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Ischaemic heart disease (IHD) is the leading cause of death worldwide. Although myocardial cell death plays a significant role in myocardial infarction (MI), its underlying mechanism remains to be elucidated. To understand the progression of MI and identify potential therapeutic targets, we performed tandem mass tag (TMT)-based quantitative proteomic analysis using an MI mouse model. Gene ontology (GO) analysis and gene set enrichment analysis (GSEA) revealed that the glutathione metabolic pathway and reactive oxygen species (ROS) pathway were significantly downregulated during MI. In particular, glutathione peroxidase 4 (GPX4), which protects cells from ferroptosis (an iron-dependent programme of regulated necrosis), was downregulated in the early and middle stages of MI. RNA-seq and qRT-PCR analyses suggested that GPX4 downregulation occurred at the transcriptional level. Depletion or inhibition of GPX4 using specific siRNA or the chemical inhibitor RSL3, respectively, resulted in the accumulation of lipid peroxide, leading to cell death by ferroptosis in H9c2 cardiomyoblasts. Although neonatal rat ventricular myocytes (NRVMs) were less sensitive to GPX4 inhibition than H9c2 cells, NRVMs rapidly underwent ferroptosis in response to GPX4 inhibition under cysteine deprivation. Our study suggests that downregulation of GPX4 during MI contributes to ferroptotic cell death in cardiomyocytes upon metabolic stress such as cysteine deprivation.

Phytochrome B (phyB) is a plant photoreceptor that forms a membraneless organelle called a photobody. However, its constituents are not fully known. Here, we isolated phyB photobodies from Arabidopsis leaves using fluorescence-activated particle sorting and analyzed their components. We found that a photobody comprises ~1,500 phyB dimers along with other proteins that could be classified into two groups: The first includes proteins that directly interact with phyB and localize to the photobody when expressed in protoplasts, while the second includes proteins that interact with the first group proteins and require co-expression of a first-group protein to localize to the photobody. As an example of the second group, TOPLESS interacts with PHOTOPERIODIC CONTROL OF HYPOCOTYL 1 (PCH1) and localizes to the photobody when co-expressed with PCH1. Together, our results support that phyB photobodies include not only phyB and its primary interacting proteins but also its secondary interacting proteins. Phytochrome is a photoreceptor forming a membraneless organelle called a photobody. The authors isolated the photobody and found that the photobody is made of not only phytochrome but also its primary and secondary interacting proteins.

Pancreatic cancer (PC) has a high mortality rate due to its poor prognosis and the possibility of surgical resection in patients with the disease. Importantly, adjuvant chemotherapy is necessary to improve PC prognosis. Chrysin, a natural product with anti-inflammatory, antioxidant, and anticancer properties, has been studied for several years. Our previous study demonstrated that chrysin induced G protein-coupled estrogen receptor (GPER) expression and regulated its activity in breast cancer. Herein, we investigated whether chrysin-induced GPER activation suppresses PC progression in MIA PaCa-2 cells and a xenograft model. To determine its mechanism of action, cytotoxicity and clonogenic assays, a FACS analysis, and Western blotting were performed. Furthermore, the delay in tumor growth was evaluated in the MIA PaCa-2-derived xenograft model. Tumor tissues were investigated by Western blotting, immunohistochemistry, and a proteomic analysis. Chrysin caused cell cycle arrest and significantly decreased cell viability. Following co-treatment with chrysin and 17β-estradiol, the inhibitory effect of chrysin on cell proliferation was enhanced. In the xenograft model, chrysin and G1 (a GPER agonist) significantly delayed tumor growth and reduced both Ki-67 (a proliferation marker) and c-Myc expressions in tumor tissues. The proteomic analysis of tumor tissues identified that rho-associated coiled-coil containing protein kinase 1 (ROCK1), transgelin 2 (TAGLN2), and FCH and Mu domain containing endocytic adaptor 2 (FCHO2) levels were significantly reduced in chrysin-treated tumor tissues. High ROCK1, TAGLN2, and FCHO2 expressions were indicative of low overall PC survival as found using the Kaplan–Meier plotter. In conclusion, our results suggest that chrysin suppresses PC progression through the activation of GPER and reductions in ROCK1, TAGLN2, and FCHO2 expressions.

Background/Objectives: Liver cancer is a common cause of cancer-related deaths among men and women globally. A disintegrin and metalloproteinase with thrombospondin motif 1 (ADAMST1) has been associated with various cancers, including prostate, esophageal, renal, and breast cancers. However, its role in liver cancer remains unclear. The aim of this study was to investigate the relationship between G protein-coupled estrogen (GPER) activation via its agonist, G1, and ADAMTS1 in suppressing liver cancer metastasis. Methods: Following preliminary assessment of Hep3B, Huh7, and SK-Hep-1 cells, SK-Hep-1 cells were selected owing to their elevated GPER expression and reduced cell viability. Cells were subjected to flow cytometry, RNA sequencing, and proteomics analyses. We established an SK-Hep-1 xenograft model for in vivo analysis. Results: We observed G1-induced G2-M phase cell cycle arrest, increased p53 and p21, and decreased cell cycle-related factors. In vivo, G1 significantly inhibited tumor growth and increased p53 protein expression. ADAMTS1, a metastasis regulator, was significantly upregulated by G1. G1 reduced the proliferating cell nuclear antigen and increased E-cadherin expression in SK-Hep-1 cells and in vivo. Tumor invasion was reduced with G1 and ADAMTS1 expression. In vivo, G1 reduced liver metastasis, increased E-cadherin, and decreased vimentin and proliferating cell nuclear antigen in primary tumor tissues and increased ADAMTS1 at the tumor edge. Conclusions: GPER agonists, such as G1, show potential for suppressing liver cancer progression and metastasis.

The AKT signaling pathway plays critical roles in the resolution of inflammation. However, the underlying mechanisms of anti-inflammatory regulation and signal coordination remain unclear. Here, we report that anti-inflammatory AKT signaling is coordinated by glutamyl-prolyl-tRNA synthetase 1 (EPRS1). Upon inflammatory activation, AKT specifically phosphorylates Ser999 of EPRS1 in the cytoplasmic multi-tRNA synthetase complex, inducing release of EPRS1. EPRS1 compartmentalizes AKT to early endosomes via selective binding to the endosomal membrane lipid phosphatidylinositol 3-phosphate and assembles an AKT signaling complex specific for anti-inflammatory activity. These events promote AKT activation-mediated GSK3β phosphorylation, which increase anti-inflammatory cytokine production. EPRS1-deficient macrophages do not assemble the early endosomal complex and consequently exacerbate inflammation, decreasing the survival of EPRS1-deficient mice undergoing septic shock and ulcerative colitis. Collectively, our findings show that the housekeeping protein EPRS1 acts as a mediator of inflammatory homeostasis by coordinating compartment-specific AKT signaling. The PI3K/AKT signaling pathway is carefully regulated in specific cellular compartments. Lee and colleagues show that the housekeeping gene glutamyl-prolyl-tRNA synthetase 1 coordinates early endosome-specific AKT signaling necessary for inflammation resolution.

Multiple bacterial genera take advantage of the multifunctional autoprocessing repeats-in-toxin (MARTX) toxin to invade host cells. Secretion of the MARTX toxin by Vibrio vulnificus , a deadly opportunistic pathogen that causes primary septicemia, the precursor of sepsis, is a major driver of infection; however, the molecular mechanism via which the toxin contributes to septicemia remains unclear. Here, we report the crystal and cryo-electron microscopy (EM) structures of a toxin effector duet comprising the domain of unknown function in the first position (DUF1)/Rho inactivation domain (RID) complexed with human targets. These structures reveal how the duet is used by bacteria as a potent weapon. The data show that DUF1 acts as a RID-dependent transforming NADase domain (RDTND) that disrupts NAD + homeostasis by hijacking calmodulin. The cryo-EM structure of the RDTND-RID duet complexed with calmodulin and Rac1, together with immunological analyses in vitro and in mice, provide mechanistic insight into how V. vulnificus uses the duet to suppress ROS generation by depleting NAD(P) + and modifying Rac1 in a mutually-reinforcing manner that ultimately paralyzes first line immune responses, promotes dissemination of invaders, and induces sepsis. These data may allow development of tools or strategies to combat MARTX toxin-related human diseases. The MARTX toxins secreted by clinical V. vulnificus strains release the DUF1-RID effector duet in infected host cells. Here, the authors show that the duet hijacks calmodulin and Rac1, respectively, and transforms into a potent weapon to promote sepsis.

Fibroblast growth factor 21 (FGF21) has pharmaceutical potential against obesity-related metabolic disorders, including non-alcoholic fatty liver disease. Since thermal stability is a desirable factor for therapeutic proteins, we investigated the thermal behavior of human FGF21. FGF21 remained soluble after heating; thus, we examined its temperature-induced structural changes using circular dichroism (CD). FGF21 showed inter-convertible temperature-specific CD spectra. The CD spectrum at 100 °C returned to that at 20 °C when the heated FGF21 solution was cooled. Through loop swapping, the connecting loop between β10 and β12 in FGF21 was revealed to be associated with the unique thermal behavior of FGF21. According to surface plasmon resonance (SPR) experiments, in vitro cell-based assays, and model high-fat diet (HFD)-induced obesity studies, heated FGF21 maintained biological activities that were comparable to those of non-heated and commercial FGF21s. Based on sequence comparison and structural analysis, five point-mutations were introduced into FGF21. Compared with the wild type, the heated FGF21 variant displayed improved therapeutic potential in terms of body weight loss, the levels of hepatic triglycerides and lipids, and the degree of vacuolization of liver in HFD-fed mice.

Mesenchymal stem cells (MSCs), recognized as a promising candidate for treating degenerative diseases, have garnered significant attention from scientists in recent decades. However, a notable concern associated with MSCs is their low stability and viability. In a previous study, we found that dimethyl fumarate (DMF) at 10 μM concentration can enhance the proliferation of MSCs and increase their stability. In this research, we performed protein extraction and digestion on both MSCs and DMF-treated MSCs, subsequently enriching phosphorylated peptides using TiO 2 and identifying them through nanoLC-MS/MS, with data analysis carried out using MaxQuant and Perseus. The results revealed 837 phosphorylated peptides, of which 559 exhibited elevated expression levels in DMF-treated MSCs compared to untreated MSCs. These 837 and 559 phosphopeptides corresponded to 466 and 340 phosphoproteins, respectively. Furthermore, network analysis of 559 upregulated phosphopeptides using Reactome identified RNA Binding Motif Protein 39 as a potentially crucial protein in mediating cellular responses, potentially influencing RNA processing events and contributing to the regulation of gene expression. This study underscores the significant impact of DMF treatment on the phosphoproteome of MSCs. Further investigations into these identified pathways could illuminate novel therapeutic strategies and enhance the clinical efficacy of MSC-based treatments.

Autism is a neurodevelopmental disorder for which the cause and treatment have yet not been determined. The polyunsaturated fatty acid (PUFA) levels change rapidly in the blood or cerebrospinal fluid of autistic children and PUFAs are closely related to autism spectrum disorder (ASD). This finding suggests that changes in lipid metabolism are associated with ASD and result in an altered distribution of phospholipids in cell membranes. To further understand ASD, it is necessary to analyze phospholipids in organs consisting of nerve cells, such as the brain. In this study, we investigated the phospholipid distribution in the brain tissue of valproic acid-induced autistic mice using matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). Phospholipids including phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine were identified in each brain region and exhibited differences between the ASD and control groups. These phospholipids contain docosahexaenoic acid and arachidonic acid, which are important PUFAs for cell signaling and brain growth. We expect that the differences in phospholipids identified in the brain tissue of the ASD model with MALDI-MSI, in conjunction with conventional biological fluid analysis, will help to better understand changes in lipid metabolism in ASD.

Exosomes, nanosized extracellular vesicles that play key roles in intercellular communication, have great potential in diagnostic and therapeutic applications. However, isolating exosomes from complex biological matrices such as human serum remains challenging due to limitations in scalability, cost, and purity of current methods. In this study, we developed and optimized a polyethylene glycol (PEG) precipitation method as a cost-effective alternative to the commercial ExoQuick kit for efficient exosome enrichment from pretreated human serum. The efficiency and reproducibility of PEG precipitation were systematically evaluated and compared with ExoQuick using various analytical techniques, including size exclusion chromatography (SEC), scanning electron microscopy (SEM), nanoparticle tracking analysis (NTA), Western blotting, and nano-liquid chromatography–tandem mass spectrometry (nano-LC–MS/MS). SEC confirmed comparable exosome recovery between PEG and ExoQuick, while SEM and NTA analyses verified intact morphology and consistent size distribution of exosomes. Western blotting confirmed the presence of characteristic exosomal markers (CD63 and CD9) and a reduction of contaminating proteins such as albumin and apolipoprotein A1. Moreover, proteomic analysis by nano-LC–MS/MS identified diverse exosomal proteins, confirming the isolation of intact exosomes. Repeated PEG precipitation up to four cycles further improved exosome purity without compromising yield. These results demonstrate that PEG precipitation is a scalable, accessible, and cost-effective method that provides comparable exosome enrichment efficiency to ExoQuick. The optimized protocol offers a practical solution for analytical laboratories to enable cost-effective exosome-based studies in diagnostics and therapeutics.