CBP7 Interferes with the Multicellular Development of Dictyostelium Cells by Inhibiting Chemoattractant-Mediated Cell Aggregation

박병규,신동엽,전택중 한국분자세포생물학회 2018 Molecules and cells Vol.41 No.2

Calcium ions are involved in the regulation of diverse cellular processes. Fourteen genes encoding calcium binding proteins have been identified in Dictyostelium. CBP7, one of the 14 CBPs, is composed of 169 amino acids and contains four EF-hand motifs. Here, we investigated the roles of CBP7 in the development and cell migration of Dictyostelium cells and found that high levels of CBP7 exerted a negative effect on cells aggregation during development, possibly by inhibiting chemoattractant-directed cell migration. While cells lack-ing CBP7 exhibited normal development and chemotaxis similar that of wild-type cells, CBP7 overexpressing cells completely lost their chemotactic abilities to move toward increasing cAMP concentrations. This resulted in inhibition of cellular aggregation, a process required for forming multicellular organisms during development. Low levels of cytosolic free calcium were observed in CBP7 overexpressing cells, which was likely the underlying cause of their lack of chemotaxis. Our results demonstrate that CBP7 plays an important role in cell spreading and cell-substrate adhesion. cbp7 null cells showed decreased cell size and cell-substrate adhesion. The present study contributes to further understanding the role of calcium signaling in regulation of cell migration and development.

CBP7 Interferes with the Multicellular Development of Dictyostelium Cells by Inhibiting Chemoattractant-Mediated Cell Aggregation

Park, Byeonggyu,Shin, Dong-Yeop,Jeon, Taeck Joong Korean Society for Molecular and Cellular Biology 2018 Molecules and cells Vol.41 No.2

Calcium ions are involved in the regulation of diverse cellular processes. Fourteen genes encoding calcium binding proteins have been identified in Dictyostelium. CBP7, one of the 14 CBPs, is composed of 169 amino acids and contains four EF-hand motifs. Here, we investigated the roles of CBP7 in the development and cell migration of Dictyostelium cells and found that high levels of CBP7 exerted a negative effect on cells aggregation during development, possibly by inhibiting chemoattractant-directed cell migration. While cells lacking CBP7 exhibited normal development and chemotaxis similar that of wild-type cells, CBP7 overexpressing cells completely lost their chemotactic abilities to move toward increasing cAMP concentrations. This resulted in inhibition of cellular aggregation, a process required for forming multicellular organisms during development. Low levels of cytosolic free calcium were observed in CBP7 overexpressing cells, which was likely the underlying cause of their lack of chemotaxis. Our results demonstrate that CBP7 plays an important role in cell spreading and cell-substrate adhesion. cbp7 null cells showed decreased cell size and cell-substrate adhesion. The present study contributes to further understanding the role of calcium signaling in regulation of cell migration and development.

Opposite functions of RapA and RapC in cell adhesion and migration in Dictyostelium

전지현,김동주,전택중 한국통합생물학회 2021 Animal cells and systems Vol.25 No.4

There are three Rap proteins in Dictyostelium. RapA is a key regulator of cell adhesion and cytoskeletal rearrangement. Recently, RapC has been reported to be involved in cytokinesis, cell migration, and multicellular development. Here, we compare the functions of RapA and RapC using cells expressing or lacking Rap proteins, and confirm that RapA and RapC have opposite functions in cell spreading, adhesion, and migration. On the other hand, RapC has a unique function in cytokinesis and multicellular development. Activated RapA appears to stimulate spreading and adhesion of the cells to the substrate, possibly resulting in a decrease in the migration speed of the cells during chemotaxis without affecting the directionality, whereas RapC suppresses cell spreading and adhesion, thereby increasing the migration speed. Cells lacking RapC were defective in cytokinesis and multicellular development and showed multinucleation and formation of multiple tips from a mound during development. At the Cterminus, RapC has an additional stretch of amino acids, which is not found in RapA. The mechanism through which RapA and RapC perform their opposite functions in diverse cellular processes should be characterized further to understand the Rap signaling pathways in detail.

Dynamic Localization of the Actin-Bundling Pro-tein Cortexillin I during Cell Migration

Injun Cha,전택중 한국분자세포생물학회 2011 Molecules and cells Vol.32 No.3

Cortexillins are actin-bundling proteins that play a critical role in regulating cell morphology and actin cytoskeleton reorganization in Dictyostelium. Here, we investigated dynamic subcellular localization of cortexillin I in chemo-taxing Dictyostelium cells. Most of the cortexillin I was enriched on the lateral sides of moving cells. Upon che-moattractant stimulation, cortexillin I was rapidly re-leased from the cortex followed by a transient transloca-tion to the cell cortex with a peak at ~5 s and a subsequent decrease to basal levels, indicating that localization of cor-texillin I at the cortex in chemotaxing cells is controlled by two more signaling components, one for the initial delocalization from the cortex and another for the translocation to the cortex ~5 s after chemoattractant stimulation. Loss of cortexillins leads to reduced cell polarity and an in-creased number of lateral pseudopodia during chemotaxis, suggesting that cortexillins play an inhibitory role in producing pseudopodia along the lateral sides of the cell. Cells lacking cortexillins displayed extended chemoattrac-tant-mediated Arp2/3 complex translocation kinetics to the cortex. Our present study provides a new insight into the function of cortexillins during reorganization of the actin cytoskeleton and cell migration.

Chemoattractant-Mediated Rap1 Activation Requires GPCR/G Proteins

Cha, In-Jun,Lee, Sung-H.,Jeon, Taeck-J Korean Society for Molecular and Cellular Biology 2010 Molecules and cells Vol.30 No.6

Rap1 is rapidly activated upon chemoattractant stimulation and plays an important role in cell adhesion and cytoskeletal reorganization during chemotaxis. Here, we demonstrate that G-protein coupled receptors and G-proteins are essential for chemoattractant-mediated Rap1 activation in Dictyostelium. The rapid Rap1 activation upon cAMP chemoattractant stimulation was absent in cells lacking chemoattractant cAMP receptors cAR1/cAR3 or a subunit of the heterotrimeric G-protein complex G${\alpha}$2. Loss of guanylyl cyclases GCA/SGC or a cGMP-binding protein GbpC exhibited no effect on Rap1 activation kinetics. These results suggest that Rap1, a key regulator for the regulation of cytoskeletal reorganization during cell movement, is activated through the G-protein coupled receptors cAR1/cAR3 and G${\alpha}$2 proteins in a way independent of the cGMP signaling pathway.

Chemoattractant-Mediated Rap1 Activation Requires GPCR/G Proteins

Injun Cha,Sung H. Lee,전택중 한국분자세포생물학회 2010 Molecules and cells Vol.30 No.6

Rap1 is rapidly activated upon chemoattractant stimulation and plays an important role in cell adhesion and cytoskeletal reorganization during chemotaxis. Here, we demonstrate that G-protein coupled receptors and G-proteins are essential for chemoattractant-mediated Rap1 activation in Dictyostelium. The rapid Rap1 activation upon cAMP chemoattractant stimulation was absent in cells lacking chemoattractant cAMP receptors cAR1/cAR3 or a subunit of the heterotrimeric G-protein complex Gα2. Loss of guanylyl cyclases GCA/SGC or a cGMP-binding protein GbpC exhibited no effect on Rap1 activation kinetics. These results suggest that Rap1, a key regulator for the regulation of cytoskeletal reorganization during cell movement,is activated through the G-protein coupled receptors cAR1/cAR3 and Gα2 proteins in a way independent of the cGMP signaling pathway

Functional Genomics of the Social Amoebae, Dictyostelium discoideum

Hideko Urushihara 한국분자세포생물학회 2002 Molecules and cells Vol.13 No.1

Dictyostelium discoideum is one of the simplest organisms to form a multicellular structure, and it offers several advantages as a model. In order to understand the genetic basis of the multicellular development, a comprehensive analysis of cDNAs is being performed. To date, about 75,000 ESTs have been collected at different stages of development. They have been assembled into about 6,400 independent sequences that represent 70–80% of all of the expected genes in D. discoideum. The results are available on the Internet. In addition to structural analyses, functional analyses of the temporal and spatial expression patterns and gene targeting are being carried out. Furthermore, there are plans to combine the information that is obtained from the cDNA, Genome, and Proteome Projects, as well as the published results, into an integrated database, DictyBase.

Tetrahydropteridines possess antioxidant roles to guard against glucose-induced oxidative stress in Dictyostelium discoideum

( Seon Ok Park ),( Hye Lim Kim ),( Soo Woong Lee ),( Young Shik Park ) 생화학분자생물학회 2013 BMB Reports Vol.46 No.2

Glucose effects on the vegetative growth of Dictyostelium discoideum Ax2 were studied by examining oxidative stress and tetrahydropteridine synthesis in cells cultured with different concentrations (0.5X, 7.7 g L-1; 1X, 15.4 g L-1; 2X, 30.8 g L-1) of glucose. The growth rate was optimal in 1X cells (cells grown in 1X glucose) but was impaired drastically in 2X cells, below the level of 0.5X cells. There were glucose-dependent increases in reactive oxygen species (ROS) levels and mitochondrial dysfunction in parallel with the mRNA copy numbers of the enzymes catalyzing tetrahydropteridine synthesis and regeneration. On the other hand, both the specific activities of the enzymes and tetrahydropteridine levels in 2X cells were lower than those in 1X cells, but were higher than those in 0.5X cells. Given the antioxidant function of tetrahydropteridines and both the beneficial and harmful effects of ROS, the results suggest glucose-induced oxidative stress in Dictyostelium, a process that might originate from aerobic glycolysis, as well as a protective role of tetrahydropteridines against this stress. [BMB Reports 2013; 46(2): 86-91].

설악산에서의 세포성 점균의 신종 : Dictyostelium caudabasis

심규철,장남기 한국생태학회 1998 Journal of Ecology and Environment Vol.21 No.2

One new species of cellular slime molds, Dictyostelium caudabasis sp. nov. Shim et chang, is isolated from soils in the Quercus mongolica forest of Seorak monutain, South Korea. D. caudabasis is charaterized by small sorophores, scarecely phototrophic, irregularly or sparsely branches, capitate-simple or capitate-compound and sometimes obtuse-simple tips, and conical and sometimes clavate bases. Spore are elliptical, $6.52~4.82{\times}3.40~2.83{\mu}m(avg.\;5.72{times}3.17{\mu}m$), L/W index 1.70-1.92(avg. 1.80) without polar grnules.

Dictyostelium discoideum의 포자가 발아중에 유출하는 protease에 관하여

윤경하,윤철호 한국미생물학회 1989 미생물학회지 Vol.27 No.1

Characteristics and roles of protease released during the germination of Dictyostelium discoideum spores were investigated. When geat activated, the spores germinated, progressively releasing the protease into the extracellular medium. The protease activity exhibited high at pH 2.5. When cyclogeximide was added to culture, complete germination (emergence) and protease release were stopped. Addition of purified nonspecific protease to culture speeded up germination. These results suggest that excreted protease may play a role in removal of the spore wall.