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Current Opinion in Microbiology Feb 2014Many intracellular bacterial pathogens reside within a membrane-bound compartment. The biogenesis of these vacuolar compartments is complex, involving subversion of host... (Review)
Review
Many intracellular bacterial pathogens reside within a membrane-bound compartment. The biogenesis of these vacuolar compartments is complex, involving subversion of host cell secretory pathways by bacterial proteins. In recent years it has become clear that disruption of vacuole biogenesis may result in membrane rupture and escape of bacteria into the host cell cytosol. Correct modulation of the host cell cytoskeleton, signalling molecules such as small GTPases and the lipids of the vacuole membrane have all been shown to be critical in the maintenance of vacuole integrity. Increasing evidence suggests that vacuole rupture may result from aberrant mechanical forces exerted on the vacuole, possibly due to a defect in vacuole expansion.
Topics: Bacteria; Host-Pathogen Interactions; Vacuoles
PubMed: 24581692
DOI: 10.1016/j.mib.2013.11.005 -
Annual Review of Genetics 2003The vacuole/lysosome of the budding yeast Saccharomyces cerevisiae is actively divided between mother and daughter cells. Vacuole inheritance initiates early in the cell... (Review)
Review
The vacuole/lysosome of the budding yeast Saccharomyces cerevisiae is actively divided between mother and daughter cells. Vacuole inheritance initiates early in the cell cycle and ends in G2, just prior to nuclear migration. The process begins with a portion of the vacuole extending into the emerging bud. This tubular-vesicular entity, the segregation structure, enables continued exchange of vacuole contents between mother and daughter vacuoles. Genetic, biochemical, and cytological analyses of vacuole inheritance have provided insight into the molecular basis of membrane movement, the spatial and temporal control of organelle transport, and the molecular basis of membrane fusion and fission.
Topics: Flavoproteins; Intracellular Membranes; Mutation; Phosphatidylinositol Phosphates; Phosphoric Monoester Hydrolases; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Vacuoles
PubMed: 14616069
DOI: 10.1146/annurev.genet.37.050203.103207 -
Plant Signaling & Behavior Dec 2010As plants lack immune cells, each cell has to defend itself against invading pathogens. Plant cells have a large central vacuole that accumulates a variety of hydrolytic... (Review)
Review
As plants lack immune cells, each cell has to defend itself against invading pathogens. Plant cells have a large central vacuole that accumulates a variety of hydrolytic enzymes and antimicrobial compounds, raising the possibility that vacuoles play a role in plant defense. However, how plants use vacuoles to protect against invading pathogens is poorly understood. Recently, we characterized two vacuole-mediated defense strategies associated with programmed cell death (PCD). In one strategy, vacuolar processing enzyme (VPE) mediated the disruption of the vacuolar membrane, resulting in the release of vacuolar contents into the cytoplasm in response to viral infection. In the other strategy, proteasome-dependent fusion of the central vacuole with the plasma membrane caused the discharge of vacuolar antibacterial protease and cell death-promoting contents from the cell in response to bacterial infection. Intriguingly, both strategies relied on enzymes with caspase-like activities: the vacuolar membrane-collapse system required VPE, which has caspase-1-like activity, and the membrane-fusion system required a proteasome that has caspase-3-like activity. Thus, plants may have evolved a cellular immune system that involves vacuolar membrane collapse to prevent the systemic spread of viral pathogens, and membrane fusion to inhibit the proliferation of bacterial pathogens.
Topics: Cell Death; Intracellular Membranes; Membrane Fusion; Plant Cells; Plants; Vacuoles
PubMed: 21512325
DOI: 10.4161/psb.5.12.13319 -
Journal of Experimental Botany Dec 2017Due to the numerous roles plant vacuoles play in cell homeostasis, detoxification, and protein storage, the trafficking pathways to this organelle have been extensively... (Review)
Review
Due to the numerous roles plant vacuoles play in cell homeostasis, detoxification, and protein storage, the trafficking pathways to this organelle have been extensively studied. Recent evidence, however, suggests that our vision of transport to the vacuole is not as simple as previously imagined. Alternative routes have been identified and are being characterized. Intricate interconnections between routes seem to occur in various cases, complicating the interpretation of data. In this review, we aim to summarize the published evidence and link the emerging data with previous findings. We discuss the current state of information on alternative and classical trafficking routes to the plant vacuole.
Topics: Plant Proteins; Plants; Protein Transport; Secretory Pathway; Vacuoles
PubMed: 29096031
DOI: 10.1093/jxb/erx376 -
Journal of Microbiological Methods Oct 2012Fungal vacuoles are involved in a diverse range of cellular functions, participating in cellular homeostasis, degradation of intracellular components, and storage of... (Review)
Review
Fungal vacuoles are involved in a diverse range of cellular functions, participating in cellular homeostasis, degradation of intracellular components, and storage of ions and molecules. In recent years there has been a significant increase in the number of studies linking these organelles with the regulation of growth and control of cellular morphology, particularly in those fungal species able to undergo yeast-hypha morphogenetic transitions. This has contributed to the refinement of previously published protocols and the development of new techniques, particularly in the area of live-cell imaging of membrane trafficking events and vacuolar dynamics. The current review outlines recent advances in the imaging of fungal vacuoles and assays for characterization of trafficking pathways, and other physiological activities of this important cell organelle.
Topics: Fungi; Hyphae; Image Processing, Computer-Assisted; Microscopy; Vacuoles
PubMed: 22902527
DOI: 10.1016/j.mimet.2012.08.002 -
Bioarchitecture 2013The notochord is an evolutionarily conserved structure that has long been known to play an important role in patterning during embryogenesis. Structurally, the notochord... (Review)
Review
The notochord is an evolutionarily conserved structure that has long been known to play an important role in patterning during embryogenesis. Structurally, the notochord is composed of two cell layers: an outer epithelial-like sheath, and an inner core of cells that contain large fluid-filled vacuoles. We have recently shown these notochord vacuoles are lysosome-related organelles that form through Rab32a and vacuolar-type proton-ATPase-dependent acidification. Disruption of notochord vacuoles results in a shortened embryo along the anterior-posterior axis. Interestingly, we discovered that notochord vacuoles are also essential for proper spine morphogenesis and that vacuole defects lead to scoliosis of the spine. Here we discuss the cellular organization of the notochord and how key features of its architecture allow the notochord to function in embryonic axis elongation and spine formation.
Topics: Animals; Embryonic Development; Humans; Notochord; Vacuoles
PubMed: 23887209
DOI: 10.4161/bioa.25503 -
Critical Reviews in Microbiology Jun 2015The contractile vacuole complex (CVC) of freshwater protists sequesters the excess of water and ions (Ca(2+)) for exocytosis cycles at the pore. Sequestration is based... (Review)
Review
The contractile vacuole complex (CVC) of freshwater protists sequesters the excess of water and ions (Ca(2+)) for exocytosis cycles at the pore. Sequestration is based on a chemiosmotic proton gradient produced by a V-type H(+)-ATPase. So far, many pieces of information available have not been combined to a comprehensive view on CVC biogenesis and function. One main function now appears as follows. Ca(2+)-release channels, type inositol 1,4,5-trisphosphate receptors (InsP3R), may serve for fine-tuning of local cytosolic Ca(2+) concentration and mediate numerous membrane-to-membrane interactions within the tubular spongiome meshwork. Such activity is suggested by the occurrence of organelle-specific soluble N-ethylmaleimide sensitive factor attachment protein receptor (SNARE) and Ras-related in brain (Rab) proteins, which may regulate functional requirements. For tubulation, F-Bin-amphiphysin-Rvs (F-BAR) proteins are available. In addition, there is indirect evidence for the occurrence of H(+)/Ca(2+) exchangers (to sequester Ca(2+)) and mechanosensitive Ca(2+)-channels (for signaling the filling sate). The periodic activity of the CVC may be regulated by the mechanosensitive Ca(2+)-channels. Such channels are known to colocalize with and to be functionally supported by stomatins, which were recently detected in the CVC. A Kif18-related kinesin motor protein might control the length of radial arms. Two additional InsP3-related channels and several SNAREs are associated with the pore. De novo organelle biogenesis occurs under epigenetic control during mitotic activity and may involve the assembly of γ-tubulin, centrin, calmodulin and a never in mitosis A-type (NIMA) kinase - components also engaged in mitotic processes.
Topics: Eukaryotic Cells; Exocytosis; Organelle Biogenesis; Signal Transduction; Vacuoles
PubMed: 23919298
DOI: 10.3109/1040841X.2013.821650 -
Plant Science : An International... Jul 2012The plant storage vacuole is involved in a wide variety of metabolic functions a great many of which necessitate the transport of substances across the tonoplast. Some... (Review)
Review
The plant storage vacuole is involved in a wide variety of metabolic functions a great many of which necessitate the transport of substances across the tonoplast. Some solutes, depending on the origin, have to cross the plasma membrane as well. The cell is equipped with a complex web of transport systems, cellular routes, and unique intracellular environments that support their transport and accumulation against a concentration gradient. These are capable of processing a diverse nature of substances of distinct sizes, chemical properties, and origins. In this review we describe the various mechanism involved in solute transport into the vacuole of storage cells with special emphasis placed on solutes arriving through the apoplast. Transport of solutes from the cytosol to the vacuole is carried out by tonoplast-bound ABC transporters, solute/H(+) antiporters, and ion channels whereas transport from the apoplast requires additional plasma membrane-bound solute/H(+) symporters and fluid-phase endocytosis. In addition, and based on new evidence accumulated within the last decade, we re-evaluate the current notion of extracellular solute uptake as partially based on facilitated diffusion, and offer an alternative interpretation that involves membrane bound transporters and fluid-phase endocytosis. Finally, we make several assertions in regards to solute export from the vacuole as predicted by the limited available data suggesting that both membrane-bound carriers and vesicle mediated exocytosis are involved during solute mobilization.
Topics: Biological Transport; Cytosol; Models, Biological; Plants; Vacuoles
PubMed: 22608519
DOI: 10.1016/j.plantsci.2012.03.010 -
International Journal For Parasitology Jul 1998The intracellular life-cycle of Eimeria are located in the host cell within a membrane-bound parasitophorous vacuole. The invasion process and the formation of the... (Review)
Review
The intracellular life-cycle of Eimeria are located in the host cell within a membrane-bound parasitophorous vacuole. The invasion process and the formation of the parasitophorous vacuole are mediated by characteristic organelles within the apical complex. During invasion, the parasitophorous-vacuole membrane is manipulated by the parasite and functions later in the development cycle as a molecular sieve, allowing the exchange of metabolites between parasite and host cell. Unlike the cyst-forming coccidia, there is little evidence of parasitophorous-vacuole membrane transformation in the later stages of the lifecycle of Eimeria species. Compared with the human pathogens Plasmodium and Toxoplasma, rather little is known about the parasitophorous vacuole and parasitophorous-vacuole membrane of animal pathogens of the genus Eimeria.
Topics: Animals; Cell Membrane Permeability; Eimeria; Host-Parasite Interactions; Life Cycle Stages; Organelles; Vacuoles
PubMed: 9724871
DOI: 10.1016/s0020-7519(98)00079-4 -
Autophagy 2007Various modes of autophagy conspire to degrade virtually every compartment of the eukaryotic cell. In Saccharomyces cerevisiae, a process called "piecemeal... (Review)
Review
Various modes of autophagy conspire to degrade virtually every compartment of the eukaryotic cell. In Saccharomyces cerevisiae, a process called "piecemeal microautophagy of the nucleus" (PMN) even pinches off and degrades nonessential portions of the nucleus. PMN is a constitutive process induced to high levels by starvation or rapamycin, an inhibitor of TOR kinase. PMN occurs at nucleus-vacuole (NV) junctions, which are Velcro-like patches formed by interactions between the vacuole membrane protein Vac8p and the outer-nuclear-membrane protein Nvj1p. In response to nutrient depletion, Nvj1p increasingly binds and sequesters two proteins with roles in lipid metabolism, Osh1p and Tsc13p. Tsc13p is required for the normal biogenesis of PMN vesicles. The sequestration of Osh1p by Nvj1p likely serves to negatively regulate the trafficking of tryptophan permease(s) to the plasma membrane. Thus, NV junctions and PMN orchestrate novel and sophisticated responses to nutrient limitation.
Topics: Autophagy; Cell Nucleus; Lipid Metabolism; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Vacuoles
PubMed: 17204844
DOI: 10.4161/auto.3586