Kempf Stefan J, Buratovic Sonja, von Toerne Christine, Moertl Simone, Stenerlöw Bo, Hauck Stefanie M, Atkinson Michael J, Eriksson Per, Tapio Soile
Institute of Radiation Biology, Helmholtz Zentrum München, German Research Center for Environmental Health GmbH, Neuherberg, Germany.
Department of Environmental Toxicology, Uppsala University, Uppsala, Sweden.
PLoS One. 2014 Oct 20;9(10):e110464. doi: 10.1371/journal.pone.0110464. eCollection 2014.
Patients suffering from brain malignancies are treated with high-dose ionising radiation. However, this may lead to severe learning and memory impairment. Preventive treatments to minimise these side effects have not been possible due to the lack of knowledge of the involved signalling pathways and molecular targets. Mouse hippocampal neuronal HT22 cells were irradiated with acute gamma doses of 0.5 Gy, 1.0 Gy and 4.0 Gy. Changes in the cellular proteome were investigated by isotope-coded protein label technology and tandem mass spectrometry after 4 and 24 hours. To compare the findings with the in vivo response, male NMRI mice were irradiated on postnatal day 10 with a gamma dose of 1.0 Gy, followed by evaluation of the cellular proteome of hippocampus and cortex 24 hours post-irradiation. Analysis of the in vitro proteome showed that signalling pathways related to synaptic actin-remodelling were significantly affected at 1.0 Gy and 4.0 Gy but not at 0.5 Gy after 4 and 24 hours. We observed radiation-induced reduction of the miR-132 and Rac1 levels; miR-132 is known to regulate Rac1 activity by blocking the GTPase-activating protein p250GAP. In the irradiated hippocampus and cortex we observed alterations in the signalling pathways similar to those in vitro. The decreased expression of miR-132 and Rac1 was associated with an increase in hippocampal cofilin and phospho-cofilin. The Rac1-Cofilin pathway is involved in the modulation of synaptic actin filament formation that is necessary for correct spine and synapse morphology to enable processes of learning and memory. We suggest that acute radiation exposure leads to rapid dendritic spine and synapse morphology alterations via aberrant cytoskeletal signalling and processing and that this is associated with the immediate neurocognitive side effects observed in patients treated with ionising radiation.
患有脑恶性肿瘤的患者接受高剂量电离辐射治疗。然而，这可能会导致严重的学习和记忆障碍。由于缺乏对相关信号通路和分子靶点的了解，目前还无法进行预防这些副作用的治疗。将小鼠海马神经元HT22细胞分别用0.5 Gy、1.0 Gy和4.0 Gy的急性γ剂量进行照射。在照射4小时和24小时后，采用同位素编码蛋白质标记技术和串联质谱法研究细胞蛋白质组的变化。为了将研究结果与体内反应进行比较，在出生后第10天给雄性NMRI小鼠照射1.0 Gy的γ剂量，然后在照射后24小时评估海马和皮质的细胞蛋白质组。体外蛋白质组分析表明，在照射4小时和24小时后，与突触肌动蛋白重塑相关的信号通路在1.0 Gy和4.0 Gy时受到显著影响，但在0.5 Gy时未受影响。我们观察到辐射诱导的miR-132和Rac1水平降低；已知miR-132通过阻断GTP酶激活蛋白p250GAP来调节Rac1活性。在照射后的海马和皮质中，我们观察到信号通路的变化与体外相似。miR-132和Rac1表达的降低与海马中丝切蛋白和磷酸化丝切蛋白的增加有关。Rac1-丝切蛋白通路参与突触肌动蛋白丝形成的调节，而突触肌动蛋白丝形成对于正确的树突棘和突触形态以实现学习和记忆过程是必需的。我们认为，急性辐射暴露通过异常的细胞骨架信号传导和加工导致树突棘和突触形态迅速改变，这与接受电离辐射治疗的患者中观察到的即时神经认知副作用有关。
