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More KJ, Kaur H, Simpson AGB, Spiegel FW, Dacks JB. Contractile vacuoles: a rapidly expanding (and occasionally diminishing?) understanding. Eur J Protistol 2024; 94:126078. [PMID: 38688044 DOI: 10.1016/j.ejop.2024.126078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 03/18/2024] [Accepted: 03/20/2024] [Indexed: 05/02/2024]
Abstract
Osmoregulation is the homeostatic mechanism essential for the survival of organisms in hypoosmotic and hyperosmotic conditions. In freshwater or soil dwelling protists this is frequently achieved through the action of an osmoregulatory organelle, the contractile vacuole. This endomembrane organelle responds to the osmotic challenges and compensates by collecting and expelling the excess water to maintain the cellular osmolarity. As compared with other endomembrane organelles, this organelle is underappreciated and under-studied. Here we review the reported presence or absence of contractile vacuoles across eukaryotic diversity, as well as the observed variability in the structure, function, and molecular machinery of this organelle. Our findings highlight the challenges and opportunities for constructing cellular and evolutionary models for this intriguing organelle.
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Affiliation(s)
- Kiran J More
- Division of Infectious Diseases, Department of Medicine, and Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Harpreet Kaur
- Division of Infectious Diseases, Department of Medicine, and Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Alastair G B Simpson
- Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, NS, Canada; Department of Biology, Dalhousie University, Halifax, NS, Canada
| | - Frederick W Spiegel
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, 72701, USA
| | - Joel B Dacks
- Division of Infectious Diseases, Department of Medicine, and Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada; Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic; Centre for Life's Origins and Evolution, Department of Genetics, Evolution, & Environment, University College, London, United Kingdom.
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Cheng CY, Romero DP, Zoltner M, Yao MC, Turkewitz AP. Structure and dynamics of the contractile vacuole complex in Tetrahymena thermophila. J Cell Sci 2023; 136:jcs261511. [PMID: 37902010 PMCID: PMC10729820 DOI: 10.1242/jcs.261511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 10/23/2023] [Indexed: 10/31/2023] Open
Abstract
The contractile vacuole complex (CVC) is a dynamic and morphologically complex membrane organelle, comprising a large vesicle (bladder) linked with a tubular reticulum (spongiome). CVCs provide key osmoregulatory roles across diverse eukaryotic lineages, but probing the mechanisms underlying their structure and function is hampered by the limited tools available for in vivo analysis. In the experimentally tractable ciliate Tetrahymena thermophila, we describe four proteins that, as endogenously tagged constructs, localize specifically to distinct CVC zones. The DOPEY homolog Dop1p and the CORVET subunit Vps8Dp localize both to the bladder and spongiome but with different local distributions that are sensitive to osmotic perturbation, whereas the lipid scramblase Scr7p colocalizes with Vps8Dp. The H+-ATPase subunit Vma4 is spongiome specific. The live imaging permitted by these probes revealed dynamics at multiple scales including rapid exchange of CVC-localized and soluble protein pools versus lateral diffusion in the spongiome, spongiome extension and branching, and CVC formation during mitosis. Although the association with DOP1 and VPS8D implicate the CVC in endosomal trafficking, both the bladder and spongiome might be isolated from bulk endocytic input.
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Affiliation(s)
- Chao-Yin Cheng
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Daniel P. Romero
- Department of Pharmacology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Martin Zoltner
- Biotechnology Biomedicine Centre of the Academy of Sciences, České Budějovice, 370 05, Czech Republic
| | - Meng-Chao Yao
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Aaron P. Turkewitz
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
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Cheng CY, Hernández J, Turkewitz AP. VPS8D, a CORVET subunit, is required to maintain the contractile vacuole complex in Tetrahymena thermophila. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.07.566071. [PMID: 37986963 PMCID: PMC10659352 DOI: 10.1101/2023.11.07.566071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Contractile vacuole complexes (CVCs) are complex osmoregulatory organelles, with vesicular (bladder) and tubular (spongiome) subcompartments. The mechanisms that underlie their formation and maintenance within the eukaryotic endomembrane network are poorly understood. In the Ciliate Tetrahymena thermophila, six differentiated CORVETs (class C core vacuole/endosome tethering complexes), with Vps8 subunits designated A-F, are likely to direct endosomal trafficking. Vps8Dp localizes to both bladder and spongiome. We show by inducible knockdown that VPS8D is essential to CVC organization and function. VPS8D knockdown increased susceptibility to osmotic shock, tolerated in the wildtype but triggering irreversible lethal swelling in the mutant. The knockdown rapidly triggered contraction of the spongiome and lengthened the period of the bladder contractile cycle. More prolonged knockdown resulted in disassembly of both the spongiome and bladder, and dispersal of proteins associated with those compartments. In stressed cells where the normally singular bladder is replaced by numerous vesicles bearing bladder markers, Vps8Dp concentrated conspicuously at long-lived inter-vesicle contact sites, consistent with tethering activity. Similarly, Vps8Dp in cell-free preparations accumulated at junctions formed after vacuoles came into close contact. Also consistent with roles for Vps8Dp in tethering and/or fusion were the emergence in knockdown cells of multiple vacuole-related structures, replacing the single bladder.
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Affiliation(s)
- Chao-Yin Cheng
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL, USA
| | - Josefina Hernández
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL, USA
| | - Aaron P. Turkewitz
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL, USA
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Jimenez V, Miranda K, Ingrid A. The old and the new about the contractile vacuole of Trypanosoma cruzi. J Eukaryot Microbiol 2022; 69:e12939. [PMID: 35916682 PMCID: PMC11178379 DOI: 10.1111/jeu.12939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 07/27/2022] [Accepted: 07/27/2022] [Indexed: 11/28/2022]
Abstract
Osmoregulation is a conserved cellular process required for the survival of all organisms. In protists, the need for robust compensatory mechanisms that can maintain cell volume and tonicity within physiological range is even more relevant, as their life cycles are often completed in different environments. Trypanosoma cruzi, the protozoan pathogen responsible for Chagas disease, is transmitted by an insect vector to multiple types of mammalian hosts. The contractile vacuole complex (CVC) is an organelle that senses and compensates osmotic changes in the parasites, ensuring their survival upon ionic and osmotic challenges. Recent work shows that the contractile vacuole is also a key component of the secretory and endocytic pathways, regulating the selective targeting of surface proteins during differentiation. Here we summarize our current knowledge of the mechanisms involved in the osmoregulatory processes that take place in the vacuole, and we explore the new and exciting functions of this organelle in cell trafficking and signaling.
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Affiliation(s)
- Veronica Jimenez
- Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, California, USA
| | - Kildare Miranda
- Laboratorio de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- Centro Nacional de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Augusto Ingrid
- Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, California, USA
- Laboratorio de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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Plattner H. Membrane Traffic and Ca 2+ -Signals in Ciliates. J Eukaryot Microbiol 2022; 69:e12895. [PMID: 35156735 DOI: 10.1111/jeu.12895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 02/01/2022] [Accepted: 02/01/2022] [Indexed: 11/30/2022]
Abstract
A Paramecium cell has as many types of membrane interactions as mammalian cells, as established with monoclonal antibodies by R. Allen and A. Fok. Since then, we have identified key-players, such as SNARE-proteins, Ca2+ -regulating proteins, including Ca2+ -channels, Ca2+ -pumps, Ca2+ -binding proteins of different affinity etc. at the molecular level, probed their function and localized them at the light and electron microscopy level. SNARE-proteins, in conjunction with a synaptotagmin-like Ca2+ -sensor protein, mediate membrane fusion. This interaction is additionally regulated by monomeric GTPases whose spectrum in Tetrahymena and Paramecium has been established by A. Turkewitz. As known from mammalian cells, GTPases are activated on membranes in conjunction with lumenal acidification by an H+ -ATPase. For these complex molecules we found in Paramecium an unsurpassed number of 17 a-subunit paralogs which connect the polymeric head and basis part, V1 and V0. (This multitude may reflect different local functional requirements.) Together with plasmalemmal Ca2+ -influx-channels, locally enriched intracellular InsP3 -type (InsP3 R, mainly in osmoregulatory system) and ryanodine receptor-like Ca2+ -release channels (ryanodine receptor-like proteins, RyR-LP), this complexity mediates Ca2+ signals for most flexible local membrane-to-membrane interactions. As we found, the latter channel types miss a substantial portion of the N-terminal part. Caffeine and 4-chloro-meta-cresol (the agent used to probe mutations of RyRs in man during surgery in malignant insomnia patients) initiate trichocyst exocytosis by activating Ca2+ -release channels type CRC-IV in the peripheral part of alveolar sacs. This is superimposed by Ca2+ -influx, i.e. a mechanism called "store-operated Ca2+ -entry" (SOCE). For the majority of key players, we have mapped paralogs throughout the Paramecium cell, with features in common or at variance in the different organelles participating in vesicle trafficking. Local values of free Ca2+ -concentration, [Ca2+ ]i , and their change, e.g. upon exocytosis stimulation, have been registered by flurochromes and chelator effects. In parallel we have registered release of Ca2+ from alveolar sacs by quenched-flow analysis combined with cryofixation and x-ray microanalysis.
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O'Day DH, Mathavarajah S, Myre MA, Huber RJ. Calmodulin-mediated events during the life cycle of the amoebozoan Dictyostelium discoideum. Biol Rev Camb Philos Soc 2020; 95:472-490. [PMID: 31774219 PMCID: PMC7079120 DOI: 10.1111/brv.12573] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 10/30/2019] [Accepted: 11/11/2019] [Indexed: 12/14/2022]
Abstract
This review focusses on the functions of intracellular and extracellular calmodulin, its target proteins and their binding proteins during the asexual life cycle of Dictyostelium discoideum. Calmodulin is a primary regulatory protein of calcium signal transduction that functions throughout all stages. During growth, it mediates autophagy, the cell cycle, folic acid chemotaxis, phagocytosis, and other functions. During mitosis, specific calmodulin-binding proteins translocate to alternative locations. Translocation of at least one cell adhesion protein is calmodulin dependent. When starved, cells undergo calmodulin-dependent chemotaxis to cyclic AMP generating a multicellular pseudoplasmodium. Calmodulin-dependent signalling within the slug sets up a defined pattern and polarity that sets the stage for the final events of morphogenesis and cell differentiation. Transected slugs undergo calmodulin-dependent transdifferentiation to re-establish the disrupted pattern and polarity. Calmodulin function is critical for stalk cell differentiation but also functions in spore formation, events that begin in the pseudoplasmodium. The asexual life cycle restarts with the calmodulin-dependent germination of spores. Specific calmodulin-binding proteins as well as some of their binding partners have been linked to each of these events. The functions of extracellular calmodulin during growth and development are also discussed. This overview brings to the forefront the central role of calmodulin, working through its numerous binding proteins, as a primary downstream regulator of the critical calcium signalling pathways that have been well established in this model eukaryote. This is the first time the function of calmodulin and its target proteins have been documented through the complete life cycle of any eukaryote.
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Affiliation(s)
- Danton H. O'Day
- Cell and Systems BiologyUniversity of TorontoTorontoOntarioM5S 3G5Canada
- Department of BiologyUniversity of Toronto MississaugaMississaugaOntarioL5L 1C6Canada
| | | | - Michael A. Myre
- Department of Biological Sciences, Kennedy College of SciencesUniversity of Massachusetts LowellLowellMassachusetts01854USA
| | - Robert J. Huber
- Department of BiologyTrent UniversityPeterboroughOntarioK9L 0G2Canada
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Guerrier S, Plattner H, Richardson E, Dacks JB, Turkewitz AP. An evolutionary balance: conservation vs innovation in ciliate membrane trafficking. Traffic 2016; 18:18-28. [PMID: 27696651 DOI: 10.1111/tra.12450] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 09/20/2016] [Accepted: 09/20/2016] [Indexed: 12/15/2022]
Abstract
As most of eukaryotic diversity lies in single-celled protists, they represent unique opportunities to ask questions about the balance of conservation and innovation in cell biological features. Among free-living protists the ciliates offer ease of culturing, a rich array of experimental approaches, and versatile molecular tools, particularly in Tetrahymena thermophila and Paramecium tetraurelia. These attributes have been exploited by researchers to analyze a wealth of cellular structures in these large and complex cells. This mini-review focuses on 3 aspects of ciliate membrane dynamics, all linked with endolysosomal trafficking. First is nutrition based on phagocytosis and maturation of food vacuoles. Secondly, we discuss regulated exocytosis from vesicles that have features of both dense core secretory granules but also lysosome-related organelles. The third topic is the targeting, breakdown and resorption of parental nuclei in mating partners. For all 3 phenomena, it is clear that elements of the canonical membrane-trafficking system have been retained and in some cases repurposed. In addition, there is evidence that recently evolved, lineage-specific proteins provide determinants in these pathways.
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Affiliation(s)
| | - Helmut Plattner
- Department of Biology, University of Konstanz, Konstanz, Germany
| | | | - Joel B Dacks
- Department of Cell Biology, University of Alberta, Canada
| | - Aaron P Turkewitz
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois
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Abstract
Ca(2+)-signaling pathways and intracellular Ca(2+) channels are present in protozoa. Ancient origin of inositol 1,4,5-trisphosphate receptors (IP3Rs) and other intracellular channels predates the divergence of animals and fungi as evidenced by their presence in the choanoflagellate Monosiga brevicollis, the closest known relative to metazoans. The first protozoan IP3R cloned, from the ciliate Paramecium, displays strong sequence similarity to the rat type 3 IP3R. This ciliate has a large number of IP3- and ryanodine(Ry)-like receptors in six subfamilies suggesting the evolutionary adaptation to local requirements for an expanding diversification of vesicle trafficking. IP3Rs have also been functionally characterized in trypanosomatids, where they are essential for growth, differentiation, and establishment of infection. The presence of the mitochondrial calcium uniporter (MCU) in a number of protozoa indicates that mitochondrial regulation of Ca(2+) signaling is also an early appearance in evolution, and contributed to the discovery of the molecular nature of this channel in mammalian cells. There is only sequence evidence for the occurrence of two-pore channels (TPCs), transient receptor potential Ca(2+) channels (TRPCs) and intracellular mechanosensitive Ca(2+)-channels in Paramecium and in parasitic protozoa.
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Plattner H. Calcium regulation in the protozoan model, Paramecium tetraurelia. J Eukaryot Microbiol 2013; 61:95-114. [PMID: 24001309 DOI: 10.1111/jeu.12070] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 06/21/2013] [Accepted: 06/28/2013] [Indexed: 01/24/2023]
Abstract
Early in eukaryotic evolution, the cell has evolved a considerable inventory of proteins engaged in the regulation of intracellular Ca(2+) concentrations, not only to avoid toxic effects but beyond that to exploit the signaling capacity of Ca(2+) by small changes in local concentration. Among protozoa, the ciliate Paramecium may now be one of the best analyzed models. Ciliary activity and exo-/endocytosis are governed by Ca(2+) , the latter by Ca(2+) mobilization from alveolar sacs and a superimposed store-operated Ca(2+) -influx. Paramecium cells possess plasma membrane- and endoplasmic reticulum-resident Ca(2+) -ATPases/pumps (PMCA, SERCA), a variety of Ca(2+) influx channels, including mechanosensitive and voltage-dependent channels in the plasma membrane, furthermore a plethora of Ca(2+) -release channels (CRC) of the inositol 1,4,5-trisphosphate and ryanodine receptor type in different compartments, notably the contractile vacuole complex and the alveolar sacs, as well as in vesicles participating in vesicular trafficking. Additional types of CRC probably also occur but they have not been identified at a molecular level as yet, as is the equivalent of synaptotagmin as a Ca(2+) sensor for exocytosis. Among established targets and sensors of Ca(2+) in Paramecium are calmodulin, calcineurin, as well as Ca(2+) /calmodulin-dependent protein kinases, all with multiple functions. Thus, basic elements of Ca(2+) signaling are available for Paramecium.
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Affiliation(s)
- Helmut Plattner
- Department of Biology, University of Konstanz, P.O. Box 5544, 78457, Konstanz, Germany
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Plattner H. The contractile vacuole complex of protists--new cues to function and biogenesis. Crit Rev Microbiol 2013; 41:218-27. [PMID: 23919298 DOI: 10.3109/1040841x.2013.821650] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
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.
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Affiliation(s)
- Helmut Plattner
- Department of Biology, University of Konstanz , Konstanz , Germany
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Capdevila-Nortes X, López-Hernández T, Apaja PM, López de Heredia M, Sirisi S, Callejo G, Arnedo T, Nunes V, Lukacs GL, Gasull X, Estévez R. Insights into MLC pathogenesis: GlialCAM is an MLC1 chaperone required for proper activation of volume-regulated anion currents. Hum Mol Genet 2013; 22:4405-16. [DOI: 10.1093/hmg/ddt290] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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Contractile Vacuole Complex—Its Expanding Protein Inventory. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 306:371-416. [DOI: 10.1016/b978-0-12-407694-5.00009-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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