Cell Polarity Research Articles

An Alkyne-Containing Isoprenoid Analogue Based on a Farnesyl Diphosphate Scaffold Is a Biologically Functional Universal Probe for Proteomic Analysis.

Prenylation consists of the modification of proteins with either farnesyl diphosphate (FPP) or geranylgeranyl diphosphate (GGPP) at a cysteine near the C-terminus of target proteins to generate thioether-linked lipidated proteins. In recent work, metabolic labeling with alkyne-containing isoprenoid analogues including C15AlkOPP has been used to identify prenylated proteins and track their levels in different diseases. Here, a systematic study of the impact of isoprenoid length on proteins labeled with these probes was performed. Chemical synthesis was used to generate two new analogues, C15hAlkOPP and C20AlkOPP, bringing the total number of compounds to eight used in this study. Enzyme kinetics performed in vitro combined with metabolic labeling in cellulo, resulted in the identification of 8 proteins for C10AlkOPP, 70 proteins for C15AlkOPP, 41 proteins for C15hAlkOPP, and 7 proteins for C20AlkOPP. While C10AlkOPP was the most selective for farnesylated proteins and C20AlkOPP was most selective for geranylgeranylated proteins, the number of proteins identified using those probes was relatively small. In contrast, C15AlkOPP labeled the most proteins including representatives from all classes of prenylated proteins. Functional analysis of these analogues demonstrated that C15AlkOPP was particularly well suited for biological studies since it was efficiently incorporated in cellulo, was able to confer correct plasma membrane localization of H-Ras protein and complement the effects of GGPP depletion in macrophages to yield correct cell polarization and filopodia. Collectively, these results indicate that C15AlkOPP is a biologically functional, universal probe for metabolic labeling experiments that has minimal effects on cellular physiology.

Flow field design and visualization for flow-through type aqueous organic redox flow batteries

Aqueous organic redox flow batteries (AORFBs), which exploit the reversible redox reactions of water-soluble organic electrolytes to store electricity, have emerged as a promising electrochemical energy storage technology. Organic electrolytes possess fast electron-transfer rates that are two or three orders of magnitude faster than those of their inorganic or organometallic counterparts; therefore, their performance at the electrode is limited by mass transport. Direct adoption of conventional cell stacks with flow fields designed for inorganic electrolytes may compromise AORFB performance owing to severe cell polarization. Here, we report the design of a flow field for flow-through type AORFBs based on three-dimensional multiphysics simulation, to realize the uniform distribution of electrolyte flow and flow enhancements within a porous electrode. The electrolyte flow is visualized by operando imaging. Our results show that multistep distributive flow channels at the inlet and point-contact blocks at the outlet are crucial geometrical merits of the flow field, significantly reducing local concentration overpotentials. The prototype pH-neutral TEMPTMA/MV cell at 1.5 M assembled with the optimized flow field exhibits a peak power density of 267.3 mW cm-2. The flow field design enables charging of the cell at current densities up to 300 mA cm-2, which is unachievable with the conventional serpentine flow field, where immediate voltage cutoff of the cell occurs. Our results highlight the importance of AORFB cell stack engineering and provide a method to visualize electrolyte flow, which will be appealing to the field of aqueous flow batteries.

Cell polarity proteins promote macropinocytosis in response to metabolic stress

Macropinocytosis has emerged as a scavenging pathway that cancer cells exploit to survive in a nutrient-deprived microenvironment. Tumor cells are especially reliant on glutamine for their survival, and in pancreatic ductal adenocarcinoma (PDAC) cells, glutamine deficiency can enhance the stimulation of macropinocytosis. Here, we identify the atypical protein kinase C (aPKC) enzymes, PKCζ and PKCι, as regulators of macropinocytosis. In normal epithelial cells, aPKCs associate with the scaffold proteins Par3 and Par6 to regulate cell polarity, affecting several targets, including the Par1 kinases and we find that each of these proteins is required for macropinocytosis. Mechanistically, aPKCs are regulated by EGFR signaling or by the transcription factor CREM to promote the Par3 relocation to microtubules, facilitating macropinocytosis in a dynein-dependent manner. Importantly, cell fitness impairment caused by aPKC depletion is rescued by the restoration of macropinocytosis and aPKCs support PDAC growth in vivo. Our findings enhance our understanding of the mechanistic underpinnings that control macropinocytic uptake in the context of metabolic stress.

Tumor-derived miR-9-5p-loaded EVs regulate cholesterol homeostasis to promote breast cancer liver metastasis in mice

Cancer cells secrete extracellular vesicles (EV) encapsulating bioactive cargoes to facilitate inter-organ communication in vivo and are emerging as critical mediators of tumor progression and metastasis, a condition which is often accompanied by a dysregulated cholesterol metabolism. Whether EVs are involved in the control of cholesterol homeostasis during tumor metastasis is still undefined and warrant further investigation. Here, we find that breast cancer-derived exosomal miR-9-5p induces the expression of HMGCR and CH25H, two enzymes involved in cholesterol synthesis and the conversion of 25-hydroxycholesterol from cholesterol by targeting INSIG1, INSIG2 and ATF3 genes in the liver. Notably, in vivo miR-9-5p antagomir treatment and genetic CH25H ablation prevents tumor metastasis in a mouse model of breast cancer. Thus, our findings reveal the regulatory mechanism of tumor-derived miR-9-5p in liver metastasis by linking oxysterol metabolism and Kupffer cell polarization, shedding light on future applications for cancer diagnosis and treatment.

Imbalances of Th1/Th2 and Tc1/Tc2 are Associated With Active Cytomegalovirus Infection in Infant Liver Transplant Recipients

Because cytomegalovirus (CMV) infection is one of the most common complications following liver transplantation (LT), it is important to analyze the impact of CMV infection on the LT-associated changes in T cells polarization. This study aimed to investigate T helper (Th) and T cytotoxic (Tc) cells polarization and their correlation in infant LT recipients with active CMV infection. Twenty infant LT recipients with active CMV infection (the CMV group) and 20 recipients without CMV infection (the stable group) were enrolled. The percentages of Th1, Th2, Tc1, and Tc2 cells were detected by flow cytometry after intracellular staining for cytokines (IFN-γ and IL-10, respectively) in peripheral blood. The correlation between Th and Tc cells was analyzed by Pearson correlation coefficient. The percentages of Th1 and Tc1 cells were significantly decreased, whereas the percentages of Tc2 cells were significantly increased in CMV group compared with the stable group, along with significant reduction of Th1/Th2 and Tc1/Tc2 ratios (P < .01). The percentages of Th1 cells were positively correlated with Tc1 cells (P < .01). A higher Th1/Th2 and Tc1/Tc2 ratios were showed in the CMV group after antiviral therapy than those in the CMV group before therapy (P < .01). Our findings show an imbalanced Th1/Th2 and Tc1/Tc2 immunity in infant LT recipients with active CMV infection, which were involved in the pathogenesis of CMV infection.

Construction of bFGF/heparin and Fe3O4 nanoparticles functionalized scaffolds aiming at vascular repair and magnetic resonance imaging monitoring

This work develops a bioactive basic fibroblast growth factor (bFGF)/heparin and Fe3O4 nanoparticles (NPs) trifunctionalized degradable construct with the potential of using as a vascular tissue engineering scaffold with the aim of improving vascular repair and regeneration therapy. The covalent modification of heparin onto the poly(lactic acid) (PLA)-gelatin (Gel)-Fe3O4 (PGF) scaffold improves the hydrophilicity of the scaffold. Furthermore, the electrostatic adsorption of bFGF on heparin allows for a more consistent and prolonged release of bFGF in situ, hence increasing the stability and effectiveness of bFGF around the surrounding vascular tissues. The sustained release of bFGF promotes the M2 macrophage polarization, and adhesion and migration of macrophages and endothelial cells (ECs), providing a stable and favorable microenvironment for vascular regeneration. Furthermore, the covalently modified heparin minimizes platelet adhesion on the scaffold surface, potentially contributing to the long-term patency of the vascular tissue engineering scaffold. Including Fe3O4 NPs in the scaffold delays degradation and provides an in vivo magnetic resonance imaging (MRI) effect to monitor the scaffold's location and in vivo degradation. Furthermore, the mild photothermal effect of Fe3O4 NPs plays a facilitating role in bFGF release, immune modulation, and ECs manipulation, therefore contributary to the vascular tissue reconstruction.

USP22 Inhibits Microglial M1 Polarization by Regulating the PU.1/NLRP3 Inflammasome Pathway

ObjectiveThis study aimed to investigate the effect of Ubiquitin-Specific Peptidase 22 (USP22) on the inflammatory response mediated by BV-2 mouse microglia and explore the role of the PU box binding protein 1 (PU.1)/NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome in the USP22-induced polarization of BV-2 cells. MethodsThe BV-2 mouse microglia line was cultured in vitro, and plasmid and siRNA transfection was performed to overexpress or knockdown USP22. Subsequently, BV-2 cells were treated with lipopolysaccharide (LPS) and interferon-gamma (IFN-γ) and interleukin (IL)-4 to induce M1 and M2 polarization, respectively. Western blot was used to detect the expression levels of USP22, PU.1, M1 polarization markers [inducible nitric oxide synthase (iNOS), and cluster of differentiation (CD) 86], M2 polarization markers [arginase 1 (Arg1), and CD206], in BV-2 cells from different treatment groups. Additionally, measurement was performed on the inflammasome NLRP3, and its activation-related proteins [NIMA-related kinase7 (NEK7), cleaved-caspase 1, apoptosis-associated speck-like protein containing a CARD (ASC)]. Enzyme-linked immunosorbent (ELISA) assay was employed to determine the levels of inflammatory cytokines tumor necrosis factor-alpha (TNF-α), IL-1 β, and IL-10 in the cells. Furthermore, immunofluorescence was utilized to analyze the levels of iNOS and Arg1-positive BV-2 cells in different treatment groups. Moreover, the ubiquitination level of PU.1 was detected using immunoprecipitation. ResultsThe protein expression level of USP22 was significantly down-regulated in BV-2 cells treated with M1 polarization. Overexpression of USP22 remarkably reduced the protein levels of iNOS and CD86, but markedly increased the protein levels of Arg1 and CD206 in cells. Besides, there was a notable reduction in the levels of TNF-α and IL-1 β in the cell culture medium, while a remarkable increase was observed in the level of IL-10. Additionally, the level of iNOS-positive cells was significantly decreased, while the level of Arg1-positive cells was considerably increased. However, up-regulation of PU.1 expression could reverse the above results and promoted the expression of NLRP3 and its activation-related proteins. Notably, overexpression of USP22 significantly down-regulated the protein expression and ubiquitination level of PU.1. ConclusionUSP22 inhibits the M1 polarization of BV-2 mouse microglia. The PU.1/NLRP3 inflammasome pathway may be a critical regulatory pathway of USP22 in BV-2 cell polarization.

Central role of squid gene during oocyte development in the Hemiptera Rhodnius prolixus

Oocyte polarity establishment is a conserved and crucial phenomenon for embryonic development. It relies on the precise spatial localization of maternal factors deposited during oocyte development, which is essential for establishing and maintaining cell polarity and subsequently specifying embryonic axes. The heterogeneous nuclear ribonucleoprotein (hnRNP) encoded by the squid (sqd) gene has been implicated in mRNA localization and embryonic axis establishment in Drosophila melanogaster. Comparative genomics allowed for the identification of a homologue in Rhodnius prolixus. In this study, we investigated the function of Rp-sqd during oogenesis and early embryonic development. We observed persistent expression of Rp-sqd during oocyte development, with localization in the cytoplasm of ovary germarium and growing oocytes in previtellogenic and vitellogenic stages. A Parental RNA interference (RNAi) experiment targeting Rp-sqd resulted in female sterility. The ovaries showed disrupted oocyte development, disarray of follicular epithelium, and affected nurse cells integrity. Immunostaining and microscopic techniques revealed microtubule disarray and a reduction in the presence of organelles in the trophic cords that connect the germarium with the oocytes. The Rp-sqd depletion impacted the transcript expression of maternal mRNAs involved in apoptosis, axis formation, oogenesis, and cytoskeleton maintenance, indicating a pleiotropic function of Rp-sqd during oogenesis. This study provides new insights into the genetic basis of R. prolixus oogenesis, highlighting the crucial role of Rp-sqd in oocyte development, fertility, and germarium integrity. These findings contribute to our understanding of insect developmental processes, provide a foundation for future investigations into reproduction, and reveal the regulatory mechanisms governing the process.

236 Wnt/planar cell polarity impairment and the genetics of yellow nail syndrome

236 Wnt/planar cell polarity impairment and the genetics of yellow nail syndrome

SLMAP3 is essential for neurulation through mechanisms involving cytoskeletal elements, ABP, and PCP.

SLMAP3 is a tail-anchored membrane protein that targets subcellular organelles and is believed to regulate Hippo signaling. The global loss of SLMAP3 causes late embryonic lethality in mice, with some embryos exhibiting neural tube defects such as craniorachischisis. We show here that SLMAP3 -/- embryos display reduced length and increased width of neural plates, signifying arrested convergent extension. The expression of planar cell polarity (PCP) components Dvl2/3 and the activity of the downstream targets ROCK2, cofilin, and JNK1/2 were dysregulated in SLMAP3 -/- E12.5 brains. Furthermore, the cytoskeletal proteins (γ-tubulin, actin, and nestin) and apical components (PKCζ and ZO-1) were mislocalized in neural tubes of SLMAP3 -/- embryos, with a subsequent decrease in colocalization of PCP proteins (Fzd6 and pDvl2). However, no changes in PCP or cytoskeleton proteins were found in cultured neuroepithelial cells depleted of SLMAP3, suggesting an essential requirement for SLMAP3 for these processes in vivo for neurulation. The loss of SLMAP3 had no impact on Hippo signaling in SLMAP3 -/- embryos, brains, and neural tubes. Proteomic analysis revealed SLMAP3 in an interactome with cytoskeletal components, including nestin, tropomyosin 4, intermediate filaments, plectin, the PCP protein SCRIB, and STRIPAK members in embryonic brains. These results reveal a crucial role of SLMAP3 in neural tube development by regulating the cytoskeleton organization and PCP pathway.

PALS1-dependent modulations of mRNA profiles in MDCK II cells grown in non-confluent monolayers and three-dimensional cysts

In epithelia, apicobasal cell polarization is closely linked to cell-cell contact formation, both controlled by the conserved Crumbs (CRB) complex, which includes the transmembrane protein Crumbs (CRB3a) and adapter proteins PALS1, PATJ, and LIN7c. In MDCK II cells, a model for cell polarization, depletion of PALS1 - which binds to all CRB components - leads to defective cell polarization and improper distribution of tight junction proteins, resulting in severe epithelial barrier defects in 3D cyst models. This study investigated whether this phenotype is associated with transcriptional changes by analyzing wildtype (WT) and PALS1 knockout (KO) MDCK II cell lines grown under non-confluent conditions and in 3D cyst cultures. Our results indicate that the transition from non-confluent cells to 3D cysts involves numerous differentially expressed genes (DEGs) in both WT and KO cells. Importantly, the analyses revealed significant overlaps between WT and KO cells in their maturation processes, suggesting that most identified DEGs are linked to differentiation from non-confluent to polarized MDCK cells and likely not a result of PALS1 deficiency. Gene Ontology (GO) enrichment and over-representation analyses using REACTOME and KEGG databases confirmed these similarities. In contrast, the direct comparison of WT and KO cells at the two stages showed fewer DEGs and overlaps in associated biological processes and signaling pathways. DEGs associated with the 3D stage, in which the phenotype manifests, contain DEGs and pathways that were predominantly linked to cell cycle linked processes, centromere assembly, or DNA replication. Furthermore, the transcription of genes encoding key junction proteins, additional polarity proteins, and cell-substrate interaction proteins is less affected by the loss of PALS1, indicating that PALS1 influences the transcriptional profiles in epithelial cells as a modulating factor.

P2Y6R Inhibition Induces Microglial M2 Polarization by Promoting PINK1/Parkin-Dependent Mitophagy After Spinal Cord Injury.

Secondary injury presents a significant hurdle to neural regeneration following spinal cord injury (SCI), primarily driven by inflammation in which microglial cells play a crucial role. Despite the growing interest in mitophagy, studies on its occurrence post-spinal cord injury, particularly within microglial cells, are scarce. While P2Y6R has been implicated in inflammation regulation in various neurological conditions, its specific role in SCI remains uncertain. Our study revealed an upregulation of P2Y6R expression following SCI notably in microglial cells. Treatment with the P2Y6R-specific inhibitor, MRS2578, in mice facilitated M2 polarization of microglial cells and alleviated secondary damage, ultimately enhancing neural regeneration and functional recovery. In an in vitro BV2 inflammation model, our findings indicate that P2Y6R inhibition induced M2 polarization of BV2 cells and reduced neuroinflammation through PINK/Parkin-dependent mitophagy activation. In summary, our results underscore the potential of P2Y6R inhibition in promoting mitophagy-induced M2 polarization of microglial cells, thereby ameliorating secondary injury following spinal cord injury.

RNAi library screening reveals Gβ1, Casein Kinase 2 and ICAP-1 as novel regulators of LFA-1-mediated T cell polarity and migration.

The αLβ2 integrin LFA-1 plays a key role in T-cell adhesion to the endothelial vasculature and migration into both secondary lymphoid organs and peripheral tissues via interactions with its target protein ICAM-1, but the pathways that regulate LFA-1-mediated T-cell polarity and migration are not fully understood. In this study we screened two RNAi libraries targeting G protein-coupled receptors (GPCR)/GPCR-associated proteins and kinases in a HuT 78 T cell line model of LFA-1-stimulated T-cell migration. Based on staining of the actin cytoskeleton, multiple parameters to measure cell morphology were used to assess the contribution of 1109 genes to LFA-1-mediated T-cell polarity and migration. These RNAi screens identified a number of both novel and previously identified genes that either increased or decreased the polarity and migratory capacity of these cells. Following multiparametric analysis, hierarchical clustering and pathway analysis, three of these genes were characterized in further detail using primary human T cells, revealing novel roles for the heterotrimeric G protein subunit Gβ1 and Casein Kinase 2 in LFA-1-mediated T-cell polarity and migration in vitro. Our studies also highlighted a new role for ICAP-1, an adaptor protein previously described to be associated with β1 integrins, in β2 integrin LFA-1-directed migration in T cells. Knockdown of ICAP-1 expression in primary T cells revealed a role in cell polarity, cell velocity and transmigration towards SDF-1 for this adaptor protein. This study therefore uncovers new roles for GPCR/GPCR-associated proteins and kinases in T-cell migration and provides potential novel targets for modulation of the T-cell immune response.

IL-17A-Induced Redox Imbalance and Inflammatory Responses in MiceLung via Act1-TRAF6-IKBα Signaling Pathway: Implications for Lung Disease Pathogenesis.

IL-17A is a potent proinflammatory cytokine that plays a crucial role in the pathogenesis of various lung diseases. This study focused on the evaluation of the role of IL-17 receptor signaling through one-week intranasal exposure of IL-17A in lung tissues of BALB/c mice. IL-17A triggered inflammatory responses in the mice lungs and led to changes in the morphological alveolar arrangements. Exposure of IL-17A induced redox imbalance by triggering an increase in the level of the pro-oxidants (reactive oxygen species, nitrite and malondialdehyde) and reduction of the levels of antioxidant proteins (glutathione, superoxide dismutase and catalase) in the lung tissue. IL-17A also caused a significant elevation in the levels of proinflammatory cytokines lines including TNF-α, IL-1β and IL-6, in lung tissue as well as in plasma. More interestingly, these changes were accompanied by the alterations in IL-17 receptor downstream signaling through activation of IL-17R-Act1-TRAF6-IKBα-mediated pathway. IL-17A exposure also caused lung tissue injury, recruitment and polarization of immune cells from anti-inflammatory to pro-inflammatory. This study clearly demonstrated the role of IL-17A-induced signaling in worsening lung inflammatory diseases, and hence points towards its emergence as an important therapeutic target to control lung inflammation.

The Rho effector ARHGAP18 coordinates a Hippo pathway feedback loop through YAP and Merlin to regulate the cytoskeleton and epithelial cell polarity.

The organization of the cell's cytoskeletal filaments is coordinated through a complex symphony of signaling cascades originating from internal and external cues. Two major actin regulatory pathways are signal transduction through Rho family GTPases and growth and proliferation signaling through the Hippo pathway. These two pathways act to define the actin cytoskeleton, controlling foundational cellular attributes such as morphology and polarity. In this study, we use human epithelial cells to investigate the interplay between the Hippo and Rho Family signaling pathways, which have predominantly been characterized as independent actin regulatory mechanisms. We identify that the RhoA effector, ARHGAP18, forms a complex with the Hippo pathway transcription factor YAP to address a long-standing enigma in the field. Using super resolution STORM microscopy, we characterize the changes in the actin cytoskeleton, on the single filament level, that arise from CRISPR/Cas9 knockout of ARHGAP18. We report that the loss of ARHGAP18 results in alterations of the cell that derive from both aberrant RhoA signaling and inappropriate nuclear localization of YAP. These findings indicate that the Hippo and Rho family GTPase signaling cascades are coordinated in their temporal and spatial control of the actin cytoskeleton.

Uncovering the electrical synapse proteome in retinal neurons via in vivo proximity labeling.

Through decades of research, we have gained a comprehensive understanding of the protein complexes underlying function and regulation of chemical synapses in the nervous system. Despite the identification of key molecules such as ZO-1 or CaMKII, we currently lack a similar level of insight into the electrical synapse proteome. With the advancement of BioID as a tool for in vivo proteomics, it has become possible to identify complex interactomes of a given protein of interest by combining enzymatic biotinylation with subsequent streptavidin affinity capture. In the present study, we applied different BioID strategies to screen the interactomes of Connexin 36 (mouse) the major neuronal connexin and its zebrafish orthologue Cx35b in retinal neurons. For in vivo proximity labeling in mice, we took advantage of the Cx36-EGFP strain and expressed a GFP-nanobody-TurboID fusion construct selectively in AII amacrine cells. For in vivo BioID in zebrafish, we generated a transgenic line expressing a Cx35b-TurboID fusion under control of the Cx35b promoter. Both two strategies allowed us to capture a plethora of molecules that were associated with electrical synapses and showed a high degree of evolutionary conservation in the proteomes of both species. Besides known interactors of Cx36 such as ZO-1 and ZO-2 we have identified more than 50 new proteins, such as scaffold proteins, adhesion molecules and regulators of the cytoskeleton. We further determined the subcellular localization of these proteins in AII amacrine and tested potential binding interactions with Cx36. Of note, we identified signal induced proliferation associated 1 like 3 (SIPA1L3), a protein that has been implicated in cell junction formation and cell polarity as a new scaffold of electrical synapses. Interestingly, SIPA1L3 was able to interact with ZO-1, ZO-2 and Cx36, suggesting a pivotal role in electrical synapse function. In summary, our study provides a first detailed view of the electrical synapse proteome in retinal neurons.

Small Extracellular Vesicle-Associated MiRNAs in Polarized Retinal Pigmented Epithelium.

Oxidative stress in the retinal pigmented epithelium (RPE) has been implicated in age-related macular degeneration by impacting endocytic trafficking, including the formation, content, and secretion of extracellular vesicles (EVs). Using our model of polarized primary porcine RPE (pRPE) cells under chronic subtoxic oxidative stress, we tested the hypothesis that RPE miRNAs packaged into EVs are secreted in a polarized manner and contribute to maintaining RPE homeostasis. Small EVs (sEVs) enriched for exosomes were isolated from apical and basal conditioned media from pRPE cells grown for up to four weeks with or without low concentrations of hydrogen peroxide using two sEV isolation methods, leading to eight experimental groups. The sEV miRNA expression was profiled using miRNA-Seq with Illumina MiSeq, followed by quality control and bioinformatics analysis for differential expression using the R computing environment. Expression of selected miRNAs were validated using qRT-PCR. We identified miRNA content differences carried by sEVs isolated using two ultracentrifugation-based methods. Regardless of the sEV isolation method, miR-182 and miR-183 were enriched in the cargo of apically secreted sEVs, and miR-122 in the cargo of basally secreted sEVs from RPE cells during normal homeostatic conditions. After oxidative stress, miR-183 levels were significantly decreased in the cargo of apically released sEVs from stressed RPE cells. We curated RPE sEV miRNA datasets based on cell polarity and oxidative stress. Unbiased miRNA analysis identified differences based on polarity, stress, and sEV isolation methods. These findings suggest that miRNAs in sEVs may contribute to RPE homeostasis and function in a polarized manner.

Eliminating chemo-mechanical degradation of lithium solid-state battery cathodes during >4.5 V cycling using amorphous Nb2O5 coatings.

Lithium solid-state batteries offer improved safety and energy density. However, the limited stability of solid electrolytes (SEs), as well as irreversible structural and chemical changes in the cathode active material, can result in inferior electrochemical performance, particularly during high-voltage cycling (>4.3 V vs Li/Li+). Therefore, new materials and strategies are needed to stabilize the cathode/SE interface and preserve the cathode material structure during high-voltage cycling. Here, we introduce a thin (~5 nm) conformal coating of amorphous Nb2O5 on single-crystal LiNi0.5Mn0.3Co0.2O2 cathode particles using rotary-bed atomic layer deposition (ALD). Full cells with Li4Ti5O12 anodes and Nb2O5-coated cathodes demonstrate a higher initial Coulombic efficiency of 91.6% ± 0.5% compared to 82.2% ± 0.3% for the uncoated samples, along with improved rate capability (10x higher accessible capacity at 2C rate) and remarkable capacity retention during extended cycling (99.4% after 500 cycles at 4.7 V vs Li/Li+). These improvements are associated with reduced cell polarization and interfacial impedance for the coated samples. Post-cycling electron microscopy analysis reveals that the Nb2O5 coating remains intact and prevents the formation of spinel and rock-salt phases, which eliminates intra-particle cracking of the single-crystal cathode material. These findings demonstrate a potential pathway towards stable and high-performance solid-state batteries during high-voltage operation.

Magnetic Iron Oxide Nanoparticles Enhance Exosome Production by Upregulating Exosome Transport and Secretion Pathways.

Exosomes are cell-released nanovesicles that regulate intercellular communication by transporting a variety of bioactive molecules. They play a crucial role in various physiological and pathological processes, such as the immune response, tissue regeneration, aging, and tumor progression. There has been growing interest in controlling exosome production, which could offer valuable tools for unraveling complex cell communication networks and enabling novel therapeutic applications. Magnetic iron oxide nanoparticles (MNPs), one of the few nanomaterials approved for clinical use, have been shown to remotely modulate cellular activities such as cytoskeleton reorganization, ion channel activation, and cell polarization. In this study, we systematically investigate the effects of MNPs, acting as nanoscale force transducers, on exosome production in two distinct cell types with different responses to mechanical stimuli. Our findings reveal that magnetic force applied to intracellular MNPs induces vesicle relocation and promotes the formation of actin stress fibers. Gene expression analysis further shows that intracellular magnetic force upregulates genes related to exosome transport and secretion as well as other pathways linked to exosome biogenesis. Notably, these forces substantially enhance exosome production, particularly MNP-containing exosomes, which are accompanied by increased intercellular exchange of MNPs. In summary, our study offers valuable insights into MNP-driven exosome production and presents potential strategies for enhancing cell communication and modulating nanoparticle distribution in nanomedicine.

Perturbation of mammary epithelial cell apicobasal polarity by RHBDF1-facilitated nuclear translocation of PKCζ

BackgroundThe establishment of apicobasal polarity in epithelial cells is of critical importance in morphogenesis of mammary gland and other secretive gland tissues. The demise of the polarity is a critical step in early stages of tumorigenesis such as in breast ductal carcinoma in situ. The underlying molecular mechanism thus warrants in-depth investigations.ResultsProtein kinase C isoform ζ (PKCζ), which is highly expressed in breast cancer cells, accumulates in the nuclei of human mammary epithelial cells overexpressing human rhomboid family-1 (RHBDF1), an endoplasmic reticulum membrane protein. Nuclear translocation of PKCζ results in the failure of the formation of the cytosolic apicobasal polarity complex Par, of which PKCζ is an essential component. Additionally, enhanced nuclear translocation of PKCζ is accompanied by an inhibition of the expression of cell tight junction and adherens junction proteins and an increase of cell mobility. Mechanistically, RHBDF1 is able to interact with importin β1 and PKCζ and promote PKCζ phosphorylation. Consistently, treatment of RHBDF1-overexpressing cells with an inhibitor of PKCζ phosphorylation leads to restoration of apicobasal polarity and cell-cell junctions, as well as suppressed cell mobility.ConclusionsRHBDF1-facilitated nuclear translocation of PKCζ is critically responsible for the dismantlement of epithelial cell apicobasal polarity, and thus may serve as a target in the development of therapeutic approaches against early stages of breast cancer.