Membrane vesicle trafficking

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Membrane vesicle trafficking in eukaryotic animal cells involves movement of biochemical signal molecules from synthesis-and-packaging locations in the Golgi body to specific release locations on the inside of the plasma membrane of the secretory cell. It takes place in the form of Golgi membrane-bound micro-sized vesicles, termed membrane vesicles (MVs).

Contents

In this process, the packed cellular products are released or secreted outside the cell, across its plasma membrane. On the other hand, the vesicular membrane is retained and recycled by the secretory cells. This phenomenon has a major role in synaptic neurotransmission, endocrine secretion, mucous secretion, granular-product secretion by neutrophils, and other phenomena. The scientists behind this discovery were awarded Nobel prize for the year 2013.

In prokaryotic, gram-negative bacterial cells, membrane vesicle trafficking is mediated through bacterial outer membrane bounded nano-sized vesicles, called bacterial outer membrane vesicles (OMVs). In this case, however, the OMV membrane is secreted as well, along with OMV-contents to outside the secretion-active bacterium. This different phenomenon has a major role in host–pathogen interactions, endotoxic shock in patients, invasion and infection of animals or plants, inter-species bacterial competition, quorum sensing, exocytosis, and other areas.

Movement within eukaryotic cells

Here a vesicle forms as cargo, receptors and coat proteins gather. The vesicle then buds outwards and breaks free into the cytoplasm. The vesicle is moved towards its target location then docks and fuses. Vesicle Budding, Motility and Fusion.jpg
Here a vesicle forms as cargo, receptors and coat proteins gather. The vesicle then buds outwards and breaks free into the cytoplasm. The vesicle is moved towards its target location then docks and fuses.

Once vesicles are produced in the endoplasmic reticulum and modified in the Golgi body they make their way to a variety of destinations within the cell. Vesicles first leave the Golgi body and are released into the cytoplasm in a process called budding. Vesicles are then moved towards their destination by motor proteins. Once the vesicle arrives at its destination it joins with the bi-lipid layer in a process called fusion, and then releases its contents.

Budding

Receptors embedded in the membrane of the Golgi body bind specific cargo (such as dopamine) on the lumenal side of the vesicle. These cargo receptors then recruit a variety of proteins including other cargo receptors and coat proteins such as clathrin, COPI and COPII. As more and more of these coating proteins come together, they cause the vesicle to bud outward and eventually break free into the cytoplasm. The coating proteins are then shed into the cytoplasm to be recycled and reused. [1]

Motility between cell compartments

For movement between different compartments within the cell, vesicles rely on the motor proteins myosin, kinesin (primarily anterograde transport) and dynein (primarily retrograde transport). One end of the motor proteins attaches to the vesicle while the other end attaches to either microtubulees or microfilaments. The motor proteins then move by hydrolyzing ATP, which propels the vesicle towards its destination. [2]

Docking and Fusion

As a vesicle nears its intended location, RAB proteins in the vesicle membrane interact with docking proteins at the destination site. These docking proteins bring the vesicle in closer to interact with the SNARE Complex found in the target membrane. The SNARE complex reacts with synaptobrevin found on the vesicle membrane. [3] This forces the vesicle membrane against the membrane of the target complex (or the outer membrane of the cell) and causes the two membranes to fuse. Depending on whether the vesicle fuses with a target complex or the outer membrane, the contents of the vesicle are then released either into the target complex or outside the cell. [4]

Examples in eukaryotes

  1. Intracellular trafficking occurs between subcellular compartments like Golgi cisternae and multivesicular endosomes for transport of soluble proteins as MVs.
  2. Budding of MVs directly from plasma membrane as microvesicles released outside the secretory cells.
  3. Exosomes are MVs that can form inside an internal compartment like multivesicular endosome. Exosomes are released eventually due to fusion of this endosome with plasma membrane of cell.
  4. Hijacking of exosomal machinery by some viruses like retroviruses, wherein viruses bud inside multivesicular endosomes and get secreted subsequently as exosomes.

All these types (1–4) of modes of membrane vesicle trafficking, taking place in eukaryotic cells have been explained diagrammatically. [5]

In prokaryotes

Unlike in eukaryotes, membrane vesicular trafficking in prokaryotes is an emerging area in interactive biology for intra-species (quorum sensing) and inter-species signaling at the host–pathogen interface, as prokaryotes lack internal membrane-compartmentalization of their cytoplasm. Bacterial membrane vesicles dispersion along the cell surface was measured in live Escherichia coli , commensal bacteria common in the human gut. Antibiotic treatment altered vesicle dynamics, vesicle-to-membrane affinity, and surface properties of the cell membranes, generally enhancing vesicle transport along the surfaces of bacterial membranes and suggesting that their motion properties could be a signature of antibiotic stress. [6]

For more than four decades, cultures of gram negative microbes revealed the presence of nanoscale membrane vesicles. A role for membrane vesicles in pathogenic processes has been suspected since the 1970s, when they were observed in gingival plaque by electron microscopy. [7] These vesicles were suspected to promote bacterial adhesion to the host epithelial cell surface. [8] Their role in invasion of animal host cells in vivo was then demonstrated. [9] In inter-bacterial interactions, OMVs released by Pseudomonas aeruginosa microbes were shown to fuse with outer membrane of other gram negative microbes causing their bacteriolysis; these OMVs could lyse gram-positive microbes as well. [10] Role of OMVs in Helicobacter pylori infection of human primary antral epithelial cells, as model that closely resembles human stomach, has also been confirmed [11] VacA-containing OMVs could also be detected in human gastric mucosa, infected with H. pylori.. [12] Salmonella OMVs were also shown to have direct role in invasion of chicken ileal epithelial cells in vivo in the year, 1993 (ref 4) and later, in hijacking of defense macrophages into sub-service for pathogen replication and consequent apoptosis of infected macrophages in typhoid-like animal infection. [13] These studies brought the focus on OMVs into membrane vesicle trafficking and showed this phenomenon as involved in multifarious processes like genetic transformation, quorum sensing, competition arsenal among microbes, etc., and invasion, infection, immuno-modulation, etc., of animal hosts. [7] A mechanism has already been proposed for generation of OMVs by gram negative microbes involving, expansion of pockets of periplasm (named, periplasmic organelles) due to accumulation of bacterial cell secretions and their pinching off as outer membrane bounded vesicles (OMVs) on the lines of a 'soap bubble' formation with a bubble tube, and further fusion or uptake of diffusing OMVs by host/target cells (Fig. 2). [14]

Fig. 2 Membrane vesicle trafficking Mechanism (A-E), proposed for release (stages A-C) of outer membrane vesicles, OMVs from gram-negative bacteria in analogy of soap-bubble formation from a bubble-tube assembly (RC in stage C) of rivet complexes, RC, and their translocation (stage D) to animal host/target cell, TC. General secretory pathway (GSP) secretes proteins across bacterial cell membrane (CM) to bulge out lipopolysaccharide (LPS)-rich outer membrane (OM) above peptidoglycan (PDG) layer into pockets of inflated periplasm, called periplasmic organelles (PO) to pinch off OMVs containing outer membrane proteins (OMPs), secretory proteins (SP) and chaperons (CH). OMVs signal epithelial host cells (EHC) to ruffle (R) aiding macropinoctosis of gram negative (G-) microbe (stage E). Outer membrane vesicle secretion from gram-negative microbes - mechanism proposed (Original work of R C YashRoy).png
Fig. 2 Membrane vesicle trafficking Mechanism (A–E), proposed for release (stages A–C) of outer membrane vesicles, OMVs from gram-negative bacteria in analogy of soap-bubble formation from a bubble-tube assembly (RC in stage C) of rivet complexes, RC, and their translocation (stage D) to animal host/target cell, TC. General secretory pathway (GSP) secretes proteins across bacterial cell membrane (CM) to bulge out lipopolysaccharide (LPS)-rich outer membrane (OM) above peptidoglycan (PDG) layer into pockets of inflated periplasm, called periplasmic organelles (PO) to pinch off OMVs containing outer membrane proteins (OMPs), secretory proteins (SP) and chaperons (CH). OMVs signal epithelial host cells (EHC) to ruffle (R) aiding macropinoctosis of gram negative (G-) microbe (stage E).
Fig. 3 Transmission electron micrograph of human Salmonella organism bearing periplasmic organelles, (p, line arrow) on its surface and releasing bacterial outer membrane vesicles (MV) being endocytosed (curved arrow) by macrophage cell (M) in chicken ileum in vivo OMV-macrophage99.jpg
Fig. 3 Transmission electron micrograph of human Salmonella organism bearing periplasmic organelles, (p, line arrow) on its surface and releasing bacterial outer membrane vesicles (MV) being endocytosed (curved arrow) by macrophage cell (M) in chicken ileum in vivo

In conclusion, membrane vesicle trafficking via OMVs of Gram-negative organisms, cuts across species and kingdoms – including plant kingdom [15] – in the realm of cell-to-cell signaling.

See also

Related Research Articles

<span class="mw-page-title-main">Endomembrane system</span> Membranes in the cytoplasm of a eukaryotic cell

The endomembrane system is composed of the different membranes (endomembranes) that are suspended in the cytoplasm within a eukaryotic cell. These membranes divide the cell into functional and structural compartments, or organelles. In eukaryotes the organelles of the endomembrane system include: the nuclear membrane, the endoplasmic reticulum, the Golgi apparatus, lysosomes, vesicles, endosomes, and plasma (cell) membrane among others. The system is defined more accurately as the set of membranes that forms a single functional and developmental unit, either being connected directly, or exchanging material through vesicle transport. Importantly, the endomembrane system does not include the membranes of plastids or mitochondria, but might have evolved partially from the actions of the latter.

<span class="mw-page-title-main">Golgi apparatus</span> Cell organelle that packages proteins for export

The Golgi apparatus, also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic cells. Part of the endomembrane system in the cytoplasm, it packages proteins into membrane-bound vesicles inside the cell before the vesicles are sent to their destination. It resides at the intersection of the secretory, lysosomal, and endocytic pathways. It is of particular importance in processing proteins for secretion, containing a set of glycosylation enzymes that attach various sugar monomers to proteins as the proteins move through the apparatus.

<span class="mw-page-title-main">Gram-negative bacteria</span> Group of bacteria that do not retain the Gram stain used in bacterial differentiation

Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall sandwiched between an inner membrane (cytoplasmic), and an outer membrane.

<span class="mw-page-title-main">Vesicle (biology and chemistry)</span> Any small, fluid-filled, spherical organelle enclosed by a membrane

In cell biology, a vesicle is a structure within or outside a cell, consisting of liquid or cytoplasm enclosed by a lipid bilayer. Vesicles form naturally during the processes of secretion (exocytosis), uptake (endocytosis), and the transport of materials within the plasma membrane. Alternatively, they may be prepared artificially, in which case they are called liposomes. If there is only one phospholipid bilayer, the vesicles are called unilamellar liposomes; otherwise they are called multilamellar liposomes. The membrane enclosing the vesicle is also a lamellar phase, similar to that of the plasma membrane, and intracellular vesicles can fuse with the plasma membrane to release their contents outside the cell. Vesicles can also fuse with other organelles within the cell. A vesicle released from the cell is known as an extracellular vesicle.

<span class="mw-page-title-main">Exocytosis</span> Active transport and bulk transport in which a cell transports molecules out of the cell

Exocytosis is a form of active transport and bulk transport in which a cell transports molecules out of the cell. As an active transport mechanism, exocytosis requires the use of energy to transport material. Exocytosis and its counterpart, endocytosis, are used by all cells because most chemical substances important to them are large polar molecules that cannot pass through the hydrophobic portion of the cell membrane by passive means. Exocytosis is the process by which a large amount of molecules are released; thus it is a form of bulk transport. Exocytosis occurs via secretory portals at the cell plasma membrane called porosomes. Porosomes are permanent cup-shaped lipoprotein structure at the cell plasma membrane, where secretory vesicles transiently dock and fuse to release intra-vesicular contents from the cell.

<span class="mw-page-title-main">Endosome</span> Vacuole to which materials ingested by endocytosis are delivered

Endosomes are a collection of intracellular sorting organelles in eukaryotic cells. They are parts of endocytic membrane transport pathway originating from the trans Golgi network. Molecules or ligands internalized from the plasma membrane can follow this pathway all the way to lysosomes for degradation or can be recycled back to the cell membrane in the endocytic cycle. Molecules are also transported to endosomes from the trans Golgi network and either continue to lysosomes or recycle back to the Golgi apparatus.

<span class="mw-page-title-main">Secretion</span> Controlled release of substances by cells or tissues

Secretion is the movement of material from one point to another, such as a secreted chemical substance from a cell or gland. In contrast, excretion is the removal of certain substances or waste products from a cell or organism. The classical mechanism of cell secretion is via secretory portals at the plasma membrane called porosomes. Porosomes are permanent cup-shaped lipoprotein structures embedded in the cell membrane, where secretory vesicles transiently dock and fuse to release intra-vesicular contents from the cell.

The exocyst is an octameric protein complex involved in vesicle trafficking, specifically the tethering and spatial targeting of post-Golgi vesicles to the plasma membrane prior to vesicle fusion. It is implicated in a number of cell processes, including exocytosis, cell migration, and growth.

<span class="mw-page-title-main">Phagosome</span>

In cell biology, a phagosome is a vesicle formed around a particle engulfed by a phagocyte via phagocytosis. Professional phagocytes include macrophages, neutrophils, and dendritic cells (DCs).

<span class="mw-page-title-main">Vesicle-associated membrane protein</span> Protein family

Vesicle associated membrane proteins (VAMPs) are a family of SNARE proteins with similar structure, and are mostly involved in vesicle fusion.

A secretory protein is any protein, whether it be endocrine or exocrine, which is secreted by a cell. Secretory proteins include many hormones, enzymes, toxins, and antimicrobial peptides. Secretory proteins are synthesized in the endoplasmic reticulum.

<span class="mw-page-title-main">VAMP2</span> Protein-coding gene in the species Homo sapiens

Vesicle-associated membrane protein 2 (VAMP2) is a protein that in humans is encoded by the VAMP2 gene.

<span class="mw-page-title-main">NAPA (gene)</span> Protein-coding gene in the species Homo sapiens

N-ethylmaleimide-sensitive factor Attachment Protein Alpha, also known as SNAP-α, is a SNAP protein that is involved in the intra-cellular trafficking and fusing of vesicles to target membranes in cells.

<span class="mw-page-title-main">Vesicle-associated membrane protein 8</span> Protein-coding gene in the species Homo sapiens

Vesicle-associated membrane protein 8 is a protein that in humans is encoded by the VAMP8 gene.

<span class="mw-page-title-main">RAB11B</span> Protein-coding gene in the species Homo sapiens

Ras-related protein Rab-11B is a protein that in humans is encoded by the RAB11B gene. Rab11b is reported as most abundantly expressed in brain, heart and testes.

<span class="mw-page-title-main">Cytosis</span> Movement of molecules into or out of cells

-Cytosis is a suffix that either refers to certain aspects of cells ie cellular process or phenomenon or sometimes refers to predominance of certain type of cells. It essentially means "of the cell". Sometimes it may be shortened to -osis and may be related to some of the processes ending with -esis or similar suffixes.

Kiss-and-run fusion is a type of synaptic vesicle release where the vesicle opens and closes transiently. In this form of exocytosis, the vesicle docks and transiently fuses at the presynaptic membrane and releases its neurotransmitters across the synapse, after which the vesicle can then be reused.

Unconventional protein secretion represents a manner in which the proteins are delivered to the surface of plasma membrane or extracellular matrix independent of the endoplasmic reticulum or Golgi apparatus. This includes cytokines and mitogens with crucial function in complex processes such as inflammatory response or tumor-induced angiogenesis. Most of these proteins are involved in processes in higher eukaryotes, however an unconventional export mechanism was found in lower eukaryotes too. Even proteins folded in their correct conformation can pass plasma membrane this way, unlike proteins transported via ER/Golgi pathway. Two types of unconventional protein secretion are these: signal-peptid-containing proteins and cytoplasmatic and nuclear proteins that are missing an ER-signal peptide (1).

Bacterial effectors are proteins secreted by pathogenic bacteria into the cells of their host, usually using a type 3 secretion system (TTSS/T3SS), a type 4 secretion system (TFSS/T4SS) or a Type VI secretion system (T6SS). Some bacteria inject only a few effectors into their host’s cells while others may inject dozens or even hundreds. Effector proteins may have many different activities, but usually help the pathogen to invade host tissue, suppress its immune system, or otherwise help the pathogen to survive. Effector proteins are usually critical for virulence. For instance, in the causative agent of plague, the loss of the T3SS is sufficient to render the bacteria completely avirulent, even when they are directly introduced into the bloodstream. Gram negative microbes are also suspected to deploy bacterial outer membrane vesicles to translocate effector proteins and virulence factors via a membrane vesicle trafficking secretory pathway, in order to modify their environment or attack/invade target cells, for example, at the host-pathogen interface.

<span class="mw-page-title-main">Outer membrane vesicles</span> Vesicles released from the outer membranes of Gram-negative bacteria

Outer membrane vesicles (OMVs) are vesicles released from the outer membranes of Gram-negative bacteria. While Gram-positive bacteria release vesicles as well those vesicles fall under the broader category of bacterial membrane vesicles (MVs). OMVs were the first MVs to be discovered, and are distinguished from outer inner membrane vesicles (OIMVS), which are gram-negative baterial vesicles containing portions of both the outer and inner bacterial membrane. Outer membrane vesicles were first discovered and characterized using transmission-electron microscopy by Indian Scientist Prof. Smriti Narayan Chatterjee and J. Das in 1966-67. OMVs are ascribed the functionality to provide a manner to communicate among themselves, with other microorganisms in their environment and with the host. These vesicles are involved in trafficking bacterial cell signaling biochemicals, which may include DNA, RNA, proteins, endotoxins and allied virulence molecules. This communication happens in microbial cultures in oceans, inside animals, plants and even inside the human body.

References

  1. ↑ Bonifacino, Juan (January 2004). "The Mechanisms of Vesicle Budding and Fusion". Cell. 116 (2): 153–166. doi: 10.1016/S0092-8674(03)01079-1 . PMID   14744428.
  2. ↑ Hehnly H, Stamnes M (May 2007). "Regulating cytoskeleton-based vesicle motility". FEBS Letters. 581 (11): 2112–8. doi:10.1016/j.febslet.2007.01.094. PMC   1974873 . PMID   17335816.
  3. ↑ Nanavati C, Markin VS, Oberhauser AF, Fernandez JM (October 1992). "The exocytotic fusion pore modeled as a lipidic pore". Biophysical Journal. 63 (4): 1118–32. Bibcode:1992BpJ....63.1118N. doi:10.1016/S0006-3495(92)81679-X. PMC   1262250 . PMID   1420930.
  4. ↑ Papahadjopoulos D, Nir S, Düzgünes N (April 1990). "Molecular mechanisms of calcium-induced membrane fusion". Journal of Bioenergetics and Biomembranes. 22 (2): 157–79. doi:10.1007/BF00762944. PMID   2139437. S2CID   1465571.
  5. ↑ Théry C, Ostrowski M, Segura E (August 2009). "Membrane vesicles as conveyors of immune responses". Nature Reviews. Immunology. 9 (8): 581–93. doi:10.1038/nri2567. PMID   19498381. S2CID   21161202.
  6. ↑ Bos J, Cisneros LH, Mazel D (January 2021). "Real-time tracking of bacterial membrane vesicles reveals enhanced membrane traffic upon antibiotic exposure". Science Advances. 7 (4): eabd1033. doi:10.1126/sciadv.abd1033. PMC   7817102 . PMID   33523924.
  7. 1 2 Ellis TN, Kuehn MJ (March 2010). "Virulence and immunomodulatory roles of bacterial outer membrane vesicles". Microbiology and Molecular Biology Reviews. 74 (1): 81–94. doi:10.1128/MMBR.00031-09. PMC   2832350 . PMID   20197500.
  8. ↑ Halhoul N, Colvin JR (February 1975). "The ultrastructure of bacterial plaque attached to the gingiva of man". Archives of Oral Biology. 20 (2): 115–8. doi:10.1016/0003-9969(75)90164-8. PMID   1054578.
  9. ↑ YashRoy RC (1993). "Electron microscope studies of surface pili and vesicles of Salmonella 3,10:r:- organisms". Indian Journal of Animal Sciences. 63 (2): 99–102.
  10. ↑ Kadurugamuwa JL, Beveridge TJ (May 1996). "Bacteriolytic effect of membrane vesicles from Pseudomonas aeruginosa on other bacteria including pathogens: conceptually new antibiotics". Journal of Bacteriology. 178 (10): 2767–74. doi:10.1128/jb.178.10.2767-2774.1996. PMC   178010 . PMID   8631663.
  11. ↑ Heczko U, Smith VC, Mark Meloche R, Buchan AM, Finlay BB (November 2000). "Characteristics of Helicobacter pylori attachment to human primary antral epithelial cells". Microbes and Infection. 2 (14): 1669–76. doi: 10.1016/s1286-4579(00)01322-8 . PMID   11137040.
  12. ↑ Fiocca R, Necchi V, Sommi P, Ricci V, Telford J, Cover TL, Solcia E (June 1999). "Release of Helicobacter pylori vacuolating cytotoxin by both a specific secretion pathway and budding of outer membrane vesicles. Uptake of released toxin and vesicles by gastric epithelium". The Journal of Pathology. 188 (2): 220–6. doi:10.1002/(sici)1096-9896(199906)188:2<220::aid-path307>3.0.co;2-c. PMID   10398168. S2CID   44528015.
  13. ↑ Yashroy RC (2000). "Hijacking of macrophages by Salmonella (3,10:r:-) through 'type-III' secretion-like exocytotic signaling: a mechanism for infection of chicken ileum". Indian Journal of Poultry Science. 35 (3): 276–281.
  14. ↑ YashRoy RC (June 2003). "Eucaryotic cell intoxication by gram-negative pathogens: a novel bacterial outermembrane-bound nanovesicular exocytosis model for type-III secretion system". Toxicology International. 10 (1): 1–9.
  15. ↑ Bahar O, Pruitt R, Luu DD, Schwessinger B, Daudi A, Liu F, Ruan R, Fontaine-Bodin L, Koebnik R, Ronald P (2014). "The Xanthomonas Ax21 protein is processed by the general secretory system and is secreted in association with outer membrane vesicles". PeerJ. 2: e242. doi: 10.7717/peerj.242 . PMC   3897388 . PMID   24482761.
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