Effect of simulated microgravity on oxidation-sensitive gene expression in PC12 cells

Abstract

Oxygen utilization by and oxygen dependence of cellular processes may be different in biological systems that are exposed to microgravity (micro-g). A baseline in which cellular changes in oxygen sensitive molecular processes occur during micro-g conditions would be important to pursue this question. The objective of this research is to analyze oxidation-sensitive gene expression in a model cell line [rat pheochromocytoma (PC12)] under simulated micro-g conditions. The PC12 cell line is well characterized in its response to oxygen, and is widely recognized as a sensitive model for studying the responses of oxygen-sensitive molecular and cellular processes. This study uses the rotating wall vessel bioreactor (RWV) designed at NASA to simulate micro-g. Gene expression in PC12 cells in response to micro-g was analyzed by DNA microarray technology. The microarray analysis of PC12 cells cultured for 4 days under simulated micro-g under standardized oxygen environment conditions revealed more than 100 genes whose expression levels were changed at least twofold (up-regulation of 65 genes and down-regulation of 39 genes) compared with those from cells in the unit gravity (unit-g) control. This study observed that genes involved in the oxidoreductase activity category were most significantly differentially expressed under micro-g conditions. Also, known oxidation-sensitive transcription factors such as hypoxia-inducible factor-2α, c-myc, and the peroxisome proliferator-activated receptor-γ were changed significantly. Our initial results from the gene expression microarray studies may provide a context in which to evaluate the effect of varying oxygen environments on the background of differential gene regulation of biological processes under variable gravity conditions.

Differential Translocation of Nuclear Factor-KappaB in a Cardiac Muscle Cell Line Under Gravitational Changes

“…It is probably based on our current results that enhanced activity of NF- κ B under MG as compared with DC will lead to differential regulation of down-stream gene networks precipitating some of the physiological changes observed under conditions of microgravity. This claim is also supported by our recent study using DNA microarrays to show that genes involved in oxygen utilization and metabolic processes were significantly dysregulated under micro-g conditions as compared with unit-g conditions [6]. The present results let us conclude that simulated micro-g conditions regulated the translocation of a prevailing oxygen-sensitive transcription factor, NF- κ B in a cardiomyocyte cell line.…”

“…The physiological effect of NF- κ B activation can be further investigated with focus on specific target genes. 2 For instance, c-myc, NADH quinine oxidoreductase, and glucose-6-phosphate 1-dehydrogenase were suggested to be MG regulated from our preliminary DNA microarray results [6] and are transcriptional target genes of NF- κ B.…”

“…For instance, in our preliminary results from DNA microarrays with rat PC12 cells, it was shown that over 100 genes were dysregulated more than twofold under simulated micro-g in the RWV culture. Among the regulated genes, those involved in the oxidoreductase activity category were most significantly differentially expressed [6]. Although the microarray technique dealing with mRNA expression can identify differences in the expression level of thousands of gene products [7], it has a higher degree of variability that requires validation of the data by secondary techniques such as protein expression [8].…”

Protective Effects of Flavonoids Against Oxidative Stress Induced by Simulated Microgravity in SH-SY5Y Cells

“…Recent study showed that exposure to SMG induces cellular senescence in PC12 cells via an increased oxidative stress [11]. In particular, genes involved in oxidoreductase activity are the ones most significantly differentially expressed [12] under conditions of SMG produced either by a rotating wall bioreactor with a high aspect ratio vessel or by a clinostat. All these results indicate that there is increased oxidative stress in neuronal cells subjected to microgravity.…”

Oxygen transport and consumption by suspended cells in microgravity: A multiphase analysis

“…The current parametric results can be used to minimize costly cell culture experiments for optimizing conditions of cell/bead suspension in the bioreactor (Kwon et al, 2006). In addition, the present results on numerical prediction of the distribution of cell/microcarrier beads and the concentration of biochemical components such as oxygen in the bioreactor may play a significant role in the design of new bioreactors to study optimized suspension cultures of cells and tissues.…”