Reverse genetic analyses of gamete-enriched genes revealed a novel regulator of the cAMP signaling pathway in Dictyostelium discoideum

Muramoto, Tetsuya; Takeda, Shugaku; Furuya, Yoko; Urushihara, Hideko

doi:10.1016/j.mod.2004.11.015

Cited by 18 publications

(16 citation statements)

References 25 publications

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“…Knockout of an 82% similar gene, tmcC , did not alter macrocyst formation or the expression of phosphodiesterase or its inhibitor leaving its function to be resolved. Knockouts or knockdowns for two unknown proteins produced abnormal macrocysts while one for racF2 altered growth suggesting that other genes are involved which remain to be characterized (Muramoto et al , 2005). Interestingly, knockouts for 16 of the gamete‐specific genes and RNAi inhibition of 20 others had no effect on macrocyst formation.…”

Section: Heterothallic Sexual Development Of Dictyostelium Discoimentioning

confidence: 99%

Signalling and sex in the social amoebozoans

O’Day

Keszei

2011

Biological Reviews

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The social amoebozoans have a life tricycle consisting of asexual multicellular development leading to fruiting bodies, sexual multicellular development resulting in macrocysts, and unicellular development generating microcysts. This review covers the events of sexual development in the best-studied heterothallic (Dictyostelium discoideum) and homothallic (D. mucoroides) mating systems. Sexual development begins with pheromonal interactions that produce fusion-competent cells (gametes) which undergo cell and pronuclear fusion. Calcium- and calmodulin-mediated signalling mediates these early events. As they initiate chemotactic signalling, each zygote increases in size becoming a zygote giant cell. Using cyclic AMP (cAMP), the zygote chemotactically lures in amoebae and engulfs them in an act of cannibalistic phagocytosis. Chemotaxis proceeds more quickly than endocytosis because the breakdown products of cAMP (5-AMP, adenosine) bind to a presumptive adenosine receptor to inhibit sexual phagocytosis. This slowing of phagocytosis allows amoebae to accumulate around the zygote to form a precyst aggregate. Zygote giant cells also produce several other signalling molecules that feed back to regulate early events. The amoebae surrounding the zygote seal their fate as zygotic foodstuff by secreting a primary cellulose wall, the extracellular sheath, around the zygote and aggregated amoebae, which prevents their escape. Phagocytosis within this precyst continues until all peripheral amoebae are internalized as endocytes and the final macrocyst wall is formed. Endocyte digestion results in a mature macrocyst with a uniform cytoplasm containing a diploid nucleus. After detailing the morphological events of heterothallic and homothallic mating, we review the various intercellular signalling events and other mechanisms involved in each stage. This complete and comprehensive review sets the stage for future research on the unique events that characterize sex in the social amoebozoans.

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Section: Heterothallic Sexual Development Of Dictyostelium Discoimentioning

confidence: 99%

Signalling and sex in the social amoebozoans

O’Day

Keszei

2011

Biological Reviews

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“…Transformation was carried out as described (Muramoto et al, 2005). Selection of stable clones expressing GFP-PCNA used 10 μg/ml G418.…”

Section: Generation Of Transgenic Cell Linesmentioning

confidence: 99%

Live imaging of theDictyosteliumcell cycle reveals widespread S phase during development, a G2 bias in spore differentiation and a premitotic checkpoint

Muramoto

Chubb

2008

Development

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The regulation of the Dictyostelium cell cycle has remained ambiguous owing to difficulties in long-term imaging of motile cells and a lack of markers for defining cell cycle phases. There is controversy over whether cells replicate their DNA during development, and whether spores are in G1 or G2 of the cell cycle. We have introduced a live-cell S-phase marker into Dictyostelium cells that allows us to precisely define cycle phase. We show that during multicellular development, a large proportion of cells undergo nuclear DNA synthesis. Germinating spores enter S phase only after their first mitosis, indicating that spores are in G2. In addition, we demonstrate that Dictyostelium heterochromatin is copied late in S phase and replicates via accumulation of replication factors, rather than recruitment of DNA to pre-existing factories. Analysis of variability in cycle times indicates that regulation of the cycle manifests at a single random transition in G2, and we present the first identified checkpoint in Dictyostelium, which operates at the G2-M transition in response to DNA damage.

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“…During this alternative life cycle, phermonal interactions generate fusion-competent cells, which then undergo cell and pronuclear fusion through a process involving cAMP chemotaxis. kctd9 − cells show no obvious phenotypes during macrocyst formation, however kctd9 expression is enriched in gametes (e.g., sexually mature, fusion-competent cells) [117, 118] suggesting that the protein may be involved in membrane fusion during sexual development. The research community would benefit from future work examining the precise function of Kctd9 during membrane fusion as well as examining the effect of Kctd9 loss on processes that occur during the Dictyostelium asexual life cycle.…”

Section: Introductionmentioning

confidence: 99%

Using the social amoeba Dictyostelium to study the functions of proteins linked to neuronal ceroid lipofuscinosis

Huber

2016

J Biomed Sci

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Neuronal ceroid lipofuscinosis (NCL), also known as Batten disease, is a debilitating neurological disorder that affects both children and adults. Thirteen genetically distinct genes have been identified that when mutated, result in abnormal lysosomal function and an excessive accumulation of ceroid lipofuscin in neurons, as well as other cell types outside of the central nervous system. The NCL family of proteins is comprised of lysosomal enzymes (PPT1/CLN1, TPP1/CLN2, CTSD/CLN10, CTSF/CLN13), proteins that peripherally associate with membranes (DNAJC5/CLN4, KCTD7/CLN14), a soluble lysosomal protein (CLN5), a protein present in the secretory pathway (PGRN/CLN11), and several proteins that display different subcellular localizations (CLN3, CLN6, MFSD8/CLN7, CLN8, ATP13A2/CLN12). Unfortunately, the precise functions of many of the NCL proteins are still unclear, which has made targeted therapy development challenging. The social amoeba Dictyostelium discoideum has emerged as an excellent model system for studying the normal functions of proteins linked to human neurological disorders. Intriguingly, the genome of this eukaryotic soil microbe encodes homologs of 11 of the 13 known genes linked to NCL. The genetic tractability of the organism, combined with its unique life cycle, makes Dictyostelium an attractive model system for studying the functions of NCL proteins. Moreover, the ability of human NCL proteins to rescue gene-deficiency phenotypes in Dictyostelium suggests that the biological pathways regulating NCL protein function are likely conserved from Dictyostelium to human. In this review, I will discuss each of the NCL homologs in Dictyostelium in turn and describe how future studies can exploit the advantages of the system by testing new hypotheses that may ultimately lead to effective therapy options for this devastating and currently untreatable neurological disorder.

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Reverse genetic analyses of gamete-enriched genes revealed a novel regulator of the cAMP signaling pathway in Dictyostelium discoideum

Cited by 18 publications

References 25 publications

Signalling and sex in the social amoebozoans

Signalling and sex in the social amoebozoans

Live imaging of theDictyosteliumcell cycle reveals widespread S phase during development, a G2 bias in spore differentiation and a premitotic checkpoint

Using the social amoeba Dictyostelium to study the functions of proteins linked to neuronal ceroid lipofuscinosis

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