Suciu D
J Theor Biol. 1983 Dec 7;105(3):391-401. doi: 10.1016/0022-5193(83)90183-2.
A number of facts suggest that chromatin autodigestion, occurring in the early phase of apoptosis, is carried out by an enzymatic system, composed of an endonuclease and a protease, which yields oligonucleosomic chromatin fragments. Though this enzymatic system appears to be present in most mammalian cell nuclei, radiation-induced apoptosis takes place, with a high frequency, only in cell populations having less well-developed nuclear matrices, such as lymphoid cells. Moreover, apoptosis seems to occur in a different manner in cells with less well-developed nuclear matrices (radiosensitive cells) compared with cells that contain dense nuclear matrices (radioresistant cells). Thus, dying lymphocytes progressively release their degraded chromatin from nuclei, without displaying the cellular budding and formation of apoptotic bodies. Nevertheless, apoptosis remains the main cause of cell death and cell depletion in irradiated lymphoid tissues. In contrast, the process of cellular budding and formation of apoptotic bodies appears to be specific for cells having well-developed nuclear matrix, such as those from small intestine and liver. However, in these tissues the frequency of apoptosis is relatively low and cannot be considered as the main cause of radiation-induced tissue involution.
许多事实表明，发生在细胞凋亡早期的染色质自消化是由一种酶系统进行的，该酶系统由一种核酸内切酶和一种蛋白酶组成，可产生寡核小体染色质片段。尽管这种酶系统似乎存在于大多数哺乳动物细胞核中，但辐射诱导的细胞凋亡仅在核基质发育较差的细胞群体（如淋巴细胞）中高频发生。此外，与含有致密核基质的细胞（抗辐射细胞）相比，核基质发育较差的细胞（辐射敏感细胞）中的细胞凋亡似乎以不同的方式发生。因此，垂死的淋巴细胞逐渐从细胞核中释放出其降解的染色质，而不表现出细胞出芽和凋亡小体的形成。然而，细胞凋亡仍然是辐射淋巴组织中细胞死亡和细胞耗竭的主要原因。相比之下，细胞出芽和凋亡小体的形成过程似乎是核基质发达的细胞所特有的，如来自小肠和肝脏的细胞。然而，在这些组织中，细胞凋亡的频率相对较低，不能被视为辐射诱导组织退化的主要原因。
