Enhanced mitochondrial activity reshapes a gut microbiota profile that delays NASH progression.

BACKGROUND AND AIMS: Recent studies suggest that mitochondrial dysfunction promotes progression to NASH by aggravating the gut-liver status. However, the underlying mechanism remains unclear. Herein, we hypothesized that enhanced mitochondrial activity might reshape a specific microbiota signature that, when transferred to germ-free (GF) mice, could delay NASH progression. APPROACH AND RESULTS: Wild-type and methylation-controlled J protein knockout (MCJ-KO) mice were fed for 6 weeks with either control or a choline-deficient, L-amino acid-defined, high-fat diet (CDA-HFD). One mouse of each group acted as a donor of cecal microbiota to GF mice, who also underwent the CDA-HFD model for 3 weeks. Hepatic injury, intestinal barrier, gut microbiome, and the associated fecal metabolome were then studied. Following 6 weeks of CDA-HFD, the absence of methylation-controlled J protein, an inhibitor of mitochondrial complex I activity, reduced hepatic injury and improved gut-liver axis in an aggressive NASH dietary model. This effect was transferred to GF mice through cecal microbiota transplantation. We suggest that the specific microbiota profile of MCJ-KO, characterized by an increase in the fecal relative abundance of Dorea and Oscillospira genera and a reduction in AF12 , Allboaculum , and [ Ruminococcus ], exerted protective actions through enhancing short-chain fatty acids, nicotinamide adenine dinucleotide (NAD + ) metabolism, and sirtuin activity, subsequently increasing fatty acid oxidation in GF mice. Importantly, we identified Dorea genus as one of the main modulators of this microbiota-dependent protective phenotype. CONCLUSIONS: Overall, we provide evidence for the relevance of mitochondria-microbiota interplay during NASH and that targeting it could be a valuable therapeutic approach.

The outcome of boosting mitochondrial activity in alcohol-associated liver disease is organ-dependent.

BACKGROUND AND AIMS: Alcohol-associated liver disease (ALD) accounts for 70% of liver-related deaths in Europe, with no effective approved therapies. Although mitochondrial dysfunction is one of the earliest manifestations of alcohol-induced injury, restoring mitochondrial activity remains a problematic strategy due to oxidative stress. Here, we identify methylation-controlled J protein (MCJ) as a mediator for ALD progression and hypothesize that targeting MCJ may help in recovering mitochondrial fitness without collateral oxidative damage. APPROACH AND RESULTS: C57BL/6 mice [wild-type (Wt)] Mcj knockout and Mcj liver-specific silencing (MCJ-LSS) underwent the NIAAA dietary protocol (Lieber-DeCarli diet containing 5% (vol/vol) ethanol for 10 days, plus a single binge ethanol feeding at day 11). To evaluate the impact of a restored mitochondrial activity in ALD, the liver, gut, and pancreas were characterized, focusing on lipid metabolism, glucose homeostasis, intestinal permeability, and microbiota composition. MCJ, a protein acting as an endogenous negative regulator of mitochondrial respiration, is downregulated in the early stages of ALD and increases with the severity of the disease. Whole-body deficiency of MCJ is detrimental during ALD because it exacerbates the systemic effects of alcohol abuse through altered intestinal permeability, increased endotoxemia, and dysregulation of pancreatic function, which overall worsens liver injury. On the other hand, liver-specific Mcj silencing prevents main ALD hallmarks, that is, mitochondrial dysfunction, steatosis, inflammation, and oxidative stress, as it restores the NAD + /NADH ratio and SIRT1 function, hence preventing de novo lipogenesis and improving lipid oxidation. CONCLUSIONS: Improving mitochondrial respiration by liver-specific Mcj silencing might become a novel therapeutic approach for treating ALD.

Mechanisms of endothelial activation, hypercoagulation and thrombosis in COVID-19: a link with diabetes mellitus.

Early since the onset of the COVID-19 pandemic, the medical and scientific community were aware of extra respiratory actions of SARS-CoV-2 infection. Endothelitis, hypercoagulation, and hypofibrinolysis were identified in COVID-19 patients as subsequent responses of endothelial dysfunction. Activation of the endothelial barrier may increase the severity of the disease and contribute to long-COVID syndrome and post-COVID sequelae. Besides, it may cause alterations in primary, secondary, and tertiary hemostasis. Importantly, these responses have been highly decisive in the evolution of infected patients also diagnosed with diabetes mellitus (DM), who showed previous endothelial dysfunction. In this review, we provide an overview of the potential triggers of endothelial activation related to COVID-19 and COVID-19 under diabetic milieu. Several mechanisms are induced by both the viral particle itself and by the subsequent immune-defensive response (i.e., NF-κB/NLRP3 inflammasome pathway, vasoactive peptides, cytokine storm, NETosis, activation of the complement system). Alterations in coagulation mediators such as factor VIII, fibrin, tissue factor, the von Willebrand factor: ADAMST-13 ratio, and the kallikrein-kinin or plasminogen-plasmin systems have been reported. Moreover, an imbalance of thrombotic and thrombolytic (tPA, PAI-I, fibrinogen) factors favors hypercoagulation and hypofibrinolysis. In the context of DM, these mechanisms can be exacerbated leading to higher loss of hemostasis. However, a series of therapeutic strategies targeting the activated endothelium such as specific antibodies or inhibitors against thrombin, key cytokines, factor X, complement system, the kallikrein-kinin system or NETosis, might represent new opportunities to address this hypercoagulable state present in COVID-19 and DM. Antidiabetics may also ameliorate endothelial dysfunction, inflammation, and platelet aggregation. By improving the microvascular pathology in COVID-19 and post-COVID subjects, the associated comorbidities and the risk of mortality could be reduced.

The turnover of ABI5 by scaffold proteins to attenuate ABA signaling.

This article comments on: Li Z, Zhang D, Liang X, Liang J. 2024. Receptor for Activated C Kinase 1 counteracts ABSCISIC ACID INSENSITIVE5-mediated inhibition of seed germination and post-germinative growth in Arabidopsis. Journal of Experimental Botany 75, 3932-3945.

SARS-CoV-2 S protein activates NLRP3 inflammasome and deregulates coagulation factors in endothelial and immune cells.

BACKGROUND: Hyperinflammation, hypercoagulation and endothelial injury are major findings in acute and post-COVID-19. The SARS-CoV-2 S protein has been detected as an isolated element in human tissues reservoirs and is the main product of mRNA COVID-19 vaccines. We investigated whether the S protein alone triggers pro-inflammatory and pro-coagulant responses in primary cultures of two cell types deeply affected by SARS-CoV-2, such are monocytes and endothelial cells. METHODS: In human umbilical vein endothelial cells (HUVEC) and monocytes, the components of NF-κB and the NLRP3 inflammasome system, as well as coagulation regulators, were assessed by qRT-PCR, Western blot, flow cytometry, or indirect immunofluorescence. RESULTS: S protein activated NF-κB, promoted pro-inflammatory cytokines release, and triggered the priming and activation of the NLRP3 inflammasome system resulting in mature IL-1ß formation in both cell types. This was paralleled by enhanced production of coagulation factors such as von Willebrand factor (vWF), factor VIII or tissue factor, that was mediated, at least in part, by IL-1ß. Additionally, S protein failed to enhance ADAMTS-13 levels to counteract the pro-coagulant activity of vWF multimers. Monocytes and HUVEC barely expressed angiotensin-converting enzyme-2. Pharmacological approaches and gene silencing showed that TLR4 receptors mediated the effects of S protein in monocytes, but not in HUVEC. CONCLUSION: S protein behaves both as a pro-inflammatory and pro-coagulant stimulus in human monocytes and endothelial cells. Interfering with the receptors or signaling pathways evoked by the S protein may help preventing immune and vascular complications driven by such an isolated viral element. Video Abstract.

ASSESSMENT OF 1-HOUR POST-LOAD PLASMA GLUCOSE, THE METABOLIC SYNDROME AND THE FINDRISC SCORE IN THE PREDICTION OF TYPE 2 DIABETES.

OBJECTIVE: To compare the 1-hour post-load glucose (1h-PG) value of an Oral Glucose Tolerance Test (OGTT) with the Metabolic Syndrome (MetS) and the Finish Diabetes Risk Score (FINDRISC) in patients with impaired fasting glucose (IFG) to predict T2DM. METHODS: A cohort study conducted in patients addressed at a general hospital in Lima-Perú. Subjects with IFG performed an OGTT were followed up to seven years for T2DM development. The exposures variables were 1h-PG ≥ 155mg/dL, MetS, and a FINDRISC score ≥ 13 points, and the presence of T2DM was the outcome. The relative risk (RR), confidential interval (CI), and area under the curve (AUROC) were also estimated. RESULTS: Among 324 subjects with IFG, 218 completed the 7-years-follow-up. The mean age was 56.2 ±11.5 years-old, 64.0% were female and 63.8% were overweigh/obese. 36.8% had 1h-PG ≥ 155mg/dL and normal glucose tolerance (NGT), 66.8% had MetS and 64.5% FINDRISC ≥ 13 points. After 7 years, 21.1% of participants developed T2DM, 68.8% of them with 1h-PG ≥ 155mg/dL (p< 0.001), 62.2% with MetS (p= 0.013), and 67.9% with FINDRISC ≥ 13 (p= 0.68). After adjusting by age, sex and BMI, the RR were 3.52 (1.64-7.54; 95%CI), 1.81 (0.96-3.38; 95%CI) and 1.17 (0.51-2.70; 95%CI), for each exposure-variable, respectively. Also, the AUROC were 0.72 (0.60-0.83), 0.63 (0.51-0.75), and 0.51 (0.38-0.63) (p= 0.01), respectively. CONCLUSION: By performing an OGTT in IFG patients, an 1h-PG ≥ 155 mg/dL value may be helpful to predict T2DM at 7 years better than the use of MetS or FINDRISC score.

Mitochondrial bioenergetics boost macrophage activation, promoting liver regeneration in metabolically compromised animals.

BACKGROUND AND AIMS: Hepatic ischemia-reperfusion injury (IRI) is the leading cause of early posttransplantation organ failure as mitochondrial respiration and ATP production are affected. A shortage of donors has extended liver donor criteria, including aged or steatotic livers, which are more susceptible to IRI. Given the lack of an effective treatment and the extensive transplantation waitlist, we aimed at characterizing the effects of an accelerated mitochondrial activity by silencing methylation-controlled J protein (MCJ) in three preclinical models of IRI and liver regeneration, focusing on metabolically compromised animal models. APPROACH AND RESULTS: Wild-type (WT), MCJ knockout (KO), and Mcj silenced WT mice were subjected to 70% partial hepatectomy (Phx), prolonged IRI, and 70% Phx with IRI. Old and young mice with metabolic syndrome were also subjected to these procedures. Expression of MCJ, an endogenous negative regulator of mitochondrial respiration, increases in preclinical models of Phx with or without vascular occlusion and in donor livers. Mice lacking MCJ initiate liver regeneration 12 h faster than WT and show reduced ischemic injury and increased survival. MCJ knockdown enables a mitochondrial adaptation that restores the bioenergetic supply for enhanced regeneration and prevents cell death after IRI. Mechanistically, increased ATP secretion facilitates the early activation of Kupffer cells and production of TNF, IL-6, and heparin-binding EGF, accelerating the priming phase and the progression through G1 /S transition during liver regeneration. Therapeutic silencing of MCJ in 15-month-old mice and in mice fed a high-fat/high-fructose diet for 12 weeks improves mitochondrial respiration, reduces steatosis, and overcomes regenerative limitations. CONCLUSIONS: Boosting mitochondrial activity by silencing MCJ could pave the way for a protective approach after major liver resection or IRI, especially in metabolically compromised, IRI-susceptible organs.

Fine-tuned nitric oxide and hormone interface in plant root development and regeneration.

Plant root growth and developmental capacities reside in a few stem cells of the root apical meristem (RAM). Maintenance of these stem cells requires regenerative divisions of the initial stem cell niche (SCN) cells, self-maintenance, and proliferative divisions of the daughter cells. This ensures sufficient cell diversity to guarantee the development of complex root tissues in the plant. Damage in the root during growth involves the formation of a new post-embryonic root, a process known as regeneration. Post-embryonic root development and organogenesis processes include primary root development and SCN maintenance, plant regeneration, and the development of adventitious and lateral roots. These developmental processes require a fine-tuned balance between cell proliferation and maintenance. An important regulator during root development and regeneration is the gasotransmitter nitric oxide (NO). In this review we have sought to compile how NO regulates cell rate proliferation, cell differentiation, and quiescence of SCNs, usually through interaction with phytohormones, or other molecular mechanisms involved in cellular redox homeostasis. NO exerts a role on molecular components of the auxin and cytokinin signaling pathways in primary roots that affects cell proliferation and maintenance of the RAM. During root regeneration, a peak of auxin and cytokinin triggers specific molecular programs. Moreover, NO participates in adventitious root formation through its interaction with players of the brassinosteroid and cytokinin signaling cascade. Lately, NO has been implicated in root regeneration under hypoxia conditions by regulating stem cell specification through phytoglobins.

Potential Role of the mTORC1-PGC1α-PPARα Axis under Type-II Diabetes and Hypertension in the Human Heart.

Type-2 diabetes (T2DM) and arterial hypertension (HTN) are major risk factors for heart failure. Importantly, these pathologies could induce synergetic alterations in the heart, and the discovery of key common molecular signaling may suggest new targets for therapy. Intraoperative cardiac biopsies were obtained from patients with coronary heart disease and preserved systolic function, with or without HTN and/or T2DM, who underwent coronary artery bypass grafting (CABG). Control (n = 5), HTN (n = 7), and HTN + T2DM (n = 7) samples were analysed by proteomics and bioinformatics. Additionally, cultured rat cardiomyocytes were used for the analysis (protein level and activation, mRNA expression, and bioenergetic performance) of key molecular mediators under stimulation of main components of HTN and T2DM (high glucose and/or fatty acids and angiotensin-II). As results, in cardiac biopsies, we found significant alterations of 677 proteins and after filtering for non-cardiac factors, 529 and 41 were changed in HTN-T2DM and in HTN subjects, respectively, against the control. Interestingly, 81% of proteins in HTN-T2DM were distinct from HTN, while 95% from HTN were common with HTN-T2DM. In addition, 78 factors were differentially expressed in HTN-T2DM against HTN, predominantly downregulated proteins of mitochondrial respiration and lipid oxidation. Bioinformatic analyses suggested the implication of mTOR signaling and reduction of AMPK and PPARα activation, and regulation of PGC1α, fatty acid oxidation, and oxidative phosphorylation. In cultured cardiomyocytes, an excess of the palmitate activated mTORC1 complex and subsequent attenuation of PGC1α-PPARα transcription of ß-oxidation and mitochondrial electron chain factors affect mitochondrial/glycolytic ATP synthesis. Silencing of PGC1α further reduced total ATP and both mitochondrial and glycolytic ATP. Thus, the coexistence of HTN and T2DM induced higher alterations in cardiac proteins than HTN. HTN-T2DM subjects exhibited a marked downregulation of mitochondrial respiration and lipid metabolism and the mTORC1-PGC1α-PPARα axis might account as a target for therapeutical strategies.

Nitric oxide function during oxygen deprivation in physiological and stress processes.

Plants are aerobic organisms that have evolved to maintain specific requirements for oxygen (O2), leading to a correct respiratory energy supply during growth and development. There are certain plant developmental cues and biotic or abiotic stress responses where O2 is scarce. This O2 deprivation known as hypoxia may occur in hypoxic niches of plant-specific tissues and during adverse environmental cues such as pathogen attack and flooding. In general, plants respond to hypoxia through a complex reprogramming of their molecular activities with the aim of reducing the impact of stress on their physiological and cellular homeostasis. This review focuses on the fine-tuned regulation of hypoxia triggered by a network of gaseous compounds that includes O2, ethylene, and nitric oxide. In view of recent scientific advances, we summarize the molecular mechanisms mediated by phytoglobins and by the N-degron proteolytic pathway, focusing on embryogenesis, seed imbibition, and germination, and also specific structures, most notably root apical and shoot apical meristems. In addition, those biotic and abiotic stresses that comprise hypoxia are also highlighted.

Predicting gene regulatory networks by combining spatial and temporal gene expression data in Arabidopsis root stem cells.

Identifying the transcription factors (TFs) and associated networks involved in stem cell regulation is essential for understanding the initiation and growth of plant tissues and organs. Although many TFs have been shown to have a role in the Arabidopsis root stem cells, a comprehensive view of the transcriptional signature of the stem cells is lacking. In this work, we used spatial and temporal transcriptomic data to predict interactions among the genes involved in stem cell regulation. To accomplish this, we transcriptionally profiled several stem cell populations and developed a gene regulatory network inference algorithm that combines clustering with dynamic Bayesian network inference. We leveraged the topology of our networks to infer potential major regulators. Specifically, through mathematical modeling and experimental validation, we identified PERIANTHIA (PAN) as an important molecular regulator of quiescent center function. The results presented in this work show that our combination of molecular biology, computational biology, and mathematical modeling is an efficient approach to identify candidate factors that function in the stem cells.

Linking LOXL2 to Cardiac Interstitial Fibrosis.

Cardiovascular diseases (CVDs) are the leading causes of death worldwide. CVD pathophysiology is often characterized by increased stiffening of the heart muscle due to fibrosis, thus resulting in diminished cardiac function. Fibrosis can be caused by increased oxidative stress and inflammation, which is strongly linked to lifestyle and environmental factors such as diet, smoking, hyperglycemia, and hypertension. These factors can affect gene expression through epigenetic modifications. Lysyl oxidase like 2 (LOXL2) is responsible for collagen and elastin cross-linking in the heart, and its dysregulation has been pathologically associated with increased fibrosis. Additionally, studies have shown that, LOXL2 expression can be regulated by DNA methylation and histone modification. However, there is a paucity of data on LOXL2 regulation and its role in CVD. As such, this review aims to gain insight into the mechanisms by which LOXL2 is regulated in physiological conditions, as well as determine the downstream effectors responsible for CVD development.

Cardiovascular Damage in COVID-19: Therapeutic Approaches Targeting the Renin-Angiotensin-Aldosterone System.

Coronavirus disease 2019 (COVID-19) is usually more severe and associated with worst outcomes in individuals with pre-existing cardiovascular pathologies, including hypertension or atherothrombosis. Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) can differentially infect multiple tissues (i.e., lung, vessel, heart, liver) in different stages of disease, and in an age- and sex-dependent manner. In particular, cardiovascular (CV) cells (e.g., endothelial cells, cardiomyocytes) could be directly infected and indirectly disturbed by systemic alterations, leading to hyperinflammatory, apoptotic, thrombotic, and vasoconstrictive responses. Until now, hundreds of clinical trials are testing antivirals and immunomodulators to decrease SARS-CoV-2 infection or related systemic anomalies. However, new therapies targeting the CV system might reduce the severity and lethality of disease. In this line, activation of the non-canonical pathway of the renin-angiotensin-aldosterone system (RAAS) could improve CV homeostasis under COVID-19. In particular, treatments with angiotensin-converting enzyme inhibitors (ACEi) and angiotensin-receptor blockers (ARB) may help to reduce hyperinflammation and viral propagation, while infusion of soluble ACE2 may trap plasma viral particles and increase cardioprotective Ang-(1-9) and Ang-(1-7) peptides. The association of specific ACE2 polymorphisms with increased susceptibility of infection and related CV pathologies suggests potential genetic therapies. Moreover, specific agonists of Ang-(1-7) receptor could counter-regulate the hypertensive, hyperinflammatory, and hypercoagulable responses. Interestingly, sex hormones could also regulate all these RAAS components. Therefore, while waiting for an efficient vaccine, we suggest further investigations on the non-canonical RAAS pathway to reduce cardiovascular damage and mortality in COVID-19 patients.

Lipid Biomarkers as Predictors of Diastolic Dysfunction in Diabetes with Poor Glycemic Control.

Uncontrolled type-1 diabetes (T1DM) can lead to dyslipidaemia and albuminuria, which may promote cardiovascular injuries. However, some lipidemic factors could be useful in predicting cardiac dysfunction. Seventy-eight adolescents under insulin treatment due to a 6-year history of T1DM and were retrospectively examined. Glycemia, lipidemia, and albuminuria were measured in addition to development of cardiovascular abnormalities Both girls and boys showed higher HbA1c and fasting blood glucose and 27.1% females and 33.3% males exhibited microalbuminuria though their plasma levels of total cholesterol (TC), triglycerides (TG), and low-density lipoproteins (LDL) and high-density lipoproteins (HDL lipoproteins were in the normal range. They exhibited a preserved systolic function, but 50% of females and 66.6% of males had developed diastolic failures. Interestingly, girls with diastolic dysfunction showed significantly lower concentrations of HDL and higher TC/HDL and TG/HDL ratios. In fact, low HDL levels (OR 0.93; 95% CI 0.88-0.99; p = 0.029) and high TC/HDL (OR 2.55; 95% CI 1.9-5.45; p = 0.016) and TG/HDL (OR 2.74; 95% CI 1.12-6.71; p = 0.028) ratios associated with the development of diastolic complications. The cut-off values for HDL, TC/HDL, and TG/HDL were 49 mg/dL, 3.0 and 1.85, respectively. HDL and TC/HDL and TG/HDL ratios may be useful for predicting diastolic dysfunction in girls with uncontrolled T1DM.

Nitric oxide molecular targets: reprogramming plant development upon stress.

Plants are sessile organisms that need to complete their life cycle by the integration of different abiotic and biotic environmental signals, tailoring developmental cues and defense concomitantly. Commonly, stress responses are detrimental to plant growth and, despite the fact that intensive efforts have been made to understand both plant development and defense separately, most of the molecular basis of this trade-off remains elusive. To cope with such a diverse range of processes, plants have developed several strategies including the precise balance of key plant growth and stress regulators [i.e. phytohormones, reactive nitrogen species (RNS), and reactive oxygen species (ROS)]. Among RNS, nitric oxide (NO) is a ubiquitous gasotransmitter involved in redox homeostasis that regulates specific checkpoints to control the switch between development and stress, mainly by post-translational protein modifications comprising S-nitrosation of cysteine residues and metals, and nitration of tyrosine residues. In this review, we have sought to compile those known NO molecular targets able to balance the crossroads between plant development and stress, with special emphasis on the metabolism, perception, and signaling of the phytohormones abscisic acid and salicylic acid during abiotic and biotic stress responses.

Acute Community-Acquired Bacterial Meningitis: Update on Clinical Presentation and Prognostic factors.

The epidemiology of community-acquired bacterial meningitis (CABM) in adults has changed significantly in the past several years. Despite substantial improvement in patient care, CABM remains a major cause of morbidity and mortality. Thus, new prognostic factors could help improve patient stratification. We conducted a multicenter retrospective study to determine the clinical pattern of CABM in an urban area of Western Europe and to identify potential predictors of unfavorable prognosis and complicated course. Over a period of 6-8 years, 79 adult CABM cases were treated at three tertiary hospitals. A Glasgow Outcome Scale (GOS) score of ≤4 was defined as unfavorable outcome. Predictors of unfavorable prognosis or complicated course were identified through logistic-regression analysis. S. pneumoniae was the most frequent pathogen (34%). 82% of patients exhibited at least two of five signs, including fever, neck stiffness, altered mental status, headache and nausea. Almost 50% presented focal neurological deficits; the overall mortality rate was 15%. In the multivariate analysis, risk factors for an unfavorable outcome included a GCS score of ≤13, female sex, and etiology by L. monocytogenes and gram-negative bacilli. However, risk factors for systemic complications were a GCS score of ≤13 and reduced platelet count, whereas C-Reactive Protein (CRP) increase was associated with a higher rate of neurological complications. Patients with non-pneumococcal CABM were more prone to an unfavorable outcome, probably because of underutilization of empiric ampicillin in patients at risk of listeriosis and because the suspicion of pneumococcal infection was facilitated by the existence of otitis and the higher yield of Gram's stain. Patients presenting a GCS of ≤13, thrombocytopenia and/or increased CRP, may benefit from more aggressive care to avoid in-hospital complications and neurological sequelae.

Assessing the Role of ETHYLENE RESPONSE FACTOR Transcriptional Repressors in Salicylic Acid-Mediated Suppression of Jasmonic Acid-Responsive Genes.

Salicylic acid (SA) and jasmonic acid (JA) cross-communicate in the plant immune signaling network to finely regulate induced defenses. In Arabidopsis, SA antagonizes many JA-responsive genes, partly by targeting the ETHYLENE RESPONSE FACTOR (ERF)-type transcriptional activator ORA59. Members of the ERF transcription factor family typically bind to GCC-box motifs in the promoters of JA- and ethylene-responsive genes, thereby positively or negatively regulating their expression. The GCC-box motif is sufficient for SA-mediated suppression of JA-responsive gene expression. Here, we investigated whether SA-induced ERF-type transcriptional repressors, which may compete with JA-induced ERF-type activators for binding at the GCC-box, play a role in SA/JA antagonism. We selected ERFs that are transcriptionally induced by SA and/or possess an EAR transcriptional repressor motif. Several of the 16 ERFs tested suppressed JA-dependent gene expression, as revealed by enhanced JA-induced PDF1.2 or VSP2 expression levels in the corresponding erf mutants, while others were involved in activation of these genes. However, SA could antagonize JA-induced PDF1.2 or VSP2 in all erf mutants, suggesting that the tested ERF transcriptional repressors are not required for SA/JA cross-talk. Moreover, a mutant in the co-repressor TOPLESS, that showed reduction in repression of JA signaling, still displayed SA-mediated antagonism of PDF1.2 and VSP2. Collectively, these results suggest that SA-regulated ERF transcriptional repressors are not essential for antagonism of JA-responsive gene expression by SA. We further show that de novo SA-induced protein synthesis is required for suppression of JA-induced PDF1.2, pointing to SA-stimulated production of an as yet unknown protein that suppresses JA-induced transcription.

Proteomics and metabolomics in biomarker discovery for cardiovascular diseases: progress and potential.

INTRODUCTION: The process of discovering novel biomarkers and potential therapeutic targets may be shortened using proteomic and metabolomic approaches. AREAS COVERED: Several complementary strategies, each one presenting different advantages and limitations, may be used with these novel approaches. In vitro studies show how cells involved in cardiovascular disease react, although the phenotype of cultured cells differs to that occurring in vivo. Tissue analysis either in human specimens or animal models may show the proteins that are expressed in the pathological process, although the presence of structural proteins may be confounding. To identify circulating biomarkers, analyzing the secretome of cultured atherosclerotic tissue, analysis of blood cells and/or plasma may be more straightforward. However, in the latter approach, high-abundant proteins may mask small molecules that could be potential biomarkers. The study of sub-proteomes such as high-density lipoproteins may be useful to circumvent this limitation. Regarding metabolomics, most studies have been performed in small populations, and we need to perform studies in large populations in order to discover robust biomarkers. Expert commentary: It is necessary to involve the clinicians in these areas to improve the design of clinical studies, including larger populations, in order to obtain consistent novel biomarkers.