Yale University, 333 Cedar Street, P.O. Box 208023, New Haven, CT 06520, USA.
Mol Cancer Res. 2011 Jun;9(6):766-81. doi: 10.1158/1541-7786.MCR-10-0317. Epub 2011 May 6.
NFBD1/MDC1 is involved in DNA damage checkpoint signaling and DNA repair. NFBD1 binds to the chromatin component γH2AX at sites of DNA damage, causing amplification of ataxia telangiectasia-mutated gene (ATM) pathway signaling and recruitment of DNA repair factors. Residues 508-995 of NFBD1 possess transactivation activity, suggesting a possible role of NFBD1 in transcription. Furthermore, NFBD1 influences p53-mediated transcription in response to adriamycin. We sought to determine the role of NFBD1 in ionizing radiation (IR)-responsive transcription and if NFBD1 influences transcription independently of p53. Using microarray analysis, we identified genes altered upon NFBD1 knockdown. Surprisingly, most NFBD1 regulated genes are regulated in both the absence and presence of IR, thus pointing toward a novel function for NFBD1 outside of the DNA damage response. Furthermore, NFBD1 knockdown regulated genes mostly independent of p53 knockdown. These genes are involved in pathways including focal adhesion signaling, carbohydrate metabolism, and insulin signaling. We found that CAV1 and CAV2 mRNA and protein levels are reduced by both NFBD1 knockdown and knockout independently of IR and p53. NFBD1-depleted cells exhibit some similar phenotypes to Cav1-depleted cells. Furthermore, like Cav1-depletion, NFBD1 shRNA increases Erk phosphorylation. Thus, Cav1 could act as a mediator of the DNA-damage independent effects of NFBD1 in mitogenic signaling.
NFBD1/MDC1 参与 DNA 损伤检查点信号和 DNA 修复。NFBD1 与染色质成分 γH2AX 在 DNA 损伤部位结合，导致共济失调毛细血管扩张突变基因 (ATM) 途径信号的放大和 DNA 修复因子的募集。NFBD1 的 508-995 个残基具有转录激活活性，提示 NFBD1 可能在转录中起作用。此外，NFBD1 影响阿霉素诱导的 p53 介导的转录。我们试图确定 NFBD1 在电离辐射 (IR) 反应性转录中的作用，以及 NFBD1 是否独立于 p53 影响转录。通过微阵列分析，我们确定了 NFBD1 敲低后发生变化的基因。令人惊讶的是，大多数 NFBD1 调控的基因在 NFBD1 敲低和 IR 存在的情况下都受到调控，这表明 NFBD1 在 DNA 损伤反应之外具有新的功能。此外，NFBD1 敲低调控的基因大多独立于 p53 敲低。这些基因参与包括焦点黏附信号、碳水化合物代谢和胰岛素信号在内的途径。我们发现，CAV1 和 CAV2 mRNA 和蛋白水平的降低是由 NFBD1 敲低和敲除引起的，这与 IR 和 p53 无关。NFBD1 耗尽的细胞表现出与 Cav1 耗尽的细胞类似的表型。此外，与 Cav1 耗尽一样，NFBD1 shRNA 增加了 Erk 磷酸化。因此，Cav1 可以作为 NFBD1 在有丝分裂信号中对 DNA 损伤非依赖性作用的介导物。
