Acedera Jack Dalit, Cheng Yu-Che, Li Yi-Ju, Hsueh Hao-Yun, Shieh Sheau-Yann
Taiwan International Graduate Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei 112, Taiwan.
Institute of Biomedical Scien ces, Academia Sinica, Taipei 115, Taiwan.
Nucleic Acids Res. 2025 Jul 8;53(13). doi: 10.1093/nar/gkaf626.
Skin exposure to UV rays from sunlight results in the formation of mutagenic DNA photolesions that are repaired by the nucleotide excision repair (NER) machinery. The inefficient repair of photolesions can lead to stalled DNA replication and mispairing, thereby causing strand breaks and mutations. B-cell translocation gene 3 (BTG3) is expressed in the epidermis of the skin and is an antiproliferative gene upregulated in human keratinocytes after radiation injury. In this study, we found that BTG3 is required to promote the timely extraction of the lesion-binding protein XPC by the segregase VCP/p97, an essential step preceding the excision of photolesions. Mechanistically, we showed that BTG3-dependent CHK1 activation and phosphorylation of VCP/p97 at S775 are necessary for the nuclear translocation of VCP/p97 after UV irradiation. Thus, loss of BTG3 or inhibition of CHK1 results in cytoplasmic retention of VCP/p97 and accumulation of ubiquitinated XPC, leading to delayed removal of photolesions and inefficient NER, which was recapitulated in vivo in the skin of the Btg3 knockout mice showing increased photolesions and γH2AX and elevated mutations after UV. Our findings revealed that by influencing the cellular localization of VCP/p97, BTG3 is critical for the proper execution of NER to protect cells from UV-induced damage and skin carcinogenesis.
皮肤暴露于阳光中的紫外线会导致诱变DNA光损伤的形成,这些损伤由核苷酸切除修复(NER)机制修复。光损伤修复效率低下会导致DNA复制停滞和错配,从而导致链断裂和突变。B细胞易位基因3(BTG3)在皮肤表皮中表达,是辐射损伤后在人角质形成细胞中上调的一种抗增殖基因。在本研究中,我们发现BTG3是促进分离酶VCP/p97及时提取损伤结合蛋白XPC所必需的,这是光损伤切除之前的一个关键步骤。从机制上讲,我们表明紫外线照射后,BTG3依赖的CHK1激活和VCP/p97在S775处的磷酸化是VCP/p97核转位所必需的。因此,BTG3缺失或CHK1抑制会导致VCP/p97在细胞质中滞留以及泛素化XPC的积累,导致光损伤清除延迟和NER效率低下,这在Btg3基因敲除小鼠的皮肤中得到了验证,其显示紫外线照射后光损伤增加、γH2AX增加以及突变率升高。我们的研究结果表明,通过影响VCP/p97的细胞定位,BTG3对于NER的正确执行至关重要,从而保护细胞免受紫外线诱导的损伤和皮肤癌变。