Molecular Oncology Laboratory; Children's Cancer Research Unit; Kids Research Institute; The Children's Hospital at Westmead; Sydney, NSW Australia; The University of Sydney Discipline of Paediatrics and Child Health; The Children's Hospital at Westmead; Sydney, NSW Australia.
Cell Cycle. 2013 Sep 15;12(18):3083-97. doi: 10.4161/cc.26146. Epub 2013 Aug 21.
Tumor protein D52 (TPD52) is a coiled-coil motif bearing hydrophilic polypeptide known to be overexpressed in cancers of diverse cellular origins. Increased TPD52 expression is associated with increased proliferation and invasive capacity in different cell types. Recent studies have reported a correlation between TPD52 transcript levels and G 2 chromosomal radiosensitivity in lymphocytes of women at risk of hereditary breast cancer, and that TPD52 knockdown significantly reduced the radiation sensitivity of multiple cancer cell lines. In this study, we investigated possible roles for TPD52 in DNA damage response, and found that increased TPD52 expression in breast cancer and TPD52-expressing BALB/c 3T3 cells compromised ATM-mediated cellular responses to DNA double-strand breaks induced by γ-ray irradiation, which was associated with downregulation of steady-state ATM protein, but not transcript levels, regardless of irradiation status. TPD52-expressing 3T3 cells also showed significantly increased radiation sensitivity compared with vector cells evaluated by clonogenic assays. Furthermore, direct interactions between exogenous and endogenous ATM and TPD52 were detected by GST pull-down and co-immunoprecipitation assays. We also identified the interaction domains involved in this binding as TPD52 residues 111-131, and ATM residues 1-245 and 772-1102. Taken together, our results suggest that TPD52 may represent a novel negative regulator of ATM protein levels.
肿瘤蛋白 D52（TPD52）是一种具有亲水多肽的卷曲螺旋基序，已知在不同细胞来源的癌症中过度表达。TPD52 表达增加与不同细胞类型的增殖和侵袭能力增加有关。最近的研究报告称，TPD52 转录本水平与遗传性乳腺癌风险女性淋巴细胞中 G2 染色体对辐射的敏感性之间存在相关性，并且 TPD52 敲低显著降低了多种癌细胞系的辐射敏感性。在这项研究中，我们研究了 TPD52 在 DNA 损伤反应中的可能作用，发现乳腺癌中 TPD52 表达增加和表达 TPD52 的 BALB/c 3T3 细胞削弱了 ATM 介导的细胞对 γ 射线诱导的 DNA 双链断裂的反应，这与稳定状态 ATM 蛋白的下调有关，但与照射状态无关，也与转录本水平无关。通过集落形成试验评估，与载体细胞相比，表达 TPD52 的 3T3 细胞的辐射敏感性也显著增加。此外，通过 GST 下拉和共免疫沉淀试验检测到外源性和内源性 ATM 和 TPD52 之间的直接相互作用。我们还确定了参与这种结合的相互作用域为 TPD52 残基 111-131 和 ATM 残基 1-245 和 772-1102。总之，我们的结果表明，TPD52 可能代表 ATM 蛋白水平的一种新型负调控因子。
