Aggregation of Thy-1 glycoprotein induces thymocyte apoptosis through activation of CPP32-like proteases.
Mouse thymocytes are known to undergo apoptosis by ligating some unique anti-Thy-1 monoclonal antibodies (mAbs), G7 and KT16. However, the precise mechanisms of Thy-1-mediated apoptosis are as yet unclear. We investigated Thy-1-mediated apoptosis using our previously generated anti-Thy-1 mAb, MCS-34, which was similar to G7 because both antibodies recognized both Thy-1.1 and Thy-1.2 and bound Thy-1A epitope. Unlike G7, MCS-34 alone could not induce apoptosis in thymocytes; however, it could induce apoptosis when it was cross-linked with second antibodies. Thus, MCS-34 could not aggregate by itself, but G7 could. In the course of investigating the apoptosis-related molecules that were involved in the thymocyte apoptosis induced by cross-linking of MCS-34 or by G7 ligation, we found that CPP 32-like proteases were activated during the apoptosis. Furthermore, the expression of bcl-2 and bcl-XL proteins was decreased in these apoptosis processes. Whereas the ligation of MCS-34 alone could not generate apoptosis signals that led to the activation of CPP32-like proteases and the decrease in bcl-2 and bcl-XL expression, the aggregation of Thy-1 glycoprotein might be crucial to signal thymocyte apoptosis. These results indicate that MCS-34 is a useful anti-Thy-1 mAb for analyzing the Thy-1-mediated signals since MCS-34 can control the level of apoptosis by using second antibodies.
Fujita
N
N
Institute of Molecular and Cellular Biosciences, University of Tokyo, Japan.
Kodama
N
N
Kato
Y
Y
Lee
S H
SH
Tsuruo
T
T
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000918:Antibody Specificity; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D020170:Caspase 1; D053148:Caspase 3; D020169:Caspases; D003432:Cross-Linking Reagents / Q000494:pharmacology; D003546:Cysteine Endopeptidases / Q000378:metabolism / Q000502:physiology*; D004789:Enzyme Activation; D005260:Female; D019254:Genes, bcl-2; D007074:Immunoglobulin G / Q000494:pharmacology; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D008806:Mice, Inbred AKR; D008807:Mice, Inbred BALB C; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D013154:Spleen / Q000166:cytology; D013601:T-Lymphocytes / Q000166:cytology* / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D018800:Thy-1 Antigens / Q000276:immunology / Q000502:physiology*; D013950:Thymus Gland / Q000166:cytology*; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein
D000911:Antibodies, Monoclonal; C494773:Bak1 protein, mouse; C494812:Bcl2l1 protein, mouse; D003432:Cross-Linking Reagents; D007074:Immunoglobulin G; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D018800:Thy-1 Antigens; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; D003546:Cysteine Endopeptidases; D020170:Caspase 1; D013755:Tetradecanoylphorbol Acetate