Cell growth and morphology of Dictyostelium discoideum in space environment.

Ohnishi, Takeo; Takahashi, Akihisa; Okaichi, Kumio; Ohnishi, Ken; Matsumoto, Hideki; Takahashi, Sayaka; Yamanaka, Hisashi; Nakano, Tamotsu; Nagaoka, Shunji

doi:10.2187/bss.11.29

Cited by 18 publications

(7 citation statements)

References 13 publications

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“…The resulting stalk is very fragile and difficult to lift from the agar. In wild-type cells, gravitation has little effect on fruiting body formation (16). In roco4-null cells, we observed by putting the agar plates upside down that morphogenesis of a hanging fruiting body is very much improved, even though stalks are defective in cellulose.…”

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confidence: 74%

Characterization of the Roco Protein Family in Dictyostelium discoideum

Egmond

Haastert

2010

Eukaryot Cell

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The Roco family consists of multidomain Ras-GTPases that include LRRK2, a protein mutated in familial Parkinson's disease. The genome of the cellular slime mold Dictyostelium discoideum encodes 11 Roco proteins. To study the functions of these proteins, we systematically knocked out the roco genes. Previously described functions for GbpC, Pats1, and QkgA (Roco1 to Roco3) were confirmed, while novel developmental defects were identified in roco4-and roco11-null cells. Cells lacking Roco11 form larger fruiting bodies than wild-type cells, while roco4-null cells show strong developmental defects during the transition from mound to fruiting body; prestalk cells produce reduced levels of cellulose, leading to unstable stalks that are unable to properly lift the spore head. Detailed phylogenetic analysis of four slime mold species reveals that QkgA and Roco11 evolved relatively late by duplication of an ancestor roco4 gene (later than ϳ300 million years ago), contrary to the situation with other roco genes, which were already present before the split of the common ancestor of D. discoideum and Polysphondylium pallidum (before ϳ600 million years ago). Together, our data show that the Dictyostelium Roco proteins serve a surprisingly diverse set of functions and highlight Roco4 as a key protein for proper stalk cell formation.The Roco protein family is characterized by sharing a conserved core, consisting of a Ras-like GTPase called Roc (Ras of complex proteins) and a COR (C-terminal Of Roc) domain, often with a C-terminal kinase domain and several N-terminal leucine-rich repeats (LRR) (5, 14). The Dictyostelium cyclic GMP (cGMP)-binding protein GbpC was the seed of the family, in combination with 10 other genes encoding Roco proteins in Dictyostelium. Although the family did not draw much attention in the first years after its discovery, this rapidly changed when mutations in the human Roco protein LRRK2 were linked to the development of Parkinson's disease (PD) (3,15,17,22,28). Since then, most work on Roco proteins has focused on the biological and biochemical characterization of LRRK2 and GbpC. Phosphorylation studies have revealed that pathogenic mutations in LRRK2 lead to an increase in kinase activity and neuronal toxicity (26,27). Currently, it is not well understood how mutations in LRRK2 exactly lead to the loss of dopaminergic neurons and formation of so-called Lewis bodies, which are characteristic for the development of PD, but recent evidence hints at a role for LRRK2 in the activation of programmed cell death, through activation of caspase-8 (10).Dictyostelium cells that lack the cGMP-binding protein GbpC show abnormal phosphorylation and assembly of myosin II, which is needed to control the back of the cell during chemotaxis (7). The role of cGMP, and thus GbpC, in chemotaxis becomes even more evident when two other signaling pathways for chemotaxis (PLA2 and PI3K) are inhibited: under these circumstances, cells become solely dependent on the cGMP pathway for chemotaxis toward the chemoattractant cAMP (25...

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confidence: 74%

Characterization of the Roco Protein Family in Dictyostelium discoideum

Egmond

Haastert

2010

Eukaryot Cell

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“…In contrast, microgravity depressed cell killing in microorganisms of Micrococcus radiodurans (Kobayashi et al 1996). On the other hand, many reports described no observable effects from microgravity on space radiation (Harada et al, 1997(Harada et al, , 1998a(Harada et al, , 1998bOhnishi et al, 1997. Such systems include DNA repair in Escherichia coli, chemical reactions involved in rejoining activity during the repair of double strand breaks by DNA ligase (Takahashi et al, 2000), and mutation frequencies generated by chemical reactions involved in DNA polymerase repair of damaged template DNA.…”

Section: Mutation Analysismentioning

confidence: 99%

Expression of p53-Regulated Genes in Cultured Mammalian Cells After Exposure to A Space Environment

et al. 2009

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The space environment contains two major biologically significant influences; space radiation and microgravity. The tumor suppressor gene product p53 is generally thought to contribute to the genetic stability of cells with DNA damage through the activity of p53 initiated signal transduction pathways. We propose to investigate the expression of p53-regulated g e n e s i n c u l t u r e d m a m m a l i a n c e l l s a f t e r exposure to a space environment. We expect that the data from this proposal will be useful for designing physiological protection against the serious effects of space radiation during long-term stays in space. ©2009 Jpn. Soc. Biol. Sci.

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“…For the assessment and management of human health risks in space, it is necessary to obtain more basic data of the combined effects on radiation under microgravity. The diverse biological effects of space radiation have been reported such as: (i) there was no significant difference in the results between the space samples and ground samples (Bender et al, 1968;Horneck et al, 1997;Ohnishi et al, 1997;Pross and Kiefer, 1999;Takahashi et al, 2001Takahashi et al, , 2000Takahashi et al, , 1997; (ii) enhancing effects were induced in the presence of microgravity and space radiation (Bücker et al, 1986;Gao et al, 2015;Ikenaga et al, 1997;Xu et al, 2014); and (iii) suppressing effects (i.e., recovery from radiation damage was enhanced under microgravity) have also been observed (Kobayashi et al, 1996). These controversial data (Yatagai and Ishioka, 2014) may be the result of the diversity of biological experimental systems flown on spacecraft and restrictions concerning replicate experiments.…”

Section: Introductionmentioning

confidence: 99%

A New System for Three-dimensional Clinostat Synchronized X-irradiation with a High-speed Shutter for Space Radiation Research

et al. 2016

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Considering further human activity in space, it is necessary to study the biological effects of combined microgravity and space radiation; however, many aspects of these combined effects remain unclear. In the field of space biology, it is difficult to investigate relative biological effectiveness (RBE) and combined effects because the ability to conduct and replicate space experiments is restricted. Therefore, a new three-dimensional (3D) clinostat synchronized X-irradiation system with a high-speed shutter was fabricated following the development of a heavy-ion irradiation system. This study showed that the system could simultaneously irradiate rotating samples using the 3D clinostat, with the samples in a horizontal position. The samples were completely irradiated because of the flatness and symmetry of the irradiation fields. Doses were virtually identical under both standing and rotation conditions, with the difference being <1% under the assumption of X-irradiation at a dose of 1 Gy. Our new device could accurately synchronize X-irradiation and simulated microgravity at the ground level. The device is expected to greatly contribute to space radiation research as a valuable platform for studies concerning RBE and the combined effects of radiation under microgravity. ©2016 Jpn. Soc. Biol. Sci.

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Cell growth and morphology of Dictyostelium discoideum in space environment.

Cited by 18 publications

References 13 publications

Characterization of the Roco Protein Family in Dictyostelium discoideum

Characterization of the Roco Protein Family in Dictyostelium discoideum

Expression of p53-Regulated Genes in Cultured Mammalian Cells After Exposure to A Space Environment

A New System for Three-dimensional Clinostat Synchronized X-irradiation with a High-speed Shutter for Space Radiation Research

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