The regulation of DNAse activities in subcellular compartments of activated thymocytes.
Thymocytes expressing self-reactive T-cell receptors (TCR) are eliminated in the thymus through a TCR-mediated signal. This cell death signal (negative selection) generates nuclear morphological change and DNA fragmentation in thymocytes. However, the pathway leading to DNA fragmentation of thymocytes following TCR engagement remains obscure. In this study, we investigated the localization and function of caspase-activated DNAse (CAD) and its inhibitor (ICAD) in thymocytes prior to or after in vivo TCR stimulation. We showed that CAD and ICAD are co-localized in microsome, nuclei and cytosol in unstimulated thymocytes. Following in vivo TCR engagement, ICAD located in cytosol and microsome was degraded and the resulting activated CAD induced chromosomal DNA fragmentation. CAD present in cytosol and microsome of unstimulated thymocytes was activated by recombinant caspase-3, and microsomal CAD was released to the cytosol. These results demonstrate that TCR engagement of thymocytes induces caspase-3-dependent activation of CAD localized in both cytosol and microsome, leading to DNA fragmentation in harmony.
Nagata
Takuya
T
Department of Immunology, Faculty of Medicine, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama 930-0194, Japan.
Kishi
Hiroyuki
H
Liu
Qin Li
QL
Matsuda
Tadashi
T
Imanaka
Tsuneo
T
Tsukada
Kazuhiro
K
Kang
Dongchon
D
Muraguchi
Atsushi
A
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D017252:CD3 Complex / Q000276:immunology; D053148:Caspase 3; D020169:Caspases / Q000494:pharmacology; D002460:Cell Line; D002467:Cell Nucleus / Q000201:enzymology; D003600:Cytosol / Q000201:enzymology; D053938:DNA Fragmentation; D003851:Deoxyribonucleases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051379:Mice; D008813:Mice, Inbred ICR; D008861:Microsomes / Q000201:enzymology; D011506:Proteins / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology; D013601:T-Lymphocytes / Q000201:enzymology*
D000911:Antibodies, Monoclonal; D051017:Apoptosis Regulatory Proteins; D017252:CD3 Complex; D011506:Proteins; D011948:Receptors, Antigen, T-Cell; D011994:Recombinant Proteins; C109664:caspase-activated DNase inhibitor; D003851:Deoxyribonucleases; C109663:caspase-activated deoxyribonuclease; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases