic potential of biochanin A in a sepsis associated- acute kidney injury (SA-AKI) mouse model induced by lipopolysaccharide (LPS).

MAIN METHODS

Male BALB/C mice (n = 7 per group) were injected with biochanin A (40 mg/kg, i.p.) or ferrostatin-1 (5 mg/kg, i.p.) in the presence or absence of LPS (10 mg/kg, i.p.). Survival rates were monitored twice a day for up to 2 weeks. Morphologic and functional changes in kidney tissue were assessed by H&E staining and by analyzing of levels of blood-urea nitrogen (BUN) and creatinine (CR) in serum, respectively. Kidney epithelial cell death was analyzed by TUNEL staining, Prussian blue staining, iron quantification, lipid peroxide quantification, and glutathione quantification. Anti-ferroptosis mechanism of biochanin A was analyzed by RNA sequencing in mouse embryonic fibroblast cells.

KEY FINDINGS

Biochanin A increased the survival rate of septic mice and inhibited the secretion of high mobility group box 1, an important inflammatory mediator in sepsis. Biochanin A inhibited LPS-induced kidney damage by suppressing dilatation and kidney tubular epithelial cell death. Furthermore, serum levels of BUN and CR were reduced in biochanin A-treated endotoxemic mice. Biochanin A inhibited the accumulation of iron and lipid peroxide and prevented glutathione depletion in the kidney tissue. Also, nine genes associated with the anti-ferroptosis effects of biochanin A were identified by RNA sequencing analysis.

SIGNIFICANCE

The present study suggests that biochanin A is an effective inhibitor of ferroptosis, representing a potential treatment or prophylactic for sepsis-related disorders such as SA-AKI.

DJ-1 regulates astrocyte activation through miR-155/SHP-1 signaling in cerebral ischemia/reperfusion injury

Reactive astrocyte activation in the context of cerebral ischemia/reperfusion (I/R) injury gives rise to two distinct subtypes: the neurotoxic A1 type and the neuroprotective A2 type. DJ-1 (Parkinson disease protein 7, PARK7), originally identified as a Parkinson's disease-associated protein, is a multifunctional anti-oxidative stress protein with molecular chaperone and signaling functions. SHP-1 (Src homology 2 domain-containing phosphatase-1) is a protein tyrosine phosphatase closely associated with cellular signal transduction. miR-155 is a microRNA that participates in cellular functions by regulating gene expression. Recent studies have uncovered the relationship between DJ-1 and astrocyte-mediated neuroprotection, which may be related to its antioxidant properties and regulation of signaling molecules such as SHP-1. Furthermore, miR-155 may exert its effects by influencing SHP-1, providing a potential perspective for understanding the molecular mechanisms of stroke. A middle cerebral artery occlusion/reperfusion (MCAO/R) model and an oxygen-glucose deprivation/reperfusion (OGD/R) model were established to simulate focal cerebral I/R injury in vivo and in vitro, respectively. The in vivo interaction between DJ-1 and SHP-1 has been experimentally validated through immunoprecipitation. Overexpression of DJ-1 attenuates I/R injury and suppresses miR-155 expression. In addition, inhibition of miR-155 upregulates SHP-1 expression and modulates astrocyte activation phenotype. These findings suggest that DJ-1 mediates astrocyte activation via the miR-155/SHP-1 pathway, playing a pivotal role in the pathogenesis of cerebral ischemia-reperfusion injury. Our results provide a potential way for exploring the pathogenesis of ischemic stroke and present promising targets for pharmacological intervention.

The Function of ASK1 in Sepsis and Stress-Induced Disorders

Apoptosis signal-regulating kinase 1 (ASK1) is a serine-threonine kinase that is ubiquitously expressed in nucleated cells and is responsible for the activation of multiple mitogen-activated protein kinases (MAPK) to regulate cell stress. Activation of ASK1 via cellular stress leads to activation of downstream signaling components, activation of transcription factors, and proinflammatory cytokine production. ASK1 is also expressed in anucleate platelets and is a key player in platelet activation as it is important for signaling. Interestingly, the mechanism of ASK1 activation is cell type-dependent. In this review we will explore how ASK1 regulates a variety of cellular processes from innate immune function to thrombosis and hemostasis. We will discuss how ASK1 influences FcγRIIA-mediated platelet reactivity and how that reactivity drives platelet clearance. Furthermore, we will explore the role of ASK1 in thromboxane (TxA2) generation, which highlights differences in the way ASK1 functions in mouse and human platelets.

PIM1 attenuates renal ischemia-reperfusion injury by inhibiting ASK1-JNK/P38

Renal ischemia-reperfusion injury (IRI) is the main cause of acute kidney injury (AKI), yet therapeutic approaches to alleviate IRI remain limited. PIM1 (provirus integration site for Moloney murine leukemia virus 1) is a constitutive serine threonine kinase that phosphorylates various substrates to regulate cell death and survival. However, the role of PIM1 in renal IRI remains unclear. This study aims to investigate the effect of PIM1 on renal IRI and explore its downstream regulatory mechanism. In this study, we inhibited or overexpressed PIM1 in mice and cultured proximal tubular cells, and then induced renal IRI model in vivo and hypoxia reoxygenation (HR) model in vitro. Renal function, renal structure injuries and cellular death were assessed to reflect the extent of IRI. The expression of PIM1 and the levels of ASK1, MAPK and their phosphorylated forms were detected by immunoblot. RNA sequencing of kidney cortex was performed to analyze downstream pathway of PIM1 in renal IRI. The results showed that PIM1 expression was significantly upregulated in renal IRI mouse model and in renal tubular cell HR model. AZD1208 (a PIM1 inhibitor) aggravated renal IRI, while PIM1 overexpression ameliorated renal IRI. This was involved in the regulation of the ASK1-MAPK pathway. Moreover, results demonstrated that ASK1 was a downstream target of PIM1 by administering Selonsertib (an inhibitor of ASK1 activity), and inhibiting ASK1 alleviated cell death after HR in PIM1 knockdown cells by reducing JNK/P38 activation. In conclusion, this study elucidated the protective effect of PIM1 on renal IRI, and the underlying mechanism may be related to ASK1-JNK/P38 signaling pathway. Taken together, PIM1 may be a potential therapeutic target for renal IRI.

SHP-1 knockdown suppresses mitochondrial biogenesis and aggravates mitochondria-dependent apoptosis induced by all trans retinal through the STING/AMPK pathways

BACKGROUND

Oxidative stress-caused damage to the retinal pigment epithelium (RPE) underlies the onset and progression of age-related macular degeneration (AMD). Impaired mitochondrial biogenesis sensitizes RPE cells to mitochondrial dysfunction, energy insufficiency and death. Src-homology 2 domain-containing phosphatase (SHP)-1 is important in regulating immune responses and cell survival. However, its roles in cell survival are not always consistent. Until now, the effects of SHP-1 on RPE dysfunction, especially mitochondrial homeostasis, remain to be elucidated. We sought to clarify the effects of SHP-1 in RPE cells in response to atRAL-induced oxidative stress and determine the regulatory mechanisms involved.

METHODS

In the all trans retinal (atRAL)-induced oxidative stress model, we used the vector of lentivirus to knockdown the expression of SHP-1 in ARPE-19 cells. CCK-8 assay, Annexin V/PI staining and JC-1 staining were utilized to determine the cell viability, cell apoptosis and mitochondrial membrane potential. We also used immunoprecipitation to examine the ubiquitination modification of stimulator of interferon genes (STING) and its interaction with SHP-1. The expression levels of mitochondrial marker, proteins related to mitochondrial biogenesis, and signaling molecules involved were examined by western blotting analysis.

RESULTS

We found that SHP-1 knockdown predisposed RPE cells to apoptosis, aggravated mitochondrial damage, and repressed mitochondrial biogenesis after treatment with atRAL. Immunofluoresent staining and immunoprecipitation analysis confirmed that SHP-1 interacted with the endoplasmic reticulum-resident STING and suppressed K63-linked ubiquitination and activation of STING. Inhibition of STING with the specific antagonist H151 attenuated the effects of SHP-1 knockdown on mitochondrial biogenesis and oxidative damage. The adenosine monophosphate-activated protein kinase (AMPK) pathway acted as the crucial downstream target of STING and was involved in the regulatory processes.

CONCLUSIONS

These findings suggest that SHP-1 knockdown potentiates STING overactivation and represses mitochondrial biogenesis and cell survival, at least in part by blocking the AMPK pathway in RPE cells. Therefore, restoring mitochondrial health by regulating SHP-1 in RPE cells may be a potential therapeutic strategy for degenerative retinal diseases including AMD.

Transcriptomic Analysis Revealed an Important Role of Peroxisome-Proliferator-Activated Receptor Alpha Signaling in Src Homology Region 2 Domain-Containing Phosphatase-1 Insufficiency Leading to the Development of Renal Ischemia-Reperfusion Injury

In kidney transplantation, the donor kidney inevitably undergoes ischemia-reperfusion injury (IRI). It is of great importance to study the pathogenesis of IRI and find effective measures to attenuate acute injury of renal tubules after ischemia-reperfusion. Our previous study found that Src homology region 2 domain-containing phosphatase-1 (SHP-1) insufficiency aggravates renal IRI. In this study, we systematically analyzed differences in the expression profiles of SHP-1 (encoded by Ptpn6)-insufficient mice and wild-type mice by RNA-seq. We found that a total of 161 genes showed at least a twofold change, with a false discovery rate <0.05 in Ptpn6 +/mev mice after IRI and 42 genes showing more than a fourfold change. Of the eight genes encoding proteins with immunoreceptor tyrosine-based inhibitory motifs (ITIMs) that bind to Ptpn6, three were upregulated, and five were downregulated. We found that for the differentially expressed genes (DEGs) with a fold change >2, the most significantly enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were the cell division pathway and peroxisome-proliferator activated receptor PPARα signaling pathways. Furthermore, the downregulated genes of the PPARα signaling pathway were mainly related to fatty acid absorption and degradation. Using an agonist of the PPARα signaling pathway, fenofibrate, we found that renal IRI was significantly attenuated in Ptpn6 +/mev mice. In summary, our results show that insufficiency of SHP-1 inhibits the expression of genes in the PPARα signaling pathway, thereby leading to increased reactive oxygen species (ROS) and exacerbating the renal IRI. The PPARα signaling agonist fenofibrate partially attenuates renal IRI induced by SHP-1 insufficiency.

Alamandine protects against renal ischaemia-reperfusion injury in rats via inhibiting oxidative stress

OBJECTIVE

This study was to determine whether alamandine (Ala) could reduce ischaemia and reperfusion (I/R) injury of kidney in rats.

METHODS

Renal I/R was induced by an occlusion of bilateral renal arteries for 70 min and a 24-h reperfusion in vivo, and rat kidney proximal tubular epithelial cells NRK52E were exposed to 24 h of hypoxia and followed by 3-h reoxygenation (H/R) in vitro.

RESULTS

The elevated serum creatinine (Cr), blood cystatin C (CysC) and blood urea nitrogen (BUN) levels in I/R rats were inhibited by Ala treatment. Tumour necrosis factor alpha (TNF)-α, IL-1β, IL-6, cleaved caspase-3, cleaved caspase-8 and Bax were increased, and Bcl2 was reduced in the kidney of I/R rats, which were reversed by Ala administration. Ala reversed the increase of TNF-α, IL-1β, IL-6, cleaved caspase-3, cleaved caspase-8 and Bax and the decrease of Bcl2 in the H/R NRK52E cells. Ala could also inhibit the increase of oxidative stress levels in the kidney of I/R rats. NADPH oxidase 1 (Nox1) overexpression reversed the improving effects of Ala on renal function, inflammation and apoptosis of I/R rats.

CONCLUSION

These results indicated that Ala could improve renal function, attenuate inflammation and apoptosis in the kidney of I/R rats via inhibiting oxidative stress.

DUSP12 acts as a novel endogenous protective signal against hepatic ischemia-reperfusion damage by inhibiting ASK1 pathway

Ischemia–reperfusion injury (IRI) consequent to major liver surgery is a still unmet clinical problem. The activation of endogenous systems of hepatoprotection can prevent the damaging effects of ischemia–reperfusion (IR) as shown by the phenomenon known as ‘ischemic preconditioning’. The identification of endogenous signal mediators of hepatoprotection is of main interest since they could be targeted in future therapeutic interventions. Qiu et al. recently reported in Clin. Sci. (Lond.) (2020) 134(17), 2279–2294, the discovery of a novel protective molecule against hepatic IR damage: dual-specificity phosphatase 12 (DUSP12). IR significantly decreased DUSP12 expression in liver whereas DUSP12 overexpression in hepatocytes protected IRI and DUSP12 deletion in DUSP12 KO mice exacerbated IRI. The protective effects of DUSP12 depended on apoptosis signal-regulating kinase 1 (ASK1) and acted through the inhibition of the ASK1-dependent kinases c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK). These results enlighten DUSP12 as a novel intermediate negative regulator of the pro-inflammatory and pro-apoptotic ASK1/JNK-p38 MAPK pathway activated during hepatic IR and identify DUSP12 as potential therapeutic target for IRI.

Downregulation of lncRNA TUG1 attenuates inflammation and apoptosis of renal tubular epithelial cell induced by ischemia-reperfusion by sponging miR-449b-5p via targeting HMGB1 and MMP2

We aimed to evaluate the functions of long non-coding RNA taurine upregulated gene 1 (lncRNA TUG1) in renal ischemia-reperfusion (I/R) injury and identify the potential mechanisms. Pathological changes of renal tissues were examined using H&E staining after mimic renal I/R injury in vivo. The contents of serum renal functional parameters and inflammatory factors were measured. The expression of TUG1 and miR-449b-5p in renal tissues and HK-2 cells stimulated by I/R were detected. Then, the effects of TUG1 silencing on inflammation and apoptosis of cells were evaluated. Dual luciferase reporter assays were executed for determining the correlation between miR-449b-5p and TUG1, high mobility group box 1 (HMGB1), or matrix metalloproteinase 2 (MMP2). Subsequently, cells were co-transfected with miR-449b-5p mimic and pcDNA3.1 TUG1. The levels of inflammation, apoptosis, and the expression of HMGB1 and MMP2 were detected. The results revealed that renal tissues were obviously damaged after I/R accompanied by changes in renal functional markers and inflammatory factors. TUG1 was highly expressed whereas miR-449b-5p was lowly expressed. TUG1 silencing reduced the inflammation and apoptosis. Dual luciferase reporter assays confirmed that miR-449b-5p was a target of TUG1 as well as HMGB1 and MMP2 were direct targets of miR-449b-5p. Meanwhile, miR-449b-5p mimic presented the same results with TUG1 silencing, which were reversed after TUG1 overexpression. Moreover, MMP2 and HMGB1 expression was decreased after miR-449b-5p overexpression while that of was increased after TUG1 overexpression. These findings demonstrated that TUG1 silencing attenuates I/R-induced inflammation and apoptosis via targeting miR-449b-5p and regulating HMGB1 and MMP2 expression.

Toll-Like Receptors in Acute Kidney Injury

Acute kidney injury (AKI) is an important health problem, affecting 13.3 million individuals/year. It is associated with increased mortality, mainly in low- and middle-income countries, where renal replacement therapy is limited. Moreover, survivors show adverse long-term outcomes, including increased risk of developing recurrent AKI bouts, cardiovascular events, and chronic kidney disease. However, there are no specific treatments to decrease the adverse consequences of AKI. Epidemiological and preclinical studies show the pathological role of inflammation in AKI, not only at the acute phase but also in the progression to chronic kidney disease. Toll-like receptors (TLRs) are key regulators of the inflammatory response and have been associated to many cellular processes activated during AKI. For that reason, a number of anti-inflammatory agents targeting TLRs have been analyzed in preclinical studies to decrease renal damage during AKI. In this review, we updated recent knowledge about the role of TLRs, mainly TLR4, in the initiation and development of AKI as well as novel compounds targeting these molecules to diminish kidney injury associated to this pathological condition.