CD4(+)CD8(+) thymocytes are induced to cell death by a small dose of puromycin via ER stress.
When the CD4(+)CD8(+) thymic lymphoma cells were treated with puromycin, we found that most of the cells died at 0.3-1 microg/ml of puromycin within 24h. However, cell death was greatly reduced when the dose of puromycin was increased. Similar dose-pattern of cell death was observed in thymocytes and the sensitivity to puromycin was greater in CD4(+)CD8(+) thymocytes than CD4(+)CD8(-) thymocytes. The induction of apoptosis was blocked by the protein synthesis inhibitor cycloheximide, and to some extent by transfection of Bcl-xL or Bcl-2 genes. Expression of GRP78 was up-regulated after treatment with a small dose of puromycin, and the cell death by puromycin was blocked in the presence of caspase 12 inhibitor. These results indicated that the induction of cell death by low-dose puromycin was due to endoplasmic reticulum stress. Furthermore, we found that dexamethasone, a synthetic glucocorticoid, and puromycin worked synergistically to induce cell death in thymocytes.
Oguma
Takemi
T
Department of Parasitology and Immunology, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan. oguma@ndmc.ac.jp
Ono
Takeshi
T
Kajiwara
Toshimitsu
T
Sato
Masaki
M
Miyahira
Yasushi
Y
Arino
Hiroshi
H
Yoshihara
Yasuo
Y
Tadakuma
Takushi
T
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D015704:CD4 Antigens / Q000276:immunology*; D016827:CD8 Antigens / Q000276:immunology*; D002460:Cell Line; D003907:Dexamethasone / Q000008:administration & dosage; D004357:Drug Synergism; D004721:Endoplasmic Reticulum / Q000187:drug effects*; D000091342:Endoplasmic Reticulum Chaperone BiP; D005434:Flow Cytometry; D019254:Genes, bcl-2; D005938:Glucocorticoids / Q000008:administration & dosage; D006360:Heat-Shock Proteins / Q000378:metabolism; D051379:Mice; D011500:Protein Synthesis Inhibitors / Q000008:administration & dosage*; D011691:Puromycin / Q000008:administration & dosage*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016176:T-Lymphocyte Subsets / Q000187:drug effects* / Q000276:immunology; D014162:Transfection; D051020:bcl-X Protein / Q000235:genetics
D015704:CD4 Antigens; D016827:CD8 Antigens; D000091342:Endoplasmic Reticulum Chaperone BiP; D005938:Glucocorticoids; D006360:Heat-Shock Proteins; C000717248:Hspa5 protein, mouse; D011500:Protein Synthesis Inhibitors; D051020:bcl-X Protein; D011691:Puromycin; D003907:Dexamethasone