Unraveling the evolutionary origin of the complex Nuclear Receptor Element (cNRE), a cis-regulatory module required for preferential expression in the atrial chamber.

Cardiac function requires appropriate proteins in each chamber. Atria requires slow myosin to act as reservoirs, while ventricles demand fast myosin for swift pumping. Myosins are thus under chamber-biased cis-regulation, with myosin gene expression imbalances leading to congenital heart dysfunction. To identify regulatory inputs leading to cardiac chamber-biased expression, we computationally and molecularly dissected the quail Slow Myosin Heavy Chain III (SMyHC III) promoter that drives preferential expression to the atria. We show that SMyHC III gene states are orchestrated by a complex Nuclear Receptor Element (cNRE) of 32 base pairs. Using transgenesis in zebrafish and mice, we demonstrate that preferential atrial expression is achieved by a combinatorial regulatory input composed of atrial activation motifs and ventricular repression motifs. Using comparative genomics, we show that the cNRE might have emerged from an endogenous viral element through infection of an ancestral host germline, revealing an evolutionary pathway to cardiac chamber-specific expression.

Brazilian National Network of Alternative Methods (RENAMA) 10th Anniversary: Meeting of the Associated Laboratories, May 2022.

The Brazilian National Network of Alternative Methods (RENAMA), which is linked to the Ministry of Science, Technology and Innovation, is currently comprised of 51 laboratories from CROs, academia, industry and government. RENAMA's aim is to develop and validate new approach methodologies (NAMs), as well as train researchers and disseminate information on their use - thus reducing Brazilian, and consequently Latin American, dependence on external technology. Moreover, it promotes the adoption of NAMs by educators and trained researchers, as well as the implementation of good laboratory practice (GLP) and the use of certified products. The RENAMA network started its activities in 2012, and was originally comprised of three central laboratories - the National Institute of Metrology, Quality and Technology (INMETRO); the National Institute of Quality Control in Health (INCQS); and the National Brazilian Biosciences Laboratory (LNBio) - and ten associated laboratories. In 2022, RENAMA celebrated its 10th anniversary, a milestone commemorated by the organisation of a meeting attended by different stakeholders, including the RENAMA-associated laboratories, academia, non-governmental organisations and industry. Ninety-six participants attended the meeting, held on 26 May 2022 in Balneário Camboriú, SC, Brazil, as part of the programme of the XXIII Brazilian Congress of Toxicology 2022. Significant moments of the RENAMA were remembered, and new goals and discussion themes were established. The lectures highlighted recent innovations in the toxicological sciences that have translated into the assessment of consumer product safety through the use of human-relevant NAMs instead of the use of existing animal-based approaches. The challenges and opportunities in accepting such practices for regulatory purposes were also presented and discussed.

Combining a microphysiological system of three organ equivalents and transcriptomics to assess toxicological endpoints for cosmetic ingredients.

Animal testing for cosmetic ingredients and final products has been banned in Europe and is gaining legal force worldwide. However, the need for reliable testing methodologies remains for safety assessment of cosmetic ingredients. While new approach methodologies exist for many toxicological endpoints, some complex ones lack appropriate testing methods. Microphysiological systems (MPSs) have emerged as a promising tool to address this gap in pre-clinical testing, offering higher predictivity compared to animal models due to the phylogenetic distance between humans and animals. Moreover, they provide a more physiological approach than traditional in vitro testing by mimicking interconnections between different culture compartments as seen in complex organisms. This study presents a three-organ microfluidic MPS comprising skin, liver, and intestine equivalents. Combining this model with gene expression analysis, we evaluated toxicological endpoints of chemicals, demonstrating its potential for diverse applications. Our findings highlight the MPS model as a reliable and ethical method to be applied in an integrated approach for safety assessment in the cosmetic industry. It offers a promising strategy to evaluate toxicological endpoints for cosmetic ingredients and other chemicals, supporting the elimination of animal testing while ensuring consumer safety.

Obesity-Linked PPARγ Ser273 Phosphorylation Promotes Beneficial Effects on the Liver, despite Reduced Insulin Sensitivity in Mice.

Since the removal of thiazolidinediones (TZDs) from the market, researchers have been exploring alternative anti-diabetic drugs that target PPARγ without causing adverse effects while promoting insulin sensitization by blocking serine 273 phosphorylation (Ser273 or S273). Nonetheless, the underlying mechanisms of the relationship between insulin resistance and S273 phosphorylation are still largely unknown, except for the involvement of growth differentiation factor (GDF3) regulation in the process. To further investigate potential pathways, we generated a whole organism knockin mouse line with a single S273A mutation (KI) that blocks the occurrence of its phosphorylation. Our observations of KI mice on different diets and feeding schedules revealed that they were hyperglycemic, hypoinsulinemic, presented more body fat at weaning, and presented an altered plasma and hepatic lipid profile, distinctive liver morphology and gene expression. These results suggest that total blockage of S273 phosphorylation may have unforeseen effects that, in addition to promoting insulin sensitivity, could lead to metabolic disturbances, particularly in the liver. Therefore, our findings demonstrate both the beneficial and detrimental effects of PPAR S273 phosphorylation and suggest selective modulation of this post translational modification is a viable strategy to treat type 2 diabetes.

Discovery and structural characterization of chicoric acid as a SARS-CoV-2 nucleocapsid protein ligand and RNA binding disruptor.

The nucleocapsid (N) protein plays critical roles in coronavirus genome transcription and packaging, representing a key target for the development of novel antivirals, and for which structural information on ligand binding is scarce. We used a novel fluorescence polarization assay to identify small molecules that disrupt the binding of the N protein to a target RNA derived from the SARS-CoV-2 genome packaging signal. Several phenolic compounds, including L-chicoric acid (CA), were identified as high-affinity N-protein ligands. The binding of CA to the N protein was confirmed by isothermal titration calorimetry, 1H-STD and 15N-HSQC NMR, and by the crystal structure of CA bound to the N protein C-terminal domain (CTD), further revealing a new modulatory site in the SARS-CoV-2 N protein. Moreover, CA reduced SARS-CoV-2 replication in cell cultures. These data thus open venues for the development of new antivirals targeting the N protein, an essential and yet underexplored coronavirus target.

Structural dynamics of SARS-CoV-2 nucleocapsid protein induced by RNA binding.

The nucleocapsid (N) protein of the SARS-CoV-2 virus, the causal agent of COVID-19, is a multifunction phosphoprotein that plays critical roles in the virus life cycle, including transcription and packaging of the viral RNA. To play such diverse roles, the N protein has two globular RNA-binding modules, the N- (NTD) and C-terminal (CTD) domains, which are connected by an intrinsically disordered region. Despite the wealth of structural data available for the isolated NTD and CTD, how these domains are arranged in the full-length protein and how the oligomerization of N influences its RNA-binding activity remains largely unclear. Herein, using experimental data from electron microscopy and biochemical/biophysical techniques combined with molecular modeling and molecular dynamics simulations, we show that, in the absence of RNA, the N protein formed structurally dynamic dimers, with the NTD and CTD arranged in extended conformations. However, in the presence of RNA, the N protein assumed a more compact conformation where the NTD and CTD are packed together. We also provided an octameric model for the full-length N bound to RNA that is consistent with electron microscopy images of the N protein in the presence of RNA. Together, our results shed new light on the dynamics and higher-order oligomeric structure of this versatile protein.

pH and the Breast Cancer Recurrent Mutation D538G Affect the Process of Activation of Estrogen Receptor α.

Estrogen receptor α (ERα) is a regulatory protein that can access a set of distinct structural configurations. ERα undergoes extensive remodeling as it interacts with different agonists and antagonists, as well as transcription activation and repression factors. Moreover, breast cancer tumors resistant to hormone therapy have been associated with the imbalance between the active and inactive ERα states. Cancer-activating mutations in ERα play a crucial role in this imbalance and can promote the progression of cancer. However, the rate of this progression can also be increased by dysregulated pH in the tumor microenvironment. Many molecular aspects of the process of activation of ERα that can be affected by these pH changes and mutations are still unclear. Thus, we applied computational and experimental techniques to explore the activation process dynamics of ER for environments with different pHs and in the presence of one of the most recurrent cancer-activating mutations, D538G. Our results indicated that the effect of the pH increase associated with the D538G mutation promoted a robust stabilization of the active state of ER. We were also able to determine the main protein regions that have the most potential to influence the activation process under different pH conditions, which may provide targets of future therapeutics for the treatment of hormone-resistant breast cancer tumors. Finally, the approach used here can be applied for proteins associated with the proliferation of other cancer types, which can also have their function affected by small pH changes.

Green tea extract increases adiponectin and PPAR α levels to improve hepatic steatosis.

We postulated that Green tea (GT) improvements in non-alcoholic fatty liver disease (NAFLD) are dependent on adiponectin action in the liver. Male wild-type and adiponectin knockout (adipoKO) mice were induced to obesity for 8 weeks with a high-fat diet and then treated with GT for the last 12 weeks of the experimental protocol. Glucose and insulin tolerance tests, indirect calorimetry, histologic analysis of liver sections, and quantification of mRNA of hepatic genes related to glucose or fatty acid metabolism were performed. In vitro, we assessed the mechanism by which GT catechins act to improve hepatic steatosis by measuring lipid accumulation, and transcript levels of lipogenic genes in HepG2 cells treated with GT in the presence of a PPAR antagonist. Additionally, we performed a PPAR transactivation assay in 293T cells to test if catechins could activate PPARs. Different from wild-type mice, adipoKO animals treated with GT and fed a HFD gain body weight and fat mass, that were associated with a decrease in energy expenditure, were insulin resistant, and had no improvements in hepatic steatosis. Increased lipid levels were associated with no modulation of PPARα levels in the liver of adipoKO mice treated with GT. In vitro, we demonstrated GT catechins act to reduce hepatic steatosis in a PPARα-dependent manner, and especially epigallocatechin and epicatechin can indirectly activate PPARα, although it seems they are not direct ligands. By providing the mechanisms by which GT catechins act in the liver to improve steatosis, our data contribute to the discovery of novel therapeutic agents in the management of NAFLD.

Mass spectrometry-based proteomics of 3D cell culture: A useful tool to validate culture of spheroids and organoids.

Worldwide obesity, defined as abnormal or excessive fat accumulation that may result in different comorbidities, is considered a pandemic condition that has nearly tripled in the last 45 years. Most studies on obesity use animal models or adipocyte monolayer cell culture to investigate adipose tissue. However, besides monolayer cell culture approaches do not fully recapitulate the physiology of living organisms, there is a growing need to reduce or replace animals in research. In this context, the development of 3D self-organized structures has provided models that better reproduce the in vitro aspects of the in vivo physiology in comparison to traditional monolayer cell culture. Besides, recent advances in omics technologies have allowed us to characterize these cultures at the proteome, metabolome, transcription factor, DNA-binding and transcriptomic levels. These two combined approaches, 3D culture and omics, have provided more realistic data about determined conditions. Thereby, here we focused on the development of an obesity study pipeline including proteomic analysis to validate adipocyte-derived spheroids. Through the combination of collected mass spectrometry data from differentiated 3T3-L1 spheroids and from murine white adipose tissue (WAT), we identified 1732 proteins in both samples. By using a comprehensive proteomic analysis, we observed that the in vitro 3D culture of differentiated adipocytes shares important molecular pathways with the WAT, including expression of proteins involved in central metabolic process of the adipose tissue. Together, our results show a combination of an orthogonal method and an image-based analysis that constitutes a useful pipeline to be applied in 3D adipocyte culture.

High-Throughput Screening Reveals New Glutaminase Inhibitor Molecules.

The glutaminase (GLS) enzyme hydrolyzes glutamine into glutamate, an important anaplerotic source for the tricarboxylic acid cycle in rapidly growing cancer cells under the Warburg effect. Glutamine-derived α-ketoglutarate is also an important cofactor of chromatin-modifying enzymes, and through epigenetic changes, it keeps cancer cells in an undifferentiated state. Moreover, glutamate is an important neurotransmitter, and deregulated glutaminase activity in the nervous system underlies several neurological disorders. Given the proven importance of glutaminase for critical diseases, we describe the development of a new coupled enzyme-based fluorescent glutaminase activity assay formatted for 384-well plates for high-throughput screening (HTS) of glutaminase inhibitors. We applied the new methodology to screen a ∼30,000-compound library to search for GLS inhibitors. The HTS assay identified 11 glutaminase inhibitors as hits that were characterized by in silico, biochemical, and glutaminase-based cellular assays. A structure-activity relationship study on the most promising hit (C9) allowed the discovery of a derivative, C9.22, with enhanced in vitro and cellular glutaminase-inhibiting activity. In summary, we discovered a new glutaminase inhibitor with an innovative structural scaffold and described the molecular determinants of its activity.

Molecular and cellular basis of hyperassembly and protein aggregation driven by a rare pathogenic mutation in DDX3X.

Current studies estimate that 1-3% of females with unexplained intellectual disability (ID) present de novo splice site, nonsense, frameshift, or missense mutations in the DDX3X protein (DEAD-Box Helicase 3 X-Linked). However, the cellular and molecular mechanisms by which DDX3X mutations impair brain development are not fully comprehended. Here, we show that the ID-linked missense mutation L556S renders DDX3X prone to aggregation. By using a combination of biophysical assays and imaging approaches, we demonstrate that this mutant assembles solid-like condensates and amyloid-like fibrils. Although we observed greatly reduced expression of the mutant allele in a patient who exhibits skewed X inactivation, this appears to be enough to sequestrate healthy proteins into solid-like ectopic granules, compromising cell function. Therefore, our data suggest ID-linked DDX3X L556S mutation as a disorder arising from protein misfolding and aggregation.

Multifactorial Basis and Therapeutic Strategies in Metabolism-Related Diseases.

Throughout the 20th and 21st centuries, the incidence of non-communicable diseases (NCDs), also known as chronic diseases, has been increasing worldwide. Changes in dietary and physical activity patterns, along with genetic conditions, are the main factors that modulate the metabolism of individuals, leading to the development of NCDs. Obesity, diabetes, metabolic associated fatty liver disease (MAFLD), and cardiovascular diseases (CVDs) are classified in this group of chronic diseases. Therefore, understanding the underlying molecular mechanisms of these diseases leads us to develop more accurate and effective treatments to reduce or mitigate their prevalence in the population. Given the global relevance of NCDs and ongoing research progress, this article reviews the current understanding about NCDs and their related risk factors, with a focus on obesity, diabetes, MAFLD, and CVDs, summarizing the knowledge about their pathophysiology and highlighting the currently available and emerging therapeutic strategies, especially pharmacological interventions. All of these diseases play an important role in the contamination by the SARS-CoV-2 virus, as well as in the progression and severity of the symptoms of the coronavirus disease 2019 (COVID-19). Therefore, we briefly explore the relationship between NCDs and COVID-19.

Reenacting the Birth of a Function: Functional Divergence of HIUases and Transthyretins as Inferred by Evolutionary and Biophysical Studies.

Transthyretin was discovered in the 1940s, named after its ability to bind thyroid hormones and retinol. In the genomic era, transthyretins were found to be part of a larger family with homologs of no obvious function, then called transthyretin-related proteins. Thus, it was proposed that the transthyretin gene could be the result of gene duplication of an ancestral of this newly identified homolog, later found out to be an enzyme involved in uric acid degradation, then named HIUase (5-hydroxy-isourate hydrolase). Here, we sought to re-enact the evolutionary history of this protein family by reconstructing, from a phylogeny inferred from 123 vertebrate sequences, three ancestors corresponding to key moments in their evolution-before duplication; the common transthyretin ancestor after gene duplication and the common ancestor of Eutheria transthyretins. Experimental and computational characterization showed the reconstructed ancestor before duplication was unable to bind thyroxine and likely presented the modern HIUase reaction mechanism, while the substitutions after duplication prevented that activity and were enough to provide stable thyroxine binding, as confirmed by calorimetry and x-ray diffraction. The Eutheria transthyretin ancestor was less prone to characterization, but limited data suggested thyroxine binding as expected. Sequence/structure analysis suggests an early ability to bind the Retinol Binding Protein. We solved the X-ray structures from the two first ancestors, the first at 1.46 resolution, the second at 1.55 resolution with well-defined electron density for thyroxine, providing a useful tool for the understanding of structural adaptation from enzyme to hormone distributor.

Insights into the dual cleavage activity of the GH16 laminarinase enzyme class on ß-1,3 and ß-1,4 glycosidic bonds.

Glycoside hydrolases (GHs) are involved in the degradation of a wide diversity of carbohydrates and present several biotechnological applications. Many GH families are composed of enzymes with a single well-defined specificity. In contrast, enzymes from the GH16 family can act on a range of different polysaccharides, including ß-glucans and galactans. SCLam, a GH16 member derived from a soil metagenome, an endo-ß-1,3(4)-glucanase (EC 3.2.1.6), can cleave both ß-1,3 and ß-1,4 glycosidic bonds in glucans, such as laminarin, barley ß-glucan, and cello-oligosaccharides. A similar cleavage pattern was previously reported for other GH16 family members. However, the molecular mechanisms for this dual cleavage activity on (1,3)- and (1,4)-ß-D-glycosidic bonds by laminarinases have not been elucidated. In this sense, we determined the X-ray structure of a presumably inactive form of SCLam cocrystallized with different oligosaccharides. The solved structures revealed general bound products that are formed owing to residual activities of hydrolysis and transglycosylation. Biochemical and biophysical analyses and molecular dynamics simulations help to rationalize differences in activity toward different substrates. Our results depicted a bulky aromatic residue near the catalytic site critical to select the preferable configuration of glycosidic bonds in the binding cleft. Altogether, these data contribute to understanding the structural basis of recognition and hydrolysis of ß-1,3 and ß-1,4 glycosidic linkages of the laminarinase enzyme class, which is valuable for future studies on the GH16 family members and applications related to biomass conversion into feedstocks and bioproducts.

PPARγ S273 Phosphorylation Modifies the Dynamics of Coregulator Proteins Recruitment.

The nuclear receptor PPARγ is essential to maintain whole-body glucose homeostasis and insulin sensitivity, acting as a master regulator of adipogenesis, lipid, and glucose metabolism. Its activation through natural or synthetic ligands induces the recruitment of coactivators, leading to transcription of target genes such as cytokines and hormones. More recently, post translational modifications, such as PPARγ phosphorylation at Ser273 by CDK5 in adipose tissue, have been linked to insulin resistance trough the dysregulation of expression of a specific subset of genes. Here, we investigate how this phosphorylation may disturb the interaction between PPARγ and some coregulator proteins as a new mechanism that may leads to insulin resistance. Through cellular and in vitro assays, we show that PPARγ phosphorylation inhibition increased the activation of the receptor, therefore the increased recruitment of PGC1-α and TIF2 coactivators, whilst decreases the interaction with SMRT and NCoR corepressors. Moreover, our results show a shift in the coregulators interaction domains preferences, suggesting additional interaction interfaces formed between the phosphorylated PPARγ and some coregulator proteins. Also, we observed that the CDK5 presence disturb the PPARγ-coregulator's synergy, decreasing interaction with PGC1-α, TIF2, and NCoR, but increasing coupling of SMRT. Finally, we conclude that the insulin resistance provoked by PPARγ phosphorylation is linked to a differential coregulators recruitment, which may promote dysregulation in gene expression.

ADAM17 cytoplasmic domain modulates Thioredoxin-1 conformation and activity.

The activity of Thioredoxin-1 (Trx-1) is adjusted by the balance of its monomeric, active and its dimeric, inactive state. The regulation of this balance is not completely understood. We have previously shown that the cytoplasmic domain of the transmembrane protein A Disintegrin And Metalloprotease 17 (ADAM17cyto) binds to Thioredoxin-1 (Trx-1) and the destabilization of this interaction favors the dimeric state of Trx-1. Here, we investigate whether ADAM17 plays a role in the conformation and activation of Trx-1. We found that disrupting the interacting interface with Trx-1 by a site-directed mutagenesis in ADAM17 (ADAM17cytoF730A) caused a decrease of Trx-1 reductive capacity and activity. Moreover, we observed that ADAM17 overexpressing cells favor the monomeric state of Trx-1 while knockdown cells do not. As a result, there is a decrease of cell oxidant levels and ADAM17 sheddase activity and an increase in the reduced cysteine-containing peptides in intracellular proteins in ADAM17cyto overexpressing cells. A mechanistic explanation that ADAM17cyto favors the monomeric, active state of Trx-1 is the formation of a disulfide bond between Cys824 at the C-terminal of ADAM17cyto with the Cys73 of Trx-1, which is involved in the dimerization site of Trx-1. In summary, we propose that ADAM17 is able to modulate Trx-1 conformation affecting its activity and intracellular redox state, bringing up a novel possibility for positive regulation of thiol isomerase activity in the cell by mammalian metalloproteinases.

The MAF1 Phosphoregulatory Region Controls MAF1 Interaction with the RNA Polymerase III C34 Subunit and Transcriptional Repression in Plants.

MAF1 is a phosphoprotein that plays a critical role in cell growth control as the central regulator of RNA polymerase (Pol) III activity. Citrus MAF1 (CsMAF1) was identified as a direct target of PthA4, a bacterial effector protein required to induce tumors in citrus. CsMAF1 binds to Pol III to restrict transcription; however, exactly how CsMAF1 interacts with the polymerase and how phosphorylation modulates this interaction is unknown. Moreover, how CsMAF1 binds PthA4 is also obscure. Here we show that CsMAF1 binds predominantly to the WH1 domain of the citrus Pol III subunit C34 (CsC34) and that its phosphoregulatory region, comprising loop-3 and α-helix-2, contributes to this interaction. We also show that phosphorylation of this region decreases CsMAF1 affinity to CsC34, leading to Pol III derepression, and that Ser 45, found only in plant MAF1 proteins, is critical for CsC34 interaction and is phosphorylated by a new citrus AGC1 kinase. Additionally, we show that the C-terminal region of the citrus TFIIIB component BRF1 competes with CsMAF1 for CsC34 interaction, whereas the C-terminal region of CsMAF1 is essential for PthA4 binding. Based on CsMAF1 structural data, we propose a mechanism for how CsMAF1 represses Pol III transcription and how phosphorylation controls this process.

Adipogenic commitment induced by green tea polyphenols remodel adipocytes to a thermogenic phenotype.

The potential contribution of green tea (GT) to the development of thermogenic/beige cells have been scarcely investigated. Here we investigated if the beneficial effects of GT in the induction of thermogenic/beige adipocytes results from an initial cell commitment during adipogenesis. Male C57Bl/6 mice (3 months) were divided into 3 groups: Control (chow diet), Obese (cafeteria diet), and Obese + GT. Mice received GT gavage (500 mg/kg of BW) over 12 weeks (5 days/week), after 4 weeks of diet, totalizing 16 weeks of experimentation. GT treatment increased energy expenditure (EE) in mice fed with cafeteria-diet leading to reduced BW gain, decreased adiposity, reduced inflammation, and improving insulin sensitivity. Those phenotypes were associated with enhanced expression of oxidative, thermogenic and beige genes. GT induced a futile cycle through de novo lipogenesis activating the thermogenic pathway. Induction of beige phenotype occurs autonomously in adipocytes and involves the PPARγ/FGF21/AMPK/UCP1 pathway. Our study identified that metabolic changes caused by GT may involve the temporal expression of PPARγ promoting the induction of thermogenic cells by reprogramming initial steps of adipocyte commitment.

GQ-130, a novel analogue of thiazolidinedione, improves obesity-induced metabolic alterations in rats: Evidence for the involvement of PPARß/δ pathway.

The present investigation aimed to characterize the effect of a short-time treatment with a new thiazolidinedione (TZD) derivative, GQ-130, on metabolic alterations in rats fed a high-fat diet (HFD). We investigated whether metabolic alterations induced by GQ-130 were mediated though a mechanism that involves PPARß/δ transactivation. Potential binding and transactivation of PPARα, PPARß/δ or PPARγ by GQ-130 were examined through cell transactivation, 8-anilino-1-naphthalenesulfonic acid (ANS) fluorescence quenching assays and thermal shift assay. For in vivo experiments, male 8-week-old Wistar rats were divided into three groups fed for 6 weeks with: (a) a standard rat chow (14% fat) (control group), (b) a HFD (57.8% fat) alone (HFD group), or (c) a HFD associated with an oral treatment with GQ-130 (10 mg/kg/d) during the last week (HFD-GQ group). In 293T cells, unlike rosiglitazone, GQ-130 did not cause significant transactivation of PPARγ but was able to activate PPARß/δ by 153.9 folds in comparison with control values (DMSO). Surprisingly, ANS fluorescence quenching assay reveals that GQ-130 does not bind directly to PPARß/δ binding site, a finding that was further corroborated by thermal shift assay which evaluates the thermal stability of PPARß/δ in the presence of GQ-130. Compared to the control group, rats of the HFD group showed obesity, increased systolic blood pressure (SBP), insulin resistance, impaired glucose intolerance, hyperglycaemia, and dyslipidaemia. GQ-130 treatment abolished the increased SBP and improved all metabolic dysfunctions observed in the HFD group. Oral treatment with GQ-130 was effective in improving HFD-induced metabolic alterations probably through a mechanism that involves PPARß/δ activation.

Opposing action of NCoR1 and PGC-1α in mitochondrial redox homeostasis.

The ability to respond to fluctuations of reactive oxygen species (ROS) within the cell is a central aspect of mammalian physiology. This dynamic process depends on the coordinated action of transcriptional factors to promote the expression of genes encoding for antioxidant enzymes. Here, we demonstrate that the transcriptional coregulators, PGC-1α and NCoR1, are essential mediators of mitochondrial redox homeostasis in skeletal muscle cells. Our findings reveal an antagonistic role of these coregulators in modulating mitochondrial antioxidant induction through Sod2 transcriptional control. Importantly, the activation of this mechanism by either PGC-1α overexpression or NCoR1 knockdown attenuates mitochondrial ROS levels and prevents cell death caused by lipid overload in skeletal muscle cells. The opposing actions of coactivators and corepressors, therefore, exert a commanding role over cellular antioxidant capacity.