Variation of NDRG2 and c-Myc expression in rat heart during the acute stage of ischemia/reperfusion injury

Identification of biomarkers associated with programmed cell death in liver ischemia-reperfusion injury: insights from machine learning frameworks and molecular docking in multiple cohorts

Introduction

Liver ischemia-reperfusion injury (LIRI) is a major reason for liver injury that occurs during surgical procedures such as hepatectomy and liver transplantation and is a major cause of graft dysfunction after transplantation. Programmed cell death (PCD) has been found to correlate with the degree of LIRI injury and plays an important role in the treatment of LIRI. We aim to comprehensively explore the expression patterns and mechanism of action of PCD-related genes in LIRI and to find novel molecular targets for early prevention and treatment of LIRI.

Methods

We first compared the expression profiles, immune profiles, and biological function profiles of LIRI and control samples. Then, the potential mechanisms of PCD-related differentially expressed genes in LIRI were explored by functional enrichment analysis. The hub genes for LIRI were further screened by applying multiple machine learning methods and Cytoscape. GSEA, GSVA, immune correlation analysis, transcription factor prediction, ceRNA network analysis, and single-cell analysis further revealed the mechanisms and regulatory network of the hub gene in LIRI. Finally, potential therapeutic agents for LIRI were explored based on the CMap database and molecular docking technology.

Results

Forty-seven differentially expressed genes associated with PCD were identified in LIRI, and functional enrichment analysis showed that they were involved in the regulation of the TNF signaling pathway as well as the regulation of hydrolase activity. By utilizing machine learning methods, 11 model genes were identified. ROC curves and confusion matrix from the six cohorts illustrate the superior diagnostic value of our model. MYC was identified as a hub PCD-related target in LIRI by Cytoscape. Finally, BMS-536924 and PF-431396 were identified as potential therapeutic agents for LIRI.

Conclusion

This study comprehensively characterizes PCD in LIRI and identifies one core molecule, providing a new strategy for early prevention and treatment of LIRI.

Fermented Houttuynia cordata Juice Exerts Cardioprotective Effects by Alleviating Cardiac Inflammation and Apoptosis in Rats with Lipopolysaccharide-Induced Sepsis

BACKGROUND/OBJECTIVES

Sepsis-induced cardiac dysfunction is a major problem that often leads to severe complications and a poor prognosis. Despite the growing awareness of its impact, effective treatment options for sepsis-induced cardiac dysfunction remain limited. To date, fermented products of Houttuynia cordata (HC), known for its rich bioactive properties, have shown potential in modulating inflammatory and oxidative stress pathways. However, treatment with fermented HC juice (FHJ) in lipopolysaccharide (LPS)-induced sepsis in rats has not been investigated.

METHODS

Rats were pretreated with FHJ at doses of 200 mg/kg and 400 mg/kg for 2 weeks. After that, the rats were injected with a single dose of LPS (10 mg/kg), and 12 h after injection, they developed sepsis-induced cardiac dysfunction. Then, cardiac function, oxidative stress, inflammation, apoptosis, and cardiac injury markers were determined.

RESULTS

Pretreatment with FHJ at doses of 200 mg/kg and 400 mg/kg prevented LPS-induced cardiac dysfunction in rats by attenuating cardiac inflammation (IL-1β, TLR-4, and NF-κB levels), oxidative stress (MDA levels), and apoptosis (cleaved-caspase 3 and Bax/Bcl-2 expression) and reducing markers of cardiac injury (LDH and CK-MB levels).

CONCLUSIONS

These results suggest that FHJ could be a potential therapeutic agent for sepsis-induced heart disease.

N-Terminomic Identification of Intracellular MMP-2 Substrates in Cardiac Tissue

Proteases are enzymes that induce irreversible post-translational modifications by hydrolyzing amide bonds in proteins. One of these proteases is matrix metalloproteinase-2 (MMP-2), which has been shown to modulate extracellular matrix remodeling and intracellular proteolysis during myocardial injury. However, the substrates of MMP-2 in heart tissue are limited, and lesser known are the cleavage sites. Here, we used degradomics to investigate the substrates of intracellular MMP-2 in rat ventricular extracts. First, we designed a novel, constitutively active MMP-2 fusion protein (MMP-2-Fc) that we expressed and purified from mammalian cells. Using this protease, we proteolyzed ventricular extracts and used subtiligase-mediated N-terminomic labeling which identified 95 putative MMP-2-Fc proteolytic cleavage sites using mass spectrometry. The intracellular MMP-2 cleavage sites identified in heart tissue extracts were enriched for proteins primarily involved in metabolism, as well as the breakdown of fatty acids and amino acids. We further characterized the cleavage of three of these MMP-2-Fc substrates based on the gene ontology analysis. We first characterized the cleavage of sarco/endoplasmic reticulum calcium ATPase (SERCA2a), a known MMP-2 substrate in myocardial injury. We then characterized the cleavage of malate dehydrogenase (MDHM) and phosphoglycerate kinase 1 (PGK1), representing new cardiac tissue substrates. Our findings provide insights into the intracellular substrates of MMP-2 in cardiac cells, suggesting that MMP-2 activation plays a role in cardiac metabolism.

Low NDRG2, regulated by the MYC/MIZ-1 complex and methylation, predicts poor outcomes in DLBCL patients

Diffuse large B-cell lymphoma (DLBCL) represents the most common tumor in non-Hodgkin's lymphoma. N-Myc downstream-regulated gene 2 (NDRG2) is a tumor suppressor highly expressed in healthy tissues but downregulated in many cancers. Although cell proliferation-related metabolism rewiring has been well characterized, less is known about the mechanism of metabolic changes with DLBCL. Herein, we investigated the expressions of NDRG2, MYC and Myc-interacting zinc finger protein 1 (MIZ-1) in seven human lymphoma (mostly DLBCLs) cell lines. NDRG2 expression was inversely correlated with the expressions of MYC and MIZ-1. Further, we explored the regulatory mechanism and biological functions underlying the lymphomagenesis involving NDRG2, MYC and MIZ-1. MYC and MIZ-1 promoted DLBCL cell proliferation, while NDRG2 induced apoptosis in LY8 cells. Moreover, NDRG2 methylation was reversed by the 5-Aza-2'-deoxycytidine (5-Aza-CDR) treatment, triggering the downregulation of MYC and inhibiting DLBCL cell survival. MYC interacts with NDRG2 to regulate energy metabolism associated with mTOR. Remarkably, supporting the biological significance, the converse correlation between NDRG2 and MYC was observed in human DLBCL tumor tissues (R = -0.557). Bioinformatics analysis further validated the association among NDRG2, MYC, MIZ-1, mTOR, and related metabolism genes. Additionally, NDRG2 (P = 0.001) and MYC (P < 0.001) were identified as promising prognostic biomarkers in DLBCL patients through survival analysis. Together, our data demonstrate that the MYC/MIZ-1 complex interplays with NDRG2 to influence the proliferation and apoptosis of DLBCL cells and show the characterizations of NDRG2, MYC and MIZ-1 for metabolism features and prediction prognosis in DLBCL.

Histone modification landscape and the key significance of H3K27me3 in myocardial ischaemia/reperfusion injury

Histone modifications play crucial roles in the pathogenesis of myocardial ischaemia/reperfusion (I/R) injury. However, a genome-wide map of histone modifications and the underlying epigenetic signatures in myocardial I/R injury have not been established. Here, we integrated transcriptome and epigenome of histone modifications to characterize epigenetic signatures after I/R injury. Disease-specific histone mark alterations were mainly found in H3K27me3-, H3K27ac-, and H3K4me1-marked regions 24 and 48 h after I/R. Genes differentially modified by H3K27ac, H3K4me1 and H3K27me3 were involved in immune response, heart conduction or contraction, cytoskeleton, and angiogenesis. H3K27me3 and its methyltransferase polycomb repressor complex 2 (PRC2) were upregulated in myocardial tissues after I/R. Upon selective inhibition of EZH2 (the catalytic core of PRC2), the mice manifest improved cardiac function, enhanced angiogenesis, and reduced fibrosis. Further investigations confirmed that EZH2 inhibition regulated H3K27me3 modification of multiple pro-angiogenic genes and ultimately enhanced angiogenic properties in vivo and in vitro. This study delineates a landscape of histone modifications in myocardial I/R injury, and identifies H3K27me3 as a key epigenetic modifier in I/R process. The inhibition of H3K27me3 and its methyltransferase might be a potential strategy for myocardial I/R injury intervention.

Cardiomyocyte death in sepsis: Mechanisms and regulation (Review)

Sepsis‑induced cardiac dysfunction is one of the most common types of organ dysfunction in sepsis; its pathogenesis is highly complex and not yet fully understood. Cardiomyocytes serve a key role in the pathophysiology of cardiac function; due to the limited ability of cardiomyocytes to regenerate, their loss contributes to decreased cardiac function. The activation of inflammatory signalling pathways affects cardiomyocyte function and modes of cardiomyocyte death in sepsis. Prevention of cardiomyocyte death is an important therapeutic strategy for sepsis‑induced cardiac dysfunction. Thus, understanding the signalling pathways that activate cardiomyocyte death and cross‑regulation between death modes are key to finding therapeutic targets. The present review focused on advances in understanding of sepsis‑induced cardiomyocyte death pathways, including apoptosis, necroptosis, mitochondria‑mediated necrosis, pyroptosis, ferroptosis and autophagy. The present review summarizes the effect of inflammatory activation on cardiomyocyte death mechanisms, the diversity of regulatory mechanisms and cross‑regulation between death modes and the effect on cardiac function in sepsis to provide a theoretical basis for treatment of sepsis‑induced cardiac dysfunction.

Dual Function of a in vivo Albumin-Labeling Tracer for Assessment of Blood Perfusion and Vascular Permeability in Peripheral Arterial Disease by PET

Background

Peripheral arterial disease (PAD) leads to tissue ischemia in the extremities. Enhanced vascular permeability plays a critical role in targeted delivery of drugs for effective therapeutic angiogenesis and resultant blood perfusion recovery. However, optimal tracers for evaluating this process in PAD patients are lacking. At this time, we employed a novel in vivo albumin-labeling tracer of dual function, termed as ¹⁸F-NEB, to assess blood perfusion as well as vascular permeability by positron emission tomography (PET).

Methods and Results

After successful establishment of mouse hindlimb ischemia (HI) model, static PET imaging was performed 15 min and 2 h post injection (p.i.) of ¹⁸F-NEB at 1, 3, 5, 7, 10 and 14 days post-surgery respectively. Gradual recovery of blood supply was detected by PET scan 15 min p.i. and collaborated by serial Laser Doppler. In addition, the highest vascular permeability observed by high local uptake of ¹⁸F-NEB at 2 h p.i. was consistent with histological examinations. Furthermore, we quantitatively evaluated the effect of vascular endothelial growth factor (VEGF) stimulus on vascular permeability and blood perfusion by PET scan using ¹⁸F-NEB probe in HI model, which were also confirmed by immunohistological results.

Conclusion

The application of ¹⁸F-NEB probe alone by PET can successfully achieve dual imaging of blood perfusion as well as vascular permeability at different time points p.i. and monitor their responses to therapy in PAD model. The simple labeling approach and multipurpose feature suggest the great promise of using this imaging probe in theranostic applications for treating ischemic disease.

N-myc downstream regulated gene 2 ameliorates myocardial remodeling and cardiac function in heart failure rats

This study aims to explore the effect of NDRG2 (N-myc downstream regulated gene 2)-mediated Transforming growth factor-beta 1 (TGF-β1)/ Sma- and Mad-related protein (Smad) pathway in heart failure (HF) rats. HF rat models were established and treated with AdEGFP (adenovirus encoding enhanced green fluorescent protein) or AdNDRG2 (adenovirus encoding NDRG2). The echocardiography and hemodynamic parameters were detected, and the infarct size was calculated via 2,3,5-triphenyltetrazolium chloride (TTC) staining. Masson staining was performed to observe the collagen volume fraction (CVF), quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) to detect the expression of Collagen I (Col-I) and Collagen III (Col-III), and Transferase (TdT)-mediated D-UTP-biotin nick end labeling (TUNEL) staining to evaluate the apoptosis. Rats in the Model group presented with the decreases in left ventricular ejection fraction (LVEF), left ventricular shortening fraction (LVFS), left ventricular systolic pressure (LVSP) and maximal/minimum rate of left ventricular pressure (±dp/dt max), and significant increases in left ventricular end-diastolic pressure (LVEDP) and CVF. At the meantime, the expression of Col-I and Col-III as well as the apoptotic rate of myocardial cells was also elevated with increased infarct size in the Model group. The Model rats also had the significant reduction in the expression of NDRG2 and up-regulations of TGF-β1, p-Smad2/Smad2, p-Smad3/Smad3 and tissue inhibitor of metalloproteinases-2 (TIMP-2). However, model rats treated with AdNDRG2 had evident amelioration in aforementioned indicators. In conclusion, NDRG2 reduces the apoptosis of myocardial cells and improves the heart function and myocardial remodeling in HF rats via inhibiting the activity of TGF-β1/Smad.

Genomic characterization reveals novel mechanisms underlying the valosin-containing protein-mediated cardiac protection against heart failure

Chronic hypertension is a key risk factor for heart failure. However, the underlying molecular mechanisms are not fully understood. Our previous studies found that the valosin-containing protein (VCP), an ATPase-associated protein, was significantly decreased in the hypertensive heart tissues. In this study, we tested the hypothesis that restoration of VCP protected the heart against pressure overload-induced heart failure. With a cardiac-specific transgenic (TG) mouse model, we showed that a moderate increase of VCP was able to attenuate chronic pressure overload-induced maladaptive cardiac hypertrophy and dysfunction. RNA sequencing and a comprehensive bioinformatic analysis further demonstrated that overexpression of VCP in the heart normalized the pressure overload-stimulated hypertrophic signals and repressed the stress-induced inflammatory response. In addition, VCP overexpression promoted cell survival by enhancing the mitochondria resistance to the oxidative stress via activating the Rictor-mediated-gene networks. VCP was also found to be involved in the regulation of the alternative splicing and differential isoform expression for some genes that are related to ATP production and protein synthesis by interacting with long no-coding RNAs and histone deacetylases, indicating a novel epigenetic regulation of VCP in integrating coding and noncoding genomic network in the stressed heart. In summary, our study demonstrated that the rescuing of a deficient VCP in the heart could prevent pressure overload-induced heart failure by rectifying cardiac hypertrophic and inflammatory signaling and enhancing the cardiac resistance to oxidative stress, which brought in novel insights into the understanding of the mechanism of VCP in protecting patients from hypertensive heart failure.

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Deficiency of VCP contributes to the pathogenesis of hypertensive heart failure.

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Rescue of VCP prevents stress-induced cardiac remodeling and cell death.

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VCP attenuates stress-induced inflammatory and hypertrophic signaling.

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VCP promotes cardiac resistance to oxidative stress.

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VCP mediates a novel epigenetic integrating regulation in the stressed heart.

c-Myc promotes tubular cell apoptosis in ischemia-reperfusion-induced renal injury by negatively regulating c-FLIP and enhancing FasL/Fas-mediated apoptosis pathway

c-Myc plays an important role in cell proliferation, differentiation, and cell apoptosis. FasL/Fas pathway is a key regulator of cell apoptosis. This study was aimed to investigate the effects of c-Myc on the FasL/Fas pathway in ischemia-reperfusion (I/R)-induced renal injury. Rats were objected to bilateral renal ischemia for 60 min and reperfused for 24 or 48 h. NRK-52E cells were treated with hypoxia-reoxygenation (H/R) or FasL. Immunohistochemistry was used to identify the distribution of c-Myc. Cell apoptosis was assessed by TUNEL staining. Ad-c-Myc and recombinant pcDAN 3.0 were used to overexpress c-Myc and c-FLIP, respectively. ChIP assay and luciferase assay were used to detect the binding of c-Myc to c-FLIP promoter. In I/R rats, c-Myc was increased significantly and mainly located in renal tubular epithelial cells; meanwhile, c-FLIP was decreased, cleaved caspase-8, cleaved caspase-3 and TUNEL-positive staining cells were increased. Treatment of I/R rats with c-Myc inhibitor 10058-F4 significantly attenuated the decrease in c-FLIP, the increase in cleaved caspase-8, cleaved caspase-3, TUNEL-positive cells, Scr and BUN in I/R rats. In NRK-52E cells, hypoxia and reoxygen induced the increase in c-Myc and decrease in c-FLIP. ChIP and luciferase assay results indicated that c-Myc binds to the promoter region of c-FLIP gene. Overexpression of c-Myc markedly decreased c-FLIP. Overexpression of c-FLIP inhibited the increase in cleaved caspase-8 and caspase-3 induced by FasL. Data indicated that c-Myc is increased in kidneys of I/R rats and negatively regulates the expression of c-FLIP, then enhanced FasL-induced cell apoptosis in I/R stress.

Cardioprotective roles of sestrin 1 and sestrin 2 against doxorubicin cardiotoxicity

Doxorubicin is a chemotherapy medication widely used to treat a variety of cancers. Even though it offers one of the most effective anti-cancer treatments, its clinical use is limited because of its strong cardiotoxicity that can lead to fatal conditions. Here, we show that sestrin 1 and sestrin 2, members of the sestrin family of proteins that are stress-inducible regulators of metabolism, are critical for suppressing doxorubicin cardiotoxicity and coordinating the AMPK-mammalian target of rapamycin complex 1 (mTORC1) autophagy signaling network for cardioprotection. Expression of both sestrin 1 and sestrin 2 was highly increased in the mouse heart after doxorubicin injection. Genetic ablation of sestrin 1 and sestrin 2 rendered mice more vulnerable to doxorubicin and exacerbated doxorubicin-induced cardiac pathologies including cardiomyocyte apoptosis and cardiac dysfunction. These pathologies were associated with strong dysregulation of the cardiac signaling network, including suppression of the AMPK pathway and activation of the mTORC1 pathway. Consistent with AMPK downregulation and mTORC1 upregulation, autophagic activity of heart tissue was diminished, leading to prominent accumulation of autophagy substrate, p62/SQSTM1. Taken together, our results indicate that sestrin 1 and sestrin 2 are important cardioprotective proteins that coordinate metabolic signaling pathways and autophagy to minimize cardiac damage in response to doxorubicin insult. Augmenting this protective mechanism could provide a novel therapeutic rationale for prevention and treatment of doxorubicin cardiotoxicity. NEW & NOTEWORTHY Doxorubicin is a highly efficient chemotherapeutic medicine; however, its use is limited because of its strong cardiotoxicity. Here, we show that sestrin 1 and sestrin 2 are critical protectors of cardiomyocytes from doxorubicin damage. By upregulating AMPK and autophagic activities and suppressing mammalian target of rapamycin complex 1 and oxidative stress, sestrins counteract detrimental effects of doxorubicin on cardiomyocytes. Correspondingly, loss of sestrin 1 and sestrin 2 produced remarkable dysregulation of these pathways, leading to prominent cardiac cell death and deterioration of heart function.

Inhibition of miR-148b ameliorates myocardial ischemia/reperfusion injury via regulation of Wnt/β-catenin signaling pathway

Our work aims to elucidate the effect how microRNA-148b (miR-148b) participated in myocardial ischemia/reperfusion (I/R) injury via regulation of Wnt/β-catenin signaling pathway. The in vivo myocardial I/R models of SD rats and in vitro hypoxia/reoxygenation (H/R) models of H9C2 cells were established. The heart function and infarction area of rats and lactic dehydrogenase (LDH), creatine kinase (CK), malondialdehyde (MDA), and superoxide dismutase (SOD) levels were evaluated. Myocardial cell viability was measured using positron emission tomography combined with computer tomography and (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, and the apoptosis was assessed by terminal deoxynucleotidyl transferase-mediated nick-end labeling method and flow cytometry; quantitative reverse-transcription polymerase chain reaction and western blot were used to detect the related molecules expressions. The myocardial infarction area of rats was significantly increased with reductions in LVSP, + dp/dtmax, - dp/dtmax, LVFS%, LVEF% and standardized uptake value and elevation in left ventricular developed pressure after ischemia/reperfusion (I/R), and the LDH, CK, and MDA levels were enhanced with the decreased SOD. The apoptotic rates were higher in I/R rats and H/R H9C2 cells with upregulated miR-148b and cleaved caspase-3, but decreased Bcl-2/Bax ratio; and meanwhile, the Wnt/β-catenin pathway was inhibited. Additionally, the H/R-induced H9C2 cells also exhibited decreased cell viability. MiR-148b overexpression further aggravated I/R injury of rats, whereas inhibition of miR-148b reduced I/R and H/R injury through activation of Wnt/β-catenin pathway. In addition, Wnt-1 small interfering RNA exposure abolished the effect of miR-148b inhibitor on H/R injury of H9C2 cells. Inhibition of miR-148b improved the antioxidative ability and myocardial cell survival to suppress its apoptosis by activating Wnt/β-catenin signaling pathway, thus ameliorating the myocardial I/R injury.

Spatiotemporal expression of NDRG2 in the human fetal brain

N-myc downstream-regulated gene 2 (NDRG2) has been implicated in the development of central nervous system and brain diseases such as brain tumors, ischemic stroke and neurodegenerative disorders. However, it remains unclear that the spatiotemporal distribution of NDRG2 in the human fetal brain. In this study, we examined the expression pattern of NDRG2 in different regions of human fetal brain at 16-28 gestational weeks (GWs) by using RT-PCR, western blot and immunohistochemistry. Firstly, RT-PCR revealed that mRNA of NDRG2 was detected in the human brain regions of fetuses at 16-28 GWs such as medulla oblongata (MdO), mesencephalon (MeE), cerebellum (Cbl), frontal lobe (Fr), ventricular (VZ)/subventricular zone (SVZ) and hippocampus (hip), and the expressions of NDRG2 mRNA in these human fetal brain regions were increased with gestational maturation. Furthermore, western blot and immunohistochemistry results revealed that at 28 GWs, the expression of NDRG2 protein was restricted to the MdO's olivary nucleus, MeE's aqueduct, cerebellar internal granular layers, cerebral cortex of the Fr, VZ/SVZ of lateral ventricle, and hippocampal dentate gyrus, and highest expression in the VZ/SVZ, and lowest in the MeE. Finally, double immunohistochemistry results showed that NDRG2 in the MdO, Cbl and VZ/SV at 28 GWS was mainly expressed in neurons (NeuN positive cells), and in some astrocytes (GFAP positive cells). Taken together, these results suggest that NDRG2 is mainly expressed in human fetal neurons of various brain regions during development, which may be involved in neuronal growth and maturation.

Melatonin attenuates intestinal ischemia--reperfusion-induced lung injury in rats by upregulating N-myc downstream-regulated gene 2

BACKGROUND

Successful drug treatment for ischemia--reperfusion-induced lung injury remains a major clinical problem. Melatonin (MT) is a hormone that is principally synthesized in the pineal gland. It has been shown to exhibit a variety of functions including anti-inflammatory and antioxidant effects. Previous reports on N-myc downstream-regulated gene (NDRG)2 have suggested that it is involved in cellular differentiation, development, antiapoptosis, anti-inflammatory cytokine, and antioxidant. The objective of this study was to test whether MT, a novel NDRG2 activator, can protect against intestinal ischemia-reperfusion-induced lung injury (IIRI).

MATERIALS AND METHODS

IIRI was induced in rats by occlusion of the superior mesenteric artery for 60 min, and the occlusion was then released for reperfusion. Rats were randomly divided into six groups as follows: control group; MT group; IIRI group; IIRI+5 mg/kg MT group; IIRI+15 mg/kg MT group; and IIRI+25 mg/kg MT group. The effects of MT on intestinal ischemia-reperfusion-induced lung pathologic changes, inflammatory cytokines release, myeloperoxidase and superoxide dismutase activities, and malondialdehyde level were examined. In addition, the NDRG2 activation in lung tissues was detected by Western blot analysis.

RESULTS

MT pretreatment attenuated edema and the pathologic changes in the lung. MT also decreased the levels of tumor necrosis factor-α, interleukin-1β, and interleukin-8 in bronchoalveolar lavage fluid. In addition, MT markedly prevented IIRI-induced elevation of malondialdehyde and myeloperoxidase levels, as well as reduction of superoxide dismutase activity. Furthermore, the expression of NDRG2 was activated by MT pretreatment in lung tissues.

CONCLUSIONS

The present study demonstrates that MT exerted protection against IIRI-induced oxidative stress. The potential mechanism of this action may attribute partly to the activation of NDRG2 expression.

Ischemia postconditioning preventing lung ischemia-reperfusion injury

OBJECTIVE

This study evaluates the inhibitory effect of IPO against ischemia reperfusion (I/R) induced lung injury in rats.

METHODS

Anesthetized and mechanically ventilated adult Sprague-Dawley rats were randomly assigned to one of the following groups (n=12 each): the sham operated control group, the ischemia-reperfusion (IR) group (30min of left-lung ischemia and 24h of reperfusion), the IPO group (three successive cycles of 30-s reperfusion per 30-s occlusion before restoring full perfusion), and the dexamethasone plus IPO group (rats were injected with dexamethasone (3mg/kg·day(-1)) 10min prior to the experiment and the rest of the procedures were the same as the IPO group). Lung injury was assessed by wet-to-dry lung weight ratio and tissue apoptosis and biochemical changes.

RESULTS

Lung ischemia-reperfusion increased lung MDA production, serum proinflammatory cytokine count, and MPO activity and reduced antioxidant enzyme activities (all p<0.05 I/R versus sham), accompanied with a compensatory increase in caspase-3, bax, Fas, FasL proteins and a decrease in Bcl-2 protein. Plasma levels of TNF-α, IL-6, and IL-1β were increased in the I/R group (all p<0.05 versus sham). IPO attenuated or prevented all the above changes. Treatment with dexamethasone enhanced all the protective effects of postconditioning.

CONCLUSION

Postconditioning obviously inhibits I/R induced lung injury by its antioxidant, anti-inflammatory and anti-apoptosis activities.

Effect of sevoflurane on tissue permeability of lung ischemia-reperfusion injury in rats

OBJECTIVE

To investigate the effect of sevoflurane on tissue permeability of lung ischemia-reperfusion injury (LIRI) in rats.

METHODS

A total of 45 wistar rats were randomly divided into 3 groups I, II, III. Modified Eppinger method was adopted to establish the rat lung ischemia-reperfusion injury model. Group I served as the control group, group III as ischemia reperfusion group, group III as sevoflurane ischemia-reperfusion group. Blood gas index, lung permeability index (LPI) change, lung tissue pathology change and lung water content were observed and compared between groups of rats at different time points.

RESULTS

During ischemia reperfusion, all rats kept balance of the MAP during different time points, SPO2 of group II and III decreased significantly than I group (P<0.05); after reperfusion lung permeability index in Group II and III was higher than the control group significantly (P<0.05), 120 min after reperfusion LPI change and injury of group III was significantly lower than II group (P<0.05); interstitial and alveolar cavity effusion in of group III were lower than that of group II.

CONCLUSIONS

Sevoflurane pretreatment can reduce the lung tissue permeability, and LIRI plays a protective role in LIRI.

Bioinformatics analysis of time series gene expression in left ventricle (LV) with acute myocardial infarction (AMI)

This study is to investigate the key genes and their possible function in acute myocardial infarction (AMI). The data of GSE4648 downloaded from the Gene Expression Omnibus (GEO) database include 6 time points (15 min, 60 min, 4h, 12h, 24h and 48 h) of 12 left ventricle (LV) samples, 12 surviving LV free wall (FW) samples, 12 inter-ventricular septum (IVS) samples after AMI operation and corresponding sham-operated samples. The data of each sample were analyzed with Affy and Bioconductor packages, and differentially expressed genes (DEGs) were screened out using BETR package with false discovery rate (FDR)<0.01. Then, functional enrichment analysis for DEGs was conducted with Database for Annotation, Visualization and Integrated Discovery (DAVID). Totally 194 DEGs were identified in LV, and only the gene tubulin beta 2a (Tubb2a) and natriuretic peptide B (Nppb) were respectively up-regulated in surviving FW tissue and IVS tissue. The biological process response to wounding and inflammatory response were significantly enriched, as well as leukocyte transendothelial migration pathway. Besides, the expression pattern analysis showed the DEGs mostly up-regulated at 4h after AMI, and these genes were mainly associated with immunity. Additionally, in transcriptional regulatory network, early growth response 1 (Egr1), activating transcription factor 3 (Atf3), Atf4, Myc and Fos were considered as the key transcription factors related to immune response. The key transcription factors and potential target genes might provide new information for the development of AMI, and leukocyte transendothelial migration pathway might play a vital role in AMI.

Comparative differential proteomic profiles of nonfailing and failing hearts after in vivo thoracic aortic constriction in mice overexpressing FKBP12.6

Chronic pressure overload (PO) induces pathological left ventricular hypertrophy (LVH) leading to congestive heart failure (HF). Overexpression of FKBP12.6 (FK506-binding protein [K]) in mice should prevent Ca2+-leak during diastole and may improve overall cardiac function. In order to decipher molecular mechanisms involved in thoracic aortic constriction (TAC)-induced cardiac remodeling and the influence of gender and genotype, we performed a proteomic analysis using two-dimensional differential in-gel electrophoresis (2D-DIGE), mass spectrometry, and bioinformatics techniques to identify alterations in characteristic biological networks. Wild-type (W) and K mice of both genders underwent TAC. Thirty days post-TAC, the altered cardiac remodeling was accompanied with systolic and diastolic dysfunction in all experimental groups. A gender difference in inflammatory protein expression (fibrinogen, α-1-antitrypsin isoforms) and in calreticulin occurred (males > females). Detoxification enzymes and cytoskeletal proteins were noticeably increased in K mice. Both non- and congestive failing mouse heart exhibited down- and upregulation of proteins related to mitochondrial function and purine metabolism, respectively. HF was characterized by a decrease in enzymes related to iron homeostasis, and altered mitochondrial protein expression related to fatty acid metabolism, glycolysis, and redox balance. Moreover, two distinct differential protein profiles characterized TAC-induced pathological LVH and congestive HF in all TAC mice. FKBP12.6 overexpression did not influence TAC-induced deleterious effects. Huntingtin was revealed as a potential mediator for HF. A broad dysregulation of signaling proteins associated with congestive HF suggested that different sets of proteins could be selected as useful biomarkers for HF progression and might predict outcome in PO-induced pathological LVH.

α-Lipoic acid reduces infarct size and preserves cardiac function in rat myocardial ischemia/reperfusion injury through activation of PI3K/Akt/Nrf2 pathway

Background

The present study investigates the effects and mechanisms of α-Lipoic acid (LA) on myocardial infarct size, cardiac function and cardiomyocyte apoptosis in rat hearts subjected to in vivo myocardial ischemia/reperfusion (MI/R) injury.

Methodology/Principal Findings

Male adult rats underwent 30 minutes of ischemia followed by 3, 24, or 72 h of reperfusion. Animals were pretreated with LA or vehicle before coronary artery ligation. The level of MI/R- induced LDH and CK release, infarct size, cardiomyocyte apoptosis and cardiac functional impairment were examined and compared. Western blot analysis was performed to elucidate the mechanism of LA pretreatment. The level of inflammatory cytokine TNF-α released to serum and accumulated in injured myocardium as well as neutrophil accumulation in injured myocardium were also examined after MI/R injury. Our results reveal that LA administration significantly reduced LDH and CK release, attenuated myocardial infarct size, decreased cardiomyocytes apoptosis, and partially preserved heart function. Western blot analysis showed that LA pretreatment up-regulated Akt phosphorylation and Nrf2 nuclear translocation while producing no impact on p38MAPK activation or nitric oxide (NO) production. LA pretreatment also increased expression of HO-1, a major target of Nrf2. LA treatment inhibited neutrophil accumulation and release of TNF-α. Moreover, PI3K inhibition abolished the beneficial effects of LA.

Conclusions/Significance

This study indicates that LA attenuates cardiac dysfunction by reducing cardiomyoctyes necrosis, apoptosis and inflammation after MI/R. LA exerts its action by activating the PI3K/Akt pathway as well as subsequent Nrf2 nuclear translocation and induction of cytoprotective genes such as HO-1.

DNA methylation of NDRG2 in gastric cancer and its clinical significance

BACKGROUND

Gastric cancer is one of the most common digestive malignancies worldwide. N-myc downstream-regulated gene 2 (NDRG2) is a differentiation-related gene that is considered to be a metastasis suppressor gene. In this study, we examined the expression and DNA methylation of NDRG2 in gastric cancer cell lines and tissues, as well as its clinical significance.

METHODS

Six gastric cancer cell lines and 42 paired normal and gastric cancer tissue samples were used to assess NDRG2 mRNA expression using RT-PCR. NDRG2 DNA methylation status was evaluated by methylation-specific PCR (MSP) in gastric cancer cell lines and tissues. The suppression of NDRG2 in BGC823 cells by siRNA transfection was utilized to detect the role of NDRG2 in gastric cancer progression.

RESULTS

NDRG2 mRNA was down-regulated in gastric cancer cell lines and tissues, and its expression was just related to lymph node metastasis (p = 0.032). MSP showed methylation of NDRG2 in 54.0 % (47/87) of primary gastric cancer specimens and in 20.0 % (16/80) of corresponding nonmalignant gastric tissues. NDRG2 methylation was related to depth of tumor invasion, Borrmann classification and TNM stage (p < 0.05). Upon treatment with 5-aza-2'-deoxycytidine and trichostatin A, NDRG2 expression was upregulated in HGC27 cells, and demethylation of the highly metastatic cell line, MKN45, inhibited cell invasion. Furthermore, the suppression of NDRG2 by siRNA transfection enhanced BGC823 cells invasion.

CONCLUSIONS

Our results suggest that the aberrant methylation of NDRG2 may be mainly responsible for its downregulation in gastric cancer, and may play an important role in the metastasis of gastric cancer.

Recent progress in histochemistry and cell biology

Studies published in Histochemistry and Cell Biology in the year 2011 represent once more a manifest of established and newly sophisticated techniques being exploited to put tissue- and cell type-specific molecules into a functional context. The review is therefore the Histochemistry and Cell Biology's yearly intention to provide interested readers appropriate summaries of investigations touching the areas of tissue biology, developmental biology, the biology of the immune system, stem cell research, the biology of subcellular compartments, in order to put the message of such studies into natural scientific-/human- and also pathological-relevant correlations.

Deep sequencing the transcriptome reveals seasonal adaptive mechanisms in a hibernating mammal

Mammalian hibernation is a complex phenotype involving metabolic rate reduction, bradycardia, profound hypothermia, and a reliance on stored fat that allows the animal to survive for months without food in a state of suspended animation. To determine the genes responsible for this phenotype in the thirteen-lined ground squirrel (Ictidomys tridecemlineatus) we used the Roche 454 platform to sequence mRNA isolated at six points throughout the year from three key tissues: heart, skeletal muscle, and white adipose tissue (WAT). Deep sequencing generated approximately 3.7 million cDNA reads from 18 samples (6 time points ×3 tissues) with a mean read length of 335 bases. Of these, 3,125,337 reads were assembled into 140,703 contigs. Approximately 90% of all sequences were matched to proteins in the human UniProt database. The total number of distinct human proteins matched by ground squirrel transcripts was 13,637 for heart, 12,496 for skeletal muscle, and 14,351 for WAT. Extensive mitochondrial RNA sequences enabled a novel approach of using the transcriptome to construct the complete mitochondrial genome for I. tridecemlineatus. Seasonal and activity-specific changes in mRNA levels that met our stringent false discovery rate cutoff (1.0 × 10(-11)) were used to identify patterns of gene expression involving various aspects of the hibernation phenotype. Among these patterns are differentially expressed genes encoding heart proteins AT1A1, NAC1 and RYR2 controlling ion transport required for contraction and relaxation at low body temperatures. Abundant RNAs in skeletal muscle coding ubiquitin pathway proteins ASB2, UBC and DDB1 peak in October, suggesting an increase in muscle proteolysis. Finally, genes in WAT that encode proteins involved in lipogenesis (ACOD, FABP4) are highly expressed in August, but gradually decline in expression during the seasonal transition to lipolysis.