Translocation of the<i>Dictyostelium</i>TRAP1 homologue to mitochondria induces a novel prestarvation response

Morita, Tsuyoshi; Amagai, Aiko; Maeda, Yasuo

doi:10.1242/jcs.01499

Cited by 26 publications

(40 citation statements)

References 31 publications

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“…For example, the distribution of Bcl-2-associated X protein, Bax, changes from the cytoplasm to the mitochondria during apoptosis to activate the release of cytochrome c (23). Dd-TRAP1, a Dictyostelium homologue of tumor necrosis factor receptor-associated protein 1, is located in the cortex of cells growing at low density but is translocated to mitochondria when cell density is increased (24). We speculate that a post-translational modification of StarD7-I may change its localization.…”

Section: Discussionmentioning

confidence: 99%

StarD7 Mediates the Intracellular Trafficking of Phosphatidylcholine to Mitochondria

Horibata

Sugimoto

2010

Journal of Biological Chemistry

108

121

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Steroidogenic acute regulatory protein-related lipid transfer (START) domains, found in 15 mammalian proteins termed StarD1-StarD15, are lipid-binding domains implicated in the intracellular lipid transport systems. In the present study, we analyzed the lipid ligand and function of StarD7. We found two variable forms of mammalian StarD7, termed StarD7-I and StarD7-II. Unlike StarD7-II, StarD7-I contained a mitochondrial-targeting sequence in its N terminus. Overexpressed StarD7-I tagged with V5/His in HEPA-1 cells was mainly observed in the mitochondria of cells prepared at low cellular density, but it was distributed in the cytoplasm of high density cells. StarD7-II was constantly distributed in the cytoplasm at any cellular density. Endogenous StarD7 in HEPA-1 cells and rat liver was also distributed in both the cytoplasm and the mitochondria. A protease K protection assay indicated that the mitochondrial StarD7 was associated with the outer mitochondrial membrane. The purified recombinant StarD7 specifically catalyzed the transfer of PC between lipid vesicles in vitro. Furthermore, the intracellular transport of fluorescent PC that was exogenously incorporated into the mitochondria was increased in cells that overexpressed StarD7-I. These results suggest that StarD7 facilitates the delivery of PC to mitochondria in non-vesicular system.

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Section: Discussionmentioning

confidence: 99%

StarD7 Mediates the Intracellular Trafficking of Phosphatidylcholine to Mitochondria

Horibata

Sugimoto

2010

Journal of Biological Chemistry

108

121

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“…It is worth noting that the unicellular organism Dictyostelium discoideum, which does not undergo receptor-mediated caspase-dependent apoptosis, nevertheless has proteins that are homologous to components of the TNF signalling pathway. Thus it has a homologue of TNFRassociated protein 1 (TRAP1), which colocalizes with actin, as well as a TRAF-like protein (Morita et al, 2002;Morita et al, 2004). This might suggest that an ancient morphogenetic function of these components pre-dates their use in inflammatory and apoptotic functions in multicellular organisms.…”

Section: Discussionmentioning

confidence: 99%

Looking beyond death: a morphogenetic role for the TNF signalling pathway

Mathew

Haubert

Krönke

et al. 2009

Journal of Cell Science

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Tumour necrosis factor α (TNFα) is a pro-inflammatory mediator with the capacity to induce apoptosis. An integral part of its apoptotic and inflammatory programmes is the control of cell shape through modulation of the cytoskeleton, but it is now becoming apparent that this morphogenetic function of TNF signalling is also employed outside inflammatory responses and is shared by the signalling pathways of other members of the TNF-receptor superfamily. Some proteins that are homologous to the components of the TNF signalling pathway, such as the adaptor TNF-receptor-associated factor 4 and the ectodysplasin A receptor (and its ligand and adaptors), have dedicated morphogenetic roles. The mechanism by which TNF signalling affects cell shape is not yet fully understood, but Rhofamily GTPases have a central role. The fact that the components of the TNF signalling pathway are evolutionarily old suggests that an ancestral cassette from unicellular organisms has diversified its functions into partly overlapping morphogenetic, inflammatory and apoptotic roles in multicellular higher organisms.

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“…The first run was conducted with wild type Ax-2 cells in order to study starved cells in the pre-aggregating phase both in a buffer and during chemotaxis. Vegetative cells were grown axenically in growth (PS)-medium [Morita et al, 2004]. To allow the cells to differentiate, they were harvested at the exponential growth phase, washed twice in BSS (Bonner's salt solution: 0.6 g NaCl, 0.75 g KCl, 0.4 g CaCl 2 H 2 O and 1 L H 2 O, actual pH 6.4), plated on 1.5% non-nutrient agar at 5 3 10 5 cells/cm 2 during 4-6 h, and finally, collected, washed and deposited on the 22 mm circular elastomer layer at 5 3 10 4 cells/ml in a 200 lL droplet of BSS.…”

Section: Cell Culture and Developmental Conditionsmentioning

confidence: 99%

Changes in the magnitude and distribution of forces at different dictyostelium developmental stages

Delanoë-Ayari

Iwaya

Maeda

et al. 2008

Cell Motil. Cytoskeleton

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The distribution of forces exerted by migrating Dictyostelium amebae at different developmental stages was measured using traction force microscopy. By using very soft polyacrylamide substrates with a high fluorescent bead density, we could measure stresses as small as 30 Pa. Remarkable differences exist both in term of the magnitude and distribution of forces in the course of development. In the vegetative state, cells present cyclic changes in term of speed and shape between an elongated form and a more rounded one. The forces are larger in this first state, especially when they are symmetrically distributed at the front and rear edge of the cell. Elongated vegetative cells can also present a front-rear asymmetric force distribution with the largest forces in the crescent-shaped rear of the cell (uropod). Pre-aggregating cells, once polarized, only present this last kind of asymmetric distribution with the largest forces in the uropod. Except for speed, no cycle is observed. Neither the force distribution of pre-aggregating cells nor their overall magnitude are modified during chemotaxis, the later being similar to the one of vegetative cells (F(0) approximately 6 nN). On the contrary, both the force distribution and overall magnitude is modified for the fast moving aggregating cells. In particular, these highly elongated cells exert lower forces (F(0) approximately 3 nN). The location of the largest forces in the various stages of the development is consistent with the myosin II localization described in the literature for Dictyostelium (Yumura et al.,1984. J Cell Biol 99:894-899) and is confirmed by preliminary experiments using a GFP-myosin Dictyostelium strain.

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Translocation of theDictyosteliumTRAP1 homologue to mitochondria induces a novel prestarvation response

Cited by 26 publications

References 31 publications

StarD7 Mediates the Intracellular Trafficking of Phosphatidylcholine to Mitochondria

StarD7 Mediates the Intracellular Trafficking of Phosphatidylcholine to Mitochondria

Looking beyond death: a morphogenetic role for the TNF signalling pathway

Changes in the magnitude and distribution of forces at different dictyostelium developmental stages

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