부산대학교 도서관

Background: Halogenated hydrocarbon exposure is associated with changes in gene expression in adult and embryonic tissue. The present study was undertaken to identify differentially expressed mRNA transcripts in embryonic hearts from Sprague-Dawley rats exposed to trichloroethylene (TCE) or potential bio-transformation products of TCE, Dichloroethylene (DCE) and Trichloroacetic acid (TCAA). Methods: cDNA subtractive hybridization was used to selectively amplify expressed mRNA in either control or day 11 embryonic rat hearts exposed to one of these halogenated hydrocarbons from day 0 to 11. The doses used were 1100 and 110 ppm (8300 and 830 mu M) TCE, 110 and 11 ppm (1100 and 110 mu M) DCE, 27.3 and 2.75 mg/ml (100 and 10 mM) TCAA. Control animals were given distilled drinking water throughout the period of experiments. Results: Sequencing of over 100 clones derived from halogenated hydrocarbon exposed groups=resulted in identification of numerous differentially regulate gene sequences. Up-regulated transcripts identified include genes associated with stress response (Hsp 70) and homeostasis (several ribosomal proteins). Down-regulated transcripts include extracellular matrix components (GPI-p137 and vimentin) and Ca2 + responsive proteins (Serca-2 Ca2+-ATPase and beta-catenin). Two possible markers for fetal TCE exposure were identified: Serca-2 and GPI-p137, a GPI-linked protein of unknown function. Both markers show a dose-related decrease in mRNA transcript levels associated with fetal exposure to TCE. Differential regulation of expression of both markers by TCE was confirmed by dot blot analysis and semi-quantitative RT-PCR. Levels of exposure between 100 and 250 ppb (0.76 and 1.9 mu M) TCE are sufficient to decrease expression of both the Ca2+-AT Pase and GPI-p137. Conclusion: Sequences down-regulated with TCE exposure appear to be those associated with cellular=housekeeping, cell adhesion and developmental processes, while TCE=exposure up-regulates expression of numerous stress response and homeostatic genes. Two potentially useful marker genes show a correlation between increasing levels of maternal TCE exposure and a decrease in marker transcript levels expressed at E11 in fetal rat heart tissue.