Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
Center for Environmental Health Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
Sci Signal. 2019 Feb 12;12(568):eaau9216. doi: 10.1126/scisignal.aau9216.
DNA-alkylating agents are commonly used to kill cancer cells, but the base excision repair (BER) pathway they trigger can also produce toxic intermediates that cause tissue damage, such as retinal degeneration (RD). Apoptosis, a process of programmed cell death, is assumed to be the main mechanism of this alkylation-induced photoreceptor (PR) cell death in RD. Here, we studied the involvement of necroptosis (another programmed cell death process) and inflammation in alkylation-induced RD. Male mice exposed to a methylating agent exhibited a reduced number of PR cell rows, active gliosis, and cytokine induction and macrophage infiltration in the retina. Dying PRs exhibited a necrotic morphology, increased 8-hydroxyguanosine abundance (an oxidative damage marker), and overexpression of the necroptosis-associated genes and The activity of PARP1, which mediates BER, cell death, and inflammation, was increased in PR cells and associated with the release of proinflammatory chemokine HMGB1 from PR nuclei. Mice lacking the anti-inflammatory cytokine IL-10 exhibited more severe RD, whereas deficiency of RIP3 (also known as RIPK3) conferred partial protection. Female mice were partially protected from alkylation-induced RD, showing reduced necroptosis and inflammation compared to males. PRs in mice lacking the BER-initiating DNA glycosylase AAG did not exhibit alkylation-induced necroptosis or inflammation. Our findings show that AAG-initiated BER at alkylated DNA bases induces sex-dependent RD primarily by triggering necroptosis and activating an inflammatory response that amplifies the original damage and, furthermore, reveal new potential targets to prevent this side effect of chemotherapy.
DNA 烷化剂通常用于杀死癌细胞，但它们引发的碱基切除修复 (BER) 途径也会产生有毒中间体，导致组织损伤，如视网膜变性 (RD)。细胞凋亡，即程序性细胞死亡，被认为是这种烷化诱导的 RD 中光感受器 (PR) 细胞死亡的主要机制。在这里，我们研究了细胞坏死 (另一种程序性细胞死亡过程) 和炎症在烷化诱导的 RD 中的作用。暴露于烷化剂的雄性小鼠表现出 PR 细胞行数减少、活性神经胶质增生以及细胞因子诱导和巨噬细胞浸润到视网膜。垂死的 PR 表现出坏死的形态，8-羟基鸟嘌呤丰度增加（氧化损伤标志物），并且坏死相关基因 和 的表达增加。介导 BER、细胞死亡和炎症的 PARP1 的活性在 PR 细胞中增加，并与 PR 核中促炎趋化因子 HMGB1 的释放相关。缺乏抗炎细胞因子 IL-10 的小鼠表现出更严重的 RD，而 RIP3（也称为 RIPK3）缺失则提供了部分保护。雌性小鼠对烷化诱导的 RD 有部分保护作用，与雄性相比，坏死和炎症减少。缺乏 BER 起始 DNA 糖苷酶 AAG 的小鼠的 PR 不表现出烷化诱导的坏死或炎症。我们的研究结果表明，AAG 起始的 DNA 碱基烷化诱导的 BER 主要通过触发细胞坏死和激活炎症反应来诱导性别依赖性 RD，从而放大原始损伤，并且进一步揭示了预防这种化疗副作用的新的潜在靶点。
