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The peritoneal cavity (PerC) is an important site for immune responses to infection and cancer metastasis. Yet few ligand-receptor axes are known to preferentially govern immune cell accumulation in this compartment. GPR34 is a lysophosphatidylserine (lysoPS)-responsive receptor that frequently harbors gain-of-function mutations in mucosa-associated B cell lymphoma. Here, we set out to test the impact of a GPR34 knock-in (KI) allele in the B-lineage. We report that GPR34 KI promotes the PerC accumulation of plasma cells (PC) and memory B cells (MemB). These KI cells migrate robustly to lysoPS ex vivo, and the KI allele synergizes with a Bcl2 transgene to promote MemB but not PC accumulation. Gene expression and labeling studies reveal that GPR34 KI enhances PerC MemB proliferation. Both KI PC and MemB are specifically enriched at the omentum, a visceral adipose tissue containing fibroblasts that express the lysoPS-generating PLA1A enzyme. Adoptive transfer and chimera experiments revealed that KI PC and MemB maintenance in the PerC is dependent on stromal PLA1A. These findings provide in vivo evidence that PLA1A produces lysoPS that can regulate GPR34-mediated immune cell accumulation at the omentum.

TMEM16F is a calcium-activated phospholipid scramblase and nonselective ion channel, which allows the movement of lipids bidirectionally across the plasma membrane. While the functions of TMEM16F have been extensively characterized in multiple cell types, the role of TMEM16F in the central nervous system remains largely unknown. Here, we sought to study how TMEM16F in the brain may be involved in neurodegeneration. Using a mouse model that expresses the pathological P301S human tau (PS19 mouse), we found reduced tauopathy and microgliosis in 6- to 7-mo-old PS19 mice lacking TMEM16F. Furthermore, this reduction of pathology can be recapitulated in the PS19 mice with TMEM16F removed from neurons, while removal of TMEM16F from microglia of PS19 mice did not significantly impact tauopathy at this time point. Moreover, TMEM16F mediated aberrant phosphatidylserine exposure in neurons with phospho-tau burden. These studies raise the prospect of targeting TMEM16F in neurons as a potential treatment of neurodegeneration.

Phosphatidylinositol 4-kinase alpha (PI4KA) maintains the phosphatidylinositol 4-phosphate (PI4P) and phosphatidylserine pools of the plasma membrane. A key regulator of PI4KA is its association into a complex with TTC7 and FAM126 proteins. This complex can be regulated by the CNAβ1 isoform of the phosphatase calcineurin. We previously identified that CNAβ1 directly binds to FAM126A. Here, we report a cryoelectron microscopic (cryo-EM) structure of a truncated PI4KA complex bound to calcineurin, revealing a unique direct interaction between PI4KA and calcineurin. Hydrogen deuterium exchange mass spectrometry (HDX-MS) and computational analysis show that calcineurin forms a complex with an evolutionarily conserved IKISVT sequence in PI4KA's horn domain. We also characterized conserved LTLT and PSISIT calcineurin binding sequences in the C terminus of FAM126A. These dual sites in PI4KA and FAM126A are both in close proximity to phosphorylation sites in the PI4KA complex, suggesting key roles of calcineurin-regulated phosphosites in PI4KA regulation. This work reveals novel insight into how calcineurin can regulate PI4KA activity. [Display omitted] • 3.50 Å cryo-EM structure of the PI4KA complex bound to calcineurin • calcineurin interacts with the solenoid and dimerization domains of PI4KA • calcineurin engages with the disordered C-terminus of FAM126A Dysregulation of PI4KA is involved in human disease; however, the role of interacting kinases/phosphatases in its regulation is unknown. Here, Shaw et al. show a direct interaction of the phosphatase calcineurin with the PI4KA complex at two unique sites, providing molecular insight into how PI4KA is regulated. [ABSTRACT FROM AUTHOR]

P4-ATPases comprise a family of lipid flippases that translocate lipids from the exoplasmic (or luminal) to the cytoplasmic leaflet of biological membranes. Of the 14 known human P4-ATPases, ATP8B2 is a phosphatidylcholine flippase at the plasma membrane, but its physiological function is not well understood. Although ATP8B2 could interact with both CDC50A and CDC50B, it required only the CDC50A interaction for its exit from the endoplasmic reticulum and subsequent transport to the plasma membrane. Three de novo monoallelic missense variations of ATP8B2 were found in patients with intellectual disability. None of these variations affected the interaction of ATP8B2 with CDC50A or its localization to the plasma membrane. However, variations of either of two amino acid residues, which are conserved in all P4-ATPases, significantly reduced the phosphatidylcholine flippase activity of ATP8B2. Furthermore, mutations in the corresponding residues of ATP8B1 and ATP11C were found to decrease their flippase activities toward phosphatidylcholine and phosphatidylserine, respectively. These results indicate that the conserved amino acid residues are crucial for the enzymatic activities of the P4-ATPases. [ABSTRACT FROM AUTHOR]

Background: Erythrocytes are susceptible to oxidative stress throughout their lifespan. While compounds like vitamin C can help mitigate oxidative stress, the exploration of natural herbal products continues to be a compelling area of research. To examine the impact of subfractions derived from acidified chloroform fractions of fenugreek (Trigonella foenum-graecum L.) on red blood cells in the presence of H2O2 as an oxidant, we assessed the factors associated with erythrocyte aging and oxidative stress. Methods: The maceration technique was employed for extracting fenugreek seeds. Through chromatography, a total of 12 subfractions were isolated from the acidified chloroform extract of fenugreek seeds. Following an initial assessment, four subfractions exhibiting lower erythrocyte toxicity were chosen for further investigation. The objective was to evaluate their impact on erythrocyte aging by measuring the levels of phosphatidylserine (PS), sialic acid, CD47 on the erythrocyte surface, as well as oxidative stress biomarkers. The obtained results were presented as mean ± standard deviation (SD), and data analysis was performed by using ANOVA. Results: The results of this study revealed, that among the 12 subfractions derived from the acidified chloroform fraction of fenugreek, four subfractions demonstrated protective effects against H2O2-induced hemolysis and oxidative stress. Furthermore, flow cytometry analysis indicated that treatment with three of these subfractions led to elevated levels of CD47 and reduced levels of phosphatidylserine on the surface of erythrocytes. Conclusions: The results suggest that the subfractions of fenugreek extract which likely contain a higher concentration of flavonoids and a lower content of saponins could be responsible for the observed protection against erythrocyte aging processes. It appears that fenugreek seeds have the ability to safeguard human erythrocytes from oxidative damage by reducing oxidative stress, preserving the activity of antioxidative enzymes, and maintaining the integrity of erythrocyte structure. [ABSTRACT FROM AUTHOR]

Background: Severe fever with thrombocytopenia syndrome (SFTS) is a rapidly progressing infectious disease with a high fatality rate caused by a novel bunyavirus (SFTSV). The role of lipids in viral infections is well-documented; however, the specific alterations in lipid metabolism during SFTSV infection remain elusive. This study aims to elucidate the lipid metabolic dysregulations in the early stages of SFTS patients. Methods: This study prospectively collected peripheral blood sera from 11 critical SFTS patients, 37 mild SFTS patients, and 23 healthy controls during the early stages of infection for lipidomics analysis. A systematic bioinformatics analysis was conducted from three aspects integrating lipid differential expressions, lipid differential correlations, and lipid-clinical indices correlations to reveal the serum lipid metabolic dysregulation in SFTSV-infected individuals. Results: Our findings reveal significant lipid metabolic dysregulation in SFTS patients. Specifically, compared to healthy controls, SFTS patients exhibited three distinct modes of lipid differential expression: increased levels of lipids including phosphatidylserine (PS), hexosylceramide (HexCer), and triglycerides (TG); decreased levels of lipids including lysophosphatidylcholine (LPC), acylcarnitine (AcCa), and cholesterol esters (ChE); and lipids showing "dual changes" including phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Finally, based on lipid metabolic pathways and literature analysis, we systematically elucidated the potential mechanisms underlying lipid metabolic dysregulation in the early stage of SFTSV infection. Conclusions: Our study presents the first global serum lipidome profile and reveals the lipid metabolic dysregulation patterns in the early stage of SFTSV infection. These findings provide a new basis for the diagnosis, treatment, and further investigation of the disease. [ABSTRACT FROM AUTHOR]

Over the past 40 years, research has heavily emphasized stroke treatments that directly target ischemic cascades after stroke onset. Much attention has focused on studying neuroprotective drugs targeting one aspect of the ischemic cascade. However, the single-target therapeutic approach resulted in minimal clinical benefit and poor outcomes in patients. Considering the ischemic cascade is a multifaceted and complex pathophysiological process with many interrelated pathways, the spotlight is now shifting towards the development of neuroprotective drugs that affect multiple aspects of the ischemic cascade. Phosphatidylserine (PS), known as the "eat-me" signal, is a promising candidate. PS is involved in many pathophysiological changes in the central nervous system after stroke onset, including apoptosis, inflammation, coagulation, and neuronal regeneration. Moreover, PS might also exert various roles in different phases after stroke onset. In this review, we describe the synthesis, regulation, and function of PS under physiological conditions. Furthermore, we also summarize the different roles of PS after stroke onset. More importantly, we also discuss several treatment strategies that target PS. We aim to advocate a novel stroke care strategy by targeting PS through a translational perspective. [ABSTRACT FROM AUTHOR]

In the actual industrial production process, the efficient biosynthesis and secretion of Monascus pigments (MPs) tend to take place under abiotic stresses, which often result in an imbalance of cell homeostasis. The present study aimed to thoroughly describe the changes in lipid profiles in Monascus purpureus by absolute quantitative lipidomics and tandem mass tag-based quantitative proteomics. The results showed that ammonium chloride stress (15 g/L) increased MP production while inhibiting ergosterol biosynthesis, leading to an imbalance in membrane lipid homeostasis in Monascus. In response to the imbalance of lipid homeostasis, the regulation mechanism of phospholipids in Monascus was implemented, including the inhibition of lysophospholipids production, maintenance of the ratio of PC/PE, and improvement of the biosynthesis of phosphatidylglycerol, phosphatidylserine, and cardiolipin with high saturated and long carbon chain fatty acids through the CDP-DG pathway rather than the Kennedy pathway. The inhibition of lysophospholipid biosynthesis was attributed to the upregulated expression of protein and its gene related to lysophospholipase NTE1, while maintenance of the PC/PE ratio was achieved by the upregulated expression of protein and its gene related to CTP: phosphoethanolamine cytidylyltransferase and phosphatidylethanolamine N-methyltransferase in the Kennedy pathway. These findings provide insights into the regulation mechanism of MP biosynthesis from new perspectives. IMPORTANCE Monascus is important in food microbiology as it produces natural colorants known as Monascus pigments (MPs). The industrial production of MPs has been achieved by liquid fermentation, in which the nitrogen source (especially ammonium chloride) is a key nutritional parameter. Previous studies have investigated the regulatory mechanisms of substance and energy metabolism, as well as the cross-protective mechanisms in Monascus in response to ammonium chloride stress. Our research in this work demonstrated that ammonium chloride stress also caused an imbalance of membrane lipid homeostasis in Monascus due to the inhibition of ergosterol biosynthesis. We found that the regulation mechanism of phospholipids in Monascus was implemented, including inhibition of lysophospholipids production, maintenance of the ratio of PC/PE, and improvement of biosynthesis of phosphatidylglycerol, phosphatidylserine, and cardiolipin with high saturated and long carbon chain fatty acids through the CDP-DG pathway. These findings further refine the regulatory mechanisms of MP production and secretion. [ABSTRACT FROM AUTHOR]

Background: Thrombocytopenia, common in preterm newborns, may increase bleeding risk and is often treated with transfusions. Recent studies reveal that transfusing platelets at a high threshold worsens outcomes, possibly due to a "developmental mismatch" between adult‐derived platelets and neonatal hemostatic system. Cord blood‐derived platelet concentrates (CBPCs) could be an alternative for newborns. Our study aims to produce and evaluate the quality parameters of CBPCs during storage. Study Design and Methods: Cord blood was collected from placentas after near‐term and full‐term pregnancies. Several production methods were attempted to obtain CBPCs, varying centrifugation settings, filtration, and dilution procedures. Adult‐derived platelet concentrates (PCs) processed with the same methods, and standard PCs from five buffy‐coats were used as controls. Storage tests were performed on days 2, 4–5, 7 from the collection. Results: CBPCs parameters were compared with adult‐derived PCs, and no significant differences were found for mean platelet volume (MPV), swirling, morphology, glucose, lactate, pCO2, and pO2. pH and bicarbonate were lower in CBPCs. Some significant differences between methods in CD62P expression and JC‐1 ratio were observed. Compared with standard PCs, CBPCs showed lower platelet concentration, pH, and JC‐1. Additionally, both in CBPCs as well as in control PCs, the apoptosis marker phosphatidylserine was elevated. Discussion: CBPCs were of comparable quality to control PCs during storage. However, apoptosis markers in both groups were elevated, suggesting processing and storage of low volumes of PCs require further optimization. Also, filtration of low volumes leads to significant platelet loss, an issue that requires remedy. [ABSTRACT FROM AUTHOR]

Phospholipids are crucial structural components of cells. Phosphatidylcholine and phosphatidylethanolamine (both synthesized via the Kennedy pathway) and phosphatidylserine undergo interconversion. The dysregulation of this process is implicated in various diseases. This paper discusses the role of enzymes involved in the interconversion of phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine, specifically phosphatidylethanolamine N-methyltransferase (PEMT), phosphatidylserine synthases (PTDSS1 and PTDSS2), and phosphatidylserine decarboxylase (PISD), with a focus on their biochemical properties. Additionally, we describe the effects of the deregulation of these enzymes and their roles in both oncological and non-oncological diseases, including nonalcoholic fatty liver disease (NAFLD), Alzheimer's disease, obesity, insulin resistance, and type II diabetes. Current knowledge on inhibitors of these enzymes as potential therapeutic agents is also reviewed, although in most cases, inhibitors are yet to be developed. The final section of this article presents a bioinformatic analysis using the GEPIA portal to explore the significance of these enzymes in cancer processes. [ABSTRACT FROM AUTHOR]

BACKGROUND: Lack of n‐3 polyunsaturated fatty acids during the period of maternity drastically lowers the docosahexaenoic acid (DHA) level in the brain of offspring and studies have demonstrated that different molecular forms of DHA are beneficial to brain development. The aim of this study was to investigate the effect of short‐term supplementation with DHA‐enriched phosphatidylserine (PS) and phosphatidylcholine (PC) on DHA levels in the liver and brain of congenital n‐3‐deficient mice. RESULTS: Dietary supplementation with DHA significantly changed the fatty acid composition of various phospholipid molecules in the cerebral cortex and liver while DHA‐enriched phospholipid was more effective than DHA triglyceride (TG) in increasing brain and liver DHA. Both DHA‐PS and DHA‐PC could effectively increase the DHA levels, but DHA in the PS form was superior to PC in the contribution of DHA content in the brain ether‐linked PC (ePC) and liver lyso‐phosphatidylcholine molecular species. DHA‐PC showed more significant effects on the increase of DHA in liver TG, PC, ePC, phosphatidylethanolamine (PE) and PE plasmalogen (pPE) molecular species and decreasing the arachidonic acid level in liver PC plasmalogen, ePC, PE and pPE molecular species compared with DHA‐PS. CONCLUSION: The effect of dietary interventions with different molecular forms of DHA for brain and liver lipid profiles is different, which may provide theoretical guidance for dietary supplementation of DHA for people. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Bilateral communication between bones and muscles is essential for healing composite bone–muscle injuries from orthopedic surgeries and trauma. However, these injuries are often characterized by exaggerated inflammation, which can disrupt bone–muscle crosstalk, thereby seriously delaying the healing of either tissue. Existing approaches are largely effective at healing single tissues. However, simultaneous healing of multiple tissues remains challenging, with little research conducted to date. Here we introduce collagen patches that overcome this overlooked issue by harnessing the plasticity of macrophage phenotypes. Phosphatidylserine liposomes (PSLs) capable of shifting the macrophage phenotype from inflammatory M1 into anti-inflammatory/prohealing M2 were coated on collagen patches via a layer-by-layer method. Original collagen patches failed to improve tissue healing under inflammatory conditions coordinated by M1 macrophages. In contrast, PSL-coated collagen patches succeeded in accelerating bone and muscle healing by inducing a microenvironment dominated by M2 macrophages. In cell experiments, differentiation of preosteoblasts and myoblasts was completely inhibited by secretions of M1 macrophages but unaffected by those of M2 macrophages. RNA-seq analysis revealed that type I interferon and interleukin-6 signaling pathways were commonly upregulated in preosteoblasts and myoblasts upon stimulation with M1 macrophage secretions, thereby compromising their differentiation. This study demonstrates the benefit of PSL-mediated M1-to-M2 macrophage polarization for simultaneous bone and muscle healing, offering a potential strategy toward simultaneous regeneration of multiple tissues. Existing approaches for tissue regeneration, which primarily utilize growth factors, have been largely effective at healing single tissues. However, simultaneous healing of multiple tissues remains challenging and has been little studied. Here we demonstrate that collagen patches releasing phosphatidylserine liposomes (PSLs) promote M1-to-M2 macrophage polarization and are effective for simultaneous healing of bone and muscle. Transcriptome analysis using next-generation sequencing reveals that differentiation of preosteoblasts and myoblasts is inhibited by the secretions of M1 macrophages but promoted by those of M2 macrophages, highlighting the importance of timely regulation of M1-to-M2 polarization in tissue regeneration. These findings provide new insight to tissue healing of multiple tissues. [Display omitted] [ABSTRACT FROM AUTHOR]

Objective To investigate the protective effects of Sulforaphane (SFN) against high glucose (HG)-induced human platelet apoptosis and elucidate the underlying mechanisms in vitro. Methods Purified platelets obtained from healthy individuals were pre-incubated with various concentrations of SFN (5, 10, or 20 μmol/L) or a vehicle control (0.05% DMSO) for 40 minutes at 37 °C. Subsequently, the platelets were stimulated with normal glucose (NG, 5 mmol/L) or high glucose (HG, 25 mmol/L) for an additional duration of 90 minutes. Flow cytometry was employed to assess platelet mitochondrial membrane potential depolarization (Δψm), exposure of phosphatidylserine (PS), and generation of total intraplatelet reactive oxygen species (ROS). Phosphorylation levels of PI3K and Akt were determined using Western blot. Results Compared to NG-treated human platelets, HG significantly induced depolarization of platelet Δψm and exposure of PS (P < 0.001). These effects of HG were markedly attenuated by various concentrations of SFN (P < 0.001). Mechanistically, SFN down-regulated the phosphorylation levels of PI3K (P < 0.01) and Akt (P < 0.05), which were increased by HG when compared to the vehicle control, and substantially reduced total intracellular ROS levels (P < 0.001). The inhibitory effects of SFN on HG-induced phosphorylation of PI3K and Akt, as well as its efficacy on total intracellular ROS generation, Δψm depolarization, and PS exposure in HG-stimulated human platelets were completely reversed by a specific agonist for PI3K, 740 Y-P. Conclusions The current study demonstrates that SFN exerts a protective effect on platelet apoptosis induced by HG, potentially through the down-regulation of the PI3K/Akt-mediated pathway in human platelets in vitro. These findings suggest that SFN may hold promise for improving thrombosis in diabetes mellitus and related chronic metabolic diseases. [ABSTRACT FROM AUTHOR]

Microglia play a crucial role in synaptic elimination by engulfing dystrophic neurons via triggering receptors expressed on myeloid cells 2 (TREM2). They are also involved in the clearance of beta‐amyloid (Aβ) plaques in Alzheimer's disease (AD); nonetheless, the driving force behind TREM2‐mediated phagocytosis of beta‐amyloid (Aβ) plaques remains unknown. Here, using advanced 2D/3D/4D co‐culture systems with loss‐of‐function mutations in TREM2 (a frameshift mutation engineered in exon 2) brain organoids/microglia/assembloids, it is identified that the clearance of Aβ via TREM2 is accelerated by externalized phosphatidylserine (ePtdSer) generated from dystrophic neurons surrounding the Aβ plaques. Moreover, it is investigated whether microglia from both sporadic (CRISPR‐Cas9‐based APOE4 lines) and familial (APPNL‐G‐F/MAPT double knock‐in mice) AD models show reduced levels of TREM2 and lack of phagocytic activity toward ePtdSer‐positive Aβ plaques. Herein new insight is provided into TREM2‐dependent microglial phagocytosis of Aβ plaques in the context of the presence of ePtdSer during AD progression. [ABSTRACT FROM AUTHOR]

Mycobacterium abscessus (Mab) is an opportunistic nontuberculous mycobacterium responsible of difficult-to-treat pulmonary infections in vulnerable patients, such as those suffering from Cystic Fibrosis (CF), where it represents a major cause of morbidity and mortality. Additionally, due to the intrinsic extensive antimicrobial resistance spectrum displayed by this species and the side effects reported for some available antibiotics, the therapeutic management of such infections remains extremely difficult. In the present study, we show that phosphatidylserine liposomes (PS-L) enhance intracellular mycobacterial killing of Mab infected human macrophages with functional or pharmacologically inhibited cystic fibrosis conductance regulator (CFTR), by a mechanism involving phagosome acidification and reactive oxygen species (ROS) production. Additionally, PS-L significantly reduce proinflammatory response of Mab infected macrophages in terms of NF-kB activation and TNF-α production, irrespective of CFTR inhibition. Altogether, these results represent the proof of concept for a possible future development of PS-L as a therapeutic strategy against difficult-to-treat Mab infection. [ABSTRACT FROM AUTHOR]

Background: Neutrophils in sickle cell disease (SCD) are activated, contributing to disease. Red cell exchange (RCE), with the goal of lowering hemoglobin S (HbS), is an important part of therapy for many SCD patients. Whether RCE impacts neutrophil reactivity is unknown. Study Design and Methods: To determine the effect of RCE on neutrophil activation, SCD patients undergoing RCE in steady‐state were enrolled. Neutrophil degranulation responses were examined before/after RCE. Kinetic studies were completed to determine the duration of the effect of RCE on neutrophil function. Degranulation results were examined in relation to white blood cell count, neutrophil count, and HbS levels. The effect of RCE on RBC phosphatidylserine (PS) exposure was examined as a possible contributor to modulation of neutrophil function by RCE. Results: Twenty‐two patients with SCD, genotype SS, who underwent RCE (average pre‐RCE HbS 33 ± 14%) were included for the study. RCE significantly decreased neutrophil degranulation responses. The effect of RCE on neutrophil activation was unrelated to cell count and instead directly correlated with HbS. The effect of RCE on neutrophil activation was sustained over several days post‐apheresis. Furthermore, while increased RBC PS exposure results in increased neutrophil degranulation, RCE decreases RBC PS exposure. Discussion: To our knowledge, this is the first study demonstrating that RCE significantly decreases neutrophil activation in a sustained HbS‐dependent manner. Modulation of PS exposure by RCE may be a contributing mechanism by which RCE modulates neutrophil activation. These studies raise the possibility that modulation of neutrophil activation contributes significantly to the therapeutic effect of RCE. See editorial on page 1593–1596, in this issue [ABSTRACT FROM AUTHOR]

Depression is one of the most common psychiatric conditions worldwide, with an annual escalation in prevalence. The serotonin (5‐Hydroxytryptamine [5‐HT]) metabolism through the gut–brain axis has been revealed to be related to the development of depression. Our previous study demonstrated that Lactococcus lactis WHH2078 alleviated depression in mice by shaping the gut microbiome composition and 5‐HT metabolism. However, little research has explored the synergistic effects of probiotics and natural mental health‐improving products. In this study, three natural products (saffron, l‐theanine, and phosphatidylserine), either individually or in combination, were orally administrated for 4 weeks in chronic restraint stress (CRS)‐induced mice, and their depressive behaviors, hippocampal 5‐HT, and serum corticosterone were assessed. Saffron demonstrated improvement of the depressive‐like behaviors via multiple behavioral tests and reversed the declined concentration of 5‐HT and increased concentration of corticosterone. Following an initial screening, saffron was chosen to be combined with WHH2078, referred to as WHHMOOD™. Furthermore, the effects of WHHMOOD were evaluated in mice with depressive‐like behaviors. WHHMOOD reduced immobility time in the forced swimming test and tail suspension test, increased the time spent in the central area in open field test, and reduced the serum corticosterone level. Besides, WHHMOOD improved the CRS‐induced gut microbial dysbiosis by reversing gut microbial diversity and the abundances of Ligilactobacillus, Candidatus Arthromitus, and Erysipelatoclostridium. Compared to WHH2078, WHHMOOD treatment significantly increased the travel distance and hippocampal 5‐HT level in mice. In conclusion, WHHMOOD exhibited prophylactic effects on depressive‐like in CRS mice, which may act as a promising agent for improving the symptoms of depression. [ABSTRACT FROM AUTHOR]

Externalized phosphatidylserine (PS) is a phospholipid and a selective marker of the tumor microenvironment (TME). It is exposed on the outer leaflet of the plasma membrane of tumor-associated endothelial cells, apoptotic tumor cells, and some viable tumor cells, where it functions in part to suppress immune responses by binding to PS receptors expressed on tumor-infiltrating myeloid cells. PS has been targeted with antibodies, such as bavituximab, that bind the phospholipid via a cofactor, β2-glycoprotein 1 (β2GP1); these antibodies showed excellent specificity for tumor vasculature and induce an immune stimulatory environment. We have advanced this concept by developing the next generation of PS targeting agent, a fusion protein (betabody) constructed by linking PS-binding domain V of β2GP1 to the Fc of an IgG2a. Betabodies bind to externalized PS with high affinity (∼1 nM), without the requirement of a co-factor and localize robustly to the TME. We demonstrate that betabodies are a direct PS-targeting agent that has the potential to be used as anti-tumor therapy, drug delivery vehicles, and tools for imaging the TME. [ABSTRACT FROM AUTHOR]

Phosphatidylethanolamine (PE) and phosphatidylserine (PS), along with phosphatidylcholine (PC), are key phospholipids (PL) in cell membranes and lipoproteins, prone to oxidative modifications. Their oxidized forms, OxPE and OxPS, play significant roles in inflammation and immune response. This review explores their structural oxidative changes under non‐enzymatic conditions and their roles in physiological and pathological contexts, influencing inflammation, and immunity. Specific oxidations of PE and PS significantly alter their physicochemical properties, leading to enhanced biological functions, reduced activity, or inactivation. OxPE may show pro‐inflammatory actions, similar to well‐documented OxPC, while the OxPS pro‐inflammatory effects are less noted. However, OxPS and OxPE have also shown an antagonistic effect against lipopolysaccharides (LPS), suggesting a protective role against exacerbated immune responses, similar to OxPC. Further research is needed to deepen our understanding of these less‐studied OxPL classes. The role of OxPE and OxPS in disease pathogenesis remains largely unexplored, with limited studies linking them to Alzheimer's disease, diabetes, rheumatoid arthritis, traumatic brain injury, and skin inflammation. These findings highlight the potential of OxPE and OxPS as biomarkers for disease diagnosis, monitoring, and therapeutic targeting. [ABSTRACT FROM AUTHOR]

Biallelic variants in PISD cause a phenotypic spectrum ranging from short stature with spondyloepimetaphyseal dysplasia (SEMD) to a multisystem disorder affecting eyes, ears, bones, and brain. PISD encodes the mitochondrial‐localized enzyme phosphatidylserine decarboxylase. The PISD precursor is self‐cleaved to generate a heteromeric mature enzyme that converts phosphatidylserine to the phospholipid phosphatidylethanolamine. We describe a 17‐year‐old male patient, born to unrelated healthy parents, with disproportionate short stature and SEMD, featuring platyspondyly, prominent epiphyses, and metaphyseal dysplasia. Trio genome sequencing revealed compound heterozygous PISD variants c.569C>T; p.(Ser190Leu) and c.799C>T; p.(His267Tyr) in the patient. Investigation of fibroblasts showed similar levels of the PISD precursor protein in both patient and control cells. However, patient cells had a significantly higher proportion of fragmented mitochondria compared to control cells cultured under basal condition and after treatment with 2‐deoxyglucose that represses glycolysis and stimulates respiration. Structural data from the PISD orthologue in Escherichia coli suggest that the amino acid substitutions Ser190Leu and His267Tyr likely impair PISD's autoprocessing activity and/or phosphatidylethanolamine biosynthesis. Based on the data, we propose that the novel PISD p.(Ser190Leu) and p.(His267Tyr) variants likely act as hypomorphs and underlie the pure skeletal phenotype in the patient. [ABSTRACT FROM AUTHOR]

The fundamental differences in phospholipids between bacterial and mammalian cell membranes present remarkable opportunities for antimicrobial design. However, it is challenging to distinguish bacterial anionic phospholipid phosphatidylglycerol (PG) from mammalian anionic phosphatidylserine (PS) with the same net charge. Here, we report a class of radially amphiphilic a helix antimicrobial peptides (RAPs) that can selectively discriminate PG from PS, relying on the helix structure. The representative RAP, L10-MMBen, can direct the rearrangement of PG vesicles into a lamellar structure with its helix axis parallel to the PG membrane surface. The helical structure imparts both the thermodynamic and kinetic advantages of L10-MMBen/PG assembly, and the hiding of hydrophobic regions in RAPs is crucial for PG recognition. L10-MMBen exhibits high selectivity against bacteria depending on PG recognition, showing low in vivo toxicity and significant treatment efficacy in mice infection models. Our study introduces a helicity-direct bacterial phospholipid recognition paradigm for designing highly selective antimicrobial peptides. [ABSTRACT FROM AUTHOR]

Arginine‐rich cell‐penetrating peptides (CPPs) have emerged as valuable tools for the intracellular delivery of bioactive molecules, but their membrane perturbation during cell penetration is not fully understood. Here, nona‐arginine (R9)‐mediated membrane reorganization that facilitates the translocation of peptides across laterally heterogeneous membranes is directly visualized. The electrostatic binding of cationic R9 to anionic phosphatidylserine (PS)‐enriched domains on a freestanding lipid bilayer induces lateral lipid rearrangements; in particular, in real‐time it is observed that R9 fluidizes PS‐rich liquid‐ordered (Lo) domains into liquid‐disordered (Ld) domains, resulting in the membrane permeabilization. The experiments with giant unilamellar vesicles (GUVs) confirm the preferential translocation of R9 through Ld domains without pore formation, even when Lo domains are more negatively charged. Indeed, whenever R9 comes into contact with negatively charged Lo domains, it dissolves the Lo domains first, promoting translocation across phase‐separated membranes. Collectively, the findings imply that arginine‐rich CPPs modulate lateral membrane heterogeneity, including membrane fluidization, as one of the fundamental processes for their effective cell penetration across densely packed lipid bilayers. [ABSTRACT FROM AUTHOR]

Macrophages are multifunctional innate immune cells that play indispensable roles in homeostasis, tissue repair, and immune regulation. However, dysregulated activation of macrophages is implicated in the pathogenesis of various human disorders, making them a potential target for treatment. Through the expression of pattern recognition and scavenger receptors, macrophages exhibit selective uptake of pathogens and apoptotic cells. Consequently, the utilization of drug carriers that mimic pathogenic or apoptotic signals shows potential for targeted delivery to macrophages. In this study, a series of mannosylated or/and phosphatidylserine (PS) -presenting liposomes were developed to target macrophages via the design of experiment (DoE) strategy and the trial-and-error (TaE) approach. The optimal molar ratio for the liposome formulation was DOPC: DSPS: Chol: PEG-PE = 20:60:20:2 based on the results of cellular uptake and cytotoxicity evaluation on RAW 264.7 and THP-1 in vitro. Results from in vivo distribution showed that, in the DSS-induced colitis model and collagen II-induced rheumatoid arthritis model, PS-presenting liposomes (PS-Lipo) showed the highest accumulation in intestine and paws respectively, which holds promising potential for macrophage target therapy since macrophages are abundant at inflammatory sites and contribute to the progression of corresponding diseases. Organs such as the heart, liver, spleen, lung, and kidney did not exhibit histological alterations such as inflammation or necrosis when exposed to PC-presenting liposomes (PC-Lipo) or PS-Lipo. In addition, liposomes demonstrated hemobiocompatibility and no toxicity to liver or kidney for circulation and did not induce metabolic injury in the animals. Thus, the well-designed PS-Lipo demonstrated the most potential for macrophage target therapy. [ABSTRACT FROM AUTHOR]

Density reversal of senescent red blood cells has been known for a long time, yet the identity of the candidate ion transporter(s) causing the senescent cells to swell is still elusive. While performing fractionation of RBCs from healthy individuals in Percoll density gradient and characterization of the separated fractions, we identified a subpopulation of cells in low-density fraction (1.02% ± 0.47) showing signs of senescence such as loss of membrane surface area associated with a reduction in band 3 protein abundance, and Phosphatidylserine (PS) exposure to the outer membrane. In addition, we found that these cells are overloaded with Na+ and Ca2+. Using a combination of blockers and activators of ion pumps and channels, we revealed reduced activity of Plasma membrane Ca2+ ATPase and an increase in Ca2+ and Na+ leaks through ion channels in senescent-like cells. Our data revealed that Ca2+ overload in these cells is a result of reduced PMCA activity and facilitated Ca2+ uptake via a hyperactive Piezo1 channel. However, we could not exclude the contribution of other Ca2+-permeable ion channels in this scenario. In addition, we found, as a universal mechanism, that an increase in intracellular Ca2+ reduced the initially high selectivity of Piezo1 channel for Ca2+ and allowed higher Na+ uptake, Na+ accumulation, and swelling. [ABSTRACT FROM AUTHOR]

Phosphatidylserine (PS) is an important anionic phospholipid that is synthesized within the endoplasmic reticulum (ER). While PS shows the highest enrichment and serves important functional roles in the plasma membrane (PM) but its role in the nucleus is poorly explored. Using three orthogonal approaches, we found that PS is also uniquely enriched in the inner nuclear membrane (INM) and the nuclear reticulum (NR). Nuclear PS is critical for supporting the translocation of CCTα and Lipin1α, two key enzymes important for phosphatidylcholine (PC) biosynthesis, from the nuclear matrix to the INM and NR in response to oleic acid treatment. We identified the PS-interacting regions within the M-domain of CCTα and M-Lip domain of Lipin1α, and show that lipid droplet formation is altered by manipulations of nuclear PS availability. Our studies reveal an unrecognized regulatory role of nuclear PS levels in the regulation of key PC synthesizing enzymes within the nucleus. Synopsis: Phosphatidylserine (PS) is a phospholipid mainly enriched in the inner leaflet of the plasma membrane; however, its role in the nucleus remains unclear. This study describes the presence of PS in the inner nuclear membrane and nuclear reticulum, where it promotes nuclear membrane association of two key enzymes of phosphatidylcholine (PC) biosynthesis in response to oleic acid treatment. PS biosensors show its enrichment in the inner nuclear membrane (INM) and the nuclear reticulum (NR). PS in the inner nuclear membrane is synthesized at the endoplasmic reticulum. Nuclear PS interacts with two PC biosynthetic enzymes, CCTα and Lipin1α, promoting their translocation to the inner nuclear membrane. Nuclear PS biases PC biosynthesis toward membrane expansion rather than lipid droplet formation. Phosphatidylserine supports inner nuclear membrane enrichment of phosphatidylcholine biosynthetic enzymes, CCTα and Lipin1α, for nuclear membrane expansion. [ABSTRACT FROM AUTHOR]

T-cell immunoglobin and mucin domain protein-1 (TIM-1) mediates entry of chikungunya virus (CHIKV) into some mammalian cells through the interaction with envelope phospholipids. While this interaction enhances entry, TIM-1 has been shown to tether newly formed HIV and Ebola virus particles, limiting their efficient release. In this study, we investigate the ability of surface receptors such as TIM-1 to sequester newly budded virions on the surface of infected cells. We established a luminescence reporter system to produce chikungunya viral particles that integrate nano-luciferase and easily quantify viral particles. We found that TIM-1 on the surface of host cells significantly reduced CHIKV release efficiency in comparison to other entry factors. Removal of cell surface TIM-1 through direct cellular knock-out or altering the cellular lipid distribution enhanced CHIKV release. Over the course of infection, CHIKV was able to counteract the tethering effect by gradually decreasing the surface levels of TIM-1 in a process mediated by the nonstructural protein 2. This study highlights the importance of phosphatidylserine receptors in mediating not only the entry of CHIKV but also its release and could aid in developing cell lines capable of enhanced vaccine production. IMPORTANCE Chikungunya virus (CHIKV) is an enveloped alphavirus transmitted by the bites of infectious mosquitoes. Infection with CHIKV results in the development of fever, joint pain, and arthralgia that can become chronic and last for months after infection. Prevention of this disease is still highly focused on vector control strategies. In December 2023, a new live attenuated vaccine against CHIKV was approved by the FDA. We aimed to study the cellular factors involved in CHIKV release, to better understand CHIKV’s ability to efficiently infect and spread among a wide variety of cell lines. We found that TIM-1 receptors can significantly abrogate CHIKV’s ability to efficiently exit infected cells. This information can be beneficial for maximizing viral particle production in laboratory settings and during vaccine manufacturing. [ABSTRACT FROM AUTHOR]

Elucidation of pathways regulating parasite cell death is believed to contribute to identification of novel therapeutic targets for protozoan diseases, and in this context, apoptosis-like cell death has been reported in different groups of protozoa, in which metacaspases seem to play a role. In the genus Plasmodium, apoptotic markers have been detected in P. falciparum and P. berghei, and no study focusing on P. vivax cell death has been reported so far. In the present study, we investigated the susceptibility of P. vivax to undergo apoptotic cell death after incubating mature trophozoites with the classical apoptosis inducer staurosporine. As assessed by flow cytometry assays, staurosporine inhibited parasite intraerythrocytic development, which was accompanied by a decrease in cell viability, evidenced by reduced plasmodial mitochondrial activity. However, typical signs of apoptosis, such as DNA fragmentation, chromatin condensation, and nuclear segregation, were not detected in the parasites induced to cell death, and no significant alteration in metacaspase gene expression (PvMCA1) was observed under cell death stimulus. Interestingly, dying parasites positively modulated cell death (eryptosis) of host erythrocytes, which was marked by externalization of phosphatidylserine and cell shrinkage. Our study shows for the time that P. vivax blood stages may not be susceptible to apoptosis-like processes, while they could trigger eryptosis of parasitized cells by undergoing cell death. Further studies are required to elucidate the cellular machinery involved in cell death of P. vivax parasites as well as in the modulation of host cell death. [ABSTRACT FROM AUTHOR]

Branched fatty acid esters of hydroxy fatty acids (FAHFAs) represent trace lipids with significant natural biological functions. While exogenous FAHFAs have been extensively studied, research on FAHFAs in milk remains limited, constraining our grasp of their nutritional roles. This study introduces a non-targeted mass spectrometry approach combined with chemical networking of spectral fragmentation patterns to uncover FAHFAs. Through meticulous sample handling and comparisons of various data acquisition and processing modes, we validate the method's superiority, identifying twice as many FAHFAs compared to alternative techniques. This validated method was then applied to different milk samples, revealing 45 chemical signals associated with known and potential FAHFAs, alongside findings of 66 ceramide/hexosylceramide (Cer/HexCer), 48 phosphatidyl ethanolamine/lyso phosphatidyl ethanolamine (PE/LPE), 21 phosphatidylcholine/lysophosphatidylcholine (PC/LPC), 16 phosphatidylinositol (PI), 7 phosphatidylserine (PS), and 11 sphingomyelin (SM) compounds. This study expands our understanding of the FAHFA family in milk and provides a fast and convenient method for identifying FAHFAs. [ABSTRACT FROM AUTHOR]

In this issue honoring the contributions of Greg Lemke, the Earp and Graham lab teams discuss several threads in the discovery, action, signaling, and translational/clinical potential of MERTK, originally called c-mer, a member of the TYRO3, AXL, and MERTK (TAM) family of receptor tyrosine kinases. The 30-year history of the TAM RTK family began slowly as all three members were orphan RTKs without known ligands and/or functions when discovered by three distinct alternate molecular cloning strategies in the pre-genome sequencing era. The pace of understanding their physiologic and pathophysiologic roles has accelerated over the last decade. The activation of ligands bridging externalized phosphatidylserine (PtdSer) has placed these RTKs in a myriad of processes including neurodevelopment, cancer, and autoimmunity. The field is ripe for further advancement and this article hopefully sets the stage for further understanding and therapeutic intervention. Our review will focus on progress made through the collaborations of the Earp and Graham labs over the past 30 years. [ABSTRACT FROM AUTHOR]

Efficient cellular fusion of mononuclear precursors is the prerequisite for the generation of fully functional multinucleated bone-resorbing osteoclasts. However, the exact molecular factors and mechanisms controlling osteoclast fusion remain incompletely understood. Here we identify RANKL-mediated activation of caspase-8 as early key event during osteoclast fusion. Single cell RNA sequencing-based analyses suggested that activation of parts of the apoptotic machinery accompanied the differentiation of osteoclast precursors into mature multinucleated osteoclasts. A subsequent characterization of osteoclast precursors confirmed that RANKL-mediated activation of caspase-8 promoted the non-apoptotic cleavage and activation of downstream effector caspases that translocated to the plasma membrane where they triggered activation of the phospholipid scramblase Xkr8. Xkr8-mediated exposure of phosphatidylserine, in turn, aided cellular fusion of osteoclast precursors and thereby allowed generation of functional multinucleated osteoclast syncytia and initiation of bone resorption. Pharmacological blockage or genetic deletion of caspase-8 accordingly interfered with fusion of osteoclasts and bone resorption resulting in increased bone mass in mice carrying a conditional deletion of caspase-8 in mononuclear osteoclast precursors. These data identify a novel pathway controlling osteoclast biology and bone turnover with the potential to serve as target for therapeutic intervention during diseases characterized by pathologic osteoclast-mediated bone loss. [ABSTRACT FROM AUTHOR]

Phospholipids (PLs) are asymmetrically distributed at the plasma membrane. This asymmetric lipid distribution is transiently altered during calcium-regulated exocytosis, but the impact of this transient remodeling on presynaptic function is currently unknown. As phospholipid scramblase 1 (PLSCR1) randomizes PL distribution between the two leaflets of the plasma membrane in response to calcium activation, we set out to determine its role in neurotransmission. We report here that PLSCR1 is expressed in cerebellar granule cells (GrCs) and that PLSCR1-dependent phosphatidylserine egress occurred at synapses in response to neuron stimulation. Synaptic transmission is impaired at GrC Plscr1-/- synapses, and both PS egress and synaptic vesicle (SV) endocytosis are inhibited in Plscr1-/- cultured neurons from male and female mice, demonstrating that PLSCR1 controls PL asymmetry remodeling and SV retrieval following neurotransmitter release. Altogether, our data reveal a novel key role for PLSCR1 in SV recycling and provide the first evidence that PL scrambling at the plasma membrane is a prerequisite for optimal presynaptic performance. [ABSTRACT FROM AUTHOR]

The largemouth bronze gudgeon has experienced a sharp drop in its natural population and has been listed as a protected species in China. The frequent occurrence of ovarian development obstruction from stage III to IV has restricted artificial propagation. Due to lipids being a crucial factor for ovarian development, this study aimed to characterize the ovarian lipid profile at different development stages in largemouth bronze gudgeons. Using UPLC-MS/MS, 1353 lipids belonging to 46 subclasses were identified in ovaries from largemouth bronze gudgeons. The results showed that glycerolipids and glycerophospholipids were the dominant lipids during ovarian development. Lysophosphatidyl choline (LPC), phosphatidyl choline (PC), and phosphatidylserine (PS), as the crucial phospholipids for ovarian development, were significantly reduced from stage III to IV. This may be the main cause of ovarian development obstruction for largemouth bronze gudgeons. Meanwhile, the enrichment analysis revealed that lipid metabolites are present at different ovarian development stages. Glycerophospholipid, linoleic acid, and linolenic acid metabolism were significantly enriched at stage IV. This study shows the complete picture of the ovarian lipid composition profile, and also discovers that phospholipids may be the limiting factor for ovarian development; these findings offer a theoretical basis for the artificial propagation and release of the largemouth bronze gudgeon. [ABSTRACT FROM AUTHOR]

Inulin may be a promising therapeutic molecule for treating non-alcoholic fatty liver disease (NAFLD). However, the underlying mechanisms of its therapeutic activity remain unclear. To address this issue, a high-fat-diet-induced NAFLD mouse model was developed and treated with inulin. The NAFLD phenotype was evaluated via histopathological analysis and biochemical parameters, including serum levels of alanine aminotransferase, aspartate aminotransferase, liver triglycerides, etc. A serum metabolomics study was conducted using ultra-performance liquid chromatography coupled with tandem mass spectrometry. The results revealed that inulin mitigated NAFLD symptoms such as histopathological changes and liver cholesterol levels. Through the serum metabolomics study, 347 differential metabolites were identified between the model and control groups, and 139 differential metabolites were identified between the inulin and model groups. Additionally, 48 differential metabolites (such as phosphatidylserine, dihomo-γ-linolenic acid, L-carnitine, and 13-HODE) were identified as candidate targets of inulin and subjected to pathway enrichment analysis. The results revealed that these 48 differential metabolites were enriched in several metabolic pathways such as fatty acid biosynthesis and cardiolipin biosynthesis. Taken together, our results suggest that inulin might attenuate NAFLD partially by modulating 48 differential metabolites and their correlated metabolic pathways, constituting information that might help us find novel therapies for NAFLD. [ABSTRACT FROM AUTHOR]

Maintenance of appropriate muscle mass is crucial for physical activity and metabolism. Aging and various pathological conditions can cause sarcopenia, a condition characterized by muscle mass decline. Although sarcopenia has been actively studied, the mechanisms underlying muscle atrophy are not well understood. Thus, we aimed to investigate the role of Phosphatidylserine synthase (Pss) in muscle development and homeostasis in Drosophila. The results showed that muscle-specific Pss knockdown decreased exercise capacity and produced sarcopenic phenotypes. In addition, it increased the apoptosis rate because of the elevated reactive oxygen species production resulting from mitochondrial dysfunction. Moreover, the autophagy rate increased due to increased FoxO activity caused by reduced Akt activity. Collectively, these findings demonstrate that enhanced apoptosis and autophagy rates resulting from muscle-specific Pss knockdown jointly contribute to sarcopenia development, highlighting the key role of the PSS pathway in muscle health. [Display omitted] • Phosphatidylserine synthase (Pss) crucially influences muscle health in Drosophila. • Muscle-specific Pss knockdown enhances the apoptosis and autophagy rate. • Muscle-specific Pss knockdown induces sarcopenic phenotypes in Drosophila. [ABSTRACT FROM AUTHOR]

The abnormal growth of oligodendrocyte precursor cells (OPCs) significantly contributes to the progression of glioblastoma tumors. Hence, molecules that block OPC growth may be of therapeutic importance in treating gliomas. 2-Methoxyestradiol (2ME), an endogenous tubulin-interacting metabolite of estradiol, is effective against multiple proliferative disorders. Based on its anti-carcinogenic and anti-angiogenic actions, it is undergoing phase II clinical trials. We hypothesize that 2ME may prevent glioma growth by targeting OPC growth. Here, we tested this hypothesis by assessing the impact of 2ME on the growth of an OPC line, "Oli-neu", and dissected the underlying mechanism(s). Treatment with 2ME inhibited OPC growth in a concentration-dependent manner, accompanied by significant upregulation in the expression of p21 and p27, which are negative cell-cycle regulators. Moreover, treatment with 2ME altered OPC morphology from multi-arm processes to rounded cells. At concentrations of 1uM and greater, 2ME induced apoptosis, with increased expressions of caspase 3, PARP, and caspase-7 fragments, externalized phosphatidylserine staining/APOPercentage, and increased mitochondrial activity. Flow cytometry and microscopic analysis demonstrated that 2ME triggers endoreduplication in a concentration-dependent fashion. Importantly, 2ME induced cyclin E, JNK1/2, and p53 expression, as well as OPC fusion, which are key mechanisms driving endoreduplication and whole-genome duplication. Importantly, the inhibition of p53 with pifithrin-α rescued 2ME-induced endoreduplication. The pro-apoptotic and endoreduplication actions of 2ME were accompanied by the upregulation of survivin, cyclin A, Cyclin B, Cyclin D2, and ppRB. Similar growth inhibitory, apoptotic, and endoreduplication effects of 2ME were observed in CG4 cells. Taken together, our findings provide evidence that 2ME not only inhibits OPC growth and triggers apoptosis, but also activates OPCs into survival (fight or flight) mode, leading to endoreduplication. This inherent survival characteristic of OPCs may, in part, be responsible for drug resistance in gliomas, as observed for many tubulin-interacting drugs. Importantly, the fate of OPCs after 2ME treatment may depend on the cell-cycle status of individual cells. Combining tubulin-interfering molecules with drugs such as pifithrin-α that inhibit endoreduplication may help inhibit OPC/glioma growth and limit drug resistance. [ABSTRACT FROM AUTHOR]

The integrity of the plasma membrane is critical to cell function and survival. Cells have developed multiple mechanisms to repair damaged plasma membranes. A key process during plasma membrane repair is to limit the size of the damage, which is facilitated by the presence of tetraspanin-enriched rings surrounding damage sites. Here, we identify phosphatidylserineenriched rings surrounding damaged sites of the plasma membrane, resembling tetraspanin-enriched rings. Importantly, the formation of both the phosphatidylserine- and tetraspanin-enriched rings requires phosphatidylserine and its transfer proteins ORP5 and ORP9. Interestingly, ORP9, but not ORP5, is recruited to the damage sites, suggesting cells acquire phosphatidylserine from multiple sources upon plasma membrane damage. We further demonstrate that ORP9 contributes to efficient plasma membrane repair. Our results thus unveil a role for phosphatidylserine and its transfer proteins in facilitating the formation of tetraspanin-enriched macrodomains and plasma membrane repair. [ABSTRACT FROM AUTHOR]

Chronic lymphocytic leukemia (CLL) is a chronic lymphoproliferative disorder characterized by monoclonal B cell proliferation. Studies carried out in recent years suggest that extracellular vesicles (EVs) may be a potential biomarker in cancer. Tyro3‐Axl‐Mertk (TAM) Receptor Tyrosine Kinases (RTKs) and Phosphatidylserine (PS) have crucial roles in macrophage‐mediated immune response under normal conditions. In the tumor microenvironment, these molecules contribute to immunosuppressive signals and prevent the formation of local and systemic antitumor immune responses. Based on this, we aimed to evaluate the amount of PS and TAM RTK in plasma and on the surface of EVs in CLL patients and healthy volunteers in this study. In this study, 25 CLL (11 F/14 M) patients in the Rai (O‐I) stage, newly diagnosed or followed up without treatment, and 15 healthy volunteers (11 F/4 M) as a control group were included. For all samples, PS and TAM RTK levels were examined first in the plasma and then in the EVs obtained from the plasma. We detected a significant decrease in plasma PS, and TAM RTK levels in CLL patients compared to the control. Besides, we determined a significant increase in TAM RTK levels on the EV surface in CLL, except for PS. In conclusion, these receptor levels measured by ELISA in plasma may not be effective for the preliminary detection of CLL. However, especially TAM RTKs on the surface of EVs may be good biomarkers and potential targets for CLL therapies. Significance statement: In our study, we aimed to compare Phosphatidylserine and Tyro3‐Axl‐Mertk (TAM) Receptor Tyrosine Kinases (RTKs) levels on extracellular vesicles (EVs) surfaces in chronic lymphocytic leukemia (CLL) patients and healthy volunteers. Our results showed a significant increase in TAM RTK levels on the surface of EV of patients compared to those of healthy volunteers. We believe the data of this study will shed light on future studies. Larger studies involving advanced CLL patients may provide more information on this topic. Thus, the development of new treatments targeting such molecules can be achieved. [ABSTRACT FROM AUTHOR]

Oxidized low‐density lipoprotein (oxLDL), a key component in atherosclerosis and hyperlipidemia, is a risk factor for atherothrombosis in dyslipidemia, yet its mechanism is poorly understood. In this study, we used oxLDL‐induced human aortic endothelial cells (HAECs) and high‐fat diet (HFD)‐fed mice as a hyperlipidemia model. Phosphatidylserine (PS) exposure, cytosolic Ca2+, reactive oxygen species (ROS), and lipid peroxidation were measured by flow cytometer. TMEM16F expression was detected by immunofluorescence, western blot, and reverse transcription polymerase chain reaction. Procoagulant activity (PCA) was measured by coagulation time, intrinsic/extrinsic factor Xase, and thrombin generation. We found that oxLDL‐induced PS exposure and the corresponding PCA of HAECs were increased significantly compared with control, which could be inhibited over 90% by lactadherin. Importantly, TMEM16F expression in oxLDL‐induced HAECs was upregulated by enhanced intracellular Ca2+ concentration, ROS, and lipid peroxidation, which led to PS exposure. Meanwhile, the knockdown of TMEM16F by short hairpin RNA significantly inhibited PS exposure in oxLDL‐induced HAECs. Moreover, we observed that HFD‐fed mice dramatically increased the progress of thrombus formation and accompanied upregulated TMEM16F expression by thromboelastography analysis, FeCl3‐induced carotid artery thrombosis model, and western blot. Collectively, these results demonstrate that TMEM16F‐mediated PS exposure may contribute to prothrombotic status under hyperlipidemic conditions, which may serve as a novel therapeutic target for the prevention of thrombosis in hyperlipidemia. Highlights: Oxidized low‐density lipoproteins (oxLDL) could increase phosphatidylserine (PS) exposure and procoagulant activity (PCA) of human aortic endothelial cells (HAECs) in a TMEM16F‐dependent manner.Increased intracellular Ca2+ and oxidative stress may contribute to TMEM16F‐mediated phospholipid scrambling.Hyperlipidemia exhibited a prothrombotic phenotype, which was likely related to TMEM16F‐mediated PS exposure on HAECs.Inhibition of TMEM16F or PS could be a novel therapeutic strategy to alleviate the thromboembolic complication of hyperlipidemia. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the effects of dietary phosphatidylserine (PS) supplementation on the growth performance, stress response, non-specific immunity and antioxidant capacity of juvenile blunt snout bream (Megalobrama ambylcephala) cultured under a high stocking density. A 2 × 2 two-factorial design was adopted, including two stocking densities (10 and 20 fish/m3) and two dietary PS levels (0 and 50 mg/kg). After the 12-week feeding trial, the high stocking density significantly decreased the final weight; weight gain rate; specific growth rate; feed intake; nitrogen retention efficiency; plasma complement 3 (C3) level; albumin/globulin (ALB/GLB, A/G) ratio; activity of myeloperoxidase, lysozyme (LZM) and glutathione peroxidase (GPX); gpx transcription; and abundance of sirtuin3 (Sirt3) and nuclear factor erythroid-2-related factor 2 (Nrf2). However, it significantly increased the plasma levels of cortisol, glucose (GLU), lactic acid (LD), total protein and GLB; hepatic malondialdehyde (MDA) content; and sirt1 transcription. PS supplementation significantly increased the plasma ALB and C4 levels; the A/G ratio; the activity of LZM, CAT and GPX; the transcription of sirt1, nrf2, manganese-containing superoxide dismutase and catalase; and the Nrf2 abundance. However, it significantly decreased the plasma levels of cortisol, GLU and GLB, as well as the hepatic MDA content. In addition, there was a significant interaction between the stocking density and PS supplementation regarding the effects on the plasma LD, ALB, GLB and C3 levels; A/G ratio; hepatic CAT activity; and protein abundance of Sod2. In conclusion, PS supplementation can counteract the high stocking density-induced stress response, redox imbalance and immunosuppression in blunt snout bream. [ABSTRACT FROM AUTHOR]

Inflammation‐responsive hydrogels loaded with therapeutic factors are effective biomaterials for bone tissue engineering and regenerative medicine. In this study, a matrix metalloproteinase (MMP)‐responsive injectable hydrogel is constructed by integrating an MMP‐cleavable peptide (pp) into a covalent tetra‐armed poly‐(ethylene glycol) (PEG) network for precise drug release upon inflammation stimulation. To establish a pro‐regenerative environment, phosphatidylserine (PS) is encapsulated into a scaffold to form the PEG‐pp‐PS network, which could be triggered by MMP to release a large amount of PS during the early stage of inflammation and retain drug release persistently until the later stage of bone repair. The hydrogel is found to be mechanically and biologically adaptable to the complex bone defect area. In vivo and in vitro studies further demonstrated the ability of PEG‐pp‐PS to transform macrophages into the anti‐inflammatory M2 phenotype and promote osteogenic differentiation, thus, resulting in new bone regeneration. Therefore, this study provides a facile, safe, and promising cell‐free strategy on simultaneous immunoregulation and osteoinduction in bone engineering. [ABSTRACT FROM AUTHOR]

In human medicine, various pathologies, including decompression sickness, thrombocytopenia, and rheumatoid arthritis, have been linked to changes in cellular microparticles (MP) formation, particularly platelet microparticles (PMP). Similar disorders in marine mammals might be attributed to anthropogenic threats or illnesses, potentially impacting blood PMP levels. Thus, detecting platelet phosphatidylserine (PS) exposure and PMP formation could serve as a crucial diagnostic and monitoring approach for these conditions in marine mammals. Our group has developed a methodology to assess real-time PS exposure and PMP formation specifically tailored for marine mammals. This method, pioneered in species such as bottlenose dolphins, beluga whales, walruses, and California sea lions, represents a novel approach with significant implications for both clinical assessment and further research into platelet function in these animals. The adapted methodology for evaluating PS exposure and PMP formation in marine mammals has yielded promising results. By applying this approach, we have observed significant correlations between alterations in PMP levels and specific pathologies or environmental factors. These findings underscore the potential of platelet function assessment as a diagnostic and monitoring tool in marine mammal health. The successful adaptation and application of this methodology in marine mammals highlight its utility for understanding and managing health concerns in these animals. [ABSTRACT FROM AUTHOR]

Traumatic brain injury (TBI) is a global health priority. In addition to being the leading cause of trauma related death, TBI can result in long-term disability and loss of health. Disorders of haemostasis are common despite the absence of some of the traditional risk factors for coagulopathy following trauma. Similar to trauma induced coagulopathy, this manifests with a biphasic response consisting of an early hypocoagulable phase and delayed hypercoagulable state. This coagulopathy is clinically significant and associated with increased rates of haemorrhagic expansion, disability and death. The pathophysiology of TBI-induced coagulopathy is complex but there is biologic plausibility and emerging evidence to suggest that extracellular vesicles (EVs) have a role to play. TBI and damage to the blood brain barrier result in release of brain-derived EVs that contain tissue factor and phosphatidylserine on their surface. This provides a platform on which coagulation can occur. Preclinical animal models have shown that an early rapid release of EVs results in overwhelming activation of coagulation resulting in a consumptive coagulopathy. This phenomenon can be attenuated with administration of substances to promote EV clearance and block their effects. Small clinical studies have demonstrated elevated levels of procoagulant EVs in patients with TBI correlating with clinical outcome. EVs represent a promising opportunity for use as minimally invasive biomarkers and potential therapeutic targets for TBI patients. However, additional research is necessary to bridge the gap between their potential and practical application in clinical settings. [ABSTRACT FROM AUTHOR]

Mutant RAS are major contributors to cancer and signal primarily from nanoclusters on the plasma membrane (PM). Their C-terminal membrane anchors are main features of membrane association. However, the same RAS isoform bound to different guanine nucleotides spatially segregate. Different RAS nanoclusters all enrich a phospholipid, phosphatidylserine (PS). These findings suggest more complex membrane interactions. Our electron microscopy-spatial analysis shows that wild-types, G12V mutants, and membrane anchors of isoforms HRAS, KRAS4A, and KRAS4B prefer distinct PS species. Mechanistically, reorientation of KRAS4B G-domain exposes distinct residues, such as Arg 135 in orientation state 1 (OS1) and Arg 73/Arg 102 in OS2, to the PM and differentially facilitates the recognition of PS acyl chains. Allele-specific oncogenic mutations of KRAS4B also shift G-domain reorientation equilibrium. Indeed, KRAS4BG12V, KRAS4BG12D, KRAS4BG12C, KRAS4BG13D, and KRAS4BQ61H associate with PM lipids with headgroup and acyl chain specificities. Distribution of these KRAS4B oncogenic mutants favors different nanoscale membrane topography. Thus, RAS G-domains allosterically facilitate membrane lateral distribution. [ABSTRACT FROM AUTHOR]

Host restriction factor SERINC5 (SER5) incorporates into the HIV-1 membrane and inhibits infectivity by a poorly understood mechanism. Recently, SER5 was found to exhibit scramblase-like activity leading to the externalization of phosphatidylserine (PS) on the viral surface, which has been proposed to be responsible for SER5's antiviral activity. This and other reports that document modulation of HIV-1 infectivity by viral lipid composition prompted us to investigate the role of PS in regulating SER5-mediated HIV-1 restriction. First, we show that the level of SER5 incorporation into virions correlates with an increase in PS levels in the outer leaflet of the viral membrane. We developed an assay to estimate the PS distribution across the viral membrane and found that SER5, but not SER2, which lacks antiviral activity, abrogates PS asymmetry by externalizing this lipid. Second, SER5 incorporation diminished the infectivity of pseudoviruses produced from cells lacking a flippase subunit CDC50a and, therefore, exhibited a higher baseline level of surface-accessible PS. Finally, exogenous manipulation of the viral PS levels utilizing methyl-alpha-cyclodextrin revealed a lack of correlation between external PS and virion infectivity. Taken together, our study implies that the increased PS exposure to SER5-containing virions itself is not directly linked to HIV-1 restriction. [ABSTRACT FROM AUTHOR]

The human brain possesses three predominate phospholipids, phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylserine (PS), which account for approximately 35–40%, 35–40%, and 20% of the brain's phospholipids, respectively. Mitochondrial membranes are relatively diverse, containing the aforementioned PC, PE, and PS, as well as phosphatidylinositol (PI) and phosphatidic acid (PA); however, cardiolipin (CL) and phosphatidylglycerol (PG) are exclusively present in mitochondrial membranes. These phospholipid interactions play an essential role in mitochondrial fusion and fission dynamics, leading to the maintenance of mitochondrial structural and signaling pathways. The essential nature of these phospholipids is demonstrated through the inability of mitochondria to tolerate alteration in these specific phospholipids, with changes leading to mitochondrial damage resulting in neural degeneration. This review will emphasize how the structure of phospholipids relates to their physiologic function, how their metabolism facilitates signaling, and the role of organ- and mitochondria-specific phospholipid compositions. Finally, we will discuss the effects of global ischemia and reperfusion on organ- and mitochondria-specific phospholipids alongside the novel therapeutics that may protect against injury. [ABSTRACT FROM AUTHOR]

Phospholipids are widely utilized in various industries, including food, medicine, and cosmetics, due to their unique chemical properties and healthcare benefits. Phospholipase D (PLD) plays a crucial role in the biotransformation of phospholipids. Here, we have constructed a super-folder green fluorescent protein (sfGFP)-based phospholipase D (PLD) expression and surface-display system in Escherichia coli, enabling the surface display of sfGFP-PLDr34 on the bacteria. The displayed sfGFP-PLDr34 showed maximum enzymatic activity at pH 5.0 and 45 °C. The optimum Ca2+ concentrations for the transphosphatidylation activity and hydrolysis activity are 100 mM and 10 mM, respectively. The use of displayed sfGFP-PLDr34 for the conversion of phosphatidylcholine (PC) and L-serine to phosphatidylserine (PS) showed that nearly all the PC was converted into PS at the optimum conditions. The displayed enzyme can be reused for up to three rounds while still producing detectable levels of PS. Thus, Escherichia coli/sfGFP-PLD shows potential for the feasible industrial-scale production of PS. Moreover, this system is particularly valuable for quickly screening higher-activity PLDs. The fluorescence of sfGFP can indicate the expression level of the fused PLD and changes that occur during reuse. [ABSTRACT FROM AUTHOR]

Summary Skin care is currently experiencing two developments. On the one hand, there is a move away from skin‐affecting additives and an increasing use of physiological ingredients, i.e., substances that are natural to the body or are metabolised by the body without side effects. On the other hand, special attention is being paid to the harmonisation of the individual substances and the overall compositions with the skin microbiome. Phosphatidylserine – a component from the group of phospholipids that has been known for a long time – is establishing itself in skin care and does justice to both developments. [ABSTRACT FROM AUTHOR]

To examine the effect of topical phosphatidylserine (PS) on wound healing factors and tissue necrosis in in vivo models. Topical PS was applied to evaluate aspects of the wound healing process and growth factors production of vascular endothelial growth factors (VEGF) as well a necrosis reduction in the skin flap of rat models. Moreover, phenytoin (PHT) and cyclosporine A (CsA) were used topically as positive control treatments in wound and necrosis models, respectively. Immunohistochemistry (IHC) VEGF, transforming growth factor‐β (TGF‐β), fibroblast growth factor (FGF) and histopathology were analysed on the wounds of rats. In the necrosis assessment, necrotic areas were determined on photography taken from the back skin of rats. Results indicated that PS topically enhanced significantly (P < 0.05) numbers of fibroblasts and endothelium while inhibiting the neutrophils and macrophages during the 14 days of wound treatment. Moreover, higher values of collagen deposition and epithelialization scores as well as wound recovery percentage (near 80%) were determined significantly (P < 0.05) in the PS group compared with the control. IHC analysis determined that FGF and VEGF cytokine factors were elevated in the wound site by topical PS. Moreover, the necrotic area was significantly (P < 0.05) improved in the PS group. Our experiment indicated that wound improvement and flap survival values in PS treatments were superior to PHT and CsA control groups, respectively. In conclusion, these findings suggest the potential of PS application in the healing of wounds and control of necrosis development after surgery or skin injuries. [ABSTRACT FROM AUTHOR]

Purpose: 3D cell culture and hypoxia have been demonstrated to increase the therapeutic effects of mesenchymal stem/stromal cells (MSCs)-derived extracellular vesicles (EVs). In this study, a process for the production of MSC-EVs in a novel 3D bioreactor system under normoxic and hypoxic conditions was established and the resulting EVs were characterized. Methods: Human adipose-derived MSCs were seeded and cultured on a 3D membrane in the VITVO® bioreactor system for 7 days. Afterwards, MSC-EVs were isolated and characterized via fluorescence nanoparticle tracking analysis, flow cytometry with staining against annexin V (Anx5) as a marker for EVs exposing phosphatidylserine, as well as CD73 and CD90 as MSC surface markers. Results: Cultivation of MSC in the VITVO® bioreactor system demonstrated a higher concentration of MSC-EVs from the 3D bioreactor (9.1 × 109 ± 1.5 × 109 and 9.7 × 109 ± 3.1 × 109 particles/mL) compared to static 2D culture (4.2 × 109 ± 7.5 × 108 and 3.9 × 109 ± 3.0 × 108 particles/mL) under normoxic and hypoxic conditions, respectively. Also, the particle-to-protein ratio as a measure for the purity of EVs increased from 3.3 × 107 ± 1.1 × 107 particles/µg protein in 2D to 1.6 × 108 ± 8.3 × 106 particles/µg protein in 3D. Total MSC-EVs as well as CD73−CD90+ MSC-EVs were elevated in 2D normoxic conditions. The EV concentration and size did not differ significantly between normoxic and hypoxic conditions. Conclusion: The production of MSC-EVs in a 3D bioreactor system under hypoxic conditions resulted in increased EV concentration and purity. This system could be especially useful in screening culture conditions for the production of 3D-derived MSC-EVs. [ABSTRACT FROM AUTHOR]