Search Results (153)

Background/Objectives: Sepsis-induced systemic inflammation often leads to diaphragmatic dysfunction and muscle atrophy, contributing to impaired respiratory function. Phosphoglycerate mutase 2 (PGAM2), a key enzyme in glycolysis, plays a significant role in muscle energy metabolism but has not been previously linked to sepsis-induced diaphragmatic dysfunction. This study aims to investigate the role of PGAM2 in sepsis-induced diaphragmatic atrophy and its underlying mechanisms. Methods: A murine sepsis model was established using cecal ligation and puncture (CLP) in C57BL/6 mice. Body and diaphragm weights, along with muscle fiber cross-sectional areas, were measured. PGAM2 expression was evaluated using immunofluorescence, Western blotting, and real-time quantitative polymerase chain reaction (RT-qPCR). In vitro, C₂C₁₂ myotubes were treated with tumor necrosis factor alpha (TNF-α), and PGAM2 expression was manipulated via small interfering RNA (siRNA) knockdown and plasmid overexpression. Atrophy markers (MuRF1, MAFbx/atrogin-1) and JAK2/STAT3 pathway activation were assessed. Results: CLP induced significant diaphragmatic atrophy, as reflected by an approximately 38% reduction in diaphragm weight and an approximately 37% decrease in muscle fiber cross-sectional area compared with the sham group. In contrast, PGAM2 protein expression was increased by approximately 105% in septic diaphragms. PGAM2 expression was also significantly elevated in TNF-α-treated myotubes. PGAM2 knockdown resulted in reduced MuRF1 and MAFbx expression, attenuating myotube atrophy, while PGAM2 overexpression exacerbated atrophy. Moreover, PGAM2 knockdown suppressed activation of the JAK2/STAT3 signaling pathway. Conclusions: These findings demonstrate that PGAM2 contributes to sepsis-induced diaphragmatic atrophy through the activation of the JAK2/STAT3 signaling pathway. PGAM2 may therefore serve as a potential therapeutic target for sepsis-associated diaphragmatic dysfunction. Full article

2-Phosphoglycerate kinase (2PGK) and cyclic 2,3-diphosphoglycerate synthase (cDPGS) are key enzymes involved in the biosynthesis of cyclic 2,3-diphosphoglycerate (cDPG), an extremolyte known to stabilize proteins in hyperthermophilic Archaea. Using bioinformatics approaches, two candidate genes for each enzyme were identified from a range of thermophilic bacterial and archaeal genomes and metagenomes. Significantly, one gene pair derived from the Taman mud volcano metagenome represents the first indication of a bacterial cDPG biosynthesis pathway. The recombinant expression and purification of these enzymes paved the way to their biochemical and structural characterization. One 2PGK candidate displayed predominant ATPase activity, while the newly identified cDPGS variants demonstrated cDPG synthase activity. Moreover, one of the latter biocatalysts, Ts-cDPGS from the hyperthermophilic archaeon Thermococcus sibiricus, demonstrated a notable thermostability and its 3D structure was resolved at a resolution of 2.2 Å. These findings broaden our understanding of extremophilic enzyme systems and lay the foundation for biotechnological applications involving extremolyte production. Full article

Soil hypoxia caused by waterlogging severely restricts kiwifruit growth, and screening waterlogging-tolerant rootstocks and analyzing their mechanisms are of great significance for industrial development. In this study, waterlogging-tolerant Actinidia valvata ‘Shuixiu’ was used as the test material and Actinidia chinensis ‘Hongyang’ as the control. Waterlogging stress was simulated artificially, and physiological measurements combined with transcriptome sequencing were used to explore its waterlogging tolerance regulatory characteristics based on respiratory metabolism. The results showed that the waterlogging tolerance of ‘Shuixiu’ was significantly better than that of ‘Hongyang’. It upregulated sucrose synthase and α/β-amylase genes and inhibited the continuous up-regulation of trehalose-6-phosphate synthase genes, leading to significant accumulation of glucose-6-phosphate, a key glycolytic substrate. Some members of glycolytic key gene families, such as glucose-6-phosphate isomerase and phosphofructokinase, were upregulated in ‘Shuixiu’, which increased phosphoglycerate kinase activity and accumulated 3-phosphoglyceric acid and pyruvate, ensuring efficient conversion of carbon sources to ATP. Some members of core tricarboxylic acid cycle gene families, such as pyruvate dehydrogenase and citrate synthase, were upregulated in ‘Shuixiu’, with significantly higher pyruvate dehydrogenase activity and acetyl coenzyme A content, maintaining partial aerobic respiration capacity. Some members of the alanine transaminase gene family were upregulated in ‘Shuixiu’ to enhance alanine fermentation, resulting in a significant reduction in root ethanol accumulation. This study clarified the core respiratory metabolic regulatory characteristics of kiwifruit in response to waterlogging and provided key targets and a theoretical basis for molecular breeding of waterlogging-tolerant rootstocks. Full article

Background: Alzheimer’s disease (AD) represents a significant therapeutic challenge, largely attributed to the complex interplay of genetic and non-genetic mechanisms. Among the latter, metabolic dysregulation has emerged as a critical factor influencing disease progression. This study proposes a paradigm shift in our understanding of the role of phosphoglycerate dehydrogenase (PHGDH), a key metabolic enzyme, which, under pathological conditions associated with AD, transitions from a protective role to a pathogenic influence through alterations in its cellular localization and function. Methods: To elucidate the impact of exercise on PHGDH dynamics, a narrative review methodology was employed. We conducted comprehensive searches across bibliographic databases, including PubMed, Scopus, and Web of Science, focusing on peer-reviewed articles that detail the relationship between exercise, PHGDH activity, and AD-related neuroinflammation. The review was structured around specific inclusion criteria, which prioritized studies elucidating the mechanisms underlying PHGDH’s dual role in AD pathology and the influence of exercise on this process. Results: Our findings reveal that under AD-associated stress, PHGDH translocates to the nucleus, facilitating the activation of pro-inflammatory genes such as IKKα and HMGB1, while simultaneously suppressing autophagy and enhancing amyloid beta (Aβ) deposition. However, exercise induces the release of the myokine irisin, which inhibits PHGDH nuclear translocation through AMPK/PGC-1α signaling pathways. Additionally, peripheral effects of exercise are observed in hepatic Kupffer cells, where exercise attenuates PHGDH activity, leading to reduced systemic IL-1β release and neuroinflammation. Conclusions: This study underscores the potential of exercise as a precision intervention in AD management, highlighting its capacity to modulate PHGDH activity and mitigate neuroinflammatory processes. The therapeutic implications of these findings are profound, paving the way for novel diagnostic tools, such as PET probes for assessing PHGDH compartmentalization, and promoting a synergistic approach to “exercise–pharmacotherapy” in the treatment of Alzheimer’s disease. Future research should aim to further delineate the mechanisms by which exercise influences metabolic pathways in the context of neurodegeneration. Full article

Zebrafish is emerging as a model animal for phenotype-based drug screening. Drugs screened from the zebrafish platform have advanced into clinical trials, underscoring their translational potential. Amyotrophic lateral sclerosis is a progressive motor neurons (MN) degenerative disease with few approved drugs. Previously, supplementation with exogenous recombinant phosphoglycerate kinase 1 (Pgk1) was found to improve MN growth through its interaction with receptor Eno2. To bypass the high complexity and cost of full-length Pgk1 production, a short segment within Pgk1 (M08) was predicted as the key motif interacting with Eno2, and a zebrafish phenotypic screening platform was established to find the most neurotrophic compound(s) among M08 and its mutants. We first found that M08-injected zebrafish embryos significantly increased branched caudal primary MNs (CaPMNs). However, compared to M08 (59.20 ± 1.80%), M039, among 17 mutants further screened, showed even more improvement of branched CaPMNs, up to 74.54 ± 3.73%. Next, when we administered the M039 peptide to C9ORF72-knockdown ALS-like zebrafish embryos, it improved axonal growth and swimming ability. Then, we employed a cellular model as a secondary screen, and M039 exhibited improved neurite outgrowth of MN (NOMN) and reduced p-Cofilin in NSC34 neural cells grown in ALS-like condition. Therefore, by using a zebrafish MN phenotype as a primary screening platform, we identified a mutated short peptide M039 having the most pronounced positive effect on improving neurite growth among all 17 mutants in comparison to parental M08, demonstrating the feasibility of zebrafish screening as a cost-effective strategy for finding promising neuroprotective short peptides that serve as neurotherapeutic potentials. Full article

The development of males and females of the cephalopod Amphioctopus fangsiao is asynchronous. The male produces sperm after maturity for storage in a spermatophore prior to mating. After mating, the sperm enter the female spermatheca for storage until ovulation occurs, a period that lasts for 8 months. This is a biologically uncommon phenomenon because sperm cells generally fail to maintain their ability to fertilize for a long time after being ejaculated. However, the molecular mechanisms of this phenomenon are still not clear. Sperm cells are stored in the male spermatophore and the female spermatheca, each of which provides a suitable environment. To determine the molecular basis of the sperm storage mechanisms in A. fangsiao, protein profiles from spermathecal fluid and seminal plasma were characterized separately using mass spectrometry-based proteomics. The antioxidant enzymes superoxide dismutase (SOD), glutathione S-transferase (GST), and Thioredoxin (Trx), and the glycolytic enzymes lactate dehydrogenase (LDH), hexokinase (HK), pyruvate dehydrogenase kinase (PDK), and ATP synthase were significantly enriched in the spermathecal fluid. Catalase (CAT), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), triosephosphate isomerase (TIM), phosphoglycerate kinase (PGK), and Chitinase were significantly enriched in the seminal plasma. The antimicrobial proteins transforming growth factor beta regulator 1 (TBRG1) and interleukin enhancer binding factor 2 (ILF2) and the extracellular matrix-related proteins transforming growth factor beta induced protein (TGFBIp) and thrombospondin type-1 domain-containing protein 4 (THSD4) were also significantly expressed in the spermathecal fluid. These proteins may be crucial for successful long-term sperm storage. We measured the activities of four antioxidant enzymes based on the proteomic results, supporting the antioxidant mechanism during the sperm storage process. This study enhances our understanding of the sperm storage ability of A. fangsiao. Full article

Scale adhesion strength is a key trait in aquaculture, directly influencing disease resistance, survival, and commercial value. The Dongting crucian carp (Carassius auratus indigentiaus, hereafter CaDT) is valued for its rapid growth and superior flesh quality but is characterized by loosely attached scales. In this study, we investigated the morphological and molecular basis underlying scale adhesion by comparing CaDT with the tight-scaled allogynogenetic gibel carp, Zhongke No. 3 (Carassius auratus gibelio, hereafter CaGB). Morphological analysis revealed a significantly lower scale-embedding ratio in CaDT compared to CaGB. To unravel the molecular mechanisms underpinning these phenotypic differences, a comparative transcriptomic analysis was conducted on scale sac, skin, and muscle tissues in CaDT and CaGB. In CaGB, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of differentially expressed genes (DEGs) in the critical scale sac tissue showed a significant upregulation of genes involved in ribosomal pathways. Specifically, key epithelial differentiation markers, including keratin 13 (krt13), keratin 15 (krt15), and metabolic genes, enolase 3-like (eno3l), and phosphoglycerate mutase 2 (pgam2) were significantly down-regulated in CaDT, which suggests a compromised epithelial cell differentiation capacity and reduced energetic and biosynthetic activity. Quantitative PCR (qPCR) validation across three tissues showed high concordance with the RNA-seq results, thereby confirming the reliability of the transcriptomic data. The results offer insight into the molecular basis for understanding scale adhesion traits, and provide valuable insights for selective breeding strategies to improve scale retention in aquaculture species. Full article

Salt-tolerance improvement of tomatoes is largely a task of modern selection and plant molecular genetics because of cultivation on dry and irrigated lands under salt stress. To reveal the salt resistance gene, we need quantitative real-time polymerase chain reaction (qRT-PCR) normalization through reference genes analysis. Sometimes, housekeeping gene expression changes in response to various stress factors, especially salinity. In this manuscript, we evaluated expression changes of elongation factor 1α X53043.1 (EF1α), actin BT013707.1 (ACT), ubiquitin NM_001346406.1 (UBI), nuclear transcript factor XM_026030313.2 (NFT-Y), β-tubulin NM_001247878.2 (TUB), glyceraldehyde-3 phosphate dehydrogenase NM_001247874.2 (GAPDH), phosphatase 2A catalytic subunit NM_001247587.2 (PP2a), and phosphoglycerate kinase XM_004243920.4 (PGK) in salt-sensitive Solanum lycopersicum L. YaLF line and salt tolerance Rekordsmen cv. under 100 mM NaCl. We also suggested potential correlations between relative water content (RWC), ion accumulation, and reference gene expression in tomato genotypes with contrasting salinity tolerance. We used geNorm, NormFinder, BestKeeper, ∆Ct, and RefFinder algorithms to establish a set of the most reliable tomato candidate genes. The most stable genes for YaLF tomatoes were ACT, UBI, TUB, and PP2a. Despite differences in ranks, the NFT-Y was present in Rekordsmen’s stable set. Full article

Background: Meningiomas are common intracranial tumors in adults. Most are benign WHO grade I (GI) tumors, while approximately 20% are diagnosed as more aggressive WHO grade II (GII) and grade III (GIII) meningiomas. The study aimed to identify genes with tumor grade-related expression and to assess their functional relevance. Methods: RNA sequencing (RNA-seq) was performed to analyze transcriptomes of benign meningothelial (n = 19) and fibrous (n = 11), atypical (n = 18) and anaplastic (n = 12) meningiomas. The data were analyzed for differential genes expression and Gene Set Enrichment Analysis (GSEA). A deposited scRNA-seq dataset was used to define meningioma cellular composition and cell type-specific gene expression enabling deconvolution of RNA-seq data. Results: Unsupervised analysis revealed three tumor clusters corresponding to the histological subtypes of meningothelial (GI), fibrous (GI) and atypical/anaplastic (GII/GIII) meningiomas. Differential analysis identified 5518 protein-coding genes with grade-related changes in expression. GSEA showed that high-grade meningiomas were enriched for processes of cell proliferation, ribosome biogenesis, and metabolism, whereas benign tumors were enriched for cell morphogenesis, transmembrane ion transport, and immune regulation. PGK1 was the most significantly grade-related gene and increased expression of phosphoglycerate kinase 1 in GII and GIII tumors was confirmed by immunohistochemistry. Deconvolution of RNA-seq data revealed grade-related changes in the tumor microenvironment, notably a progressive decrease in border-associated macrophages from WHO GI to GIII tumors. Conclusions: In our study, we characterized key genes and processes dysregulated in high-grade meningiomas, including less understood mechanisms such as metabolic reprogramming, disrupted ion transport, altered immune regulation, and differences in the tumor microenvironment between benign and aggressive tumors. Full article

Decades ago, previous studies that used non-selective ergot derivatives suggested that blockage of the α_1A-adrenergic receptor mildly increased cognition through increased blood flow to the brain due to vasodilation and, thus, could be used as a treatment for dementia. However, further studies indicated that nicergoline was non-specific and hit many different targets. Today, a similar scenario is developing with the use of non-selective α₁-AR antagonists of the quinazoline class, referred to as “osins”, as potential treatments for COVID-19/SARS, post-traumatic stress disorder, cancer, and neurodegenerative disorders, such as Parkinson’s, Alzheimer’s, and amyotrophic lateral sclerosis. While there is extensive evidence of neuroprotection from many clinical trials, the mechanism of action of quinazolines is often not α₁-AR-mediated but keyed to its glycolysis-enhancing effects through activation of the enzyme phosphoglycerate kinase 1 (PGK1). These studies have incorrectly labeled the α_1A-adrenergic receptor as an “old target” to treat Alzheimer’s and other neurocognitive diseases, hampering drug development. This review will summarize these and other studies to indicate that activation, not blockage, of norepinephrine’s actions, through α_1A-AR, mediates cognitive, memory, and neuroprotective functions that may reverse the progression of neurocognitive diseases. Full article

Low temperature severely restricts maize seedling establishment and yield in northern China, but the proteomic basis of low-temperature tolerance in maize remains unclear. This study used TMT-labeled quantitative proteomics combined with data-independent acquisition (DIA) and liquid chromatography–tandem mass spectrometry (LC-MS/MS) to analyze dynamic proteome changes in two maize inbred lines (low-temperature-tolerant B144 and low-temperature-sensitive Q319) at the three-leaf stage under 5 °C treatment. A total of 4367 non-redundant proteins were identified. For differentially expressed proteins (DEPs, fold change >2.0 or <0.5, ANOVA-adjusted p < 0.05, false discovery rate [FDR] < 0.05), B144 showed exclusive upregulation under stress (6 DEPs at 24 h; 16 DEPs at 48 h), while Q319 exhibited mixed regulation (9 DEPs at 24 h: 6 upregulated, 3 downregulated; 21 DEPs at 48 h: 19 upregulated, 2 downregulated). Functional annotation indicated that ribosomal proteins, oxidoreductases, glycerol-3-phosphate permease, and actin were significantly upregulated in both lines. Pathway enrichment analysis revealed associations with carbohydrate metabolism, amino acid biosynthesis, and secondary metabolite synthesis. Weighted gene co-expression network analysis (WGCNA) identified genotype-specific expression patterns: B144 showed differential expression of proteins related to acetyl-CoA synthetase and fatty acid β-oxidation at 24 h and of proteins related to D-3-phosphoglycerate dehydrogenase at 48 h; Q319 showed differential expression of proteasome-related proteins at 24 h and of proteins related to elongation factor 1α (EF-1α) at 48 h. Venn analysis found no shared DEPs between the two lines at 24 h but four overlapping DEPs at 48 h. These results clarify proteomic differences underlying low-temperature tolerance divergence between maize genotypes and provide candidate targets for molecular breeding of low-temperature-tolerant maize. Full article

The effects of storage temperature (4 °C, −1 °C, and −4 °C) after the very fast chilling (VFC) treatment on the glycolysis in lamb were investigated. The meat tenderness, glycolytic rates, activity, phosphorylation, and acetylation levels of glycolytic enzymes in meat stored at different temperatures were measured. It was shown that there was no significant difference in the degradation degree of desmin and troponin T in meat at different storage temperatures after VFC treatment (p < 0.05). The decrease rate of pH and ATP in meat was the same under different storage temperatures. The promoted phosphorylation and acetylation levels of phosphofructokinase (PFKM) and phosphoglycerate kinase (PGK) and inhibited acetylation level of aldolase (ALDOA) in the samples stored at different temperatures maintained the same glycolytic rate. In conclusion, chilling treatment is the key step in improving meat tenderness rather than storage temperature, which is achieved by the increased phosphorylation of ALDOA, PFKM, and PGK and decreased acetylation of ALDOA. It indicated that the chilling rate promoted the improvement of meat quality mainly by delaying glycolysis compared to the storage temperature. Full article

Global climate change is pushing insects into colder regions. Understanding their cold tolerance is important for predicting population dynamics. During overwintering, Streltzoviella insularis larvae activate the AMPK signaling pathway. This suggests that energy metabolism plays a key role under cold stress. In this study, we used enzyme activity assays, LC-MS-based targeted metabolomics, and transcriptome sequencing. We focused on six key enzymes in glycolysis and the TCA cycle. We also measured related metabolites and regulatory genes. Hexokinase (HK) and citrate synthase (CS) activities were highly sensitive to temperature. HK increased then markedly decreased; CS was significantly downregulated. Pyruvate kinase (PK), isocitrate dehydrogenase (IDH), and α-ketoglutarate dehydrogenase (KGD) showed trends that matched changes in larval cold tolerance, exhibiting an up–down–up expression trend. Glycolytic metabolites (glucose-6-phosphate, fructose-6-phosphate, 1,6-fructose-diphosphate, phosphoenolpyruvic acid) peaked at −10 °C. TCA intermediates (citrate, acetyl-CoA, α-ketoglutaric acid, and isocitrate) were more abundant at 0–4 °C. Pyruvate increased significantly. PYR content showed a significant increase followed by a decrease, peaking at 0 °C. It was converted into lactate and acetyl-CoA. ATP levels dropped and then increased, reaching their lowest level at 0 °C. These results suggest a shift from aerobic to mixed aerobic–anaerobic metabolism. Transcriptome data showed differential expression of key metabolic genes such as phosphoenolpyruvate carboxykinase, phosphoglycerate kinase, and ATP synthase subunit beta. These gene changes supported the trends in enzymes and metabolites. Our findings reveal a coordinated metabolic and transcriptional response to cold. This provides a basis for understanding the cold adaptation and potential range expansion of S. insularis. Full article

Salt stress severely impairs photosynthesis and development in tomato seedlings. This study investigated the regulatory role of exogenous melatonin (MT) on photosynthetic performance under salt stress by determining chlorophyll content, chlorophyll a fluorescence parameters, Calvin cycle enzyme activities, and related gene expression. Results showed that salt stress significantly reduced chlorophyll content and impaired photosystem II (PSII) functionality, as evidenced by the increased minimum fluorescence (F_o) and decreased maximum quantum efficiency of PSII (F_v/F_m) and effective PSII quantum yield (Φ_PSII). MT application mitigated these negative effects, as reflected by higher F_v/F_m, increased chlorophyll content, and lower non-photochemical quenching (NPQ). In addition, MT-treated plants exhibited improved PSII electron transport and more efficient use of absorbed light energy, as shown by elevated Φ_PSII and qP values. These changes suggest improved PSII functional stability and reduced excess thermal energy dissipation. Furthermore, MT significantly enhanced both the activity and expression of key enzymes involved in the Calvin cycle, including ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), Rubisco activase (RCA), phosphoglycerate kinase (PGK), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), fructose-1,6-bisphosphatase (FBPase), fructose-bisphosphate aldolase (FBA), transketolase (TK), and sedoheptulose-1,7-bisphosphatase (SBPase), thereby promoting carbon fixation and ribulose-1,5-bisphosphate (RuBP) regeneration under salt stress. Conversely, inhibition of endogenous MT synthesis by p-CPA exacerbated salt stress damage, further confirming MT’s crucial role in salt tolerance. These findings demonstrate that exogenous MT enhances salt tolerance in tomato seedlings by simultaneously improving photosynthetic electron transport efficiency and upregulating the activity and gene expression of key Calvin cycle enzymes, thereby promoting the coordination between light reactions and carbon fixation processes. This study provides valuable insights into the comprehensive regulatory role of MT in maintaining photosynthetic performance under saline conditions. Full article

The areca palm (Areca catechu L.), a medicinal tropical crop, hosts three novel viruses, areca palm necrotic ringspot virus (ANRSV), areca palm necrotic spindle-spot virus (ANSSV), and ANRSV2, which form a new genus Arepavirus in the family Potyviridae. Both viruses feature a unique tandem leader protease arrangement (HCPro1-HCPro2). To elucidate HCPro2’s role, this study identified its interaction partners in infected cells using affinity purification coupled with liquid chromatography-tandem mass spectrometry, a yeast two-hybrid system, and co-immunoprecipitation. Thirteen host proteins and five viral factors (HCPro1, 6K2, VPg, NIa-Pro, NIb) were validated as HCPro2 interactors. Among the host proteins interacting with HCPro2, the expression of five genes (NbeIF4A, NbSAMS1α, NbTEF1α, NbUEP1, and NbRan2) was upregulated under the condition of viral infection, while the expression of another five genes (NbpsbS1, NbPGK, NbchIP, NbClpC1A, and NbCysPrx) was downregulated. Functional assays showed that silencing NbeIF4A or NbPGK significantly reduced viral accumulation in Nicotiana benthamiana. These findings reveal HCPro2’s network of virus-host interaction, highlighting its critical role in viral pathogenesis. Further exploration of these interactions may clarify the evolutionary significance of tandem leader proteases and inform novel plant antiviral strategies. Full article