Trichloroethylene effects on gene expression during cardiac development.
BACKGROUND
Halogenated hydrocarbon exposure is associated with changes in gene expression in adult and embryonic tissue. Our 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 dichloroethylene (DCE) and trichloroacetic acid (TCAA).


METHODS
cDNA subtractive hybridization was used to selectively amplify expressed mRNA obtained from control or halogenated hydrocarbon exposed rat embryos. The doses used were 1100 and 110 ppm (8300 and 830 microM) TCE, 110 and 11 ppm (1100 and 110 microM) DCE, and 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 regulated 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 Ca(2+) responsive proteins (Serca-2 Ca(2+)-ATPase and beta-catenin). Two possible markers for fetal TCE exposure were identified: Serca-2 Ca(2+)-ATPase and GPI-p137, a GPI-linked protein of unknown function. Differential regulation of expression of both markers by TCE was confirmed by dot blot analysis and semi-quantitative RT-PCR with levels of TCE exposure between 100 and 250 ppb (0.76 and 1.9 microM) sufficient to decrease expression.


CONCLUSIONS
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.
Collier
J Michael
JM
Life Science Division, Genome Sciences, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA. mcollier@lbl.gov
Selmin
Ornella
O
Johnson
Paula D
PD
Runyan
Raymond B
RB
D000818:Animals; D004000:Dichloroethylenes / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005314:Embryonic and Fetal Development / Q000187:drug effects; D005260:Female; D015870:Gene Expression / Q000187:drug effects*; D020869:Gene Expression Profiling; D005819:Genetic Markers; D006330:Heart Defects, Congenital / Q000139:chemically induced / Q000235:genetics*; D008297:Male; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012997:Solvents / Q000633:toxicity*; D014238:Trichloroacetic Acid / Q000494:pharmacology; D014241:Trichloroethylene / Q000633:toxicity*
D004000:Dichloroethylenes; D005819:Genetic Markers; D012333:RNA, Messenger; D012997:Solvents; D014241:Trichloroethylene; D014238:Trichloroacetic Acid