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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 -
International Journal of Molecular... Feb 2023Large vacuoles are a predominant cell organelle throughout the plant body. They maximally account for over 90% of cell volume and generate turgor pressure that acts as a... (Review)
Review
Large vacuoles are a predominant cell organelle throughout the plant body. They maximally account for over 90% of cell volume and generate turgor pressure that acts as a driving force of cell growth, which is essential for plant development. The plant vacuole also acts as a reservoir for sequestering waste products and apoptotic enzymes, thereby enabling plants to rapidly respond to fluctuating environments. Vacuoles undergo dynamic transformation through repeated enlargement, fusion, fragmentation, invagination, and constriction, eventually resulting in the typical 3-dimensional complex structure in each cell type. Previous studies have indicated that such dynamic transformations of plant vacuoles are governed by the plant cytoskeletons, which consist of F-actin and microtubules. However, the molecular mechanism of cytoskeleton-mediated vacuolar modifications remains largely unclear. Here we first review the behavior of cytoskeletons and vacuoles during plant development and in response to environmental stresses, and then introduce candidates that potentially play pivotal roles in the vacuole-cytoskeleton nexus. Finally, we discuss factors hampering the advances in this research field and their possible solutions using the currently available cutting-edge technologies.
Topics: Vacuoles; Cytoskeleton; Microtubules; Plants; Actin Cytoskeleton
PubMed: 36835552
DOI: 10.3390/ijms24044143 -
Cells Aug 2022Recent studies have highlighted the importance of autophagy and particularly non-canonical autophagy in the development and progression of acute pancreatitis (a frequent... (Review)
Review
Recent studies have highlighted the importance of autophagy and particularly non-canonical autophagy in the development and progression of acute pancreatitis (a frequent disease with considerable morbidity and significant mortality). An important early event in the development of acute pancreatitis is the intrapancreatic activation of trypsinogen, (i.e., formation of trypsin) leading to the autodigestion of the organ. Another prominent phenomenon associated with the initiation of this disease is vacuolisation and specifically the formation of giant endocytic vacuoles in pancreatic acinar cells. These organelles develop in acinar cells exposed to several inducers of acute pancreatitis (including taurolithocholic acid and high concentrations of secretagogues cholecystokinin and acetylcholine). Notably, early trypsinogen activation occurs in the endocytic vacuoles. These trypsinogen-activating organelles undergo activation, long-distance trafficking, and non-canonical autophagy. In this review, we will discuss the role of autophagy in acute pancreatitis and particularly focus on the recently discovered LAP-like non-canonical autophagy (LNCA) of endocytic vacuoles.
Topics: Acute Disease; Autophagy; Humans; Pancreatitis; Trypsinogen; Vacuoles
PubMed: 36010591
DOI: 10.3390/cells11162514 -
Molecular Medicine (Cambridge, Mass.) 2003Autophagy is a conserved trafficking pathway that is highly regulated by environmental conditions. During autophagy, portions of cytoplasm are sequestered into a... (Review)
Review
Autophagy is a conserved trafficking pathway that is highly regulated by environmental conditions. During autophagy, portions of cytoplasm are sequestered into a double-membrane autophagosome and delivered to a degradative organelle, the vacuole in yeast and the lysosome in mammalian cells, for breakdown and recycling. Autophagy is induced under starvation conditions and in mammalian cells is also invoked in response to specific hormones. In yeast, under nutrient-rich conditions, a constitutive biosynthetic pathway, termed the cytoplasm to vacuole targeting (Cvt) pathway, utilizes most of the same molecular machinery and topologically similar vesicles for the delivery of the resident hydrolase aminopeptidase I to the vacuole. Both autophagy and the Cvt pathway have been extensively studied and comprehensively reviewed in the past few years. In this review, we focus on the yeast system, which has provided most of the insight into the molecular mechanism of autophagy and the Cvt pathway, and highlight the most recent additions to our current knowledge of both pathways.
Topics: Autophagy; Biological Transport; Cell Membrane; Cytoplasm; Humans; Models, Biological; Protein Transport; Saccharomyces cerevisiae; Vacuoles; Yeasts
PubMed: 12865942
DOI: No ID Found -
Autophagy Feb 2019Hydrolysis within the vacuole in yeast and the lysosome in mammals is required for the degradation and recycling of a multitude of substrates, many of which are... (Review)
Review
Hydrolysis within the vacuole in yeast and the lysosome in mammals is required for the degradation and recycling of a multitude of substrates, many of which are delivered to the vacuole/lysosome by autophagy. In humans, defects in lysosomal hydrolysis and efflux can have devastating consequences, and contribute to a class of diseases referred to as lysosomal storage disorders. Despite the importance of these processes, many of the proteins and regulatory mechanisms involved in hydrolysis and efflux are poorly understood. In this review, we describe our current knowledge of the vacuolar/lysosomal degradation and efflux of a vast array of substrates, focusing primarily on what is known in the yeast . We also highlight many unanswered questions, the answers to which may lead to new advances in the treatment of lysosomal storage disorders. : Ams1: α-mannosidase; Ape1: aminopeptidase I; Ape3: aminopeptidase Y; Ape4: aspartyl aminopeptidase; Atg: autophagy related; Cps1: carboxypeptidase S; CTNS: cystinosin, lysosomal cystine transporter; CTSA: cathepsin A; CTSD: cathepsin D; Cvt: cytoplasm-to-vacuole targeting; Dap2: dipeptidyl aminopeptidase B; GS-bimane: glutathione--bimane; GSH: glutathione; LDs: lipid droplets; MVB: multivesicular body; PAS: phagophore assembly site; Pep4: proteinase A; PolyP: polyphosphate; Prb1: proteinase B; Prc1: carboxypeptidase Y; V-ATPase: vacuolar-type proton-translocating ATPase; VTC: vacuolar transporter chaperone.
Topics: Animals; Humans; Hydrolysis; Lysosomes; Macromolecular Substances; Models, Biological; Vacuoles
PubMed: 30422029
DOI: 10.1080/15548627.2018.1545821 -
International Journal of Molecular... Mar 2020Autophagy is an evolutionarily conserved process that occurs in yeast, plants, and animals. Despite many years of research, some aspects of autophagy are still not fully... (Review)
Review
Autophagy is an evolutionarily conserved process that occurs in yeast, plants, and animals. Despite many years of research, some aspects of autophagy are still not fully explained. This mostly concerns the final stages of autophagy, which have not received as much interest from the scientific community as the initial stages of this process. The final stages of autophagy that we take into consideration in this review include the formation and degradation of the autophagic bodies as well as the efflux of metabolites from the vacuole to the cytoplasm. The autophagic bodies are formed through the fusion of an autophagosome and vacuole during macroautophagy and by vacuolar membrane invagination or protrusion during microautophagy. Then they are rapidly degraded by vacuolar lytic enzymes, and products of the degradation are reused. In this paper, we summarize the available information on the trafficking of the autophagosome towards the vacuole, the fusion of the autophagosome with the vacuole, the formation and decomposition of autophagic bodies inside the vacuole, and the efflux of metabolites to the cytoplasm. Special attention is given to the formation and degradation of autophagic bodies and metabolite salvage in plant cells.
Topics: Autophagosomes; Autophagy; Biological Transport; Cytoplasm; Phagosomes; Plant Physiological Phenomena; Proteolysis; Vacuoles
PubMed: 32210003
DOI: 10.3390/ijms21062205 -
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 -
International Review of Cell and... 2013While free-living protists are usually subjected to hyposmotic environments, parasitic protists are also in contact with hyperosmotic habitats. Recent work in one of... (Review)
Review
While free-living protists are usually subjected to hyposmotic environments, parasitic protists are also in contact with hyperosmotic habitats. Recent work in one of these parasites, Trypanosoma cruzi, has revealed that its contractile vacuole complex, which usually collects and expels excess water as a mechanism of regulatory volume decrease after hyposmotic stress, has also a role in cell shrinking when the cells are submitted to hyperosmotic stress. Trypanosomes also have an acidic calcium store rich in polyphosphate (polyP), named the acidocalcisome, which is involved in their response to osmotic stress. Here, we review newly emerging insights on the role of acidocalcisomes and the contractile vacuole complex in the cellular response to hyposmotic and hyperosmotic stresses. We also review the current state of knowledge on the composition of these organelles and their other roles in calcium homeostasis and protein trafficking.
Topics: Organelles; Osmoregulation; Trypanosoma cruzi; Vacuoles
PubMed: 23890380
DOI: 10.1016/B978-0-12-407695-2.00002-0 -
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 -
Biochimica Et Biophysica Acta Jan 2012Plasmepsins (PMs) are pepsin-like aspartic proteases present in different species of parasite Plasmodium. Four Plasmodium spp. (P. vivax, P. ovale, P. malariae, and the... (Review)
Review
Plasmepsins (PMs) are pepsin-like aspartic proteases present in different species of parasite Plasmodium. Four Plasmodium spp. (P. vivax, P. ovale, P. malariae, and the most lethal P. falciparum) are mainly responsible for causing human malaria that affects millions worldwide. Due to the complexity and rate of parasite mutation coupled with regional variations, and the emergence of P. falciparum strains which are resistant to antimalarial agents such as chloroquine and sulfadoxine/pyrimethamine, there is constant pressure to find new and lasting chemotherapeutic drug therapies. Since many proteases represent therapeutic targets and PMs have been shown to play an important role in the survival of parasite, these enzymes have recently been identified as promising targets for the development of novel antimalarial drugs. The genome of P. falciparum encodes 10 PMs (PMI, PMII, PMIV-X and histo-aspartic protease (HAP)), 4 of which (PMI, PMII, PMIV and HAP) reside within the food vacuole, are directly involved in degradation of human hemoglobin, and share 50-79% amino acid sequence identity. This review focuses on structural studies of only these four enzymes, including their orthologs in other Plasmodium spp.. Almost all original crystallographic studies were performed with PMII, but more recent work on PMIV, PMI, and HAP resulted in a more complete picture of the structure-function relationship of vacuolar PMs. Many structures of inhibitor complexes of vacuolar plasmepsins, as well as their zymogens, have been reported in the last 15 years. Information gained by such studies will be helpful for the development of better inhibitors that could become a new class of potent antimalarial drugs. This article is part of a Special Issue entitled: Proteolysis 50 years after the discovery of lysosome.
Topics: Amino Acid Sequence; Animals; Aspartic Acid Endopeptidases; Humans; Models, Biological; Models, Molecular; Molecular Sequence Data; Protease Inhibitors; Protein Conformation; Sequence Homology, Amino Acid; Structure-Activity Relationship; Vacuoles
PubMed: 21540129
DOI: 10.1016/j.bbapap.2011.04.008