QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: mol.107.044669v1 74/1/255    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Dong, B. Articles by Matsumura, F. PubMed PubMed Citation Articles by Dong, B. Articles by Matsumura, F.

Roles of Cytosolic Phospholipase A2 and Src Kinase in the Early Action of 2,3,7,8-Tetrachlorodibenzo-p-dioxin through a Nongenomic Pathway in MCF10A Cells

Department of Environmental Toxicology, University of California, Davis, California

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD, or dioxin) is known to induce rapid inflammatory cellular responses through the mechanism that has not yet been fully elucidated. In this report, we show that in MCF10A cells, an immortalized, normal mammary epithelial cell line, TCDD rapidly activates the enzymatic activity of cytosolic phospholipase A2 (cPLA2) as at-tested to by arachidonic acid release within 15 min, followed by activation of Src kinase and induction of several inflammation markers. Such an action of TCDD is clearly blocked by methylarachidonyl fluorophosphonate, a specific inhibitor of cPLA2, short interfering RNA against cPLA2, and several calcium signaling blockers, indicating that this action of TCDD is mediated by calcium-triggered activation of cPLA2. This action of TCDD is quite different from the classic action of TCDD to induce cytochrome P450 1A1 (CYP1A1) because blocking this newly identified pathway did not affect the induction of CYP1A1. Moreover, this newly identified pathway was found to depend only on aryl hydrocarbon receptor but not on aryl hydrocarbon receptor nuclear translocator. Together, these findings support the model that the early action of TCDD to induce rapid inflammatory responses is carried out through a characteristic "nongenomic" pathway, which is clearly different from the conventional model of action of TCDD through the "genomic" pathway.

Address correspondence to: Dr. Fumio Matsumura, Department of Environmental Toxicology, University of California, Davis, One Shields Avenue, Davis, CA 95616. E-mail: fmatsumura{at}ucdavis.edu