Search Results (140)

Mycosporine-like amino acids (MAAs), a class of secondary metabolites characterized by a cyclohexenone or cyclohexenimine ring structure bound to amino acid residues, are widely distributed in algae. These compounds exhibit strong ultraviolet-absorbing and antioxidant activities, making them attractive candidates for natural sunscreen formulations. However, the low productivity of MAAs in microalgae severely hampers commercial viability. Asterarcys sp., a fast-growing, heat- and light-tolerant microalga, has recently been demonstrated to produce high levels of MAAs under UV irradiation. In this study, phosphorus limitation was found to stimulate rapid MAAs accumulation in Asterarcys sp. SCSIO-46548. After eight days of cultivation, microalgal cells grown in phosphorus-free medium (0 mg L⁻¹) showed a sixfold higher MAAs content (1.08% DW) compared to the group supplied with 5.60 mg L⁻¹ phosphorus (0.18% DW). However, the accumulation of MAAs began to plateau under phosphorus deprivation. Based on integrated homology alignment with cyanobacteria and functional domain validation, a putative biosynthetic pathway for mycosporine-serine in Asterarcys sp. SCSIO-46548 was proposed. Importantly, the gene expression of desmethyl-4-deoxygadusol synthase (DDGS) exhibited a 2.75-fold upregulation under phosphorus limitation. Complementary bioinformatic analyses further characterized the subcellular localization and major physicochemical properties of the candidate enzymes involved. In conclusion, phosphorus limitation is an effective strategy to enhance MAAs production in Asterarcys sp. SCSIO-46548 by upregulating the expression of key biosynthetic genes, such as DDGS. This finding provides an effective solution to the low MAAs productivity in microalgae cultivation. Full article

Laryngeal squamous cell carcinoma (LSCC) remains a major clinical challenge within head and neck oncology, with five-year survival rates showing minimal improvement over recent decades despite advances in surgical and multimodal therapeutic strategies. Increasing evidence identifies metabolic reprogramming as a central driver of tumor progression, therapeutic resistance, and immune evasion in LSCC. Beyond the classical Warburg effect, LSCC exhibits profound metabolic reprogramming, involving coordinated alterations in carbohydrate, amino acid, lipid, and iron metabolism that support adaptation to hypoxic and nutrient-deprived microenvironments. Hypoxia-inducible factors, particularly HIF-1α, coordinate these key biochemical pathways and enzymatic steps by integrating glycolysis, glutaminolysis, folate-dependent one-carbon pathways, lipid synthesis, and mitochondrial remodeling, while also influencing stromal and immune components of the tumor microenvironment. Metabolic crosstalk between tumor cells, cancer-associated fibroblasts, and immune populations promotes immunosuppression through nutrient competition and accumulation of metabolites such as lactate and lipid-derived mediators. In parallel, dysregulated iron handling and altered ferroptosis susceptibility emerge as key determinants of tumor aggressiveness and treatment response. This review synthesizes current evidence on metabolic rewiring in laryngeal squamous cell carcinoma, highlighting how alterations in metabolic pathways create targetable vulnerabilities that drive tumor biology, immune modulation, and resistance to conventional and emerging therapies. Elucidating these metabolic dependencies may support the development of metabolism-based biomarkers and therapeutic strategies in laryngeal squamous cell carcinoma, providing an integrated and translational perspective that links tumor metabolism with microenvironmental interactions and immune modulation, while highlights emerging therapeutic vulnerabilities. Full article

Selenium (Se) is an essential trace element. The bioactivity of Se arises from its incorporation into the 21st amino acid, selenocysteine (Sec). Twenty-five human genes have been identified that encode selenoproteins, each of which contains at least one Sec residue. Selenoprotein functions include antioxidant responses, thyroid hormone synthesis, and maintenance of cellular redox homeostasis. Due to its role in critical cellular functions, Se deficiency is associated with morbidities of the cardiovascular system and connective tissue in regions of countries with low soil Se content. While these morbidities are geography-specific and have been mitigated in adults through public health interventions, preterm infants remain susceptible to Se deficiency worldwide. Infants born preterm are deprived of fetal Se accrual in the 3rd trimester of pregnancy, a deficiency compounded by higher Se needs than term infants and older infants and dependence on parenteral nutrition (PN) and fortification. In addition, the composition of selenoproteins and selenometabolites in human milk is different from that in formula and PN, yet little is known about the biological impact of these differences. The knowledge gap in optimal Se supplementation is reflected in discrepant guidelines between North American and European/Chinese nutrition societies, whose recommended Se supplementation in preterm infants differs by more than 2-fold. In this review, we describe the biosynthesis, metabolism, and maternal-fetal transfer of Se. In addition, we address how developmentally regulated aspects of metabolism may impact how preterm infants respond to supplementation with different forms of Se. Lastly, we highlight current challenges and recommendations for optimizing Se levels in neonates based on available data. Full article

Tachykinins (TKs), a conserved family of neuropeptides, play critical roles in regulating multiple physiological processes such as feeding and energy metabolism in insects. This study identified the TK gene (ApTK) from the Chinese oak silkworm, Antheraea pernyi, an economically important insect species. Bioinformatic analysis showed that ApTK possesses four FX₁GX₂R motifs (X₁ and X₂ represent variable amino acid residues), comprising FMGVR, FYGVR, FIGVR, and FFGMR, in the C-terminus and shares a close phylogenetic relationship with TKs from Bombyx mori and Manduca sexta. Tissue-specific expression profiling demonstrated that ApTK was mainly expressed in the brain and midgut. Starvation–refeeding experiments showed that the expression of ApTK was significantly upregulated during food deprivation and returned to baseline after refeeding, evincing its involvement in hunger signaling. RNA interference (RNAi)-mediated knockdown of ApTK led to a significant increase in larval body weight and increased levels of triglyceride, glycogen, and trehalose, indicating enhanced energy storage. Collectively, these results demonstrate that ApTK acts as a key regulator in restraining feeding and modulating energy homeostasis in A. pernyi. Our findings provide insights into the neuroendocrine mechanisms underlying feeding behavior and energy metabolism in A. pernyi. Full article

As diets shift towards more plant-based patterns, nutrients mainly supplied by animal-sourced foods are receiving greater attention. Among these are sulphur-containing amino acids (SCAAs) such as taurine, methionine, and cysteine. These compounds play important roles in neuroprotection, antioxidant defence, and cellular signalling; functions that are closely linked to cognitive health. This systematic review examined the effects of SCAA supplementation on cognitive performance in randomised controlled trials (RCTs). Eight RCTs involving 244 healthy participants met the inclusion criteria. All trials focused exclusively on taurine; no studies were found that tested methionine or cysteine. Each used an acute, single-dose design, assessing key cognitive domains and mood outcomes. Overall, acute doses of taurine (typically 1–3 g, up to ~50 mg/kg) produced, at best, small and inconsistent improvements in cognitive function. Most cognitive outcomes showed no effect. Trials that combined taurine with caffeine showed more reliable performance benefits, but they did not isolate taurine’s independent effects. Similarly, any positive effects on mood or well-being were minor, inconsistent, and typically observed only under specific conditions, such as when taurine was combined with caffeine, exercise, or sleep deprivation. Importantly, none of the studies measured participants’ habitual diets, baseline SCAA status, or specifically recruited individuals with low intake of animal-source foods. This means the cognitive effects of reduced SCAA intake in plant-based diets remain unknown. Current evidence from acute taurine trials provides limited support for short-term benefits to cognition or mood. Longer-term, well-designed studies are urgently needed. These should assess habitual diet and baseline SCAA status and focus on populations with lower animal-derived food intake. Only then can we determine whether lower SCAA availability in plant-based diets represents a nutritional ‘green gap’ with implications for brain health. Full article

Starvation elicits profound metabolic adaptations in skeletal muscle, enabling survival during nutrient scarcity. While global proteomic changes underpinning muscle atrophy have been studied, the role of lysine β-hydroxybutyrylation (Kbhb), a novel metabolite-derived post-translational modification linked to ketone metabolism, remains largely unexplored. In this study, we subjected mice to 72 h of food deprivation and performed integrative quantitative proteomics and Kbhb-modified peptide profiling on gastrocnemius muscle. Starvation induced significant body weight and muscle mass loss, accompanied by increased systemic β-hydroxybutyrate levels and widespread Kbhb modification of muscle proteins. Proteomic analysis revealed extensive downregulation of ribosomal and translation-associated proteins, coupled with upregulation of autophagy and lipid catabolism pathways, highlighting a coordinated shift from anabolic processes to catabolic and oxidative metabolism. Deep Kbhb profiling identified over 7500 modified lysine sites across 2000 proteins, with starvation triggering a global increase in Kbhb on key metabolic enzymes involved in glycolysis, TCA cycle, fatty acid β-oxidation, and amino acid metabolism. Notably, starvation-enhanced Kbhb preferentially targeted evolutionarily conserved lysines proximal to catalytic or cofactor-binding domains, implicating a regulatory role in enzymatic activity modulation. Conversely, Kbhb on structural and contractile proteins was downregulated, suggesting functional reprioritization of muscle physiology during fasting. Our findings uncover lysine β-hydroxybutyrylation as a dynamic, metabolically responsive PTM mediating gastrocnemius muscle adaptation to energy deficiency, expanding the paradigm of potentially metabolite-driven epigenetic and non-epigenetic regulatory mechanisms in muscle metabolism. Full article

Nutritional immunity is a major facet of host defense, wherein the host immune system strategically limits pathogen access to critical nutrients, including iron, zinc, vitamins, lipids, and amino acids, to repress microbial proliferation and virulence. This review provides a comprehensive synthesis of the molecular mechanisms that power nutrient immunity, including metal homeostasis, nutrient competition, transporter modulation, hormonal regulation, and direct antimicrobial actions. We examine nutrient-specific strategies employed by the host, such as iron-withholding mechanisms, vitamin deprivation, and copper-mediated toxicity. We also explore how diverse pathogens, including extracellular, intracellular, and eukaryotic pathogens, adapt to these hostile nutritional landscapes through siderophore diversification, regulatory integration, and metabolic rewiring. Comparative genomic analyses reveal convergent evolution in nutrient acquisition systems, illuminating the dynamic arms race between host restriction and microbial evasion. We examine the immunological mechanisms that regulate nutritional immunity. Further, we discuss the translational potential of nutritional immunity, cutting across nutrient-based therapies, host-directed interventions, and emerging diagnostic biomarkers. Finally, we suggest future directions that synergize nutritional immunity with microbiome ecology, global malnutrition, and personalized medicine. By elucidating the interconnection between metabolism and immunity, this review highlights the therapeutic promise of starving or toxifying the pathogen to save the host. Full article

Background: Many inhibitors have been discovered to target hypoxia-induced carbonic anhydrase IX (CAIX) due to its critical role in lung cancers. This study discovers a novel compound, 3-(E-3,4-dihydroxycinnamaoyloxyl)-2-hydroxypropyl-9Z,12Z-octadeca-9,12-dienoate, which is produced by the seagrass Cymodocea serrulata and has binding sites at CAIX that are distinct from those of current inhibitors. Methods: Compound and reference drug treatment for cell lines; Cell viability: MTT; Staining: Ao/PI/DAPI; MMP shifts and cell cycle: FACS; Gene and protein expression of CAIX, BAX, BAD: qPCR and Western blotting. Results: The compound binds to the CAIX protein, raises extracellular pH, and kills A549 cells [IC₅₀: 11.61 µM], producing results that are lower than those of the reference drug doxorubicin [13.7 µM]. The substance depolarised the electrical potential of the mitochondrial membrane, caused S-phase arrest, and fragmented DNA. Additionally, it downregulated CAIX by 0.9 times while increasing apoptotic mRNA, BAX and BAD by 5.2 and 3.08 times, respectively, as demonstrated by qPCR. Between 0 and 24 h, the untreated hypoxic cells had a ΔpHe of 0.15, but the compound-treated cells had a ΔpHe of 0.6 indicative of intracellular acidosis. MD simulations verify the stability of the CAIX–C1 complex for more than 100 ns, and in silico studies show a strong binding affinity of the molecule to CAIX [−7.55 kcal/mol]. Conclusions: This implies that the amount of extracellular alkalosis was increased by the combination of treatment and hypoxia induction. As a result, when the cells were deprived of O₂, the compound provided less defense against ROS. The compound binds to the glutamine and alanine amino acids at positions 242 and 392, respectively, at the central Zn atom of CAIX, which sets it apart from conventional sulphonamide CAIX inhibitors. This naturally occurring compound may be a potent CAIX inhibitor with newer binding sites, which could help treat hypoxic lung cancers. Full article

Prostate-specific membrane antigen (PSMA) targeting agents have been the cornerstone of advanced prostate cancer (PCa) management in theranostics due to their high sensitivity for detecting and treating metastatic disease. However, approximately one-third of metastatic castration-resistant PCa (mCRPC) lesions may exhibit low or absent PSMA expression due to tumor heterogeneity, prior androgen deprivation therapy, or loss of androgen receptor expression, subsequently altering their response to PSMA-targeted therapy. The molecular and biological mechanisms underlying PSMA downregulation remain elusive but may include neuroendocrine differentiation or epithelial-to-mesenchymal transition (EMT). This review addresses this knowledge gap by examining recent preclinical and clinical evidence on novel radiotracers with the potential to provide alternative strategies beyond PSMA for imaging and treating PCa. The diagnostic performance and therapeutic potential of three emerging radiotracer classes are discussed, including gastrin-releasing peptide receptor (GRPR) ligands, androgen receptor (AR) ligands, and amino acid analogs. This article further highlights the complementary roles of these radiotracers along with their utility in specific patient populations, such as those with low prostate-specific antigen (PSA), biochemical recurrence (BCR), or confirmed PSMA-negative disease. For instance, GRPR-targeted radiotracers have achieved sensitivity of up to 88% and specificity of up to 90% for detecting primary tumors in PCa. The radiolabeled androgen agonist, fluorine-18 (¹⁸F)-fluoro-5α-dihydrotestosterone (FDHT), has demonstrated 98% true-positive rate in predicting lesions on positron emission tomography (PET) scans of mCRPC patients. On the other hand, the synthetic amino acid analog ¹⁸F-fluciclovine demonstrated a lesion detection rate of 84% for PSA levels at or above 5, and 62.5% for PSA levels ranging from 0.7 to less than 1. This review concludes with future directions on the paradigm of multi-tracer and dual-targeting strategies, which can effectively address challenges associated with PCa tumor heterogeneity and facilitate personalized approaches in theranostics. Full article

The ability of common carp to withstand both short-term and long-term oxygen deprivation has been well documented; however, the potential genetic mechanisms behind common carp’s hypoxia response remain unclear. Therefore, to understand the possible genetic foundation of their response to hypoxia, comparative genomic analyses were conducted among six common carp varieties: Color, Songpu, European, Yellow, Mirror, and Hebao common carps. We identified 118 single-copy orthologous positively selected genes (PSGs) (dN/dS > 1) in all common carps under study, with GO functions directly related to the cellular responses to hypoxia in Color and European common carp PSGs, such as oxygen transport activity, oxygen binding activity, respiratory burst activity, and superoxide anion production. The Bayes Empirical Bayes (BEB) technique identified possible amino acid substitutions in mitochondrial and hypoxic genes under positive selection. Exonic and intronic structural variations (SVs) were discovered in the CYGB2 hypoxia-related gene of Color and European common carps, as well as in several mitochondrial genes, including MRPL20, MRPL32, NSUN3, GUF1, TMEM17B, PDE12, ACAD6, and COX10 of Color, European, Songpu, Yellow, and Hebao common carps. Moreover, Color common carp and Songpu common carp were found to share the greatest percentage of collinear genes (49.8%), with seven Songpu common carp chromosomes (chr A2, chr A9, chr A13, chr B13, chr B15, chr B2, and chr B12) showing distinct translocation events with the corresponding chromosomes of Color common carp. Additionally, we found 570 translocation sites that contained 3572 translocation-related genes in Color common carp, some of which are directly relevant to mitochondrial and hypoxic GO functions and KEGG pathways. Our results offer strong genome-wide evidence of the possible evolutionary response of Cyprinus carpio to hypoxia, providing important insights into the potential molecular mechanisms that explain their survival in hypoxic environments and guiding future research into carp hypoxia tolerance. Full article

Background: Metabolic stress from amino acid (AA) insufficiency is increasingly linked to pathological angiogenesis, but specific essential AA (EAA) roles remain undefined. Neovascular age-related macular degeneration (AMD), a major cause of blindness driven by aberrant ocular neovascularization, has limited efficacy with current VEGFA-targeting therapies. We sought to identify specific EAAs that regulate pathological angiogenesis and dissect their mechanisms to propose new therapeutic strategies. Methods: Human retinal microvascular endothelial cells (HRMVECs) were used to identify angiogenesis-regulating amino acids through systematic EAA screening. The molecular mechanism was investigated using shRNA-mediated knockdown of key stress response regulators (HRI, PKR, PERK, GCN2) and ATF4. Angiogenesis was assessed via tubule formation and migration assays. Therapeutic potential was examined in a laser-induced choroidal neovascularization (CNV) mouse model, evaluated by fluorescein angiography and histomorphometry. Results: Deprivation of methionine, lysine, and threonine potently induced capillary-like tube formation (p < 0.01). Mechanistically, restriction of these three EAAs activated HRI and GCN2 kinases, converging on eIF2α phosphorylation to induce ATF4 and its target VEGFA. Dual, but not single, knockdown of HRI and GCN2 abolished eIF2α-ATF4 signaling and angiogenic responses. Restricting these EAAs exacerbated CNV area in mice. Conclusions: Our findings reveal a coordinated HRI/GCN2-ATF4-VEGFA axis linking EAA scarcity to vascular remodeling, establishing proof-of-concept for targeting this pathway in CNV. This work highlights the therapeutic potential of modulating specific AA availability or targeting the HRI/GCN2-ATF4 axis to treat CNV. Full article

Global seafood production and consumption have increased in recent years, leading to a significant rise in side streams. Process waters are often disposed as wastewater, causing difficulties for industries in meeting the discharge standards. This is particularly relevant to the mussel processing industry, where one-third of the raw material ends up as high-organic content effluent. This study aims to optimize a nanofiltration–diafiltration (NF–DF) strategy to recover valuable savory compounds from mussel cooking water, to reduce the effluent organic pollution, and to evaluate its environmental sustainability using Life Cycle Assessment. Pilot trials lead to a configuration, combining a volumetric concentration factor of 10 in NF and 20 in DF, which achieved enhanced protein concentration (1.5-fold), amino acid concentration (5.2-fold), and COD removal (98.2%). The environmental assessment highlighted electricity consumption during NF and DF as the primary environmental hotspot, resulting in a carbon footprint of 0.12 kg CO₂ eq. kg⁻¹ of savory compounds and water use of 0.65 m³ deprived kg⁻¹. Prospective scenarios projected that ongoing energy system transitions could significantly reduce climate change and acidification impacts by over 75% by 2050. The proposed NF–DF strategy enhances resource efficiency and sustainability in seafood processing by recovering high-value compounds and facilitating water reuse. Full article

Cancer metabolism is a hallmark of cancer. However, the impact of systemic metabolism and diet on tumour evolution is less understood. This study delves into the role of glucagon, as a component of the pancreatic microenvironment, in regulating features of pancreatic neuroendocrine tumour (pNET) cells and the metabolic remodelling occurring in the presence and absence of glucose. pNET cell lines (BON-1 and QGP-1) and the non-malignant pancreatic α-TC1 cell line were used as models. Results showed that pNET cells responded differently to glucose deprivation than α-TC1 cells. Specifically, pNET cells upregulated the GCGR in the absence of glucose, while α-TC1 cells did so in high-glucose conditions, allowing the glucagon-related pERK1/2 activation under these conditions in pNET cells. Glucagon enhanced cancerous features in pNET BON-1 cells under glucose-deprived and hyperglucagonemia-compatible concentrations. In the α-TC1 cell line, glucagon modulated cell features under high-glucose and physiological glucagon levels. NMR exometabolome analysis revealed differences in metabolic processes based on glucose availability and glucagon stimulation across cell lines, highlighting amino acid metabolism, glycolysis, and gluconeogenesis. The expression of metabolic genes was consistent with these findings. Interestingly, QGP-1 and α-TC1 cells produced glucose in no-glucose conditions, and glucagon upregulated glucose production in α-TC1 cells. This suggests that gluconeogenesis may be beneficial for some pNET subsets, pointing out novel metabolism-based strategies to manage pNETs, as well as a step forward in endocrinology and systemic metabolism. The association between GCGR expression and malignancy and a negative correlation between glucagon receptor (GCGR) and glucagon-like peptide-1 receptor (GLP-1R) expression was observed, indicating a biological role of glucagon in pNETs that deserves to be explored. Full article

Background: Natural astaxanthin, a commercially valuable carotenoid, is primarily sourced from Haematococcus pluvialis, a microalga known for its remarkable resilience to environmental stress. Methods: In this study, the physiological and transcriptomic responses of H. pluvialis to ND were investigated at various time points under high light conditions. Results: Under high light conditions, nitrogen deprivation (ND) enhances astaxanthin content (33.23 mg g⁻¹) while inhibiting the formation of the secondary cell wall (SCW), increasing astaxanthin content by 29% compared to the nitrogen-replete group (25.64 mg g⁻¹); however, the underlying mechanisms remain unclear. ND reduced chlorophyll fluorescence parameters, elevated reactive oxygen species (ROS) levels, and increased starch and total sugar accumulation while decreasing protein and lipid content. Fatty acid content increased on the first day but had declined by the fifth day. A transcriptomic analysis revealed substantial alterations in gene expression in response to ND. Genes associated with the TCA cycle, glycolysis, astaxanthin biosynthesis, and cell motility were upregulated, while those involved in photosynthesis, lipid synthesis, ribosome biogenesis, amino acid synthesis, and SCW synthesis were downregulated. Additionally, ND modulated the expression of genes involved in ROS scavenging. Conclusions: These findings provide critical insights into the adaptive mechanisms of H. pluvialis in response to ND under high light, contributing to the development of strategies for enhanced production of astaxanthin-rich motile cells. Full article

Glioblastoma (GBM) is a highly aggressive primary brain cancer with dismal prognoses despite current standards of care. Immunotherapy is being explored for GBM, given its promising results in other solid malignancies; however, the results from early clinical studies in GBM are disappointing. It has been discovered that GBM has numerous mechanisms of immune resistance, including the physical blood–brain barrier, high intratumoral and intertumoral heterogeneity, and numerous cellular and molecular components in the tumor microenvironment (TME) that promote immunosuppression. Furthermore, GBM utilizes numerous metabolic pathways to establish a survival advantage in the TME. Recently, it has begun to become evident that these complex metabolic pathways that promote GBM growth and invasion also contribute to tumor immune resistance. Aerobic glycolysis provides tumor cells with ample ATP while depleting key glucose and increasing acidity in the TME. Increased glutamine, tryptophan, and arginine metabolism deprives T cells of these necessary amino acids for proper anti-tumor function. Sphingolipid metabolism promotes an immunosuppressive phenotype in the TME and affects immune cell trafficking. This review will discuss, in detail, the key metabolic pathways relevant to GBM pathophysiology which also modulate host immunosuppression. Full article