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Virus Research Jul 2023Japanese encephalitis virus (JEV) is a mosquito-borne zoonotic virus that can cause severe viral encephalitis. Initial interactions between JEV and host cells are... (Review)
Review
Japanese encephalitis virus (JEV) is a mosquito-borne zoonotic virus that can cause severe viral encephalitis. Initial interactions between JEV and host cells are required for productive viral infection and initiation of the viral life cycle. The elucidation of these interactions is critical, not only to understand the pathogenesis of JEV infection, but also to design efficient antiviral strategies. In this review, we outline the known viral and cellular components involved in JEV entry into host cells, with a particular focus on the initial virus-host cell interaction on the cell surface and the downstream early events such as endocytosis, membrane fusion, and viral genome release.
Topics: Animals; Humans; Encephalitis Virus, Japanese; Host Microbial Interactions; Virus Internalization; Encephalitis, Japanese; Endocytosis; Encephalitis Viruses, Japanese; Virus Replication
PubMed: 37086856
DOI: 10.1016/j.virusres.2023.199120 -
Nature Communications Aug 2023The delivery of genetic cargo remains one of the largest obstacles to the successful translation of experimental therapies, in large part due to the absence of...
The delivery of genetic cargo remains one of the largest obstacles to the successful translation of experimental therapies, in large part due to the absence of targetable delivery vectors. Enveloped delivery modalities use viral envelope proteins, which determine tropism and induce membrane fusion. Here we develop DIRECTED (Delivery to Intended REcipient Cells Through Envelope Design), a modular platform that consists of separate fusion and targeting components. To achieve high modularity and programmable cell type specificity, we develop multiple strategies to recruit or immobilize antibodies on the viral envelope, including a chimeric antibody binding protein and a SNAP-tag enabling the use of antibodies or other proteins as targeting molecules. Moreover, we show that fusogens from multiple viral families are compatible with DIRECTED and that DIRECTED components can target multiple delivery chassis (e.g., lentivirus and MMLV gag) to specific cell types, including primary human T cells in PBMCs and whole blood.
Topics: Humans; Antibodies; Lentivirus; Membrane Fusion; Tropism; Viral Envelope Proteins
PubMed: 37612276
DOI: 10.1038/s41467-023-40788-8 -
Nature Dec 2023Four endemic seasonal human coronaviruses causing common colds circulate worldwide: HKU1, 229E, NL63 and OC43 (ref. ). After binding to cellular receptors, coronavirus...
Four endemic seasonal human coronaviruses causing common colds circulate worldwide: HKU1, 229E, NL63 and OC43 (ref. ). After binding to cellular receptors, coronavirus spike proteins are primed for fusion by transmembrane serine protease 2 (TMPRSS2) or endosomal cathepsins. NL63 uses angiotensin-converting enzyme 2 as a receptor, whereas 229E uses human aminopeptidase-N. HKU1 and OC43 spikes bind cells through 9-O-acetylated sialic acid, but their protein receptors remain unknown. Here we show that TMPRSS2 is a functional receptor for HKU1. TMPRSS2 triggers HKU1 spike-mediated cell-cell fusion and pseudovirus infection. Catalytically inactive TMPRSS2 mutants do not cleave HKU1 spike but allow pseudovirus infection. Furthermore, TMPRSS2 binds with high affinity to the HKU1 receptor binding domain (Kd 334 and 137 nM for HKU1A and HKU1B genotypes) but not to SARS-CoV-2. Conserved amino acids in the HKU1 receptor binding domain are essential for binding to TMPRSS2 and pseudovirus infection. Newly designed anti-TMPRSS2 nanobodies potently inhibit HKU1 spike attachment to TMPRSS2, fusion and pseudovirus infection. The nanobodies also reduce infection of primary human bronchial cells by an authentic HKU1 virus. Our findings illustrate the various evolution strategies of coronaviruses, which use TMPRSS2 to either directly bind to target cells or prime their spike for membrane fusion and entry.
Topics: Humans; Betacoronavirus; Bronchi; Common Cold; Membrane Fusion; Receptors, Virus; SARS-CoV-2; Serine Endopeptidases; Single-Domain Antibodies; Species Specificity; Spike Glycoprotein, Coronavirus; Virus Internalization
PubMed: 37879362
DOI: 10.1038/s41586-023-06761-7 -
Cell Host & Microbe Nov 2023Epstein-Barr virus (EBV) is a global public health concern, as it is known to cause multiple diseases while also being etiologically associated with a wide range of...
Epstein-Barr virus (EBV) is a global public health concern, as it is known to cause multiple diseases while also being etiologically associated with a wide range of epithelial and lymphoid malignancies. Currently, there is no available prophylactic vaccine against EBV. gB is the EBV fusion protein that mediates viral membrane fusion and participates in host recognition, making it critical for EBV infection in both B cells and epithelial cells. Here, we present a gB nanoparticle, gB-I53-50 NP, that displays multiple copies of gB. Compared with the gB trimer, gB-I53-50 NP shows improved structural integrity and stability, as well as enhanced immunogenicity in mice and non-human primate (NHP) preclinical models. Immunization and passive transfer demonstrate a robust and durable protective antibody response that protects humanized mice against lethal EBV challenge. This vaccine candidate demonstrates significant potential in preventing EBV infection, providing a possible platform for developing prophylactic vaccines for EBV.
Topics: Cricetinae; Animals; Mice; Herpesvirus 4, Human; Epstein-Barr Virus Infections; Antibody Formation; CHO Cells; Vaccines; Antibodies, Neutralizing; Antibodies, Viral
PubMed: 37848029
DOI: 10.1016/j.chom.2023.09.011 -
Nature Reviews. Molecular Cell Biology Feb 2024Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are a family of small conserved eukaryotic proteins that mediate membrane fusion between... (Review)
Review
Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are a family of small conserved eukaryotic proteins that mediate membrane fusion between organelles and with the plasma membrane. SNAREs are directly or indirectly anchored to membranes. Prior to fusion, complementary SNAREs assemble between membranes with the aid of accessory proteins that provide a scaffold to initiate SNARE zippering, pulling the membranes together and mediating fusion. Recent advances have enabled the construction of detailed models describing bilayer transitions and energy barriers along the fusion pathway and have elucidated the structures of SNAREs complexed in various states with regulatory proteins. In this Review, we discuss how these advances are yielding an increasingly detailed picture of the SNARE-mediated fusion pathway, leading from first contact between the membranes via metastable non-bilayer intermediates towards the opening and expansion of a fusion pore. We describe how SNARE proteins assemble into complexes, how this assembly is regulated by accessory proteins and how SNARE complexes overcome the free energy barriers that prevent spontaneous membrane fusion.
Topics: SNARE Proteins; Membrane Fusion; Cell Membrane
PubMed: 37848589
DOI: 10.1038/s41580-023-00668-x -
Nature Cell Biology Jul 2023The low-density lipoprotein (LDL) is a major cholesterol carrier in circulation and is internalized into cells through LDL receptor (LDLR)-mediated endocytosis. The LDLR...
The low-density lipoprotein (LDL) is a major cholesterol carrier in circulation and is internalized into cells through LDL receptor (LDLR)-mediated endocytosis. The LDLR protein is highly expressed in the steroidogenic organs and LDL cholesterol is an important source for steroidogenesis. Cholesterol must be transported into the mitochondria, where steroid hormone biosynthesis initiates. However, how LDL cholesterol is conveyed to the mitochondria is poorly defined. Here, through genome-wide small hairpin RNA screening, we find that the outer mitochondrial membrane protein phospholipase D6 (PLD6), which hydrolyses cardiolipin to phosphatidic acid, accelerates LDLR degradation. PLD6 promotes the entrance of LDL and LDLR into the mitochondria, where LDLR is degraded by mitochondrial proteases and LDL-carried cholesterol is used for steroid hormone biosynthesis. Mechanistically, the outer mitochondrial membrane protein CISD2 binds to the cytosolic tail of LDLR and tethers LDLR vesicles to the mitochondria. The fusogenic lipid phosphatidic acid generated by PLD6 facilitates the membrane fusion of LDLR vesicles with the mitochondria. This intracellular transport pathway of LDL-LDLR bypasses the lysosomes and delivers cholesterol to the mitochondria for steroidogenesis.
Topics: Cholesterol, LDL; Cholesterol; Mitochondria; Membrane Proteins; Hormones
PubMed: 37277481
DOI: 10.1038/s41556-023-01160-6 -
FEBS Letters Sep 2023Evidence from biochemistry, genetics, and electron microscopy strongly supports the idea that a ring of Synaptotagmin is central to the clamping and release of synaptic... (Review)
Review
Evidence from biochemistry, genetics, and electron microscopy strongly supports the idea that a ring of Synaptotagmin is central to the clamping and release of synaptic vesicles (SVs) for synchronous neurotransmission. Recent direct measurements in cell-free systems suggest there are 12 SNAREpins in each ready-release vesicle, consisting of six peripheral and six central SNAREpins. The six central SNAREpins are directly bound to the Synaptotagmin ring, are directly released by Ca , and they initially open the fusion pore. The six peripheral SNAREpins are indirectly bound to the ring, each linked to a central SNAREpin by a bridging molecule of Complexin. We suggest that the primary role of peripheral SNAREpins is to provide additional force to 'turbocharge' neurotransmitter release, explaining how it can occur much faster than other forms of membrane fusion. The SV protein Synaptophysin forms hexamers that bear two copies of the v-SNARE VAMP at each vertex, one likely assembling into a peripheral SNAREpin and the other into a central SNAREpin.
Topics: Biological Transport; Cell-Free System; Head; Synaptic Transmission; Synaptotagmins
PubMed: 37643878
DOI: 10.1002/1873-3468.14718 -
Nature Jul 2023Understanding protective immunity to COVID-19 facilitates preparedness for future pandemics and combats new SARS-CoV-2 variants emerging in the human population....
Understanding protective immunity to COVID-19 facilitates preparedness for future pandemics and combats new SARS-CoV-2 variants emerging in the human population. Neutralizing antibodies have been widely studied; however, on the basis of large-scale exome sequencing of protected versus severely ill patients with COVID-19, local cell-autonomous defence is also crucial. Here we identify phospholipid scramblase 1 (PLSCR1) as a potent cell-autonomous restriction factor against live SARS-CoV-2 infection in parallel genome-wide CRISPR-Cas9 screens of human lung epithelia and hepatocytes before and after stimulation with interferon-γ (IFNγ). IFNγ-induced PLSCR1 not only restricted SARS-CoV-2 USA-WA1/2020, but was also effective against the Delta B.1.617.2 and Omicron BA.1 lineages. Its robust activity extended to other highly pathogenic coronaviruses, was functionally conserved in bats and mice, and interfered with the uptake of SARS-CoV-2 in both the endocytic and the TMPRSS2-dependent fusion routes. Whole-cell 4Pi single-molecule switching nanoscopy together with bipartite nano-reporter assays found that PLSCR1 directly targeted SARS-CoV-2-containing vesicles to prevent spike-mediated fusion and viral escape. A PLSCR1 C-terminal β-barrel domain-but not lipid scramblase activity-was essential for this fusogenic blockade. Our mechanistic studies, together with reports that COVID-associated PLSCR1 mutations are found in some susceptible people, identify an anti-coronavirus protein that interferes at a late entry step before viral RNA is released into the host-cell cytosol.
Topics: Animals; Humans; Mice; Antibodies, Neutralizing; Antibodies, Viral; Chiroptera; COVID-19; Exome Sequencing; Hepatocytes; Interferon-gamma; Lung; Membrane Fusion; Phospholipid Transfer Proteins; SARS-CoV-2; Virus Internalization
PubMed: 37438530
DOI: 10.1038/s41586-023-06322-y -
Nature Aug 2023Dominant optic atrophy is one of the leading causes of childhood blindness. Around 60-80% of cases are caused by mutations of the gene that encodes optic atrophy protein...
Dominant optic atrophy is one of the leading causes of childhood blindness. Around 60-80% of cases are caused by mutations of the gene that encodes optic atrophy protein 1 (OPA1), a protein that has a key role in inner mitochondrial membrane fusion and remodelling of cristae and is crucial for the dynamic organization and regulation of mitochondria. Mutations in OPA1 result in the dysregulation of the GTPase-mediated fusion process of the mitochondrial inner and outer membranes. Here we used cryo-electron microscopy methods to solve helical structures of OPA1 assembled on lipid membrane tubes, in the presence and absence of nucleotide. These helical assemblies organize into densely packed protein rungs with minimal inter-rung connectivity, and exhibit nucleotide-dependent dimerization of the GTPase domains-a hallmark of the dynamin superfamily of proteins. OPA1 also contains several unique secondary structures in the paddle domain that strengthen its membrane association, including membrane-inserting helices. The structural features identified in this study shed light on the effects of pathogenic point mutations on protein folding, inter-protein assembly and membrane interactions. Furthermore, mutations that disrupt the assembly interfaces and membrane binding of OPA1 cause mitochondrial fragmentation in cell-based assays, providing evidence of the biological relevance of these interactions.
Topics: Cryoelectron Microscopy; GTP Phosphohydrolases; Membrane Fusion; Mitochondria; Mitochondrial Dynamics; Mitochondrial Membranes; Mutation; Nucleotides; Protein Binding; Protein Domains; Protein Folding; Protein Multimerization; Protein Structure, Secondary; Humans
PubMed: 37612506
DOI: 10.1038/s41586-023-06462-1 -
Advanced Materials (Deerfield Beach,... Nov 2023Existing solid-nanoparticle-based drug delivery systems remain a great challenge for glioblastoma chemotherapy due to their poor capacities in crossing the blood-brain...
Existing solid-nanoparticle-based drug delivery systems remain a great challenge for glioblastoma chemotherapy due to their poor capacities in crossing the blood-brain barrier/blood-brain tumor barrier (BBB/BBTB). Herein, fruit-derived extracellular-vesicle (EV)-engineered structural droplet drugs (ESDDs) are demonstrated by programming the self-assembly of fruit-derived EVs at the DOX@squalene-PBS interface, greatly enhancing the antitumor efficacy against glioblastoma. The ESDDs experience a flexible delivery via deformation-amplified macropinocytosis and membrane fusion, enabling them to highly efficiently cross the BBB/BBTB and deeply penetrate glioblastoma tissues. As expected, the ESDDs exhibit approximately 2.5-fold intracellular uptake, 2.2-fold transcytosis, and fivefold membrane fusion higher than cRGD-modified EVs (REs), allowing highly efficient accumulation, deep penetration, and cellular internalization into the glioblastoma tissues, and thereby significantly extending the survival time of glioblastoma mice.
Topics: Mice; Animals; Glioblastoma; Pharmaceutical Preparations; Fruit; Brain Neoplasms; Drug Delivery Systems; Blood-Brain Barrier; Cell Line, Tumor
PubMed: 37589312
DOI: 10.1002/adma.202304187