Search Results (853)

Cardiolipin (CL), a dimeric phospholipid with four acyl chains and a small polar head group, is one of the most striking examples of evolutionary continuity in cell biology. Present in the plasma membrane of α-proteobacteria and retained without fundamental modification in the inner mitochondrial membrane (IMM) of every eukaryote examined, CL has persisted across roughly two billion years of evolution, a period over which the mitochondrion shed the great majority of its ancestral genes. This review develops, as an organizing hypothesis rather than an established fact, the proposal that CL acts as a programmable signaling hub: a lipid whose physical chemistry and membrane address allow it to nucleate distinct supramolecular platforms in response to discrete stress signals, each platform coupling a specific mitochondrial state to a defined cell fate outcome. Three CL-dependent platforms are examined, together with a fourth, emerging axis, and the evidence supporting each is explicitly graded. Platform 1, the catalytic peroxidase platform, converts the constitutive CL–cytochrome c (cyt c) structural complex into an enzymatic reaction under oxidative stress, generating oxidized CL (oxCL) species that contribute to cyt c release from the IMM; this platform is the best supported of the four. Platform 2, the receptor-like mitophagy platform, exploits NME4-dependent CL scramblase activity to translocate CL from the IMM to the outer mitochondrial membrane (OMM) surface upon membrane potential dissipation, creating an externalized “eat-me” signal recognized by LC3-II; the evidence here is moderate and largely cell-based. Platform 3, the caspase-8/BID activation platform, is proposed to assemble a CL microdomain scaffold at the OMM that recruits caspase-8, markedly accelerates BID cleavage, and couple extrinsic apoptotic signals to mitochondrial outer membrane permeabilization (MOMP); this model rests substantially on reconstituted systems and requires further validation in intact cells and in vivo. A fourth, still-debated axis links CL externalization to innate immune activation through NLRP3 recruitment, for which alternative membrane-recruitment models exist. The argument advanced here is that the conservation of CL is unlikely to be explained by its structural roles alone, although those roles are themselves sufficient to impose strong selection; disentangling structural from signaling contributions remains an open problem, and the comparative genomic work needed to do so has not yet been performed. Full article

The spatial organisation of plasma membrane proteins such as G protein-coupled receptors (GPCRs) plays a critical role in regulating cell signalling, function, and ultimately cell fate. Resolving this organisation requires techniques capable of probing dynamics at the single-molecule level with high spatial and temporal resolution. In this study, we employ the complementary fluorescence fluctuation spectroscopy approaches, Fluorescence Correlation Spectroscopy (FCS), Photon Counting Histogram Analysis (PCH), Raster Image Correlation Spectroscopy (RICS) and Number and Brightness Analysis (N&B), in conjunction with Fluorescence Recovery After Photobleaching (FRAP), to investigate the membrane organisation of the C-X-C chemokine receptor 4 (CXCR4), a GPCR known to undergo ligand-induced reorganisation. At the nanoscale, FCS highlighted opposing effects on diffusion after agonist (CXCL12) and inverse agonist (IT1t) treatment, whilst RICS also showed ligand-mediated changes in particle number. Both single-point and image-based brightness analyses (PCH and N&B) showed increased brightness after CXCL12 treatment, consistent with the pre-internalisation clustering of CXCR4. At the microscale, FRAP showed an increase in immobile CXCR4, not visible to FFS approaches, following CXCL12 stimulation. This integrated approach, performed on a single commercial confocal microscope, provides valuable insight into the reorganisation of CXCR4 in the plasma membrane over a range of temporal and spatial scales, which are not detectable using standard imaging. Full article

Brassinosteroids (BRs) are essential steroid hormones that coordinate plant growth, development and adaptation to changing environments. Although BR signaling has long been viewed primarily as a phosphorylation-dependent pathway, increasing evidence shows that ubiquitination provides an additional regulatory layer that shapes the abundance, activity, subcellular distribution and turnover of key signaling components. Ubiquitin-mediated regulation operates at multiple points in the BR pathway, including receptor homeostasis at the plasma membrane, turnover of GSK3-like kinases, and stability control of the transcription factors BES1/BZR1. These processes determine not only the strength and duration of BR signaling but also its coordination with other hormonal and stress-response pathways. In this review, we discuss recent advances in ubiquitin-mediated regulation of BR signaling, focusing on receptor-level control, proteolytic regulation of core signaling components, and modulation of transcriptional outputs. We also highlight emerging links between ubiquitination, selective autophagy, deubiquitination and BR-associated stress responses and outline key questions concerning ubiquitin chain specificity, substrate recognition and conservation of these regulatory modules in crops. Defining how ubiquitination fine-tunes BR signaling will deepen our understanding of plant steroid hormone regulation and may provide new strategies for optimizing crop architecture, productivity, and stress resilience. Full article

Thioredoxin domain-containing protein 5 (TXNDC5) plays a role in diseases related to oxidative stress, energy metabolism, and cellular inflammation. This protein has also been associated with diabetes and insulin folding. To gain insight into these relationships, glucose metabolism was characterized using Txndc5-deficient mice. The absence of TXNDC5 lowered glycemia, which was correlated with higher non-esterified fatty acid (NEFA) levels following an overnight fast on a chow diet in males. Several tolerance tests (pyruvate, glucose, and insulin) revealed no impairment in gluconeogenesis, but rather, higher insulin sensitivity. In vitro assays using an engineered hepatic cell line corroborated the results of increased glucose uptake. When a high-fat, high-sucrose diet was administered to induce a prediabetic state, the absence of TXNDC5 reproduced the lower glycemia and higher NEFA levels observed in mice consuming the chow diet. However, higher levels of plasma insulin were observed in Txndc5-deficient mice. The insulin receptor was increased in the hepatic plasma membranes. Increased hepatic gene expression of G6pc, Irs2, and Igfbp1 was also observed in the absence of TXNDC5. These results indicate that TXNDC5 plays a role in the hepatic sex-differential handling of glucose and lipids, and in retaining the insulin receptor on the plasma membrane. Full article

Background/Objectives: The aim of this systematic review was to analyze the impact of dietary modifications on unsaturated fatty acids (UFAs) intake on the course of three oral autoimmune conditions: oral lichen planus (OLP), recurrent aphthous stomatitis (RAS), and pemphigus. These acids serve a structural function as key components of cell membrane phospholipids, influencing their fluidity and membrane receptor activity. The proper ratio of these acids in the diet may be crucial for maintaining normal functioning of the human immune system. Methods: The following bases were searched with no time restrictions: PUMS Library, Embase/Elsevier, PubMed/MEDLINE, Scopus, and Web of Science. Of the 247 results identified in pre-screening, 6 studies that met all search criteria were included in the final systematic review. The risk of bias was assessed using the Revised Cochrane Risk of Bias Tool for randomized trials and the Newcastle–Ottawa Scale for non-randomized studies. Results: The outcome measures included: proportions of LA-derived oxylipins (9-HODE, 13-HODE), ulcer size (mm), monthly number of ulcers, average pain (VAS), duration of episodes, and quality of life (OHIP-14), healing time, and fatty acid analysis of total plasma phospholipid fraction, Pemphigus Disease Area Index (PDAI) for disease severity (mild ≤ 15, severe > 15); AHEI-2010 score (9–90 points) for diet quality. In all studies, improvements in clinical parameters and subjective complaints were observed after implementing a dietary intervention. Conclusions: Dietary modification may be a valuable component of adjunctive therapy. Nutritional optimization offers a genuine opportunity to reduce reliance on conventional pharmaceuticals, thereby limiting the risk of systemic adverse effects associated with long-term pharmacotherapy. Full article

B-cell receptor (BCR) is indispensable for B-cell responses, and its signaling relies on the rearrangement of cytoskeletal proteins. Cytoskeletal protein 4.1R has been previously implicated in the regulation of immune function. However, the specific role of 4.1R in BCR-mediated B-cell activation remains unknown. Here, we performed single-cell RNA (scRNA) sequencing on splenic B cells isolated from wild-type (WT) and 4.1R-knockout (4.1R-KO) mice to systematically characterize the functional contribution of 4.1R to B-cell biology. Transcriptomic analyses suggested a critical role for 4.1R in modulating BCR signaling. Ex vivo stimulation of primary B cells with anti-IgM demonstrated that 4.1R-KO B cells exhibited marked overactivation, hyperproliferation, and enhanced antibody secretion. Furthermore, unbiased phosphoproteomic profiling, identified sustained AKT1 phosphorylation as a key feature in 4.1R-KO B cells. Subsequent functional validation confirmed that 4.1R regulates BCR signaling by constraining AKT1 activation. Mechanistically, 4.1R rapidly colocalized with the coreceptor CD19 at the plasma membrane upon BCR engagement, and co-immunoprecipitation confirmed their physical interaction. Loss of 4.1R disrupted this interaction and resulted in sustained and amplified AKT1 phosphorylation (but not AKT2) in stimulated B cells. Collectively, our findings identify 4.1R as a novel negative regulator of BCR signaling that interacts with CD19 to constrain AKT1 activation. Full article

Theranostics is a novel approach that integrates diagnostic and therapeutic efficacy on a single platform, holding great promise for precision medicine by enabling real-time monitoring of disease progression and therapeutic response. Despite significant advances, the successful development and delivery of theranostic systems are critically limited by multiple biological barriers present at systemic, tissue, cellular, anatomical, and immunological levels. These barriers restrict bioavailability, target accessibility, and therapeutic efficacy, while often increasing off-target accumulation and adverse effects. This review provides a comprehensive overview of the major biological barriers encountered in theranostic development, including physiological barriers such as plasma protein binding, renal clearance, and hepatic metabolism; anatomical barriers like endothelial linings, the blood–brain barrier (BBB), and the tumor microenvironment; cellular barriers involving membrane permeability, intracellular trafficking, and endo-lysosomal entrapment; and immunological barriers such as immune recognition, inflammatory responses, and complement activation. Special emphasis is placed on the BBB, highlighting its structural complexity, transport mechanisms, and strategies such as molecular Trojan-horse technology, receptor-mediated and adsorptive-mediated transcytosis, and nanocarrier-based approaches to enhance central nervous system delivery. The review further discusses targeted delivery challenges, including receptor heterogeneity and multidrug resistance, and critically evaluates current strategies to overcome these barriers through surface functionalization, stimuli-responsive systems, biomimetic carriers, and controlled-release mechanisms. Finally, recent advances, clinical challenges, and future perspectives—including personalized theranostics, artificial intelligence—assisted design, and next-generation barrier-penetrating systems—are explored. Overall, this review aims to provide a structured understanding of biological barriers in theranostics and highlight innovative approaches to improve their translational potential. Full article

A therapeutic antibody, CSL305, has been developed, which combines inhibition of the complement classical and lectin pathways via complement C2 binding with an ability to act as an antagonist of the neonatal Fc receptor (FcRn). CSL305 binds to human C2 (huC2) but shows no binding or activity against mouse C2 precluding its use in mouse models of disease to fully assess in vivo efficacy. To circumvent this, a mouse strain was developed that replaced the expression of mouse C2 with huC2 by homologous recombination. These mice (huC2 “knock-in”; KI) were shown to express huC2 protein and to have complement activity. Interestingly, male huC2-KI mice showed much stronger complement activity compared to female mice and were also sensitive to inhibition by CSL305. Two models of disease using male huC2-KI mice were then used to assess the in vivo efficacy of CSL305. The first was an attenuated passive anti-glomerular basement membrane (GBM) glomerulonephritis model involving complement activation as its primary mechanism of action. CSL305 showed dose-dependent inhibition of disease as measured by urine albumin, with reductions in kidney cellular infiltration and plasma C3 cleaved fragments C3b/C3c/iC3b also observed. The second model was a collagen autoantibody-induced arthritis (CAIA) mouse model. Here, CSL305 showed a significant and dose-dependent inhibition of clinical score in both prophylactic and therapeutic settings, mediated exclusively via its FcRn mechanism of action. Although the animal models used in this study were found to preclude the demonstration of a synergistic effect on both mechanisms, CSL305 does act in vivo as both a complement inhibitor and as a FcRn antagonist to ameliorate disease. Full article

Leucine, an essential branched-chain amino acid, serves not only as a substrate for protein synthesis but also as a key regulator of placental function and fetal development. This study investigated the effects of dietary supplementation with RP-Leu during late gestation on placental development and offspring performance in Hu sheep. Sixty twin-pregnant ewes at day 80 of pregnancy were randomly assigned to either a control group (fed a basal diet) or an RP-Leu group (fed a basal diet supplemented with 19 g/day RP-Leu). The feeding trial lasted for 60 d. The ewes were slaughtered at day 140 of gestation. Maternal slaughter traits and fetal organ weights were recorded. Blood and milk samples were collected for milk composition analysis and targeted metabolomic profiling. Leucine supplementation significantly increased the percentage of milk fat content, total solid content, and the birth weight of lambs (p < 0.05). Improvements in placental morphology and antioxidant capacity were observed, including a significant increase in cotyledon density and a significant enhancement of catalase (CAT) activity (p < 0.05). Gene expression analysis indicated that the NOS3, SLC38A1 and FABP4 genes in the placental cotyledons (p < 0.05), and the VEGFA, NOS3, SLC27A1 and FABP4 genes were significantly upregulated in the maternal caruncles (p < 0.05). Plasma metabolomic profiling revealed increased L-glutamic acid levels and alterations in several amino acids, with pathway enrichment indicating involvement in amino acid metabolism and membrane transport processes. Transcriptomic analysis identified 739 differentially expressed genes, which were mainly enriched in the PI3K/Akt signaling pathway, ECM–receptor interaction pathway, and cytokine–cytokine receptor interaction pathway. Collectively, these findings suggest that RP-Leu supplementation during late gestation may enhance offspring growth by modulating amino acid metabolism, promoting placental development, and improving placental nutrient transport capacity, thereby supporting fetal growth and development. Full article

The CD40–CD154 receptor-ligand axis is a core costimulatory regulator of antiviral immunity in mammals, but its functional role in teleosts remains largely unknown. Here, we identified the CD40 and CD154 homologs (MsCD40 and MsCD154) from largemouth bass (Micropterus salmoides), a globally farmed perciform teleost. Bioinformatic analysis confirmed that MsCD40 and MsCD154 harbor the conserved domain architectures of tumor necrosis factor receptor superfamily and TNF superfamily, respectively, with a teleost-specific phylogenetic clustering pattern. Both genes were ubiquitously expressed in immune-relevant tissues, and their transcription was dynamically regulated in response to viral hemorrhagic septicemia virus (VHSV) and largemouth bass virus (LMBV) challenge in vivo. Co-immunoprecipitation and immunofluorescence co-localization assays verified that MsCD40 and MsCD154 physically interact at the plasma membrane, forming a functional receptor-ligand complex. Functional assays showed that overexpression of either MsCD40 or MsCD154 significantly suppressed VHSV and LMBV infection in vitro. Furthermore, MsCD40 and MsCD154 overexpression dose-dependently activated nuclear factor-κB (NF-κB) reporter activity, and markedly upregulated the transcription of NF-κB downstream effector genes, including IL-8, NLRP3 and P105, under both VHSV and LMBV infection. Collectively, our findings demonstrate that the teleost CD40–CD154 costimulatory axis restricts both RNA and DNA viral infection in largemouth bass through NF-κB-mediated immune activation, which provides promising molecular targets for the development of broad-spectrum antiviral strategies in largemouth bass aquaculture. Full article

Excitotoxicity is one of the factors that participates in neurodegeneration, impairing neuronal and glial cells’ function, and leading to the development of chronic neurodegenerative diseases. The main mechanism of action lies in the overstimulation of excitatory receptors, especially the NMDA (N-methyl-D-aspartic acid) receptor, by glutamate, which promotes a massive influx of Ca²⁺ that is not sufficiently buffered by the intracellular machinery, or not released by mechanisms such as Ca²⁺ ATPase and plasma membrane Ca²⁺/Na⁺ exchanger promoting, among other toxic effects, mitochondrial damage and an increase in reactive oxygen species (ROS). Notably, many cases reported of long COVID-19 describe significant brain alterations and neuropsychiatric disorders, including delirium, depression, etc., and patients required increased use of antidepressant or anxiolytic drugs, for example. In addition, emerging evidence links neurodegeneration as a potential long-term sequelae associated with an increased number of patients with cognitive disorders. This review analyzes data from the literature regarding brain alterations associated with post-COVID-19 syndrome and explores a potential link to the excitotoxicity pathways, due to its participation in neurodegeneration by homeostatic failure, and it is clearly present in various brain conditions, such as Alzheimer’s and Parkinson’s diseases. Full article

Recently, the existence of a new class of plant phosphotransfer proteins (HPts) with transmembrane (TM) domains was predicted by a large-scale bioinformatics method. These non-canonical proteins belong to the multistep phosphorelay (MSP) signal transduction system. The gene for one of these predicted TM-HPt was first cloned from tea (Camellia sinensis L.) plant cells. The membrane localization of the encoded protein (TM-CsHPt1) was confirmed using confocal microscopy and immunoblotting. These proteins were detected in the endoplasmic reticulum-enriched but not plasma membrane-enriched fractions. Using the BiFC method, the ability of TM-CsHPt1 to homodimerize was shown, similar to classical soluble HPt. However, heterodimerization between canonical and non-canonical CsHPts was not detected. Furthermore, TM-CsHPt1 was capable of specific interaction with the Arabidopsis cytokinin (CK) receptor AHK3, but not its paralogs AHK2 and AHK4. The obtained data are compatible with the involvement of TM-CsHPt1 in CK signaling (which utilizes the MSP system), possibly through a suggested non-canonical membrane branch. In addition, the key components of the CK signaling system in C. sinensis were uncovered and characterized by bioinformatics and phylogenetic analysis. The putative functions of the predicted MSP membrane branch in the tea plant are discussed. Full article

Angelman syndrome (AS) is a neurodevelopmental disorder caused by the loss of maternal UBE3A expression, leading to disrupted proteostasis and synaptic dysfunction. Adenosine is a ubiquitous neuromodulator whose G protein-coupled receptors (ARs) regulate neuronal differentiation and neurite outgrowth during development. Here, we investigated AR signaling and their influence on survival–autophagy balance and neuronal morphology in an AS cellular model. Using SH-SY5Y cells with silenced UBE3A, we found that UBE3A loss markedly decreased A1AR, A2BAR, and A3AR protein levels while significantly increasing A2AR expression. Ligand affinity was preserved across genotypes, but A1AR and A2AAR desensitization kinetics were significantly slower in UBE3A-deficient cells. These effects were associated with reduced recruitment of G protein-coupled receptor kinase 2 (GRK2) to the plasma membrane and decreased GRK2–AR association in UBE3A-deficient cells, suggesting a possible contribution of altered GRK2 dynamics to prolonged AR signaling. Functionally, A1AR and A2AR agonists preferentially promoted survival of UBE3A-deficient cells and modulated the MDM2–p53 axis and autophagy markers; A1R stimulation also increased neurite density in UBE3A-deficient cells. Together, these results identify AR-level alterations and defective desensitization machinery in AS neuronal cells and link receptor changes to downstream proteostasis and morphological phenotypes relevant to AS pathophysiology. Full article

Rice blast, caused by the fungus Magnaporthe oryzae, is one of the most devastating threatening to global rice production. The narrow genetic background of modern rice cultivars exacerbates the shortage of durable resistance resources. In contrast, the wild rice species Oryza officinalis harbors abundant stress-resistance alleles and represents a valuable gene pool for identifying novel broad blast-resistance genes. The cloned resistance gene Pid2 is encoded in a receptor-like protein kinase conferring race-specific resistance against the M. oryzae isolate ZB15. In this study, three Pid2 homologs were isolated from O. officinalis. The special allele Pid2of-MD33 was transformed into “Yunjing 37(YG37), a blast-susceptible japonica rice cultivar” via Agrobacterium-mediated transformation. Quantitative real-time PCR analysis showed that Pid2of-MD33 was consistently expressed in various tissues of O. officinalis, with the highest transcript abundance detected in leaf mesophyll cells and plasma membranes. Inoculation with the M. oryzae isolate ZB15 revealed that transgenic YG37 lines expressing Pid2of-MD33 displayed significantly reduced lesion size and pathogen proliferation, suggesting recovered race-specific resistance. These results enrich the resistance gene resources for rice blast research and provide a promising candidate gene for rice blast resistance breeding. Full article

Integrins are obligate αβ heterodimeric receptors that mediate cell–extracellular matrix interactions and exhibit bidirectional signal transduction across the plasma membrane. This integrin-mediated signal transduction regulates the expression of genes, a subset of which encode cytokines—small, secreted proteins that exhibit cell–cell communication in an autocrine or paracrine manner to regulate cell survival, proliferation, migration, ECM remodeling, and the immune response. This review examines epithelial integrins in the regulation of paracrine-acting cytokines that crosstalk to immune and stromal cells to coordinate normal and pathological tissue remodeling. Contexts explored include wound repair, fibrosis, and cancer. Full article