Translocation of the Dictyostelium TRAP1 homologue to mitochondria induces a novel prestarvation response.
Dd-TRAP1 is a Dictyostelium homologue of tumor necrosis factor receptor-associated protein 1 (TRAP-1). Dd-TRAP1 is located in the cortex of cells growing at a low density, but was found to be translocated to mitochondria with the help of a novel prestarvation factor that was accumulated in growth medium along with increased cell densities. The knockdown mutant of Dd-TRAP1 (TRAP1-RNAi cells) exhibited a significant defect in prestarvation response. Although TRAP1-RNAi cells showed normal expressions of classical prestarvation genes [dscA (discoidin I) and car1 (carA; cAMP receptor)], the expression of differentiation-associated genes (dia1 and dia3) induced by the prestarvation response were markedly repressed. By contrast, transformants overexpressing Dd-TRAP1 showed an early prestarvation response and also increased expression of dia1 and dia3 in a cell-density-dependent manner. Importantly, introduction of Dd-TRAP1 antibody into D. discoideum Ax-2 cells by electroporation inhibited the translocation of Dd-TRAP1 from the cortex to mitochondria and greatly inhibited the initiation of differentiation. Taken together, these results indicate that Dd-TRAP1 is translocated to mitochondria by sensing the cell density in growth medium and enhances the early developmental program through a novel prestarvation response.
Morita
Tsuyoshi
T
Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aoba, Sendai 980-8578, Japan.
Amagai
Aiko
A
Maeda
Yasuo
Y
D000818:Animals; D015152:Blotting, Northern; D002454:Cell Differentiation; D000242:Cyclic AMP / Q000378:metabolism; D003594:Cytoplasmic Granules / Q000378:metabolism; D004023:Dictyostelium; D000070821:Discoidins; D018274:Electroporation; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism; D037102:Lectins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000378:metabolism*; D008957:Models, Genetic; D009154:Mutation; D021381:Protein Transport; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D012313:RNA / Q000378:metabolism; D034622:RNA Interference; D011953:Receptors, Cyclic AMP / Q000378:metabolism; D033761:Spores, Protozoan / Q000254:growth & development; D013997:Time Factors; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins / Q000378:metabolism*
C412162:Dia1 protein, Dictyostelium; D000070821:Discoidins; D018841:HSP90 Heat-Shock Proteins; D037102:Lectins; D015800:Protozoan Proteins; D011953:Receptors, Cyclic AMP; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins; C068125:cyclic AMP receptor cAR1; D012313:RNA; D000242:Cyclic AMP