自噬被 UVA 诱导,并促进表皮角质形成细胞中氧化磷脂和蛋白聚集体的清除。
Autophagy is induced by UVA and promotes removal of oxidized phospholipids and protein aggregates in epidermal keratinocytes.
机构信息
Department of Dermatology, Medical University of Vienna, Vienna, Austria.
出版信息
J Invest Dermatol. 2013 Jun;133(6):1629-37. doi: 10.1038/jid.2013.26. Epub 2013 Jan 22.
The skin is exposed to environmental insults such as UV light that cause oxidative damage to macromolecules. A centerpiece in the defense against oxidative stress is the Nrf2 (nuclear factor (erythroid-derived-2)-like 2)-mediated transcriptional upregulation of antioxidant and detoxifying enzymes and the removal of oxidatively damaged material. Autophagy has an important role in the intracellular degradation of damaged proteins and entire organelles, but its role in the epidermis has remained elusive. Here, we show that both UVA and UVA-oxidized phospholipids induced autophagy in epidermal keratinocytes. Oxidative stressors induced massive accumulation of high-molecular-weight protein aggregates containing the autophagy adaptor protein p62/SQSTM1 in autophagy-deficient (autophagy-related 7 (ATG7) negative) keratinocytes. Strikingly, even in the absence of exogenous stress, the expression of Nrf2-dependent genes was elevated in autophagy-deficient keratinocytes. Furthermore, we show that autophagy-deficient cells contained significantly elevated levels of reactive oxidized phospholipids. Thus, our data demonstrate that autophagy is crucial for both the degradation of proteins and lipids modified by environmental UV stress and for limiting Nrf2 activity in keratinocytes. Lipids that promote inflammation and tissue damage because of their reactivity and signaling functions are commonly observed in aged and diseased skin, and thus targeting autophagy may be a promising strategy to counteract the damage promoted by excessive lipid oxidation.
皮肤暴露于环境刺激物(如紫外线)下,这些刺激物会导致大分子物质发生氧化损伤。Nrf2(核因子(红细胞衍生 2)样 2)介导的抗氧化和解毒酶的转录上调,以及氧化损伤物质的清除,是抵御氧化应激的核心。自噬在细胞内降解受损蛋白质和整个细胞器方面起着重要作用,但它在表皮中的作用仍然难以捉摸。在这里,我们表明 UVA 和 UVA 氧化磷脂均可诱导表皮角质形成细胞发生自噬。氧化应激诱导物在自噬缺陷型(自噬相关 7(ATG7)阴性)角质形成细胞中诱导大量含有自噬衔接蛋白 p62/SQSTM1 的高分子量蛋白聚集体的积累。引人注目的是,即使在没有外源应激的情况下,自噬缺陷型角质形成细胞中 Nrf2 依赖性基因的表达也会升高。此外,我们还表明,自噬缺陷型细胞中含有明显升高水平的反应性氧化磷脂。因此,我们的数据表明,自噬对于环境 UV 应激修饰的蛋白质和脂质的降解以及角质形成细胞中 Nrf2 活性的限制都是至关重要的。由于其反应性和信号功能而导致炎症和组织损伤的脂质在衰老和患病皮肤中很常见,因此靶向自噬可能是一种有前途的策略,可以对抗过度脂质氧化引起的损伤。