Expression analysis of genes involved in fat assimilation in human monocytes

The metabolic syndrome X is characterized by a group of risk factors such as obesity, atherogenic dyslipidemia, hypertension, and insulin resistance. To study the functional alterations resulting from genetic variations, ex vivo studies are one option to be carried out. Since it is not an easy procedure to obtain cells from the related tissues ex vivo, the aim of the present study was to investigate whether monocytes can serve as model cells. The purpose was to check if monocytes are insulin target cells or not and to elucidate the expression of genes involved in fat assimilation. Human monocytes were drawn from venous blood of healthy donors, aged 25 - 30, using density gradient separation and antibody-based magnetic cell sorting of CD14-positive cells. An expression analysis of genes was performed using RT-PCR and Western Blot. Transcripts of the three splice-variants of the Acyl-CoA binding protein (ACBP), the Medium-chain Acyl-CoA Synthetase 1 (MACS1), the Insulin Receptor (INSR) and the Peroxisome Proliferator-activated Receptor gamma (PPARgamma) are consistently expressed in monocytes of all donors. Differences in gene expression between donors are found for two other members of the MACS-family, the fatty acid transport protein 3 (FATP3) and the FATP4. On protein level, we tested for ACBP expression. The ACBP protein is consistently expressed in monocytes of all donors. Human monocytes are insulin target cells and capable of fatty acid metabolism to some extent. Ex vivo-derived monocytes could be used in additional studies for analyzing differences in genotype-dependent expression levels of genes involved in fat assimilation such as ACBP, MACS1 or PPARgamma.