Anzai N, Kawabata H, Hirama T, Masutani H, Ueda Y, Yoshida Y, Okuma M
Department of Medicine, Faculty of Medicine, Kyoto University, Japan.
Blood. 1995 Aug 1;86(3):917-23.
A hallmark of apoptosis is internucleosomal DNA fragmentation resulting from the activation of endonucleases. We characterized the endonuclease activity of human myeloid cell nuclei that cleaved their own nuclear chromatin to oligonucleosomal length fragments. Polymorphonuclear leukocytes (PMNs) of normal peripheral blood contained both Ca2+/Mg(2+)-dependent and DNase II-like acidic endonuclease activities in their nuclei. Immature myeloid cells of normal bone marrow at various stages of granulocytic maturation had similar nuclease activities. In contrast, a clear difference was shown in the circulating CD34+ cells, in that only Mg(2+)-dependent, Ca(2+)-independent endonuclease activity was detected. Consistent with these findings is the emergence of the Ca2+/Mg(2+)-dependent and acidic endonuclease concomitantly with the disappearance of the Mg(2+)-dependent endonuclease when CD34+ cells were induced to differentiate in vitro toward granulocytes. Leukemic cell lines of all lineages also had Mg(2+)-dependent nuclease activity. Our results suggest an association of the Mg(2+)-dependent endonuclease with hematopoietic progenitor cells and that the relative activities of the nuclear nuclease in human myeloid cells change substantially during granulocytic differentiation.
细胞凋亡的一个标志是由于核酸内切酶激活导致的核小体间DNA片段化。我们对人髓样细胞核的核酸内切酶活性进行了表征，该酶可将自身的核染色质切割成寡核小体长度的片段。正常外周血的多形核白细胞（PMN）细胞核中含有Ca2+/Mg(2+)依赖性和DNase II样酸性核酸内切酶活性。正常骨髓中处于粒细胞成熟不同阶段的未成熟髓样细胞具有相似的核酸酶活性。相比之下，循环中的CD34+细胞表现出明显差异，即仅检测到Mg(2+)依赖性、Ca(2+)非依赖性核酸内切酶活性。与这些发现一致的是，当CD34+细胞在体外被诱导向粒细胞分化时，Ca2+/Mg(2+)依赖性和酸性核酸内切酶出现，同时Mg(2+)依赖性核酸内切酶消失。所有谱系的白血病细胞系也具有Mg(2+)依赖性核酸酶活性。我们的结果表明Mg(2+)依赖性核酸内切酶与造血祖细胞有关，并且人髓样细胞核核酸酶的相对活性在粒细胞分化过程中发生了显著变化。
