Regulatory networks and regulatory sequences in familial combined hyperlipidemia patients.

Familial combined hyperlipidemia (FCHL) is the most frequent dislipidemic syndrome in our population, and it is strictly associated to the insurgence of coronary artery diseases in affected patients. In a previous project we have carried out a “genome wide” gene expression profiles analysis in FCHL patients as compared to normal control individuals, showing that the expression levels of approx. 300 genes are significantly altered (increased or reduced) in association to the disease. Statins are the elective drugs for treatment of this syndrome. The gene expression profiles of FCHL patients before and after statin treatment reveal that administration the drug for a minimum of 4 weeks "restores” the expression levels of most of the altered genes to "normal" values, in some cases causing hypo-expressed genes to became hyper-expressed. These results reveal the existence of regulatory interconnections among subsets of genes affected by FCHL syndrome. In order to identify putative common cis-acting sequence elements involved in the transcriptional regulation by statins, we searched the 5' upstream region of these genes for enriched short sequence motifs. We have analysed the -400/-200, -200/+1 and +1/+200 (relative to the transcriptional start site) human genomic sequences corresponding to both up- and down-regulated genes, obtaining six dataset. Each dataset has been searched with the MEME algorithm, setting the program to display up to 10 motifs, and using three different width windows (5-10, 6-15 or 10-20 nucleotides). We have identified some specifically enriched consensus sequences. One of these motifs is present in either the -400/-200 or the -200/+1 region of the majority (70%) of the up-regulated genes. We have synthesised double strand DNA fragments containing this consensus sequence in order to carry out EMSA (electrophoretic mobility shift assays) experiments with nuclear extracts from statin-treated cell cultures. These experiments are in presently in progress.