Activation of mouse and human peroxisome proliferator-activated receptors (PPARs) by phthalate monoesters.
Administration of phthalates is known to cause toxicity and liver cancer in rodents through the activation of peroxisome proliferator-activated receptors (PPARs), and the monoesters appear to be the active metabolites that function as ligands of PPARs. There is evidence that PPARs exhibit significant species differences in response to ligand activation. In this study, the activation of mouse and human PPARalpha, PPARbeta, and PPARgamma by a broad class of phthalate monoesters was investigated using a trans-activation assay, functional analysis of PPARalpha target gene expression, and a PPARgamma-mediated differentiation assay. These studies demonstrated a range in the ability of various phthalate monoesters to activate PPARalpha, with the mouse PPARalpha generally being activated at lower concentrations and exhibiting a greater response than human PPARalpha. Similarly, a range in the trans-activation of mouse PPARbeta by phthalate monoesters was also observed, but this effect was not found with human PPARbeta. A number of phthalate monoesters activated both mouse and human PPARgamma, with similar sensitivity being exhibited by both receptors. These studies show that the potency and efficacy of phthalate monoesters for the activation of PPARalpha and PPARgamma increase with increasing side-chain length. These studies also show that mouse PPARalpha and PPARbeta are generally activated at lower concentrations of phthalate monoesters than human PPARalpha and PPARbeta, and that both mouse and human PPARgamma exhibit similar sensitivity to phthalate monoesters. Lastly, there is a good relationship between the relative ability of phthalate monoesters to trans-activate PPARalpha and PPARgamma, and the relative induction of PPARalpha target gene mRNA and PPARgamma-mediated adipocyte differentiation, respectively.
Bility
Moses T
MT
Department of Veterinary Science and The Center for Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, University Park, PA 16802, USA.
Thompson
Jerry T
JT
McKee
Richard H
RH
David
Raymond M
RM
Butala
John H
JH
Vanden Heuvel
John P
JP
Peters
Jeffrey M
JM
D016475:3T3 Cells; D000818:Animals; D006528:Carcinoma, Hepatocellular; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004785:Environmental Pollutants / Q000633:toxicity*; D006801:Humans; D051379:Mice; D047492:Peroxisome Proliferator-Activated Receptors / Q000096:biosynthesis* / Q000145:classification / Q000235:genetics; D010795:Phthalic Acids / Q000633:toxicity*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D013045:Species Specificity; D013329:Structure-Activity Relationship; D015533:Transcriptional Activation / Q000187:drug effects
D004785:Environmental Pollutants; D047492:Peroxisome Proliferator-Activated Receptors; D010795:Phthalic Acids; D012333:RNA, Messenger