Enhancement of current density by dc electric concentrator.
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ABSTRACT:
SUBMITTER: Jiang WX
PROVIDER: S-EPMC3518816 | biostudies-other | 2012
REPOSITORIES: biostudies-other
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2008-02-12 | GSE5192 | GEO
Project description:The control of cellular processes by direct electronic interface will facilitate the development of biosensors, synthetic biology, and nanobiotechnology by providing the means to pass information from synthetic to living elements of hybrid systems. To investigate the potential of manipulating cellular gene expression by means of electric current, Escherichia coli cultures were screened for electric current inducible genes using global gene expression profiling. Cells in stationary phase were subjected to a DC current density of 2.5 mA/cm2 for 2 min after which the cells were lysed and the total RNA extracted. Of the 4290 expressed genes in E. coli , 432 genes were found to be significantly differentially expressed at an effective alpha value of 5.8 X 10-6. Of these, 333 genes were induced and 99 repressed. Several genes were verified as differentially expressed by quantitative real-time RT-PCR. The set of differentially expressed genes were examined for the presence of regulatory factors, subsidiary regulon genes, and biological function, particularly redox functions. Transcripts for the regulatory proteins fnr, sspB, soxS, oxyR, creB and yeiL were found to be up-regulated, and crp was down regulated. While soxS and oxyR were up-regulated, the downstream genes controlled by these regulatory proteins were not differentially expressed, suggesting that the oxidative stress level of low-current electric exposure is small. Genes controlled by FNR and CRP, many of which have redox function, were found to be differentially expressed suggesting modulation by direct reduction that can only be partially explained as a response to the reducing environment created by the electrolytic generation of H2 at the cathode. Genes associated with phosphate metabolism and membrane proteins were also differentially expressed. Three biological replicates were exposed to electric current along with three biological replicate controls.
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Project description:Naturally-occurring, endogenous electric fields (EFs) have been detected at skin wounds, damaged tissue sites and vasculature. Applied EFs guide migration of many types of cells, including endothelial cells to migrate directionally. Homing of endothelial progenitor cells (EPCs) to an injury site is important for repair of vasculature and also for angiogenesis. However, it has not been reported whether EPCs respond to applied EFs. Aiming to explore the possibility to use electric stimulation to regulate the progenitor cells and angiogenesis, we tested the effects of direct-current (DC) EFs on EPCs. We first used immunofluorescence to confirm the expression of endothelial progenitor markers in three lines of EPCs. We then cultured the progenitor cells in EFs. Using time-lapse video microscopy, we demonstrated that an applied DC EF directs migration of the EPCs toward the cathode. The progenitor cells also align and elongate in an EF. Inhibition of vascular endothelial growth factor (VEGF) receptor signaling completely abolished the EF-induced directional migration of the progenitor cells. We conclude that EFs are an effective signal that guides EPC migration through VEGF receptor signaling in vitro. Applied EFs may be used to control behaviors of EPCs in tissue engineering, in homing of EPCs to wounds and to an injury site in the vasculature.
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Project description:BackgroundThe formation of acetylcholine receptor (AChR) cluster is a key event during the development of the neuromuscular junction. It is induced through the activation of muscle-specific kinase (MuSK) by the heparan-sulfate proteoglycan agrin released from the motor axon. On the other hand, DC electric field, a non-neuronal stimulus, is also highly effective in causing AChRs to cluster along the cathode-facing edge of muscle cells.Methodology/principal findingsTo understand its molecular mechanism, quantum dots (QDs) were used to follow the movement of AChRs as they became clustered under the influence of electric field. From analyses of trajectories of AChR movement in the membrane, it was concluded that diffuse receptors underwent Brownian motion until they were immobilized at sites of cluster formation. This supports the diffusion-mediated trapping model in explaining AChR clustering under the influence of this stimulus. Disrupting F-actin cytoskeleton assembly and interfering with rapsyn-AChR interaction suppressed this phenomenon, suggesting that these are integral components of the trapping mechanism induced by the electric field. Consistent with the idea that signaling pathways are activated by this stimulus, the localization of tyrosine-phosphorylated forms of AChR β-subunit and Src was observed at cathodal AChR clusters. Furthermore, disrupting MuSK activity through the expression of a kinase-dead form of this enzyme abolished electric field-induced AChR clustering.ConclusionsThese results suggest that DC electric field as a physical stimulus elicits molecular reactions in muscle cells in the form of cathodal MuSK activation in a ligand-free manner to trigger a signaling pathway that leads to cytoskeletal assembly and AChR clustering.
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