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Journal of Structural Biology Mar 2022Protein transport between the membranous compartments of the eukaryotic cells is mediated by the constant fission and fusion of the membrane-bounded vesicles from a... (Review)
Review
Protein transport between the membranous compartments of the eukaryotic cells is mediated by the constant fission and fusion of the membrane-bounded vesicles from a donor to an acceptor membrane. While there are many membrane remodelling complexes in eukaryotes, COPII, COPI, and clathrin-coated vesicles are the three principal classes of coat protein complexes that participate in vesicle trafficking in the endocytic and secretory pathways. These vesicle-coat proteins perform two key functions: deforming lipid bilayers into vesicles and encasing selective cargoes. The three trafficking complexes share some commonalities in their structural features but differ in their coat structures, mechanisms of cargo sorting, vesicle formation, and scission. While the structures of many of the proteins involved in vesicle formation have been determined in isolation by X-ray crystallography, elucidating the proteins' structures together with the membrane is better suited for cryogenic electron microscopy (cryo-EM). In recent years, advances in cryo-EM have led to solving the structures and mechanisms of several vesicle trafficking complexes and associated proteins.
Topics: Coat Protein Complex I; Cryoelectron Microscopy; Crystallography, X-Ray; Membranes; Protein Transport
PubMed: 35101600
DOI: 10.1016/j.jsb.2022.107836 -
Cell Calcium Jan 2022In some lysosomal storage diseases (LSD) cholesterol accumulates in vesicles. Whether increased vesicle cholesterol affects vesicle fusion with the plasmalemma, where...
In some lysosomal storage diseases (LSD) cholesterol accumulates in vesicles. Whether increased vesicle cholesterol affects vesicle fusion with the plasmalemma, where the fusion pore, a channel between the vesicle lumen and the extracellular space, is formed, is unknown. Super-resolution microscopy revealed that after stimulation of exocytosis, pituitary lactotroph vesicles discharge cholesterol which transfers to the plasmalemma. Cholesterol depletion in lactotrophs and astrocytes, both exhibiting Ca-dependent exocytosis regulated by distinct Casources, evokes vesicle secretion. Although this treatment enhanced cytosolic levels of Ca in lactotrophs but decreased it in astrocytes, this indicates that cholesterol may well directly define the fusion pore. In an attempt to explain this mechanism, a new model of cholesterol-dependent fusion pore regulation is proposed. High-resolution membrane capacitance measurements, used to monitor fusion pore conductance, a parameter related to fusion pore diameter, confirm that at resting conditions reducing cholesterol increases, while enrichment with cholesterol decreases the conductance of the fusion pore. In resting fibroblasts, lacking the Npc1 protein, a cellular model of LSD in which cholesterol accumulates in vesicles, the fusion pore conductance is smaller than in controls, showing that vesicle cholesterol controls fusion pore and is relevant for pathophysiology of LSD.
Topics: Animals; Cell Membrane; Cholesterol; Exocytosis; Lactotrophs; Membrane Fusion; Rats; Rats, Wistar; Secretory Vesicles
PubMed: 34844123
DOI: 10.1016/j.ceca.2021.102503 -
Extreme Mechanics Letters Feb 2021The physico-mechanical properties of nanoscale lipid vesicles (e.g., natural nano-vesicles and artificial nano-liposomes) dictate their interaction with biological...
The physico-mechanical properties of nanoscale lipid vesicles (e.g., natural nano-vesicles and artificial nano-liposomes) dictate their interaction with biological systems. Understanding the interplay between vesicle size and stiffness is critical to both the understanding of the biological functions of natural nano-vesicles and the optimization of nano-vesicle-based diagnostics and therapeutics. It has been predicted that, when vesicle size is comparable to its membrane thickness, the effective bending stiffness of the vesicle increases dramatically due to both the entropic effect as a result of reduced thermal undulation and the nonlinear curvature elasticity effect. Through systematic molecular dynamics simulations, we show that the vesicle membrane thins and softens with the decrease in vesicle size, which effectively counteracts the stiffening effects as already mentioned. Our simulations indicate that the softening of nano-vesicles results from a change in the bilayer's interior structure - a decrease in lipid packing order - as the membrane curvature increases. Our work thus leads to a more complete physical framework to understand the physico-mechanical properties of nanoscale lipid vesicles, paving the way to further advances in the biophysics of nano-vesicles and their biomedical applications.
PubMed: 33542946
DOI: 10.1016/j.eml.2021.101174 -
International Journal of Molecular... Sep 2022Bone mineralization entails two mineralization phases: primary and secondary mineralization. Primary mineralization is achieved when matrix vesicles are secreted by... (Review)
Review
Bone mineralization entails two mineralization phases: primary and secondary mineralization. Primary mineralization is achieved when matrix vesicles are secreted by osteoblasts, and thereafter, bone mineral density gradually increases during secondary mineralization. Nearby extracellular phosphate ions (PO) flow into the vesicles via membrane transporters and enzymes located on the vesicles' membranes, while calcium ions (Ca), abundant in the tissue fluid, are also transported into the vesicles. The accumulation of Ca and PO in the matrix vesicles induces crystal nucleation and growth. The calcium phosphate crystals grow radially within the vesicle, penetrate the vesicle's membrane, and continue to grow outside the vesicle, ultimately forming mineralized nodules. The mineralized nodules then attach to collagen fibrils, mineralizing them from the contact sites (i.e., collagen mineralization). Afterward, the bone mineral density gradually increases during the secondary mineralization process. The mechanisms of this phenomenon remain unclear, but osteocytes may play a key role; it is assumed that osteocytes enable the transport of Ca and PO through the canaliculi of the osteocyte network, as well as regulate the mineralization of the surrounding bone matrix via the Phex/SIBLINGs axis. Thus, bone mineralization is biologically regulated by osteoblasts and osteocytes.
Topics: Bone Matrix; Calcification, Physiologic; Collagen; Extracellular Matrix; Osteoblasts; Osteocytes
PubMed: 36077336
DOI: 10.3390/ijms23179941 -
Frontiers in Molecular Neuroscience 2023The release of extracellular vesicles is observed across numerous cell types and serves a range of biological functions including intercellular communication and waste... (Review)
Review
The release of extracellular vesicles is observed across numerous cell types and serves a range of biological functions including intercellular communication and waste disposal. One cell type which stands out for its robust capacity to release extracellular vesicles is the vertebrate photoreceptor cell. For decades, the release of extracellular vesicles by photoreceptors has been documented in many different animal models of photoreceptor degeneration and, more recently, in wild type photoreceptors. Here, I review all studies describing extracellular vesicle release by photoreceptors and discuss the most unifying theme among them-a photoreceptor cell fully, or partially, diverts its light sensitive membrane material to extracellular vesicles when it has defects in the delivery or morphing of this material into the photoreceptor's highly organized light sensing organelle. Because photoreceptors generate an enormous amount of light sensitive membrane every day, the diversion of this material to extracellular vesicles can cause a massive accumulation of these membranes within the retina. Little is known about the uptake of photoreceptor derived extracellular vesicles, although in some cases the retinal pigment epithelial cells, microglia, Müller glia, and/or photoreceptor cells themselves have been shown to phagocytize them.
PubMed: 37273908
DOI: 10.3389/fnmol.2023.1182573 -
FEBS Letters Mar 2023COPI-coated vesicles mediate transport between Golgi stacks and retrograde transport from the Golgi to the endoplasmic reticulum. The COPI coat exists as a stable... (Review)
Review
COPI-coated vesicles mediate transport between Golgi stacks and retrograde transport from the Golgi to the endoplasmic reticulum. The COPI coat exists as a stable heptameric complex in the cytosol termed coatomer and is recruited en bloc to the membrane for vesicle formation. Recruitment of COPI onto membranes is mediated by the Arf family of small GTPases, which, in their GTP-bound state, bind both membrane and coatomer. Arf GTPases also influence cargo selection, vesicle scission and vesicle uncoating. Guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs) regulate nucleotide binding by Arf GTPases. To understand the mechanism of COPI-coated vesicle trafficking, it is necessary to characterize the interplay between coatomer and Arf GTPases and their effectors. It is also necessary to understand interactions between coatomer and cargo, cargo adaptors/receptors and tethers facilitating binding to the target membrane. Here, we summarize current knowledge of COPI coat protein structure; we describe how structural and biochemical studies contributed to this knowledge; we review mechanistic insights into COPI vesicle biogenesis and disassembly; and we discuss the potential to answer open questions in the field.
Topics: Humans; ADP-Ribosylation Factors; Carrier Proteins; COP-Coated Vesicles; Enzyme Activation; GTPase-Activating Proteins; Guanine Nucleotide Exchange Factors; Substrate Specificity
PubMed: 36513395
DOI: 10.1002/1873-3468.14560 -
International Journal of Molecular... Dec 2022Cells have the ability to communicate with their immediate and distant neighbors through the release of extracellular vesicles (EVs). EVs facilitate intercellular... (Review)
Review
Cells have the ability to communicate with their immediate and distant neighbors through the release of extracellular vesicles (EVs). EVs facilitate intercellular signaling through the packaging of specific cargo in all type of cells, and perturbations of EV biogenesis, sorting, release and uptake is the basis of a number of disorders. In this review, we summarize recent advances of the complex roles of the sphingolipid ceramide and lysosomes in the journey of EV biogenesis to uptake.
Topics: Ceramides; Protein Transport; Extracellular Vesicles; Biological Transport; Lysosomes
PubMed: 36499644
DOI: 10.3390/ijms232315317 -
Philosophical Transactions of the Royal... Mar 2021Neurosecretory vesicles are highly specialized trafficking organelles that store neurotransmitters that are released at presynaptic nerve endings and are, therefore,...
Neurosecretory vesicles are highly specialized trafficking organelles that store neurotransmitters that are released at presynaptic nerve endings and are, therefore, important for animal cell-cell signalling. Despite considerable anatomical and functional diversity of neurons in animals, the protein composition of neurosecretory vesicles in bilaterians appears to be similar. This similarity points towards a common evolutionary origin. Moreover, many putative homologues of key neurosecretory vesicle proteins predate the origin of the first neurons, and some even the origin of the first animals. However, little is known about the molecular toolkit of these vesicles in non-bilaterian animals and their closest unicellular relatives, making inferences about the evolutionary origin of neurosecretory vesicles extremely difficult. By comparing 28 proteins of the core neurosecretory vesicle proteome in 13 different species, we demonstrate that most of the proteins are present in unicellular organisms. Surprisingly, we find that the vesicular membrane-associated soluble N-ethylmaleimide-sensitive factor attachment protein receptor protein synaptobrevin is localized to the vesicle-rich apical and basal pole in the choanoflagellate Our 3D vesicle reconstructions reveal that the choanoflagellates and exhibit a polarized and diverse vesicular landscape reminiscent of the polarized organization of chemical synapses that secrete the content of neurosecretory vesicles into the synaptic cleft. This study sheds light on the ancestral molecular machinery of neurosecretory vesicles and provides a framework to understand the origin and evolution of secretory cells, synapses and neurons. This article is part of the theme issue 'Basal cognition: multicellularity, neurons and the cognitive lens'.
Topics: Biological Evolution; Choanoflagellata; R-SNARE Proteins; Synaptic Vesicles
PubMed: 33550951
DOI: 10.1098/rstb.2019.0759 -
International Journal of Nanomedicine 2023Extracellular vesicles (EVs) are lipid containers that are actively released by cells and contain complex molecular cargoes. These cargoes include abundant material such... (Review)
Review
Extracellular vesicles (EVs) are lipid containers that are actively released by cells and contain complex molecular cargoes. These cargoes include abundant material such as genomes and proteins from cells of origin. They are involved in intercellular communication and various pathological processes, showing excellent potential for diagnosing and treating diseases. Given the significant heterogeneity of EVs in complex physiopathological processes, unveiling their composition is essential to understanding their function. Bulk detection methods have been previously used to analyze EVs, but they often mask their heterogeneity, leading to the loss of valuable information. To overcome this limitation, single extracellular vesicle (SEV) analysis techniques have been developed and advanced. These techniques allow for analyzing EVs' physical information and biometric molecules at the SEV level. This paper reviews recent advances in SEV detection methods and summarizes some clinical applications for SEV detection strategies.
Topics: Extracellular Vesicles; Cell Communication
PubMed: 37750091
DOI: 10.2147/IJN.S421342 -
Nature Protocols Mar 2023Transport vesicles mediate protein traffic between endomembrane organelles in a highly selective and efficient manner. In vitro reconstitution systems have been widely... (Review)
Review
Transport vesicles mediate protein traffic between endomembrane organelles in a highly selective and efficient manner. In vitro reconstitution systems have been widely used for studying mechanisms of vesicle formation, polar trafficking, and cargo specificity in mammals and yeast. However, this technique has not yet been applied to plants because of the large lytic vacuoles and rigid cell walls. Here, we describe an Arabidopsis-derived in vitro vesicle formation system to reconstitute, purify and characterize plant-derived coat protein complex II (COPII) vesicles. In this protocol, we provide a detailed method for the isolation of microsomes and cytosol from Arabidopsis thaliana suspension-cultured cells (7-8 h), in vitro COPII vesicle reconstitution and purification (4-5 h) and biochemical and microscopic analysis using specific antibodies against COPII cargo molecules for reconstitution efficiency evaluation (2 h). We also include detailed sample-preparation steps for analyzing vesicle morphology by cryogenic electron microscopy (1 h) and vesicle cargoes by quantitative proteomics (4 h). Routinely, the whole procedure takes ~18-20 h of operation time and enables plant researchers without specific expertise to achieve organelle purification or vesicle reconstitution for further characterization.
Topics: Animals; Arabidopsis; Proteins; Transport Vesicles; Microscopy, Electron; Saccharomyces cerevisiae; Cells, Cultured; Mammals
PubMed: 36599961
DOI: 10.1038/s41596-022-00781-9