Yap overexpression attenuates septic cardiomyopathy by inhibiting DRP1-related mitochondrial fission and activating the ERK signaling pathway

Context: Yes-associated protein (Yap) has been linked to several cardiovascular disorders, but the role of this protein in septic cardiomyocytes is not fully understood.

Objective: The aim of our study was to explore the influence of Yap in septic cardiomyopathy in vivo and in vitro.

Materials and methods: In the current study, Yap transgenic mice and Yap adenovirus-mediated gain-of-function assays were used in an LPS-established septic cardiomyopathy model. Mitochondrial function and mitochondrial fission were determined through western blotting, immunofluorescence analysis and ELISA.

Results: Our results demonstrated that Yap expression was downregulated by LPS, whereas Yap overexpression sustained cardiac function and attenuated cardiomyocyte death. The functional exploration revealed that LPS treatment induced cardiomyocyte mitochondrial stress, as manifested by mitochondrial superoxide overproduction, cardiomyocyte ATP deprivation, and caspase-9 apoptosis activation. Furthermore, we demonstrated that LPS-mediated mitochondrial damage was controlled by mitochondrial fission. However, Yap overexpression reduced mitochondrial fission and therefore improved mitochondrial function. A molecular investigation revealed that Yap overexpression inhibited mitochondrial fission by reversing ERK activity, and the inhibition of the ERK pathway promoted DRP1 upregulation and thereby mediated mitochondrial fission activation in the presence of Yap overexpression.

Conclusions: Overall, our results suggest that the cause of septic cardiomyopathy appears to be connected with Yap downregulation. The overexpression of Yap can attenuate myocardial inflammation injury through the reduction of DRP1-related mitochondrial fission in an ERK pathway activation-dependent manner.     

Oxidative insults disrupt OPA1-mediated mitochondrial dynamics in cultured mammalian cells

Objective: To explore the impact of oxidative insults on mitochondrial dynamics. In mammalian cells, oxidative insults activate stress response pathways including inflammation, cytokine secretion, and apoptosis. Intriguingly, mitochondria are emerging as a sensitive network that may function as an early indicator of subsequent cellular stress responses. Mitochondria form a dynamic network, balancing fusion, mediated by optic atrophy-1 (OPA1), and fission events, mediated by dynamin-related protein-1 (DRP1), to maintain homeostasis.

Methods: Here, we examine the impact of oxidative insults on mitochondrial dynamics in 143B osteosarcoma and H9c2 cardiomyoblast cell lines via confocal microscopy, flow cytometry, and protein-based analyses.

Results: When challenged with hydrogen peroxide (H₂O₂), a ROS donor, both cell lines display fragmentation of the mitochondrial network and loss of fusion-active OPA1 isoforms, indicating that OPA1-mediated mitochondrial fusion is disrupted by oxidative damage in mammalian cells. Consistent with this, cells lacking OMA1, a key protease responsible for cleavage of OPA1, are protected against OPA1 cleavage and mitochondrial fragmentation in response to H₂O₂ challenge.

Discussion: Taken together, these findings indicate that oxidative insults damage OPA1-mediated mitochondrial dynamics in mammalian cells via activation of OMA1, consistent with an emerging role for mitochondrial dynamics as an early indicator of cellular stress signaling.     

Inhibitory effect of Tanshinone IIA on inverted formin-2 protects HaCaT cells against oxidative injury via regulating mitochondrial stress

Context: Epidermal cells play an important role in regulating the regeneration of skin after burns and wounds.

Objective: The aim of our study is to explore the role of Tanshinone IIA (Tan IIA) in the apoptosis of epidermal HaCaT cells induced by H₂O₂, with a focus on mitochondrial homeostasis and inverted formin-2 (INF2).

Materials and methods: Cellular viability was determined using the MTT assay, TUNEL staining, western blot analysis and LDH release assay. Adenovirus-loaded INF2 was transfected into HaCaT cells to overexpress INF2 in the presence of Tan IIA treatment. Mitochondrial function was determined using JC-1 staining, mitochondrial ROS staining, immunofluorescence and western blotting.

Results: Oxidative stress promoted the death of HaCaT cells and this effect could be reversed by Tan IIA. At the molecular levels, Tan IIA treatment sustained mitochondrial energy metabolism, repressed mitochondrial ROS generation, stabilized mitochondrial potential, and blocked the mitochondrial apoptotic pathway. Furthermore, we demonstrated that Tan IIA modulated mitochondrial homeostasis via affecting INF2-related mitochondrial stress. Overexpression of INF2 could abolish the protective effects of Tan IIA on HaCaT cells viability and mitochondrial function. Besides, we also reported that Tan IIA regulated INF2 expression via the ERK pathway; inhibition of this pathway abrogated the beneficial effects of Tan IIA on HaCaT cells survival and mitochondrial homeostasis.

Conclusions: Overall, our results indicated that oxidative stress-mediated HaCaT cells apoptosis could be reversed by Tan IIA treatment via reducing INF2-related mitochondrial stress in a manner dependent on the ERK signaling pathway.     

Gender-dependent differences of mitochondrial function and oxidative stress in rat skeletal muscle at rest and after exercise training

Objective: This study investigated gender-dependent differences of mitochondrial function and sensitivity to in vitro ROS exposure in rat skeletal muscle at rest and after exercise training.

Methods: Wistar rats underwent running training for 6 weeks. In vitro measurements of hydroxyl radical production, oxygen consumption (under basal and maximal respiration conditions) and ATP production were made on permeabilized fibers. Mitochondrial function was examined after exposure and non-exposure to an in vitro generator system of reactive oxygen species (ROS). Antioxidant enzyme activities and malondialdehyde (MDA) content were also determined.

Results: Compared with sedentary males, females showed a greater resistance of mitochondrial function (oxygen consumption and ATP production) to ROS exposure, and lower MDA content and antioxidant enzyme activities. The training protocol had more beneficial effects in males than females with regard to ROS production and oxidative stress. In contrast to male rats, the susceptibility of mitochondrial function to ROS exposure in trained females was unchanged.

Discussion: Exercise training improves mitochondrial function oxidative capacities in both male and female rats, but is more pronounced in males as a result of different mechanisms. The resistance of mitochondrial function to in vitro oxidative stress exposure and the antioxidant responses are gender- and training-dependent, and may be related to the protective effects of estrogen.     

EGFR signaling and autophagy dependence for growth,survival, and therapy resistance

The epidermal growth factor receptor (EGFR) is amplified or mutated in various human epithelial tumors. Its expression and activation leads to cell proliferation, differentiation, and survival. Consistently, EGFR amplification or expression of EGFR variant 3 (EGFRvIII) is associated with resistance to conventional cancer therapy through activation of pro-survival signaling and DNA-repair mechanisms. EGFR targeting has successfully been exploited as strategy to increase treatment efficacy. Nevertheless, these targeting strategies have only been proven effective in a limited percentage of human tumors.

Recent knowledge indicates that EGFR deregulated tumors display differences in autophagy and dependence on autophagy for growth and survival and the use of autophagy to increase resistance to EGFR-targeting drugs. In this review the dependency on autophagy and its role in mediating resistance to EGFR-targeting agents will be discussed. Considering the current knowledge, autophagy inhibition could provide a novel strategy to enhance therapy efficacy in treatment of EGFR deregulated tumors.     

Hepatitis C virus core or NS3/4A protein expression preconditions hepatocytes against oxidative stress and endoplasmic reticulum stress

Objectives: The occurrence of oxidative stress and endoplasmic reticulum (ER) stress in hepatitis C virus (HCV) infection has been demonstrated and play an important role in liver injury. During viral infection, hepatocytes must handle not only the replication of the virus, but also inflammatory signals generating oxidative stress and damage. Although several mechanisms exist to overcome cellular stress, little attention has been given to the adaptive response of hepatocytes during exposure to multiple noxious triggers.

Methods: In the present study, Huh-7 cells and hepatocytes expressing HCV Core or NS3/4A proteins, both inducers of oxidative and ER stress, were additionally challenged with the superoxide anion generator menadione to mimic external oxidative stress. The production of reactive oxygen species (ROS) as well as the response to oxidative stress and ER stress were investigated.

Results: We demonstrate that hepatocytes diminish oxidative stress through a reduction in ROS production, ER-stress markers (HSPA5 [GRP78], sXBP1) and apoptosis (caspase-3 activity) despite external oxidative stress. Interestingly, the level of the autophagy substrate protein p62 was downregulated together with HCV Core degradation, suggesting that hepatocytes can overcome excess oxidative stress through autophagic degradation of one of the stressors, thereby increasing cell survival.

Duscussion: In conclusion, hepatocytes exposed to direct and indirect oxidative stress inducers are able to cope with cellular stress associated with viral hepatitis and thus promote cell survival.     

Proteomic analysis of mitochondria: biological and clinical progresses in cancer

Introduction: Mitochondria play important roles in regulating multiple biological processes and signalling pathways in eukaryotic cells, and mitochondrial dysfunction may result in a wide range of serious diseases, including cancer. With improvements in the identification of mitochondrial proteins, mitochondrial proteomics has made great achievements. In particular, this approach has been widely used to compare tumour cells at different stages of malignancy. Therefore, there is an urgent need to identify and characterize the function of mitochondrial proteins in cancer progression and to determine the involved mechanisms.

Areas covered: We provide an overview of recent progress related to mitochondrial proteomics in cancer and the application of comparative mitochondrial proteomics in various biological processes, including apoptosis, necroptosis, autophagy and metastasis, as well as clinical progress in cancer. Proteomics-related reports were found using PubMed and Google Scholar databases.

Expert commentary: Understanding both post-translational modification and post-translational processing is important in the comprehensive characterization of protein function. The application of comparative mitochondrial proteomics to investigate clinical samples and cancer cells will contribute to our understanding of the molecular interplay of mitochondrial proteins in the development of cancer. This approach will mine more biomarkers for diagnosis and prognosis and improve therapeutic outcomes among cancer patients.     

Evaluation of genetic diversity and population structure of Macqueen’s Bustard Chlamydotis macqueenii in Iran

Capsule: There is low genetic diversity in the Macqueen’s Bustard Chlamydotis macqueenii in Iran.

Aims: To investigate the genetic diversity and population structure of Macqueen’s Bustard in Iran, using two mitochondrial DNA loci.

Methods: Molecular diversity of the mitochondrial cytochrome oxidase c subunit I (COI) gene and part of the mitochondrial control region D-loop (in total 1183 base pairs) were analysed from 26 individual Macqueen’s Bustards from three regions of Iran.

Results: There was little variation in nucleotides and haplotypes in the populations for genes of both CR and COI. The population had free breeding and gene flow between the three study regions in Iran: Petregan, Ferdows and Yazd.

Conclusion: The use of molecular and genetic studies is essential to strengthen the protection of genetic diversity of the Macqueen’s Bustard.     

Restraining reactive oxygen species in Listeria monocytogenes promotes the apoptosis of glial cells

Objectives: Listeria monocytogenes is a facultative anaerobic foodborne pathogen that can traverse the blood–brain barrier and cause brain infection. L. monocytogenes infection induces host cell apoptosis in several cell types. In this study, we investigated the apoptosis of human glioma cell line U251 invaded by L. monocytogenes and evaluated the function of bacterial reactive oxygen species (ROS) during infection.

Methods: Bacterial ROS level was reduced by carrying out treatment with N-acetyl cysteine (NAC) and diphenyleneiodonium chloride (DPI). After infection, the apoptosis of U251 cells was examined by flow cytometry assay and propidium iodide staining.

Results: DPI and NAC efficiently decreased ROS level in L. monocytogenes without affecting bacterial growth. Moreover, the apoptosis of glial cells was enhanced upon invasion of DPI- and NAC-pretreated L. monocytogenes.

Discussion: Results indicate that the apoptosis of glial cells can be induced by L. monocytogenes, and that the inhibition of bacterial ROS increases the apoptosis of host cells.     

A pseudo-receiver domain in Atg32 is required for mitophagy

Mitochondria are targeted for degradation by mitophagy, a selective form of autophagy. In Saccharomyces cerevisiae, mitophagy is dependent on the autophagy receptor, Atg32, an outer mitochondrial membrane protein. Once activated, Atg32 recruits the autophagy machinery to mitochondria, facilitating mitochondrial capture in phagophores, the precursors to autophagosomes. However, the mechanism of Atg32 activation remains poorly understood. To investigate this crucial step in mitophagy regulation, we examined the structure of Atg32. We have identified a structured domain in Atg32 that is essential for the initiation of mitophagy, as it is required for the proteolysis of the C-terminal domain of Atg32 and the subsequent recruitment of Atg11. The solution structure of this domain was determined by NMR spectroscopy, revealing that Atg32 contains a previously undescribed pseudo-receiver (PsR) domain. Our data suggests that the PsR domain of Atg32 regulates Atg32 activation and the initiation of mitophagy.

Abbreviations:AIM: Atg8-interacting motif; GFP: green fluorescent protein; LIR: LC3-interacting region; NMR: nuclear magnetic resonance; NOESY: nuclear Overhauser effect spectroscopy; PDB: protein data bank; PsR: pseudo-receiver; RMSD: root-mean-square deviation     

Potential of serum soluble CD93 as a biomarker for asthma in an ovalbumin-induced asthma murine model

Background: CD93 is a membrane-associated glycoprotein, which can be released in a soluble form (sCD93) into the serum. CD93 has received renewed attention as a candidate biomarker of inflammation in various inflammatory and immune-mediated diseases, including asthma.

Objective: We aimed to evaluate the effects of airway inflammation on CD93 levels in murine models.

Methods: We established an ovalbumin (OVA)-induced acute asthma murine model (OVA model) and a lipopolysaccharide (LPS)-induced airway inflammation murine model (LPS model). Dexamethasone was administered by gavage to attenuate the airway inflammation.

Results: The OVA model demonstrated typical allergic asthma features with increased airway hyper-responsiveness, inflammatory cell infiltration, increased Th2 cytokine levels, compared to the control group. CD93 levels were decreased in lung homogenates and, respiratory epithelial cells, whereas serum sCD93 levels were increased in the OVA model, as compared to the control group. Dexamethasone reversed these effects of OVA. In contrast, in the LPS model, CD93 levels were not affected in neither respiratory epithelial cells nor serum.

Conclusions: Our findings demonstrate the potential of using sCD93 as a biomarker for allergic asthma.     

Kallistatin levels in HIV-infected patients and effects of statin therapy

Background: Kallistatin, a serine proteinase inhibitor, has vasodilatory and anti-inflammatory properties and is increased in other inflammatory conditions. We measured kallistatin in HIV for the first time, examined its relationship with inflammation, and determined if statin therapy affected levels.

Methods: Kallistatin levels were measured in subjects from a randomized, double-blinded, placebo-controlled trial.

Results: One hundred and thirty-five HIV-infected subjects were included. Kallistatin levels were 28.4?μg/mL at baseline and not affected by rosuvastatin. Levels were correlated with high-sensitivity C-reactive protein (hsCRP), interleukin-6, fibrinogen and insulin resistance.

Conclusions: Kallistatin levels were correlated with some markers of systemic inflammation and should be further explored in the HIV population.     

Early warning biomarkers in major depressive disorder: a strategic approach to a testing question

Purpose: Identification of biomarkers in major depressive disorder (MDD) has proceeded in an extemporised manner. No single biomarker has been identified with utility in screening, diagnosis, prognosis, or monitoring, and screening tests have different characteristics than the other functions. Using chaos, bifurcation, and perturbation (CBP) theories, the aim is to identify biomarkers to aid clinicians in screening for MDD.

Materials and methods: MDD is a complex disorder; consequently, a reductionist approach to characterize the complex system changes found in MDD will be inchoate and unreliable. A holistic approach is used to identify biomarkers reflecting the tipping points seen before the catastrophic bifurcation that results in MDD.

Results: Applying CBP theories revealed skew, resistance to change, flickering, increased variance and autocorrelation as patterns of biomarkers. Integrals and differentials of extracellular and intracellular biomarkers were identified, specifically focussed on hypothalamo-pituitary axis (HPA) dysfunction, metabolic dysfunction, inflammation and mitochondrial oxidative stress, and tryptophan metabolism.

Conclusions: Applying CBP theories to the dysfunctional complex biological systems in MDD led to development of integrals and differentials of biomarkers that can be used in screening for MDD and planning future biomarker research, targeting intracellular and extracellular inflammation, HPA axis dysfunction, and tryptophan metabolism.     

Parameters of oxidative stress in saliva from patients with aggressive and chronic periodontitis

Objectives: Free radicals play an important role in the onset and progression of many diseases. The aim of this study was to investigate the contribution of oxidative stress in the pathology of aggressive (AgP) and chronic (CP) periodontitis and its relation with the clinical periodontal status.

Methods: Eighty subjects were divided into two groups: 20 patients with AgP and 20 patients with CP with their 20 corresponding matched controls, based on clinical attachment loss (CAL), probing pocket depth (PPD), and bleeding on probing (BOP). Saliva reactive oxygen species (ROS), lipid peroxidation, and non-enzymatic antioxidant defences were measured by luminol-dependent chemiluminescence assay, as thiobarbituric acid-reactive substances (TBARs) and total radical-trapping antioxidant potential (TRAP), respectively. Pearson's correlation and multivariate analysis were used to determine the relationship between ROS and TBARs and the clinical parameters.

Results: ROS and TBARs were increased in AgP while TRAP was decreased, comparing with CP. In AgP, a strong and positive correlation was observed between ROS and TBARs and they were closely associated with CAL and PPD.

Discussion: In AgP, but not in CP, oxidative stress is a high contributor to periodontal pathology and it is closely associated with the clinical periodontal status.     

Soluble TREM-1 as a diagnostic and prognostic biomarker in patients with septic shock: an observational clinical study

Objectives: The impact of TREM-1-mediated inflammation was investigated in different inflammatory settings.

Methods: Secondary analyses of an observational clinical pilot study, including 60 patients with septic shock, 30 postoperative controls and 30 healthy volunteers.

Results: Plasma levels of sTREM-1 were found to identify patients with septic shock more effectively than procalcitonin and C-reactive protein. Moreover, sTREM-1 was identified to be an early predictor for survival in patients with septic shock.

Conclusion: Due to its diagnostic as well as prognostic value in sepsis syndrome, implementation of sTREM-1 measurements in routine diagnostics should be taken into account.     

Blood markers of inflammation and endothelial dysfunction in cardioembolic stroke: systematic review and meta-analysis

Context: Various processes including inflammation and endothelial dysfunction have been implicated in the pathogenesis of cardioembolic (CE) strokes.

Objective: To review the evidence and investigate the association between immune-inflammatory biomarkers and CE strokes versus other stroke subtypes.

Methods: We systematically reviewed the literature (sources: MEDLINE, web-based register http://stroke-biomarkers.com, reference lists) with quality assessment and meta-analysis of selected articles.

Results: The most consistent association was found between C-reactive protein (CRP) and CE strokes when compared to other stroke subtypes (standardized mean difference 0.223 (0.116, 0.343); p?<?0.001)

Conclusions: Our findings confirm a possible association between selected inflammatory biomarkers and CE stroke.     

Mechanisms involved in the development of diabetic retinopathy induced by oxidative stress

Background: Diabetic retinopathy (DR) is one of the main complications in patients with diabetes and has been the leading cause of visual loss since 1990. Oxidative stress is a biological process resulting from excessive production of reactive oxygen species (ROS). This process contributes to the development of many diseases and disease complications. ROS interact with various cellular components to induce cell injury. Fortunately, there is an antioxidan t system that protects organisms against ROS. Indeed, when ROS exceed antioxidant capacity, the resulting cell injury can cause diverse physiological and pathological changes that could lead to a disease like DR.

Objective: This paper reviews the possible mechanisms of common and novel biomarkers involved in the development of DR and explores how these biomarkers could be used to monitor the damage induced by oxidative stress in DR, which is a significant complication in people with diabetes.

Conclusion: The poor control of glucemy in pacients with DB has been shown contribute to the development of complications in eyes as DR.     

Downregulation of IDH2 exacerbates H2O2-mediated cell death and hypertrophy

Objectives: Reactive oxygen species-mediated cell death contributes to the pathophysiology of cardiovascular disease and myocardial dysfunction. We recently showed that mitochondrial NADP⁺-dependent isocitrate dehydrogenase (IDH2) functions as an antioxidant and anti-apoptotic protein by supplying NADPH to antioxidant systems.

Methods: In the present study, we demonstrated that H₂O₂-induced apoptosis and hypertrophy of H9c2 cardiomyoblasts was markedly exacerbated by small interfering RNA (siRNA) specific for IDH2.

Results: Attenuated IDH2 expression resulted in the modulation of cellular and mitochondrial redox status, mitochondrial function, and cellular oxidative damage. MitoTEMPO, a mitochondria-targeted antioxidant, efficiently suppressed increased caspase-3 activity, increased cell size, and depletion of cellular GSH levels in IDH2 siRNA-transfected cells that were treated with H₂O₂.

Discussion: These results indicated that the disruption of cellular redox balance might be responsible for the enhanced H₂O₂-induced apoptosis and hypertrophy of cultured cardiomyocytes by the attenuated IDH2 expression.     

Bile: miRNA pattern and protein-based biomarkers may predict acute cellular rejection after liver transplantation

Context: Bile rather than blood depicts the local inflammation in the liver and may improve prediction and diagnosis of acute cellular rejection (ACR) after liver transplantation (OLT).

Methods: Secretome and miRNAs were analyzed during the first two weeks and on clinical suspicion of ACR in the bile of 45 OLT recipients.

Results: Levels of CD44, CXCL9, miR-122, miR-133a, miR-148a and miR-194 were significantly higher in bile of patients who developed ACR within the first 6 months after OLT and during ACR.

Conclusion: Analysis of secretome and miRNA in bile could improve our understanding of the local inflammatory process during rejection.