Induction of a Ca2+, Mg2+-dependent endonuclease activity during the early stages of murine erythroleukemic cell differentiation.
Induction of a Ca2+, Mg2+-dependent endonuclease activity during the early stages of murine erythroleukemic cell differentiation.
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在鼠红白血病细胞分化的早期阶段诱导 Ca2、Mg2 依赖性核酸内切酶活性。
DOI：
10.1073/pnas.81.23.7461
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发表时间：
1984
影响因子：
11.1
通讯作者：
S. Levy
中科院分区：
文献类型：
--
作者：
G. Mcmahon;J. Alsina;S. Levy
在体外分化的红白血病细胞中检测到一种Ca ~（2+）、Mg ~（2+）依赖的核酸内切酶活性，该酶对二甲基亚砜（Me_2SO）或六亚甲基双乙酰胺（HMBA）诱导的反应作出响应。在加入诱导剂后6小时内，在分离的细胞核中证明了核酸内切酶活性，在24和48小时之间达到最大水平，并在72小时内恢复到对照水平。该活性引起高分子量天然DNA的单链断裂，其可以用大肠杆菌DNA聚合酶I和放射性标记的核苷酸在暴露的3 '-OH末端标记。碱性洗脱研究显示DNA片段化似乎与核酸内切酶活性的存在一致。单链DNA断裂的检测和水平与Me 2SO或HMBA诱导的终末分化相关。诱导的核酸内切酶活性是可逆的：从生长培养基中的Me 2SO处理后6和18小时的消耗导致活性水平的快速下降。诱导物的去除阻止了终末分化，这一发现强烈表明内切核酸酶活性存在于分化的预定型阶段。在与氯高铁血红素孵育的细胞中未观察到DNA片段化，氯高铁血红素先前已显示增加珠蛋白mRNA的细胞质水平而不引起终末成熟的承诺。Me 2SO在不可诱导的Friend细胞系中不诱导核酸内切酶活性或DNA片段化。
A Ca2+, Mg2+-dependent endonuclease activity was detected in erythroleukemic cells undergoing differentiation in vitro in response to induction by dimethyl sulfoxide (Me2SO) or hexamethylene-bis-acetamide (HMBA). The endonuclease activity was demonstrated in isolated nuclei within 6 hr after the addition of inducer, reached maximum levels between 24 and 48 hr, and returned to control levels within 72 hr. The activity caused single strand breaks in high molecular weight native DNA, which could be labeled at exposed 3'-OH termini with Escherichia coli DNA polymerase I and radiolabeled nucleotides. Alkaline elution studies revealed DNA fragmentation that appeared coincident with the presence of the endonuclease activity. The detection and levels of single strand DNA breakage correlated with induction of terminal differentiation by Me2SO or HMBA. Induction of the endonuclease activity was reversible: depletion of Me2SO from the growth medium after treatment for 6 and 18 hr led to a rapid decrease in the level of activity. Removal of the inducer prevented terminal differentiation, a finding that strongly suggests the endonuclease activity is present during the precommitment phase of differentiation. DNA fragmentation was not observed in cells incubated with hemin, which has been shown previously to increase the cytoplasmic level of globin mRNA without causing commitment to terminal maturation. Me2SO did not induce the endonuclease activity or DNA fragmentation in an uninducible Friend cell line.