1
|
Sen MG, Sanislav O, Fisher PR, Annesley SJ. The Multifaceted Interactions of Dictyostelium Atg1 with Mitochondrial Function, Endocytosis, Growth, and Development. Cells 2024; 13:1191. [PMID: 39056773 PMCID: PMC11274416 DOI: 10.3390/cells13141191] [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: 05/29/2024] [Revised: 07/04/2024] [Accepted: 07/09/2024] [Indexed: 07/28/2024] Open
Abstract
Autophagy is a degradative recycling process central to the maintenance of homeostasis in all eukaryotes. By ensuring the degradation of damaged mitochondria, it plays a key role in maintaining mitochondrial health and function. Of the highly conserved autophagy proteins, autophagy-related protein 1 (Atg1) is essential to the process. The involvement of these proteins in intracellular signalling pathways, including those involving mitochondrial function, are still being elucidated. Here the role of Atg1 was investigated in the simple model organism Dictyostelium discoideum using an atg1 null mutant and mutants overexpressing or antisense-inhibiting atg1. When evaluated against the well-characterised outcomes of mitochondrial dysfunction in this model, altered atg1 expression resulted in an unconventional set of phenotypic outcomes in growth, endocytosis, multicellular development, and mitochondrial homeostasis. The findings here show that Atg1 is involved in a tightly regulated signal transduction pathway coordinating energy-consuming processes such as cell growth and multicellular development, along with nutrient status and energy production. Furthermore, Atg1's effects on energy homeostasis indicate a peripheral ancillary role in the mitochondrial signalling network, with effects on energy balance rather than direct effects on electron transport chain function. Further research is required to tease out these complex networks. Nevertheless, this study adds further evidence to the theory that autophagy and mitochondrial signalling are not opposing but rather linked, yet strictly controlled, homeostatic mechanisms.
Collapse
Affiliation(s)
| | | | | | - Sarah Jane Annesley
- Department of Microbiology, Anatomy, Physiology and Pharmacology, La Trobe University, Bundoora, Melbourne 3086, Australia; (M.G.S.); (O.S.); (P.R.F.)
| |
Collapse
|
2
|
Allan CY, Sanislav O, Fisher PR. Polycystin-2 Mediated Calcium Signalling in the Dictyostelium Model for Autosomal Dominant Polycystic Kidney Disease. Cells 2024; 13:610. [PMID: 38607049 PMCID: PMC11012017 DOI: 10.3390/cells13070610] [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: 02/08/2024] [Revised: 03/26/2024] [Accepted: 03/27/2024] [Indexed: 04/13/2024] Open
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) occurs when the proteins Polycystin-1 (PC1, PKD1) and Polycystin-2 (PC2, PKD2) contain mutations. PC1 is a large membrane receptor that can interact and form a complex with the calcium-permeable cation channel PC2. This complex localizes to the plasma membrane, primary cilia and ER. Dysregulated calcium signalling and consequential alterations in downstream signalling pathways in ADPKD are linked to cyst formation and expansion; however, it is not completely understood how PC1 and PC2 regulate calcium signalling. We have studied Polycystin-2 mediated calcium signalling in the model organism Dictyostelium discoideum by overexpressing and knocking down the expression of the endogenous Polycystin-2 homologue, Polycystin-2. Chemoattractant-stimulated cytosolic calcium response magnitudes increased and decreased in overexpression and knockdown strains, respectively, and analysis of the response kinetics indicates that Polycystin-2 is a significant contributor to the control of Ca2+ responses. Furthermore, basal cytosolic calcium levels were reduced in Polycystin-2 knockdown transformants. These alterations in Ca2+ signalling also impacted other downstream Ca2+-sensitive processes including growth rates, endocytosis, stalk cell differentiation and spore viability, indicating that Dictyostelium is a useful model to study Polycystin-2 mediated calcium signalling.
Collapse
Affiliation(s)
| | | | - Paul R. Fisher
- Department of Microbiology, Anatomy, Physiology and Pharmacology, La Trobe University, Bundoora, Melbourne, VIC 3086, Australia; (C.Y.A.)
| |
Collapse
|
3
|
Kuwayama H, Kikuchi H, Kubohara Y. Derivatives of Differentiation-Inducing Factor 1 Differentially Control Chemotaxis and Stalk Cell Differentiation in Dictyostelium discoideum. BIOLOGY 2023; 12:873. [PMID: 37372157 DOI: 10.3390/biology12060873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 06/15/2023] [Accepted: 06/15/2023] [Indexed: 06/29/2023]
Abstract
Differentiation-inducing factors 1 and 2 (DIF-1 and DIF-2) are small lipophilic signal molecules that induce stalk cell differentiation but differentially modulate chemotaxis toward cAMP in the cellular slime mold Dictyostelium discoideum; DIF-1 suppresses chemotactic cell movement in shallow cAMP gradients, whereas DIF-2 promotes it. The receptor(s) for DIF-1 and DIF-2 have not yet been identified. We examined the effects of nine derivatives of DIF-1 on chemotactic cell movement toward cAMP and compared their chemotaxis-modulating activity and stalk cell differentiation-inducing activity in wild-type and mutant strains. The DIF derivatives differentially affected chemotaxis and stalk cell differentiation; for example, TM-DIF-1 suppressed chemotaxis and showed poor stalk-inducing activity, DIF-1(3M) suppressed chemotaxis and showed strong stalk-inducing activity, and TH-DIF-1 promoted chemotaxis. These results suggest that DIF-1 and DIF-2 have at least three receptors: one for stalk cell induction and two for chemotaxis modulation. In addition, our results show that the DIF derivatives can be used to analyze the DIF-signaling pathways in D. discoideum.
Collapse
Affiliation(s)
- Hidekazu Kuwayama
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan
| | - Haruhisa Kikuchi
- Division of Natural Medicines, Faculty of Pharmacy, Keio University, Tokyo 105-8512, Japan
| | - Yuzuru Kubohara
- Laboratory of Health and Life Science, Graduate School of Health and Sports Science, Juntendo University, Inzai 270-1695, Japan
| |
Collapse
|
4
|
Paraburkholderia Symbionts Display Variable Infection Patterns That Are Not Predictive of Amoeba Host Outcomes. Genes (Basel) 2020; 11:genes11060674. [PMID: 32575747 PMCID: PMC7349545 DOI: 10.3390/genes11060674] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/07/2020] [Accepted: 06/18/2020] [Indexed: 12/17/2022] Open
Abstract
Symbiotic interactions exist within a parasitism to mutualism continuum that is influenced, among others, by genes and context. Dynamics of intracellular invasion, replication, and prevalence may underscore both host survivability and symbiont stability. More infectious symbionts might exert higher corresponding costs to hosts, which could ultimately disadvantage both partners. Here, we quantify infection patterns of diverse Paraburkholderia symbiont genotypes in their amoeba host Dictyostelium discoideum and probe the relationship between these patterns and host outcomes. We exposed D. discoideum to thirteen strains of Paraburkholderia each belonging to one of the three symbiont species found to naturally infect D. discoideum: Paraburkholderia agricolaris, Paraburkholderia hayleyella, and Paraburkholderia bonniea. We quantified the infection prevalence and intracellular density of fluorescently labeled symbionts along with the final host population size using flow cytometry and confocal microscopy. We find that infection phenotypes vary across symbiont strains. Symbionts belonging to the same species generally display similar infection patterns but are interestingly distinct when it comes to host outcomes. This results in final infection loads that do not strongly correlate to final host outcomes, suggesting other genetic factors that are not a direct cause or consequence of symbiont abundance impact host fitness.
Collapse
|
5
|
Jiang T, Saito T, Nanbu S. Theoretical Molecular Dynamics Simulation of the DIF-1 Receptor Activation. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2019. [DOI: 10.1246/bcsj.20190071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Tianlong Jiang
- Department of Materials and Life Sciences, Sophia University, Tokyo 102-8554, Japan
| | - Tamao Saito
- Department of Materials and Life Sciences, Sophia University, Tokyo 102-8554, Japan
| | - Shinkoh Nanbu
- Department of Materials and Life Sciences, Sophia University, Tokyo 102-8554, Japan
| |
Collapse
|
6
|
Kubohara Y, Kikuchi H. Dictyostelium: An Important Source of Structural and Functional Diversity in Drug Discovery. Cells 2018; 8:E6. [PMID: 30583484 PMCID: PMC6356392 DOI: 10.3390/cells8010006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 12/19/2018] [Accepted: 12/19/2018] [Indexed: 12/12/2022] Open
Abstract
The cellular slime mold Dictyostelium discoideum is an excellent model organism for the study of cell and developmental biology because of its simple life cycle and ease of use. Recent findings suggest that Dictyostelium and possibly other genera of cellular slime molds, are potential sources of novel lead compounds for pharmacological and medical research. In this review, we present supporting evidence that cellular slime molds are an untapped source of lead compounds by examining the discovery and functions of polyketide differentiation-inducing factor-1, a compound that was originally isolated as an inducer of stalk-cell differentiation in D. discoideum and, together with its derivatives, is now a promising lead compound for drug discovery in several areas. We also review other novel compounds, including secondary metabolites, that have been isolated from cellular slime molds.
Collapse
Affiliation(s)
- Yuzuru Kubohara
- Laboratory of Health and Life Science, Graduate School of Health and Sports Science, Juntendo University, Inzai, Chiba 270-1695, Japan.
| | - Haruhisa Kikuchi
- Laboratory of Natural Product Chemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aza-aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan.
| |
Collapse
|
7
|
Kubohara Y, Kikuchi H, Nguyen VH, Kuwayama H, Oshima Y. Evidence that differentiation-inducing factor-1 controls chemotaxis and cell differentiation, at least in part, via mitochondria in D. discoideum. Biol Open 2017; 6:741-751. [PMID: 28619991 PMCID: PMC5483011 DOI: 10.1242/bio.021345] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Differentiation-inducing factor-1 [1-(3,5-dichloro-2,6-dihydroxy-4-methoxyphenyl)hexan-1-one (DIF-1)] is an important regulator of cell differentiation and chemotaxis in the development of the cellular slime mold Dictyostelium discoideum However, the entire signaling pathways downstream of DIF-1 remain to be elucidated. To characterize DIF-1 and its potential receptor(s), we synthesized two fluorescent derivatives of DIF-1, boron-dipyrromethene (BODIPY)-conjugated DIF-1 (DIF-1-BODIPY) and nitrobenzoxadiazole (NBD)-conjugated DIF-1 (DIF-1-NBD), and investigated their biological activities and cellular localization. DIF-1-BODIPY (5 µM) and DIF-1 (2 nM) induced stalk cell differentiation in the DIF-deficient strain HM44 in the presence of cyclic adenosine monosphosphate (cAMP), whereas DIF-1-NBD (5 µM) hardly induced stalk cell differentiation under the same conditions. Microscopic analyses revealed that the biologically active derivative, DIF-1-BODIPY, was incorporated by stalk cells at late stages of differentiation and was localized to mitochondria. The mitochondrial uncouplers carbonyl cyanide m-chlorophenylhydrazone (CCCP), at 25-50 nM, and dinitrophenol (DNP), at 2.5-5 µM, induced partial stalk cell differentiation in HM44 in the presence of cAMP. DIF-1-BODIPY (1-2 µM) and DIF-1 (10 nM), as well as CCCP and DNP, suppressed chemotaxis in the wild-type strain Ax2 in shallow cAMP gradients. These results suggest that DIF-1-BODIPY and DIF-1 induce stalk cell differentiation and modulate chemotaxis, at least in part, by disturbing mitochondrial activity.
Collapse
Affiliation(s)
- Yuzuru Kubohara
- Department of Molecular and Cellular Biology, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan .,Laboratory of Health and Life Science, Graduate School of Health and Sports Science, Juntendo University, Inzai, Chiba 270-1695, Japan
| | - Haruhisa Kikuchi
- Laboratory of Natural Product Chemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Van Hai Nguyen
- Laboratory of Natural Product Chemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Hidekazu Kuwayama
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan
| | - Yoshiteru Oshima
- Laboratory of Natural Product Chemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| |
Collapse
|
8
|
Golstein P. Conserved nucleolar stress at the onset of cell death. FEBS J 2017; 284:3791-3800. [DOI: 10.1111/febs.14095] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 03/31/2017] [Accepted: 04/26/2017] [Indexed: 01/19/2023]
Affiliation(s)
- Pierre Golstein
- Centre d'Immunologie de Marseille‐Luminy Aix Marseille Université Inserm, CNRS France
| |
Collapse
|
9
|
Early nucleolar disorganization in Dictyostelium cell death. Cell Death Dis 2017; 8:e2528. [PMID: 28055008 PMCID: PMC5386361 DOI: 10.1038/cddis.2016.444] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 11/23/2016] [Accepted: 11/30/2016] [Indexed: 12/13/2022]
Abstract
Cell death occurs in all eukaryotes, but it is still not known whether some core steps of the cell death process are conserved. We investigated this using the protist Dictyostelium. The dissection of events in Dictyostelium vacuolar developmental cell death was facilitated by the sequential requirement for two distinct exogenous signals. An initial exogenous signal (starvation and cAMP) recruited some cells into clumps. Only within these clumps did subsequent cell death events take place. Contrary to our expectations, already this initial signal provoked nucleolar disorganization and irreversible inhibition of rRNA and DNA synthesis, reflecting marked cell dysfunction. The initial signal also primed clumped cells to respond to a second exogenous signal (differentiation-inducing factor-1 or c-di-GMP), which led to vacuolization and synthesis of cellulose encasings. Thus, the latter prominent hallmarks of developmental cell death were induced separately from initial cell dysfunction. We propose that (1) in Dictyostelium vacuolization and cellulose encasings are late, organism-specific, hallmarks, and (2) on the basis of our observations in this protist and of similar previous observations in some cases of mammalian cell death, early inhibition of rRNA synthesis and nucleolar disorganization may be conserved in some eukaryotes to usher in developmental cell death.
Collapse
|
10
|
Mesquita A, Cardenal-Muñoz E, Dominguez E, Muñoz-Braceras S, Nuñez-Corcuera B, Phillips BA, Tábara LC, Xiong Q, Coria R, Eichinger L, Golstein P, King JS, Soldati T, Vincent O, Escalante R. Autophagy in Dictyostelium: Mechanisms, regulation and disease in a simple biomedical model. Autophagy 2016; 13:24-40. [PMID: 27715405 DOI: 10.1080/15548627.2016.1226737] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Autophagy is a fast-moving field with an enormous impact on human health and disease. Understanding the complexity of the mechanism and regulation of this process often benefits from the use of simple experimental models such as the social amoeba Dictyostelium discoideum. Since the publication of the first review describing the potential of D. discoideum in autophagy, significant advances have been made that demonstrate both the experimental advantages and interest in using this model. Since our previous review, research in D. discoideum has shed light on the mechanisms that regulate autophagosome formation and contributed significantly to the study of autophagy-related pathologies. Here, we review these advances, as well as the current techniques to monitor autophagy in D. discoideum. The comprehensive bioinformatics search of autophagic proteins that was a substantial part of the previous review has not been revisited here except for those aspects that challenged previous predictions such as the composition of the Atg1 complex. In recent years our understanding of, and ability to investigate, autophagy in D. discoideum has evolved significantly and will surely enable and accelerate future research using this model.
Collapse
Affiliation(s)
- Ana Mesquita
- a Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM) , Madrid , Spain.,b University of Cincinnati College of Medicine , Cincinnati , OH , USA
| | - Elena Cardenal-Muñoz
- c Départment de Biochimie , Faculté des Sciences, Université de Genève , Switzerland
| | - Eunice Dominguez
- a Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM) , Madrid , Spain.,d Departamento de Genética Molecular , Instituto de Fisiología Celular, Universidad Nacional Autónoma de México , Mexico City , México
| | - Sandra Muñoz-Braceras
- a Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM) , Madrid , Spain
| | | | - Ben A Phillips
- e Department of Biomedical Sciences , University of Sheffield , UK
| | - Luis C Tábara
- a Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM) , Madrid , Spain
| | - Qiuhong Xiong
- f Center for Biochemistry, Medical Faculty, University of Cologne , Cologne , Germany
| | - Roberto Coria
- d Departamento de Genética Molecular , Instituto de Fisiología Celular, Universidad Nacional Autónoma de México , Mexico City , México
| | - Ludwig Eichinger
- f Center for Biochemistry, Medical Faculty, University of Cologne , Cologne , Germany
| | - Pierre Golstein
- g Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université UM2 , Inserm, U1104, CNRS UMR7280, Marseille , France
| | - Jason S King
- e Department of Biomedical Sciences , University of Sheffield , UK
| | - Thierry Soldati
- c Départment de Biochimie , Faculté des Sciences, Université de Genève , Switzerland
| | - Olivier Vincent
- a Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM) , Madrid , Spain
| | - Ricardo Escalante
- a Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM) , Madrid , Spain
| |
Collapse
|
11
|
Secreted Cyclic Di-GMP Induces Stalk Cell Differentiation in the Eukaryote Dictyostelium discoideum. J Bacteriol 2016; 198:27-31. [PMID: 26013485 PMCID: PMC4686194 DOI: 10.1128/jb.00321-15] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Cyclic di-GMP (c-di-GMP) is currently recognized as the most widely used intracellular signal molecule in prokaryotes, but roles in eukaryotes were only recently discovered. In the social amoeba Dictyostelium discoideum, c-di-GMP, produced by a prokaryote-type diguanylate cyclase, induces the differentiation of stalk cells, thereby enabling the formation of spore-bearing fruiting bodies. In this review, we summarize the currently known mechanisms that control the major life cycle transitions of Dictyostelium and focus particularly on the role of c-di-GMP in stalk formation. Stalk cell differentiation has characteristics of autophagic cell death, a process that also occurs in higher eukaryotes. We discuss the respective roles of c-di-GMP and of another signal molecule, differentiation-inducing factor 1, in autophagic cell death in vitro and in stalk formation in vivo.
Collapse
|
12
|
Song Y, Luciani MF, Giusti C, Golstein P. c-di-GMP induction of Dictyostelium cell death requires the polyketide DIF-1. Mol Biol Cell 2014; 26:651-8. [PMID: 25518941 PMCID: PMC4325836 DOI: 10.1091/mbc.e14-08-1337] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Two inducers, DIF-1 and c-di-GMP, each separately shown to play a major role in Dictyostelium cell death induction in vitro, in fact cooperate. A similar cooperation with polyketides might occur for c-di-GMP effects in other situations and organisms, in particular in innate immunity and cell death in animal cells. Cell death in the model organism Dictyostelium, as studied in monolayers in vitro, can be induced by the polyketide DIF-1 or by the cyclical dinucleotide c-di-GMP. c-di-GMP, a universal bacterial second messenger, can trigger innate immunity in bacterially infected animal cells and is involved in developmental cell death in Dictyostelium. We show here that c-di-GMP was not sufficient to induce cell death in Dictyostelium cell monolayers. Unexpectedly, it also required the DIF-1 polyketide. The latter could be exogenous, as revealed by a telling synergy between c-di-GMP and DIF-1. The required DIF-1 polyketide could also be endogenous, as shown by the inability of c-di-GMP to induce cell death in Dictyostelium HMX44A cells and DH1 cells upon pharmacological or genetic inhibition of DIF-1 biosynthesis. In these cases, c-di-GMP–induced cell death was rescued by complementation with exogenous DIF-1. Taken together, these results demonstrated that c-di-GMP could trigger cell death in Dictyostelium only in the presence of the DIF-1 polyketide or its metabolites. This identified another element of control to this cell death and perhaps also to c-di-GMP effects in other situations and organisms.
Collapse
Affiliation(s)
- Yu Song
- Centre d'Immunologie de Marseille-Luminy, UM2 Aix-Marseille Université; Institut National de la Santé et de la Recherche Médicale, U1104; and Centre National de la Recherche Scientifique, UMR7280, 13288 Marseille, France
| | - Marie-Françoise Luciani
- Centre d'Immunologie de Marseille-Luminy, UM2 Aix-Marseille Université; Institut National de la Santé et de la Recherche Médicale, U1104; and Centre National de la Recherche Scientifique, UMR7280, 13288 Marseille, France
| | - Corinne Giusti
- Centre d'Immunologie de Marseille-Luminy, UM2 Aix-Marseille Université; Institut National de la Santé et de la Recherche Médicale, U1104; and Centre National de la Recherche Scientifique, UMR7280, 13288 Marseille, France
| | - Pierre Golstein
- Centre d'Immunologie de Marseille-Luminy, UM2 Aix-Marseille Université; Institut National de la Santé et de la Recherche Médicale, U1104; and Centre National de la Recherche Scientifique, UMR7280, 13288 Marseille, France
| |
Collapse
|
13
|
Singleton CK, Xiong Y. Loss of the histidine kinase DhkD results in mobile mounds during development of Dictyostelium discoideum. PLoS One 2013; 8:e75618. [PMID: 24086589 PMCID: PMC3783435 DOI: 10.1371/journal.pone.0075618] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Accepted: 08/15/2013] [Indexed: 12/04/2022] Open
Abstract
Background Histidine kinases are receptors for sensing cellular and environmental signals, and in response to the appropriate cue they initiate phosphorelays that regulate the activity of response regulators. The Dictyostelium discoideum genome encodes 15 histidine kinases that function to regulate several processes during the multicellular developmental program, including the slug to culmination transition, osmoregulation, and spore differentiation. While there are many histidine kinases, there is only a single response regulator, RegA. Not surprisingly given the ubiquitous involvement of cAMP in numerous processes of development in Dictyostelium, RegA is a cAMP phosphodiesterase that is activated upon receiving phosphates through a phosphorelay. Hence, all of the histidine kinases characterized to date regulate developmental processes through modulating cAMP production. Here we investigate the function of the histidine kinase DhkD. Principal Findings The dhkD gene was disrupted, and the resulting cells when developed gave a novel phenotype. Upon aggregation, which occurred without streaming, the mounds were motile, a phenotype termed the pollywog stage. The pollywog phenotype was dependent on a functional RegA. After a period of random migration, the pollywogs attempted to form fingers but mostly generated aberrant structures with no tips. While prestalk and prespore cell differentiation occurred with normal timing, proper patterning did not occur. In contrast, wild type mounds are not motile, and the cAMP chemotactic movement of cells within the mound facilitates proper prestalk and prespore patterning, tip formation, and the vertical elongation of the mound into a finger. Conclusions We postulate that DhkD functions to ensure the proper cAMP distribution within mounds that in turn results in patterning, tip formation and the transition of mounds to fingers. In the absence of DhkD, aberrant cell movements in response to an altered cAMP distribution result in mound migration, a lack of proper patterning, and an inability to generate normal finger morphology.
Collapse
Affiliation(s)
- Charles K. Singleton
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- * E-mail:
| | - Yanhua Xiong
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| |
Collapse
|