Involvement of the glucose-regulated protein 94 (Dd-GRP94) in starvation response of Dictyostelium discoideum cells.
Upon deprivation of nutrients, Dictyostelium discoideum Ax-2 cells arrest proliferation and initiate a metamorphosed developmental program including induction of altered gene expressions which are necessary for differentiation. In Ax-2 cells, we found out a member of Hsp90 family usually contained in the endoplasmic reticulum (ER), Dd-GRP94 (Dictyostelium discoideum glucose-regulated protein 94). In general, GRP94 are induced either by glucose-depletion or by depletion of Ca(2+) in intracellular Ca(2+) stores. Unexpectedly, however, the expression of Dd-grp94 was greatly reduced within 60 min of starvation. Dd-grp94-overexpressing cells (GRP94(OE) cells) collected without forming distinct aggregation streams, and never formed normal fruiting bodies. Also, prespore differentiation as well as maturation into spores and stalk cells were particularly impaired in the GRP94(OE) cells. Thus Dd-GRP94 seems to be crucial in late differentiation as well as in starvation response.
Biological Institute, Graduate School of Science, Tohoku University, Aoba, Sendai, 980-8578, Japan. tsuyo@biology.tohoku.ac.jp
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Morita
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Saitoh
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Takagi
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Maeda
D000596:Amino Acids / Q000172:deficiency / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation / Q000502:physiology; D000242:Cyclic AMP / Q000378:metabolism / Q000494:pharmacology; D004023:Dictyostelium / Q000166:cytology / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D018274:Electroporation; D005508:Food Deprivation / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D005947:Glucose / Q000172:deficiency / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D011953:Receptors, Cyclic AMP / Q000096:biosynthesis; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D000596:Amino Acids; D018840:HSP70 Heat-Shock Proteins; D008565:Membrane Proteins; D011953:Receptors, Cyclic AMP; C068125:cyclic AMP receptor cAR1; C018551:glucose-regulated proteins; D000242:Cyclic AMP; D005947:Glucose