CUEDC2 modulates cardiomyocyte oxidative capacity by regulating GPX1 stability

Oxidative Stress and Epithelial-Mesenchymal Transition: The Impact of Ubiquitin C-terminal Hydrolase L1 in Cigarette Smoke-Induced COPD

PURPOSE

Cigarette smoke (CS) has been demonstrated to mediate oxidative stress (OS) and epithelial-mesenchymal transition (EMT) in bronchial epithelial cells, thereby contributing to airway remodeling in chronic obstructive pulmonary disease (COPD). Studies have shown upregulation of Ubiquitin C-terminal hydrolase L1 (UCHL1), a deubiquitinating enzyme, in the airway epithelium of smokers. Many studies indicate that UCHL1's regulation of EMT and OS has a complex role in various cell types, including respiratory epithelium. Thus, we aimed to investigate UCHL1's regulation of EMT, OS, and related mechanisms in cigarette smoke-exposed airway epithelium.

METHODS

Exposure to cigarette smoke (CS) or cigarette smoke extract (CSE) was employed to establish both animal and cellular models. Protein expression was analyzed using immunohistochemistry, immunofluorescence, and Western blotting. Lentiviral UCHL1 or GPX1-siRNA was used to modulate UCHL1 or GPX1 expression, respectively. Transwell assays were employed to evaluate cell migration and EMT-related alterations. Oxidative stress levels were assessed using specific assay kits.

RESULTS

This study validated that exposure to CS induces UCHL1 expression in bronchial epithelial cells both in vitro and in vivo, a phenomenon positively correlated with increased OS and EMT in the airway. Notably, UCHL1 overexpression counteracted CSE's impact on EMT markers, cell migration, and oxidative stress in BEAS-2B cells, while UCHL1 knockdown exacerbated these effects. Furthermore, in BEAS-2B cells treated with CSE, upregulation of UCHL1 was found to enhance the expression of glutathione peroxidase 1 (GPX1), an antioxidant enzyme. The effect of UCHL1 overexpression on EMT-related protein markers and cell migration was reversed upon GPX1 silencing via siRNA.

CONCLUSIONS

These findings suggest that UCHL1-mediated regulation of GPX1 expression alleviates cigarette smoke-induced EMT-related protein markers change and cell migration in BEAS-2B cell.

Polystyrene microplastics trigger testosterone decline via GPX1

As an emerging environmental endocrine disruptor, polystyrene microplastics (PS-MPs) are considered to have the anti-androgenic feature and impair male reproductive function. To explore the adverse effects of PS-MPs on testosterone synthesis and male reproduction and further elucidate underlying mechanisms, BALB/c mice and Leydig cells were employed in the present work. The results indicated that 50 μm PS-MPs accumulated in mouse testes and were internalized into the cytoplasm. This not only damaged the testicular histomorphology and ultrastructure, but also reduced the viability of Leydig cells and the serum level of GnRH, FSH, LH, and testosterone. After PS-MPs exposure, the ubiquitination degradation and miR-425-3p-targeted modulation synergistically contributed to the suppression of GPX1, which induced oxidative stress and subsequently activated the PERK-EIF2α-ATF4-CHOP pathway of endoplasmic reticulum (ER) stress. The transcription factor CHOP positively regulated the expression of SRD5A2 by directly binding to its promoter region, thereby accelerating testosterone metabolism and ultimately lowing testosterone levels. Besides, PS-MPs compromised testosterone homeostasis via interfering with the hypothalamic-pituitary-testis (HPT) axis. Taken together, PS-MPs possess an anti-androgenic characteristic and exert male reproductive damage effects. The antioxidant enzyme GPX1 plays a crucial role in the PS-MPs-mediated testosterone decline.

Selenium Deficiency-Induced Oxidative Stress Causes Myocardial Injury in Calves by Activating Inflammation, Apoptosis, and Necroptosis

Selenium (Se) is essential for human and animal health, but there have been few studies on the mechanisms of injury in dairy cows with Se deficiency. This study aimed to evaluate the effects of Se deficiency on myocardial injury in weaned calves. The Se-D group had significantly lower myocardial Se concentrations than the Se-C group. Histological analysis indicated that Se deficiency induced a large area of necrosis in the myocardium, accompanied by inflammatory changes. Se deficiency significantly decreased the expression of 10 of the 21 selenoprotein genes and increased the expression of SEPHS2. Furthermore, we found that oxidative stress occurred in the Se-D group by detection of redox-related indicators. Additionally, TUNEL staining showed that Se deficiency causes severe apoptosis in the myocardium, which was characterized by activating the exogenous apoptotic pathway and the mitochondrial apoptotic pathway. Se deficiency also induced necroptosis in the myocardium by upregulating MLKL, RIPK1, and RIPK3. Moreover, Se-deficient calves have severe inflammation in the myocardium. Se deficiency significantly reduced anti-inflammatory factor levels while increasing pro-inflammatory factor levels. We also found that the NF-κB pathway and MAPK pathway were activated in Se-deficient conditions. Our findings suggest that Se deficiency causes myocardial injury in weaned calves by regulating oxidative stress, inflammation, apoptosis, and necroptosis.

Salvianolic acid B inhibits myocardial I/R-induced ROS generation and cell apoptosis by regulating the TRIM8/GPX1 pathway

CONTEXT

Salvianolic acid B (SalB) can attenuate myocardial ischemia/reperfusion (I/R) injury, but the mechanisms are not entirely known.

OBJECTIVE

Our study investigates if SalB protects cardiomyocytes against I/R injury by regulating Tripartite motif (TRIM) protein.

MATERIALS AND METHODS

AC16 cardiomyocytes were treated with I/R, and then with SalB (10, 25 and 50 μM) for 24 h, while control cells were cultured under normal conditions. Female Sprague-Dawley rats were subjected to I/R injury, and then intravenously injected with 20, 40, or 60 mg/kg SalB or saline, as a control, rats received sham operation and saline injection.

RESULTS

Upon treatment, apoptotic rate, reactive oxygen species (ROS), and malondialdehyde (MDA) were increased 10-, 3.8-, and 1.3-fold, respectively, while superoxide dismutase (SOD) activity was reduced by 62.1% compared to control cells. I/R treatment elevated the mRNA and protein expression of TRIM8. SalB treatment remarkably abolished the above-mentioned effects of I/R treatment. TRIM8 knock-down could partially alleviate I/R-induced myocardial injury. TRIM8 overexpression promoted cardiomyocyte injury, which was alleviated by SalB. Moreover, TRIM8 negatively regulated protein expression of antioxidant enzyme glutathione peroxidase 1 (GPX1). TRIM8 protein interacted with GPX1 and TRIM8 overexpression promoted GPX1 ubiquitnation. GPX1 knock-down abolished the protective effects of SalB on I/R-injured cardiomyocytes. Our in vivo experiments confirmed the effects of SalB on I/R-induced myocardial injury.

DISCUSSION AND CONCLUSIONS

SalB protected cardiomyocytes from I/R-induced apoptosis and oxidative stress in vitro and in vivo, which was partly mediated by the TRIM8/GPX1 axis. This suggests that down-regulation of TRIM8 expression may ameliorate I/R-induced myocardial injury.

TRIM21 aggravates cardiac injury after myocardial infarction by promoting M1 macrophage polarization

Macrophage polarization followed by myocardial infarction (MI) is essential for wound healing. Tripartite motif-containing protein 21 (TRIM21), a member of E3 ubiquitin ligases, is emerging as a mediator in cardiac injury and heart failure. However, its function in modulating post-MI macrophage polarization remains elusive. Here, we detected that the levels of TRIM21 significantly increased in macrophages of wild-type (WT) mice after MI. In contrast, MI was ameliorated in TRIM21 knockout (TRIM21-/-) mice with improved cardiac remodeling, characterized by a marked decrease in mortality, decreased infarct size, and improved cardiac function compared with WT-MI mice. Notably, TRIM21 deficiency impeded the post-MI apoptosis and DNA damage in the hearts of mice. Consistently, the accumulation of M1 phenotype macrophages in the infarcted tissues was significantly reduced with TRIM21 deletion. Mechanistically, the deletion of TRIM21 orchestrated the process of M1 macrophage polarization at least partly via a PI3K/Akt signaling pathway. Overall, we identify TRIM21 drives the inflammatory response and cardiac remodeling by stimulating M1 macrophage polarization through a PI3K/Akt signaling pathway post-MI.

Acidifiers Attenuate Diquat-Induced Oxidative Stress and Inflammatory Responses by Regulating NF-κB/MAPK/COX-2 Pathways in IPEC-J2 Cells

In this study, we evaluated the protective effects and potential mechanisms of acidifiers on intestinal epithelial cells exposure to oxidative stress (OS). IPEC-J2 cells were first pretreated with 5 × 10⁻⁵ acidifiers for 4 h before being exposed to the optimal dose of diquat to induce oxidative stress. The results showed that acidifiers attenuated diquat-induced oxidative stress, which manifests as the improvement of antioxidant capacity and the reduction in reactive oxygen species (ROS) accumulation. The acidifier treatment decreased cell permeability and enhanced intestinal epithelial barrier function through enhancing the expression of claudin-1 and occludin in diquat-induced cells. Moreover, acidifier treatment attenuated diquat-induced inflammatory responses, which was confirmed by the decreased secretion and gene expression of pro-inflammatory (TNF-α, IL-8) and upregulated anti-inflammatory factors (IL-10). In addition, acidifiers significantly reduced the diquat-induced gene and protein expression levels of COX-2, NF-κB, I-κB-β, ERK1/2, and JNK2, while they increased I-κB-α expression in IPEC-J2 cells. Furthermore, we discovered that acidifiers promoted epithelial cell proliferation (increased expression of PCNA and CCND1) and inhibited apoptosis (decreased expression of BAX, increased expression of BCL-2). Taken together, these results suggest that acidifiers are potent antioxidants that attenuate diquat-induced inflammation, apoptosis, and maintain cellular barrier integrity by regulating the NF-κB/MAPK/COX-2 signaling pathways.

SYVN1/GPX5 axis affects ischemia/reperfusion induced apoptosis of AC16 cells by regulating ROS generation

Ischemia/reperfusion (I/R) induced injury is a major cause of coronary heart disease (CHD). Increased production of reactive oxygen species (ROS) can lead to an I/R injury in CHD, and the ROS level can be regulated by Glutathione peroxidase (GPX) enzyme family. In this study, we investigated the role and underlying molecular mechanism of GPX5 in I/R-induced AC16 cells. We found that the serum level of GPX5 was down-regulated in patients with CHD and I/R-induced AC16 cells. Overexpression of GPX5 inhibited I/R-induced apoptosis by suppressing the production of ROS. On the other hand, knock-down of GPX5 promoted apoptosis in AC16 cells by up-regulating the level of ROS. Furthermore, we found that GPX5 was regulated by synovial apoptosis inhibitor 1 (SYVN1)-mediated ubiquitination in AC16 cells. In I/R-induced AC16 cells, the expression of SYVN1 was up-regulated, and SYVN1 knock-down decreased the ROS levels and apoptotic rate but increased GPX5 levels. Moreover, GPX5 knockdown promoted ROS production and apoptosis, while its effects were attenuated by SYVN1 knockdown. Furthermore, SYVN1 was up-regulated while GPX5 was down-regulated in the myocardial tissue of I/R-injured rats. Taken together, our data demonstrate that GPX5 inhibits I/R-induced apoptosis of AC16 cells by down-regulating ROS level, and its stabilization is regulated by SYVN1-mediated ubiquitination.

CUEDC2 ablation enhances the efficacy of mesenchymal stem cells in ameliorating cerebral ischemia/reperfusion insult

Mesenchymal stem cell (MSC) therapy has been reported to be a promising therapeutic option for cerebral ischemia/reperfusion (I/R) insult. However, the poor survival rate of engrafted MSCs under unfavorable cerebral I/R-induced microenvironment inhibits their efficiency during clinical application. CUE domain-containing 2(CUECD2) exhibits its protective role on cardiomyocytes by mediating the antioxidant capacity. Our study explored the functional role of CUEDC2 in cerebral I/R challenge and determined whether CUECD2-modified MSCs could improve the efficacy of treatment of the insulted neurons. We also evaluated the possible mechanisms involved in cerebral I/R condition. Cerebral I/R stimulation suppressed CUEDC2 levels in brain tissues and neurons. siRNA-CUEDC2 in neurons significantly inhibited cerebral I/R-induced apoptosis and oxidative stress levels in vitro. Moreover, siRNA-CUEDC2 in the MSCs group remarkably enhanced the therapeutic efficacies in cerebral I/R-induced neuron injury and brain tissue impairment when compared to the non-genetic MSCs treatment group. At the molecular level, siRNA-CUEDC2 in MSCs markedly enhanced its antioxidant and anti-inflammatory effect in co-cultured neurons by upregulating glutathione peroxidase 1 (GPX1) expression levels while suppressing NF-kB activation. These findings provide a novel strategy for the utilization of MSCs to promote cerebral ischemic stroke outcomes.

Zenglv Fumai Granule protects cardiomyocytes against hypoxia/reoxygenation-induced apoptosis via inhibiting TRIM28 expression

Myocardial ischemia/reperfusion (MIR) injury, which occurs following acute myocardial infarction, can cause secondary damage to the heart. Tripartite interaction motif (TRIM) proteins, a class of E3 ubiquitin ligases, have been recognized as critical regulators in MIR injury. Zenglv Fumai Granule (ZFG) is a clinical prescription for the treatment of sick sinus syndrome, a disease that is associated with MIR injury. The present study aimed to investigate the effect of ZFG on MIR injury and to determine whether ZFG exerts its effects via regulation of TRIM proteins. In order to establish an in vitro MIR model, human cardiomyocyte cell line AC16 was cultured under hypoxia for 5 h and then under normal conditions for 1 h. Following hypoxia/reoxygenation (H/R) treatment, these cells were cultured with different ZFG concentrations. ZFG notably inhibited H/R-induced cardiomyocyte apoptosis. The expression levels of four TRIM proteins, TRIM7, TRIM14, TRIM22 and TRIM28, were also detected. These four proteins were significantly upregulated in H/R-injured cardiomyocytes, whereas their expression was inhibited following ZFG treatment. Moreover, TRIM28 knockdown inhibited H/R-induced cardiomyocyte apoptosis, whereas TRIM28 overexpression promoted apoptosis and generation of reactive oxygen species (ROS) in cardiomyocytes. However, the effects of TRIM28 overexpression were limited by the action of ROS inhibitor N-acetyl-L-cysteine. In addition, the mRNA and protein levels of antioxidant enzyme glutathione peroxidase (GPX)1 were significantly downregulated in H/R-injured cardiomyocytes. TRIM28 knockdown restored GPX1 protein levels but had no effect on mRNA expression levels. Co-immunoprecipitation and ubiquitination assays demonstrated that TRIM28 negatively regulated GPX1 via ubiquitination. In sum, the present study revealed that ZFG attenuated H/R-induced cardiomyocyte apoptosis by regulating the TRIM28/GPX1/ROS pathway. ZFG and TRIM28 offer potential therapeutic options for the treatment of MIR injury.

Down-Regulated CUEDC2 Increases GDNF Expression by Stabilizing CREB Through Reducing Its Ubiquitination in Glioma

Abnormally high expression of glial cell line-derived neurotrophic factor (GDNF) derived from glioma cells has essential impacts on gliomagenesis and development, but the molecular basis underlying increased GDNF expression in glioma cells remain unclear. This work aimed to study the molecular mechanisms that may explain the accumulation of GDNF in glioma. Firstly, we observed that cAMP response element-binding protein (CREB), known as an important transcription factor for binding of GDNF promoter region, was highly expressed with an apparent accumulation into the nucleus of glioma cells, which may contribute to the transcription of GDNF. Secondly, CUE domain-containing protein 2 (CUEDC2), a ubiquitin-regulated protein, could increase the amount of binding between the E3 ligase tripartite motif-containing 21 (TRIM21) and CREB and affect the CREB level. Like our previous study, it showed that there was a significantly down-regulation of CUEDC2 in glioma. Finally, our data suggest that GDNF expression is indirectly regulated by transcription factor ubiquitination. Indeed, down-regulation of CUEDC2, decreased the ubiquitination and degradation of CREB, which was associated to high levels of GDNF. Furthermore, abundant CREB involved in the binding to the GDNF promoter region contributes to GDNF high expression in glioma cells. Collectively, it was verified the GDNF expression was affected by CREB ubiquitination regulated by CUEDC2 level.

CUEDC2 controls osteoblast differentiation and bone formation via SOCS3-STAT3 pathway

The CUE domain-containing 2 (CUEDC2) protein plays critical roles in many biological processes, such as the cell cycle, inflammation, and tumorigenesis. However, whether CUEDC2 is involved in osteoblast differentiation and plays a role in bone regeneration remains unknown. This study investigated the role of CUEDC2 in osteogenesis and its underlying molecular mechanisms. We found that CUEDC2 is expressed in bone tissues. The expression of CUEDC2 decreased during bone development and BMP2-induced osteoblast differentiation. The overexpression of CUEDC2 suppressed the osteogenic differentiation of precursor cells, while the knockdown of CUEDC2 showed the opposite effect. In vivo studies showed that the overexpression of CUEDC2 decreased bone parameters (bone volume, bone area, and bone mineral density) during ectopic bone formation, whereas its knockdown increased bone volume and the reconstruction percentage of critical-size calvarial defects. We found that CUEDC2 affects STAT3 activation by regulating SOCS3 protein stability. Treatment with a chemical inhibitor of STAT3 abolished the promoting effect of CUEDC2 silencing on osteoblast differentiation. Together, we suggest that CUEDC2 functions as a key regulator of osteoblast differentiation and bone formation by targeting the SOCS3–STAT3 pathway. CUEDC2 manipulation could serve as a therapeutic strategy for controlling bone disease and regeneration.

The Lysosomal Membrane Protein Lamp2 Alleviates Lysosomal Cell Death by Promoting Autophagic Flux in Ischemic Cardiomyocytes

Lysosomal membrane permeabilization (LMP) has recently been recognized as an important cell death pathway in various cell types. However, studies regarding the correlation between LMP and cardiomyocyte death are scarce. Lysosomal membrane-associated protein 2 (Lamp2) is an important component of lysosomal membranes and is involved in both autophagy and LMP. In the present study, we found that the protein content of Lamp2 gradually decreased in response to oxygen, glucose and serum deprivation (OGD) treatment in vitro. To further elucidate its role in ischemic cardiomyocytes, particularly with respect to autophagy and LMP, we infected cardiomyocytes with adenovirus carrying full-length Lamp2 to restore its protein level in cells. We found that OGD treatment resulted in the occurrence of LMP and a decline in the viability of cardiomyocytes, which were remarkably reversed by Lamp2 restoration. Exogenous expression of Lamp2 also significantly alleviated the autophagic flux blockade induced by OGD treatment by promoting the trafficking of cathepsin B (Cat B) and cathepsin D (Cat D). Through drug intervention and gene regulation to alleviate and exacerbate autophagic flux blockade respectively, we found that impaired autophagic flux in response to ischemic injury contributed to the occurrence of LMP in cardiomyocytes. In conclusion, our present data suggest that Lamp2 overexpression can improve autophagic flux blockade probably by promoting the trafficking of cathepsins and consequently conferring cardiomyocyte resistance against lysosomal cell death (LCD) that is induced by ischemic injury. These results may indicate a new therapeutic target for ischemic heart damage.

Downregulation of CUEDC2 prevents doxorubicin‑induced cardiotoxicity in H9c2 cells

Treatment with doxorubicin (DOX), which is an effective anticancer agent, is limited by cardiotoxicity. CUE domain-containing 2 (CUEDC2) serves a role in numerous cellular processes. The present study aimed to elucidate the potential function of CUEDC2 in DOX-induced cardiotoxicity. Cell Counting kit-8 assay demonstrated that DOX induced cytotoxicity of H9c2 cells in a dose-dependent manner. Flow cytometry demonstrated that downregulation of CUEDC2 reduced the levels of DOX-induced reactive oxygen species. Furthermore, compared with in the DOX-treated group, the activity of superoxide dismutase was increased in the DOX + small interfering RNA (si)CUEDC2 group; whereas, the malondialdehyde content was reduced in the DOX + siCUEDC2 group. In addition, flow cytometric analysis indicated that mitochondrial membrane potential was maintained following the depletion of CUEDC2. Furthermore, CUEDC2 downregulation significantly inhibited DOX-induced apoptosis. The expression levels of proapoptotic genes, including B-cell lymphoma 2 (Bcl-2)-associated X protein, cleaved caspase-3 and cytochrome c were inhibited by the depletion of CUEDC2. Conversely, the expression levels of the anti-apoptotic gene Bcl-2 were elevated in the CUEDC2 knockdown group. Downregulation of CUEDC2 also increased phosphorylation of protein kinase B and forkhead box O3a, and decreased the expression of Bcl-2-like protein 11 according to western blot analysis. Taken together, the present study demonstrated that CUEDC2 downregulation prevented DOX-induced cardiotoxicity in H9c2 cells. Therefore, CUEDC2 may be a promising target for the prevention of DOX-induced cardiotoxicity.

Proteomics analysis of human placenta reveals glutathione metabolism dysfunction as the underlying pathogenesis for preeclampsia

Hypertensive disorder in pregnancy (HDP) refers to a series of diseases that cause the hypertension during pregnancy, including HDP, preeclampsia (PE) and eclampsia. This study screens differentially expressed proteins of placenta tissues in PE cases using 2D LC-MS/MS quantitative proteomics strategy. A total of 2281 proteins are quantified, of these, 145 altering expression proteins are successfully screened between PE and control cases (p<0.05). Bioinformatics analysis suggests that these proteins are mainly involved in many biological processes, such as oxidation reduction, mitochondrion organization, and acute inflammatory response. Especially, the glutamine metabolic process related molecules, GPX1, GPX3, SMS, GGCT, GSTK1, NFκB, GSTT2, SOD1 and GCLM, are involved in the switching process from oxidized glutathione (GSSG) conversion to the reduced glutathione (GSH) by glutathione, mercapturic acid and arginine metabolism process. Results of this study revealed that glutathione metabolism disorder of placenta tissues may contribute to the occurrence of PE disease.

CUEDC2 modulates cardiomyocyte oxidative capacity by regulating GPX1 stability

The irreversible loss of cardiomyocytes due to oxidative stress is the main cause of heart dysfunction following ischemia/reperfusion (I/R) injury and ageing-induced cardiomyopathy. Here, we report that CUEDC2, a CUE domain-containing protein, plays a critical role in oxidative stress-induced cardiac injury. Cuedc2(-/-) cardiomyocytes exhibited a greater resistance to oxidative stress-induced cell death. Loss of CUEDC2 enhanced the antioxidant capacity of cardiomyocytes, promoted reactive oxygen species (ROS) scavenging, and subsequently inhibited the redox-dependent activation of signaling pathways. Notably, CUEDC2 promoted E3 ubiquitin ligases tripartite motif-containing 33 (TRIM33)-mediated the antioxidant enzyme, glutathione peroxidase 1 (GPX1) ubiquitination, and proteasome-dependent degradation. Ablation of CUEDC2 upregulated the protein level of GPX1 in the heart significantly. Strikingly, in vivo, the infarct size of Cuedc2(-/-) heart was significantly decreased after I/R injury, and aged Cuedc2(-/-) mice preserved better heart function as the overall ROS levels in their hearts were significantly lower. Our results demonstrated a novel role of CUEDC2 in cardiomyocyte death regulation. Manipulating CUEDC2 level might be an attractive therapeutic strategy for promoting cardiomyocyte survival following oxidative stress-induced cardiac injury.