Department of Pathophysiology, Xiangya School of Medicine, Central South University, 110 Xiangya Road, Changsha, Hunan 410008, People's Republic of China.
Cell Stress Chaperones. 2012 Jan;17(1):121-30. doi: 10.1007/s12192-011-0292-4. Epub 2011 Sep 30.
It has been reported that nucleolar fragmentation is a part of the overall apoptotic morphology, however, it is currently obscure whether and how nucleolar fragmentation can be induced by hydrogen peroxide (H(2)O(2)) and heat shock protein 70 (Hsp70) can prevent nucleolar fragmentation. To dissect these two questions, C(2)C(12) myogenic cells and immortalized mouse embryonic fibroblasts (MEFs) with heat shock transcriptional factor 1 (HSF1) null mutation were treated with heat shock response (HS) (42.5 ± 0.5°C for 1 h and recovery at 37°C for 24 h) and then were insulted with 0.5 mmol/L H(2)O(2). Morphological changes of nucleoli were observed under contrast microscope or electronic microscope. It was found that (1) stimulation with H(2)O(2)-induced nucleolar fragmentation by mediating cleavage and down-regulation of nucleolar protein, nucleolin in C(2)C(12) myocytes and MEFs; (2) HS suppressed nucleolar fragmentation by inducing the expression of Hsp70 in an HSF1-dependent manner as indicated by assays of transfection with Hsp70 antisense oligonucleotides (AS-ONs) or recombinant plasmids of full-length Hsp70 cDNA; (3) protection of Hsp70 against nucleolar fragmentation was related to its accumulation in nucleolus mediated by nuclear localization sequence and its inhibition against cleavage and down-regulation of nucleolin. These results suggested that H(2)O(2)-induced nucleolar fragmentation and HS or Hsp70 inhibit H(2)O(2)-induced nucleolar fragmentation through the translocation of Hsp70 into nucleolar and its protection against impairment of nucleolin.
据报道核仁碎裂是细胞凋亡形态学的一部分，然而，目前尚不清楚过氧化氢（H2O2）和热休克蛋白 70（Hsp70）是否以及如何诱导核仁碎裂，热休克转录因子 1（HSF1）缺失突变的永生化小鼠胚胎成纤维细胞（MEFs）和 C2C12 成肌细胞用热休克反应（HS）（42.5±0.5°C 1 小时，然后在 37°C 恢复 24 小时）处理，然后用 0.5mmol/L H2O2 刺激。在相差显微镜或电子显微镜下观察核仁形态变化。结果发现：（1）H2O2 刺激通过介导核仁蛋白核仁素的切割和下调导致 C2C12 成肌细胞和 MEFs 核仁碎裂；（2）HS 通过 HSF1 依赖性方式诱导 Hsp70 的表达抑制核仁碎裂，这可以通过转染 Hsp70 反义寡核苷酸（AS-ONs）或全长 Hsp70 cDNA 重组质粒来检测；（3）Hsp70 对核仁碎裂的保护与其在核仁中的积累有关，核定位序列介导其进入核仁，抑制核仁素的切割和下调。这些结果表明，H2O2 诱导的核仁碎裂和 HS 或 Hsp70 通过 Hsp70 易位到核仁并防止核仁素受损来抑制 H2O2 诱导的核仁碎裂。
