Peroxisome proliferator-activated receptor alpha (PPARalpha) agonists down-regulate alpha2-macroglobulin expression by a PPARalpha-dependent mechanism.
Fibrates are peroxisome proliferator-activated receptor alpha (PPARalpha) ligands used to normalize lipid and glucose parameters and exert anti-inflammatory effects. The acute-phase response (APR) is an important inflammatory process. One of the most important acute-phase proteins in rats is alpha2-macroglobulin (A2Mg). Whereas normal adult rats present low serum levels, pregnant rats display high amounts. Therefore, we used pregnant rats to detect the effect of fenofibrate on hepatic A2Mg expression by RT-PCR and Northern blot. Virgin rats were used as controls. The expression of other APR genes, a known fibrate-responder gene, gamma-chain fibrinogen (gamma-Fib), and one gene from the same family as A2Mg, complement component 3 (C3), were also measured in liver. In order to determine whether the fibrate-effects were mediated by PPARalpha, wild-type mice and PPARalpha-null mice were also used and treated with WY-14,643 (WY) or di-2-ethylhexyl phthalate (DEHP). Fenofibrate depressed A2Mg expression in virgin rats, but expression was decreased more sharply in pregnant rats. Expression of C3 and gamma-Fib was diminished after treatment only in pregnant rats. On the other hand, WY, but not DEHP, reduced A2Mg and gamma-Fib expression in the livers of wild-type mice, without any effect in PPARalpha-null mice. WY or DEHP did not affect C3 expression. Therefore, A2Mg expression is modified by PPARalpha agonists not only in pregnant rats under augmented APR protein synthesis, but also in virgin rats and mice under basal conditions. Interestingly, our results also identify A2Mg as a novel PPARalpha agonist-regulated gene.
González
María del Carmen
MC
Universidad San Pablo-CEU, Madrid, Spain.
Corton
J Christopher
JC
Cattley
Russell C
RC
Herrera
Emilio
E
Bocos
Carlos
C
D000818:Animals; D015536:Down-Regulation / Q000187:drug effects*; D005260:Female; D011345:Fenofibrate / Q000494:pharmacology*; D008297:Male; D051379:Mice; D047493:PPAR alpha / Q000819:agonists* / Q000378:metabolism; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D012746:Sexual Abstinence; D000511:alpha-Macroglobulins / Q000235:genetics*
D047493:PPAR alpha; D000511:alpha-Macroglobulins; D011345:Fenofibrate