Repression of Metallothionein Expression by Dietary Procyanidins

ISABEL M. QUESADA; CINTA BLADÉ; ANNA ARDÈVOL; MAYTE BLAY; M. JOSEPA SALVADÓ; GERARD PUJADAS; JUAN FERNÁNDEZ-LARREA; LLUÍS AROLA

Paris

Congreso; 10th European Nutrition Conference; 2007

Procyanidins are the most abundant polyphenols in red wine and are also found in cereals, fruits, chocolate and tea. They exert many beneficial health effects, especially on the cardiovascular system (1-4). Here, we show that oral administration of a grape seed procyanidins extract (GSPE) to healthy rats results, 5 h after treatment, in a 70% inhibition of metallothionein (MT) gene expression in the liver, as determined by oligonucleotide microarray hybridization. Similarly, in cultured human hepatocytes HepG2, GSPE downregulate the expression of MT genes at the mRNA level, as evaluated by quantitative RTPCR. Thus, mRNA levels of six functional MT genes, MT1A, 1E, 1F, 1G, 1X and MT2A, are diminished between 50 and 80% when HepG2 cells are treated during 12 h with GSPE. Only the expression of two human MT genes, MT1G and MT1E, is transiently increased during the first 2 h of treatment. GSPE-induced inhibition of MT genes expression is dose dependent, at concentrations that are not toxic for the cells. Our findings demonstrate that metallothionein genes are direct targets of procyanidins action, both in vivo and in vitro, in hepatic cells. Thus, this study will help to elucidate the mechanisms by which procyanidin exert their beneficial actions. 1. Bagchi D, Sen CK, Ray SD, Das DK, Bagchi M, Preuss HG, Vinson JA (2003) Molecular mechanism of cardioprotection by a novel grape seed proanthocyanidin extract. Mutat Res 523–524: 87–97 2. Williams RJ, Spencer JPE, Rice-Evans C (2004) Flavonoids: antioxidants or signalling molecules? Free Radic Biol Med 36:838–849 3. Dell’Agli M, Busciala A, Bosisio E (2004) Vascular effects of wine polyphenols. Cardiovasc Res 63(4):593–602 4. Del Bas JM et al. (2005) Grape seed procyanidins improve atherosclerotic risk index and induce liver CYP7A1 and SHP expression in healthy rats. FASEB J 19:479–481