Analysis of the functional sequences in the promoter region of the human adhesion molecule close homolog of L1

Abstract

Background Close Homolog of L1 (CHL1) is a member of the L1 family of cell adhesion molecules. CHL1 gene is located on human chromosome 3 and has been linked to several pathologies, including 3p deletion syndrome, schizophrenia, and tumor growth and metastasis. Objective The goal of the present study was to determine which region of the CHL1 promoter is most competent in driving CHL1 gene expression. Methods: Five candidate DNA fragments in the promoter regions were selected by screening across six species for evolutionary conserved sequences. The activity of these five promoter regions was quantitatively evaluated using a GFP reporter gene in transfection experiments, performed in C6 glioma cells. Results Of the five promoter regions tested, three drove reporter GFP expression, with the conserved region 6 (CR6, Gene ID AC066595.5, 25851-26850) being the most active for transcription. Conclusion The identification of the CR6 activity provides a better understanding of the regulatory mechanisms underlying CHL1 expression. It may help future discovery of therapeutic strategies that involve influencing critical promoter regions to drive transcriptional regulation of the mammalian CHL1 gene. HIGHLIGHTS Conserved regions of CHL1 promoter sequences were identified by in-silico analysis. Five conserved regions were tested for gene regulatory activity using a reporter assay. Conserved regions CR5, CR6 and CR7 show gene regulatory function in a reporter assay. Co-transfection of CR5 and CR6 yielded the highest reporter activity. The core region of CR6 (CR6core) was identified as a cis-acting element. In-tandem promoter CR5core-CR6core was the best in a reporter assay.