[Background and objectives]: Methionine and ATP are joined by methionine adenosyltransferases (MATs) to produce S-adenosylmethionine in the first step of the methionine/homocysteine cycle. MAT1A and MAT2A are the genes encoding mammalian MAT catalytic subunits (á1 and á2, respectively), whereas MAT2B codifies for the regulatory subunit (ß). High methionine levels increase the flux through this pathway, leading to enhanced homocysteine levels that may be secreted to the plasma. Such mechanism could contribute to explain the potential atherogenic properties of dietary methionine excess and the epidemiological relationship between elevated homocysteine levels and cardiovascular disease. In order to analyze this possibility, the effect of a range of methionine concentrations was assessed using several cell lines. [Methods]: H35 and Cos7 cell lines were grown in DMEM culture medium supplemented with 10% FBS and including 0.01, 0.05, 0.2 (control), 2 or 15 mM methionine for 4 days. Total mRNA was obtained and the expression levels of MAT genes analyzed by real-time RT-PCR (7300 RT PCR System, Applied Biosystems). [Results]: Methionine concentrations below control levels induced expression of the three MAT genes in H35 cells, whereas only MAT2A and MAT2B were induced in Cos7 cells. In contrast, methionine concentrations above control levels induced no significant expression changes in Cos-7 cells and only MAT2B was modified in H35 cells. (p<0.05 Unpaired t test). [Conclusions]: Our results show that methionine deficient medium affects expression of MAT genes in several cell lines, the specific effect depending on the cell origin. High methionine, however, seems have no effect regardless of the concentration.

This work was financed by the Science and Innovation Ministry (BFU20009-08977, Madrid, Spain) and Vitamin Metabolism and Aging Lab from the Jean Mayer USDA HNRCA at Tufts University (Boston, MA, EEUU).

Póster presentado al IUNS 20th International Congress of Nutrition: "Joining Cultures Through Nutrititon", celebrado en Granada (España) del 15 al 20 de septiembre de 2013.

Peer Reviewed