Okamura Hirohiko, Yoshida Kaya, Amorim Bruna Rabelo, Haneji Tatsuji
Department of Histology and Oral Histology, Institute of Health Biosciences, The University of Tokushima Graduate School, Kuramoto, Tokushima 770-8504, Japan.
J Cell Biochem. 2008 Apr 1;103(5):1488-96. doi: 10.1002/jcb.21537.
Bleomycin induces single- and double-stranded breaks in DNA, with consequent mitochondrial membrane aberrations that lead to the apoptotic cell death. It is poorly understood how DNA damage-inducing apoptotic signals are transmitted to mitochondria, from which apoptotic factors are released into the cytoplasm. Here, we investigated the localization of histone H1.2 in the bleomycin-treated human squamous carcinoma SCCTF cells. The presence of DNA double-strand breaks in the bleomycin-treated cells was examined by Western analysis using antibody against phosphorylated histone H2AX (gamma-H2AX). Incubation of SCCTF cells for 48 h with 10 microM bleomycin induced apoptosis, as determined by cleavage of lamin B1 to 28 kDa fragment and DNA ladder formation. The mitochondrial permeabilization causing apoptotic feature was also detected with MitoCapture in the bleomycin-treated cells. Histone H1.2 was translocated from the nucleus to the mitochondria after treatment with bleomycin and co-localized with Bak in mitochondria. Our present results suggest that histone H1.2 plays an important role in transmitting apoptotic signals from the nucleus to the mitochondria following double-stranded breaks of DNA by bleomycin.
博来霉素可诱导DNA单链和双链断裂，进而导致线粒体膜畸变，引发细胞凋亡。目前人们对DNA损伤诱导的凋亡信号如何传递到线粒体，以及凋亡因子如何从线粒体释放到细胞质中了解甚少。在此，我们研究了博来霉素处理的人鳞状癌细胞SCCTF中组蛋白H1.2的定位。通过使用抗磷酸化组蛋白H2AX（γ-H2AX）抗体的Western分析检测博来霉素处理细胞中DNA双链断裂的存在情况。用10微摩尔博来霉素处理SCCTF细胞48小时可诱导细胞凋亡，这通过核纤层蛋白B1切割为28 kDa片段和DNA梯状条带形成得以确定。在用MitoCapture检测博来霉素处理的细胞中，也检测到了导致凋亡特征的线粒体通透性改变。博来霉素处理后，组蛋白H1.2从细胞核转移到线粒体，并在线粒体中与Bak共定位。我们目前的结果表明，在博来霉素导致DNA双链断裂后，组蛋白H1.2在将凋亡信号从细胞核传递到线粒体的过程中发挥重要作用。
