Division of Experimental Pathology, Department of Clinical and Experimental Medicine, Linköping University, Linköping SE-581 85, Sweden.
Free Radic Biol Med. 2012 Dec 1;53(11):2054-61. doi: 10.1016/j.freeradbiomed.2012.09.007. Epub 2012 Sep 15.
Oxysterol accumulation and p53 expression mainly in macrophages have been associated with cell death and necrotic core formation in human atheroma progression. Oxidative stress and lysosomal membrane permeabilization (LMP) in macrophages are important causes of macrophage apoptosis. However, it is not understood how p53 and oxysterols interact in the process. We show here that 7-oxysterols induce endogenous full-length p53 and phospho-p53 (p53-Ser15) in both nucleus and cytoplasm of THP1 and J774 cells, which is followed by cellular oxidative stress and apoptotic cell death. The role of p53 in 7-oxysterol-mediated cell death is further investigated in temperature sensitive p53-transfected (M1-t-p53) and in p53-deficient (M1) cells. These results reveal that 7-oxysterols induce induction and nuclear translocation of p53 in M1-t-p53 cells, which in turn enhances LMP, mitochondrial translocation of Bax, mitochondrial membrane permeabilization, cytosolic release of cytochrome c, and cell death. Most importantly, the above effects of 7-oxysterols were not observed in p53-deficient M1 cells. The findings reveal that 7-oxysterol-induced cell death occurs via p53-dependent pathways. Subsequent p53 nuclear translocation and induction of wild-type and phosphorylated p53 are early steps in oxysterol-induced lysosomal-mitochondrial pathways involved in cell death.
氧化固醇的积累和 p53 的表达主要存在于巨噬细胞中，与人类动脉粥样硬化进展中的细胞死亡和坏死核心形成有关。巨噬细胞中的氧化应激和溶酶体膜通透性（LMP）是巨噬细胞凋亡的重要原因。然而，p53 和氧化固醇如何相互作用尚不清楚。我们在这里表明，7-氧化固醇诱导 THP1 和 J774 细胞的内源性全长 p53 和磷酸化 p53（p53-Ser15）在细胞核和细胞质中，随后发生细胞氧化应激和凋亡性细胞死亡。在温度敏感型 p53 转染（M1-t-p53）和 p53 缺失（M1）细胞中进一步研究了 p53 在 7-氧化固醇介导的细胞死亡中的作用。这些结果表明，7-氧化固醇诱导 M1-t-p53 细胞中 p53 的诱导和核转位，进而增强 LMP、Bax 的线粒体易位、线粒体膜通透性、细胞色素 c 的胞质释放和细胞死亡。最重要的是，p53 缺失的 M1 细胞中未观察到 7-氧化固醇的上述作用。这些发现表明，7-氧化固醇诱导的细胞死亡是通过 p53 依赖性途径发生的。随后的 p53 核转位和野生型和磷酸化 p53 的诱导是氧化固醇诱导的溶酶体-线粒体途径中涉及细胞死亡的早期步骤。
