N ϵ -Carboxymethyllysine Increases the Expression of miR-103/143 and Enhances Lipid Accumulation in 3T3-L1 Cells

Advanced glycation end products, formed in vivo but also by the Maillard reaction upon thermal treatment of foods, have been associated with the progression of pathological conditions such as diabetes mellitus. In addition to the accumulation with age, exogenous AGEs are introduced into the circulation from dietary sources. In this study, we investigated the effects of addition of free N(ϵ) -carboxymethyllysine (CML), a well-characterized product of the Maillard reaction, on adipogenesis in 3T3-L1 preadipocytes. Treatment with 5 µM, 50 µM or 500 µM CML resulted in increased lipid accumulation to similar extents, by 11.5 ± 12.6%, 12.9 ± 8.6% and 12.8 ± 8.5%, respectively. Long-term treatment with 500 µM CML during adipogenesis resulted in increases in miR-103 and miR-143 levels, two miRNAs described to be involved in impaired glucose homeostasis and increased lipid accumulation. Furthermore, the expression of genes associated with these miRNAs, consisting of Akt1, PI3k and Cav1 was regulated by CML. Short term treatment of mature 3T3-L1 adipocytes with CML resulted in decreased basal glucose uptake. These results indicate that the addition of protein-free CML to 3T3-L1 cells influence parameters associated with adipogenesis and glucose homeostasis at transcriptional and functional level; this indicates that free CML derived from exogenous sources, in addition to protein-bound CML may be relevant in this context.