Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, 110016, Liaoning, PR China.
Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, 110016, Liaoning, PR China; Department of Chemistry and Life Science, School of Advanced Engineering, Kogakuin University, 2665-1, Nakanomachi, Hachioji, Tokyo, 192-0015, Japan; Nippi Research Institute of Biomatrix, Toride, Ibaraki, 302-0017, Japan.
Mol Immunol. 2021 Mar;131:180-190. doi: 10.1016/j.molimm.2020.12.037. Epub 2021 Jan 8.
Exposure to ultraviolet B (UVB) from sunlight causes DNA damage, serious cellular inflammation and aging, and even cell death in the skin, commonly known as sunburn, leading to cutaneous tissue disorders. DNA damage can be sensed as a danger-associated molecular pattern (DAMP) by the innate immune system. It has not been studied, however, whether cGAS-STING activation is involved in the apoptosis induced by UVB irradiation or by cisplatin treatment. Here we report the findings that within hours of DNA damages keratinocytes show an innate immune response, which involves the activation of cGAS-STING; a cytosolic DNA receptor, cGAS (cyclic guanosine monophosphate-adenosine monophosphate synthase), cyclic GMP-AMP (cGAMP) synthase, and DNA sensing adaptor, STING (protein stimulator of interferon genes). Either UVB irradiation or cisplatin treatment can cause DNA damages, releasing fragmented DNA from nucleus and/or mitochondria. Roles of cGAS-STING were examined in the HaCaT cells with DNA damages caused by UVB irradiation or cisplatin treatment. Silencing STING by siRNA rescued HaCaT cells from UVB or cisplatin-induced apoptosis. NF-κB, one of the major downstream components of STING pathway, which usually regulates the classical STING apoptotic pathway, was translocated to nucleus in the HaCaT cells irradiated with UVB. This translocation was attenuated by STING silencing. Treatment with BAY, an inhibitor of NF-κB pathway, blocked UVB-induced apoptosis. cGAS-STING-mediated production of IFNβ was induced by nuclear translocation of interferon regulatory factor 3 (IRF3). UVB irradiation inceased the nuclear translocation of IRF3, accompanied by enhanced expression level of IFNβ mRNA. The nuclear translocation of IRF3 and expression of IFNβ mRNA were attenuated by STING silencing. Treatment with MRT67307, an inhibitor of TBK1-IRF3-IFNβ pathway, blocked UVB-induced apoptosis. Therefore, we conclude that NF-κB pathway and IFNβ pathway residing in the downstream of STING are resposible for apoptosis of UVB-irradiated or cisplatin-treated HaCaT cells.
暴露于阳光中的紫外线 B（UVB）会导致 DNA 损伤、严重的细胞炎症和衰老，甚至导致皮肤细胞死亡，通常称为晒伤，从而导致皮肤组织紊乱。DNA 损伤可被先天免疫系统视为危险相关分子模式（DAMP）。然而，尚未研究 cGAS-STING 的激活是否参与 UVB 照射或顺铂处理诱导的细胞凋亡。在这里，我们报告了这样的发现：在 DNA 损伤后的数小时内，角质形成细胞就会表现出先天免疫反应，其中涉及 cGAS-STING 的激活；一种细胞质 DNA 受体 cGAS（环鸟苷酸-腺苷酸合酶）、环状 GMP-AMP（cGAMP）合酶和 DNA 感应衔接子 STING（干扰素基因刺激蛋白）。UVB 照射或顺铂处理均可导致 DNA 损伤，从而将核内和/或线粒体中的断裂 DNA 释放出来。我们在经 UVB 照射或顺铂处理导致 DNA 损伤的 HaCaT 细胞中研究了 cGAS-STING 的作用。用 siRNA 沉默 STING 可挽救 HaCaT 细胞免受 UVB 或顺铂诱导的凋亡。NF-κB 是 STING 途径的主要下游成分之一，通常调节经典的 STING 凋亡途径，在经 UVB 照射的 HaCaT 细胞中向核内易位。这种易位被 STING 沉默减弱。用 NF-κB 途径抑制剂 BAY 处理可阻断 UVB 诱导的凋亡。IFNβ的 cGAS-STING 介导的产生是由干扰素调节因子 3（IRF3）的核易位引起的。UVB 照射增加了 IRF3 的核易位，同时增强了 IFNβ mRNA 的表达水平。STING 沉默减弱了 IRF3 的核易位和 IFNβ mRNA 的表达。用 TBK1-IRF3-IFNβ 途径抑制剂 MRT67307 处理可阻断 UVB 诱导的凋亡。因此，我们得出结论，STING 下游的 NF-κB 途径和 IFNβ 途径负责 UVB 照射或顺铂处理的 HaCaT 细胞凋亡。
