Laboratory of Animal Molecular and Cellular Biology, Institute of Life Sciences, Université catholique de Louvain, Croix du Sud 4-5, Louvain-la-Neuve 1348, Belgium.
Unité de Recherche en Physiologie Moléculaire, Namur Research Institute for Life Sciences, School of Medicine, University of Namur, rue de Bruxelles 61, Namur 5000, Belgium.
Cell Death Differ. 2018 Jan;25(1):190-203. doi: 10.1038/cdd.2017.143. Epub 2017 Sep 22.
The tumor suppressor p53 is a key regulator of apoptosis induced by various cellular stresses. p53 can induce apoptosis by two mechanisms. First, p53 acts as a transcription factor inducing and repressing pro-apoptotic and anti-apoptotic targets genes, respectively. Second, p53 is able to translocate to the mitochondria, where it interacts with BCL-2 family members to induce membrane permeabilization and cytochrome c release. p53 transcriptional activity is regulated by a set of post-translational modifications that have been well documented. However, how these modifications impact the direct mitochondrial pathway of death remain poorly understood. In this study, we focused on the role of serine 392 phosphorylation in the control of p53-dependent apoptosis. We used CRISPR/Cas9 genome editing to substitute serine 392 by a non-phosphorylatable alanine in HCT-116 colon carcinoma cells. The S392A mutant displayed normal transcriptional activity following genotoxic stress, but markedly impaired ability to localize to mitochondria. The decreased mitochondrial localization of the S392A mutant correlated with a lower ability to induce apoptosis. Confirmatory observations were made following enforced expression of the S392A p53 mutant or a phospho-mimetic S392E mutant in H1299 lung carcinoma cells. Our observations support the premise that serine 392 phosphorylation of p53 influences its mitochondrial translocation and transcription-independent apoptotic function.
肿瘤抑制因子 p53 是各种细胞应激诱导细胞凋亡的关键调节因子。p53 可以通过两种机制诱导凋亡。首先，p53 作为转录因子，分别诱导和抑制促凋亡和抗凋亡靶基因。其次，p53 能够易位到线粒体，在那里它与 BCL-2 家族成员相互作用，诱导膜通透性和细胞色素 c 释放。p53 的转录活性受一系列已被充分记录的翻译后修饰调节。然而，这些修饰如何影响死亡的直接线粒体途径仍知之甚少。在这项研究中，我们专注于丝氨酸 392 磷酸化在控制 p53 依赖性凋亡中的作用。我们使用 CRISPR/Cas9 基因组编辑将丝氨酸 392 突变为 HCT-116 结肠癌细胞中的非磷酸化丙氨酸。S392A 突变体在遗传毒性应激后显示出正常的转录活性，但明显削弱了向线粒体定位的能力。S392A 突变体向线粒体的定位减少与诱导凋亡的能力降低相关。在 H1299 肺癌细胞中强制表达 S392A p53 突变体或磷酸模拟 S392E 突变体后进行了确认性观察。我们的观察结果支持这样的前提，即 p53 的丝氨酸 392 磷酸化影响其线粒体易位和转录非依赖性凋亡功能。
