Project description:Consistent and independently replicated laboratory evidence to support a causative relationship between environmental exposure to extremely low frequency electromagnetic fields (ELF-EMF) at power line frequencies and the associated increase in risk of childhood leukaemia has not been obtained. In particular, although gene expression responses have been reported in a wide variety of cells, none have emerged as robust, widely replicated effects. DNA microarrays facilitate comprehensive searches for changes in gene expression without a requirement to select candidate responsive genes. To determine if gene expression changes occur in white blood cells of volunteers exposed to an ELF-EMF, each of 17 pairs of male volunteers age 20-30 was subjected either to a 50 Hz EMF exposure of 62.0 ± 7.1 μT for 2 h or to a sham exposure (0.21 ± 0.05 μT) at the same time (11:00-13:00). The alternative regime for each volunteer was repeated on the following day and the two-day sequence was repeated 6 days later except that a null exposure (0.085 ± 0.01 μT) replaced the sham exposure. Five blood samples (10 ml) were collected at 2 h intervals from 9:00 to 17:00 with five additional samples during the exposure and sham or null exposure periods on each study day at 11.05, 11.10, 11.20, 11.40 and 12.20. RNA samples were pooled for the same time points on each study day for the 17 volunteers that were subjected to the ELF-EMF exposure/sham or null exposure sequence and were analysed on Illumina microarrays. Time courses for 16 mammalian genes previously reported to be responsive to ELF-EMF exposure, including immediate early genes, stress response, cell proliferation and apoptotic genes were examined in detail. No genes or gene sets significantly expressed on the arrays showed consistent response profiles to repeated ELF-EMF exposures. A stress response was detected as a transient increase in plasma cortisol at the onset of either exposure or sham exposure on the first study day. The cortisol response diminished progressively on subsequent exposures or sham exposures and was attributable to mild stress associated with the experimental protocol.

Project description:Consistent and independently replicated laboratory evidence to support a causative relationship between environmental exposure to extremely low frequency electromagnetic fields (ELF-EMF) at power line frequencies and the associated increase in risk of childhood leukaemia has not been obtained. In particular, although gene expression responses have been reported in a wide variety of cells, none have emerged as robust, widely replicated effects. DNA microarrays facilitate comprehensive searches for changes in gene expression without a requirement to select candidate responsive genes. To determine if gene expression changes occur in white blood cells of volunteers exposed to an ELF-EMF, each of 17 pairs of male volunteers age 20-30 was subjected either to a 50 Hz EMF exposure of 62.0 ± 7.1 μT for 2 h or to a sham exposure (0.21 ± 0.05 μT) at the same time (11:00-13:00). The alternative regime for each volunteer was repeated on the following day and the two-day sequence was repeated 6 days later except that a null exposure (0.085 ± 0.01 μT) replaced the sham exposure. Five blood samples (10 ml) were collected at 2 h intervals from 9:00 to 17:00 with five additional samples during the exposure and sham or null exposure periods on each study day at 11.05, 11.10, 11.20, 11.40 and 12.20. RNA samples were pooled for the same time points on each study day for the 17 volunteers that were subjected to the ELF-EMF exposure/sham or null exposure sequence and were analysed on Illumina microarrays. Time courses for 16 mammalian genes previously reported to be responsive to ELF-EMF exposure, including immediate early genes, stress response, cell proliferation and apoptotic genes were examined in detail. No genes or gene sets significantly expressed on the arrays showed consistent response profiles to repeated ELF-EMF exposures. A stress response was detected as a transient increase in plasma cortisol at the onset of either exposure or sham exposure on the first study day. The cortisol response diminished progressively on subsequent exposures or sham exposures and was attributable to mild stress associated with the experimental protocol. The study design described in the summary gave a total of 40 pooled RNA samples (10 for each study day) using equal amounts of RNA from the 17 volunteers exposed to ELF-EMF on study days 1 and 3, a sham exposure on study day 2 and a null exposures on study day 4. The pooled sample from 11:00 on Day1 (immediately prior to ELF-EMF exposure) was used as a reference sample that was amplified and labelled 4 times with the other samples from each of the 4 study days (titled as replicates 1 to 4). Each replicate was hybridised twice (titled replicates a and b for each day ( e.g. 1a, 1b) to give a total of 8 arrays from the reference RNA sample (Sample names 2 and 41-47, i.e.GSM879110-GSM879117).

Project description:KRIT1 is a gene responsible for Cerebral Cavernous Malformations (CCM), a major cerebrovascular disease characterized by abnormally enlarged and leaky capillaries that predispose to seizures, focal neurological deficits, and fatal intracerebral hemorrhage. Comprehensive analysis of the KRIT1 gene in CCM patients has suggested that KRIT1 functions need to be severely impaired for pathogenesis. However, the molecular and cellular functions of KRIT1 as well as CCM pathogenesis mechanisms are still research challenges. We found that KRIT1 plays an important role in molecular mechanisms involved in the maintenance of the intracellular Reactive Oxygen Species (ROS) homeostasis to prevent oxidative cellular damage. In particular, we demonstrate that KRIT1 loss/down-regulation is associated with a significant increase in intracellular ROS levels. Conversely, ROS levels in KRIT1(-/-) cells are significantly and dose-dependently reduced after restoration of KRIT1 expression. Moreover, we show that the modulation of intracellular ROS levels by KRIT1 loss/restoration is strictly correlated with the modulation of the expression of the antioxidant protein SOD2 as well as of the transcriptional factor FoxO1, a master regulator of cell responses to oxidative stress and a modulator of SOD2 levels. Furthermore, we show that the KRIT1-dependent maintenance of low ROS levels facilitates the downregulation of cyclin D1 expression required for cell transition from proliferative growth to quiescence. Finally, we demonstrate that the enhanced ROS levels in KRIT1(-/-) cells are associated with an increased cell susceptibility to oxidative DNA damage and a marked induction of the DNA damage sensor and repair gene Gadd45alpha, as well as with a decline of mitochondrial energy metabolism. Taken together, our results point to a new model where KRIT1 limits the accumulation of intracellular oxidants and prevents oxidative stress-mediated cellular dysfunction and DNA damage by enhancing the cell capacity to scavenge intracellular ROS through an antioxidant pathway involving FoxO1 and SOD2, thus providing novel and useful insights into the understanding of KRIT1 molecular and cellular functions.

Dataset Information

A 60 Hz uniform electromagnetic field promotes human cell proliferation by decreasing intracellular reactive oxygen species levels.

Publications

A 60 Hz uniform electromagnetic field promotes human cell proliferation by decreasing intracellular reactive oxygen species levels.

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