Lee Jae-Seon, Huang Tai-Qin, Lee Je-Jung, Pack Jeong-Ki, Jang Ja-June, Seo Jeong-Sun
Laboratory of Functional Genomics, Korea Institute of Radiological & Medical Sciences, Seoul.
Int J Radiat Biol. 2005 Oct;81(10):781-92. doi: 10.1080/09553000500500188.
Heat shock protein 70 (HSP70) is one of the most inducible proteins to play a cytoprotective role under stressful conditions. Previously we generated hsp70.1-deficient mice to elucidate the in vivo function of HSP70 in detail. The renal tissues and embryonic fibroblasts of these mice were shown to be more vulnerable to hyperosmotic stress. Since RF (radiofrequency) energy has been suggested to be an environmental stressor, we carried out a study to determine whether sub-chronic RF exposure can cause constitutive induction of a stress response at a cellular and/or molecular level in hsp70.1-deficient mice due to repeated stimulation.
Eight-week-old hsp70.1-deficient mice were exposed twice daily for 45 min, with a 15 min interval, 5 days a week for 10 weeks. Whole-body average specific absorption rate was 0.4 W/Kg for fields of both 849 MHz and 1763 MHz. Major tissues were histopathologically analysed, and immunocytochemically evaluated for cell proliferative activity. Apoptosis was investigated by TdT-mediated dUTP nick-end labeling (TUNEL) assay. To determine whether RF radiation elicits a stress response, the expression level of heat shock proteins (HSP) and phosphorylation of the stress-activated kinases were also observed by western blots.
No difference was observed in the histopathological analysis between sham- and RF-exposed mice. There was no evidence of increased proliferative and apoptotic activities. The levels of HSP90, HSP70, and HSP25 showed no obvious changes. RF exposure did not affect the phosphorylation status of the major stress-activated kinase (MAPK); extracellular signal-regulated kinase 1/2 (ERK1/2), C-Jun N-terminal kinase 1/2 (JNK1/2) or p38 MAPK.
The hsp70.1-deficient mice did not show any significant changes in terms of cell proliferation, apoptosis, or stress response due to exposure of 849 or 1,763 MHz RF fields.
热休克蛋白70（HSP70）是在应激条件下起细胞保护作用的最易诱导的蛋白之一。此前我们培育了hsp70.1基因缺失小鼠，以详细阐明HSP70在体内的功能。这些小鼠的肾组织和胚胎成纤维细胞显示出对高渗应激更敏感。由于射频（RF）能量被认为是一种环境应激源，我们开展了一项研究，以确定亚慢性RF暴露是否会因反复刺激而在hsp70.1基因缺失小鼠的细胞和/或分子水平上引起应激反应的组成性诱导。
8周龄的hsp70.1基因缺失小鼠，每周5天，每天暴露两次，每次45分钟，间隔15分钟，共暴露10周。849 MHz和1763 MHz场的全身平均比吸收率均为0.4 W/Kg。对主要组织进行组织病理学分析，并通过免疫细胞化学评估细胞增殖活性。通过TdT介导的dUTP缺口末端标记（TUNEL）试验研究细胞凋亡。为了确定RF辐射是否引发应激反应，还通过蛋白质免疫印迹法观察热休克蛋白（HSP）的表达水平和应激激活激酶的磷酸化情况。
假暴露组和RF暴露组小鼠的组织病理学分析未观察到差异。没有证据表明增殖和凋亡活性增加。HSP90、HSP70和HSP25的水平没有明显变化。RF暴露不影响主要应激激活激酶（MAPK）；细胞外信号调节激酶1/2（ERK1/2）、C-Jun氨基末端激酶1/2（JNK1/2）或p38 MAPK的磷酸化状态。
由于暴露于849 MHz或1763 MHz RF场，hsp70.1基因缺失小鼠在细胞增殖、凋亡或应激反应方面未显示任何显著变化。
