The activation of caspase-3 and DNA fragmentation in B cells phagocytosed by macrophages
The activation of caspase-3 and DNA fragmentation in B cells phagocytosed by macrophages
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巨噬细胞吞噬B细胞中caspase-3的激活和DNA片段化
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
Y. Otsuki
中科院分区：
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作者：
E. Ninomiya;Y. Ito;M. Shibata;Keisei Kawashima;Takeshi Sakamoto;E. Maruyama;H. Doi;K. Tokitsu;Y. Otsuki
哺乳动物细胞凋亡信号通路包括死亡受体通路和线粒体通路。在这项体内研究中，我们利用透射电子显微镜（TEM）、末端脱氧核苷酸转移酶（TdT）介导的dutp -生物素镍端标记（TUNEL）、caspase家族成员和cFLIPL的免疫荧光以及caspase活性测定，研究了小鼠肠相关淋巴组织（GALTs）生发中心（GCs） B细胞的凋亡信号。在构成gc的B细胞中，很难从超微结构上区分发生凋亡的B细胞与分化为记忆细胞或浆细胞的B细胞。GCs中分离的B细胞没有活性形式的caspase-3或TUNEL免疫反应，但表达cFLIPL。与分离的B细胞相反，被巨噬细胞吞噬的凋亡B细胞表现出caspase-3和TUNEL活性形式的免疫反应性，但缺乏cFLIPL的表达。galt的caspase活性测定清楚地显示caspase-3、caspase-9和caspase- 8的活性依次高。因此，伴随caspase-3和caspase-8活性升高的死亡受体通路可能被GALTs B细胞中cFLIPL的表达阻断。此外，caspase-3的激活和DNA的断裂首先发生在B细胞被巨噬细胞吞噬时。
Apoptotic signaling of mammalian cells involves two pathways: the death receptor and mitochondrial pathways. In this in vivo study, we investigated apoptotic signaling of B cells in mouse germinal centers (GCs) of gut-associated lymphoid tissues (GALTs) using transmission electron microscopy (TEM), terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick-end labeling (TUNEL), immunofluorescence of members of caspase family and cFLIPL, and caspase activity assay. It was very difficult to ultrastructurally differentiate B cells undergoing apoptosis from B cells differentiating into memory cells or plasma cells among B cells constituting GCs. Isolated B cells in GCs showed no active form of caspase-3 or TUNEL immunoreactivity, but expressed cFLIPL. Contrary to isolated B cells, apoptotic B cells phagocytosed by macrophages exhibited immunoreactivity of the active form of caspase-3 and TUNEL, but lacked the cFLIPL expression. The caspase activity assay in GALTs clearly showed intense activity of caspase-3, caspase-9, and caspace-8 that was high in order. Therefore, the death receptor pathway accompanying the increased activity of caspase-3 and caspase-8 may be blocked by the expression of cFLIPL in B cells of GALTs. Moreover, both the activation of caspase-3 and DNA fragmentation first occur only when B cells are phagocytosed by macrophages.