We previously showed a preferential degradation and down-regulation of mitochondrial DNA and RNA in hamster fibroblasts in response to hydrogen peroxide. Subsequent studies by others demonstrated that mitochondrial DNA can stimulate immune cells as a DAMP (damage associated molecular patterns) family member. However, the actual physical structure of this mitochondrial DNA DAMP and its importance in non-immune cell types are poorly understood. Here we report that transfected oxidant-initiated degraded mitochondrial polynucleotides, which we term "DeMPs", strongly induce the proinflammatory cytokines interleukin 6, monocyte chemotactic protein-1, and tumor necrosis factor α in mouse primary astrocytes. Additionally, proinflammatory IL1β was induced, implicating DeMPs in inflammasome activation. Furthermore, human cerebrospinal fluid (CSF) and plasma were found to contain detectable DeMP signal. Finally, significant degradation of mitochondrial DNA was observed in response to either a bolus or steady state hydrogen peroxide. Combined, these studies demonstrate, all for the first time, that a pathophysiologically relevant form of mitochondrial DNA (degraded) can elicit a proinflammatory cytokine induction; that a brain cell type (astrocytes) elicits a proinflammatory cytokine induction in response to these DeMPs; that this induction includes the inflammasome; that astrocytes are capable of inflammasome activation by DeMPs; that DeMPs are detectable in CSF and plasma; and that hydrogen peroxide can stimulate an early stage cellular degradation of mitochondrial DNA. These results provide new insights and are supportive of our hypothesis that DeMPs are a newly identified trigger of neurodegenerative diseases such as Alzheimer's disease, which are known to be associated with early stage inflammation and oxidation.
Background-The effects of ethanol on development of postmitotic neurons include altered neurite outgrowth and differentiation, which may contribute to neuropathology associated with fetal alcohol spectrum disorders. We previously reported that ethanol exposure alters axon growth dynamics in dissociated cultures of rat hippocampal pyramidal neurons. Given the important regulatory role of small Rho GTPases in cytoskeletal reorganization associated with axon growth, and reports that ethanol alters whole cell Rho GTPase activity in other cell types, this study explored the hypothesis that ethanol alters Rho GTPase activity specifically in axonal growth cones.
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