Induction of thymocyte apoptosis by Ca2+-independent protein kinase C (nPKC) activation and its regulation by calcineurin activation.
Glucocorticoids appear to participate in apoptosis of unselected CD4(+)CD8(+) thymocytes. Activation of Ca2+-independent novel protein kinase C (nPKC) precedes glucocorticoid-induced thymocyte apoptosis, while proper levels of Ca2+-dependent protein kinase C (cPKC) and calcineurin activities contribute to rescue thymocytes. To clarify the role of nPKC in thymocyte apoptosis, murine thymocytes were stimulated with the diterpene diester, ingenol 3, 20-dibenzoate (IDB). IDB induced selective translocation of nPKC-delta, -epsilon, and -theta and PKC-mu from the cytosolic fraction to the particulate fraction and induced morphologically typical apoptosis through de novo synthesis of macromolecules. The apoptosis was also induced by thymeleatoxin, a diterpene ester, at relatively high concentrations that induced translocation of cPKC, nPKC-theta, and PKC-mu. The IDB- or thymeleatoxin-induced death was inhibited by non-isoform-selective PKC inhibitors, but not by their structural analogs with weak PKC-inhibitory activity or the selective inhibitor of cPKC and PKC-mu, Gö 6976. The death was also inhibited by calcium ionophore ionomycin at concentrations within a narrow range. The range corresponded to the concentration range that contributes to the inhibition of glucocorticoid-induced apoptosis. The antiapoptotic effect was canceled by the immunosuppressant FK506 but not by rapamycin. These results indicate that activation of nPKC, especially nPKC-theta, induces apoptosis in thymocytes and that calcineurin activation regulates the apoptosis.
Integrative Projects, Mitsubishi Kasei Institute of Life Sciences, 11 Minamiooya, Machida-shi, Tokyo 194, Japan.
A
A
Asada
Y
Y
Zhao
S
S
Kondo
M
M
Iwata
D000818:Animals; D017209:Apoptosis; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D019703:Calcineurin / Q000378:metabolism*; D003907:Dexamethasone / Q000276:immunology / Q000494:pharmacology; D004224:Diterpenes / Q000494:pharmacology; D004789:Enzyme Activation; D005938:Glucocorticoids / Q000276:immunology / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010703:Phorbol Esters / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D051744:Protein Kinase C-epsilon; D000074121:Protein Kinase C-theta; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000473:pathology; D013950:Thymus Gland / Q000187:drug effects / Q000276:immunology* / Q000473:pathology
D004224:Diterpenes; D005938:Glucocorticoids; D007527:Isoenzymes; D010703:Phorbol Esters; C011875:ingenol dibenzoate; D003907:Dexamethasone; C080287:thymeleatoxin; C497256:Prkce protein, mouse; C115197:calcium-independent protein kinase C; C089212:protein kinase D; C489593:Prkcq protein, mouse; D011493:Protein Kinase C; D051744:Protein Kinase C-epsilon; D000074121:Protein Kinase C-theta; D019703:Calcineurin