Cloning and Characterization of the 5′-Flanking Region for the Mouse Phospholipase C-δ1 Gene

To date, little is known about the molecular mechanisms controlling the regulation of phospholipase C-δ1 (PLC-δ1) gene expression. To understand the mechanisms responsible for the regulation of PLC-δ1 gene expression, the 5′-flanking region of the mouse PLC-δ1 gene was isolated from a mouse genomic DNA library. Primer extension analysis revealed that there is a single transcriptional start site located at 127 bases upstream from the translation start codon in the mouse PLC-δ1 gene. DNA sequence analysis showed that the sequence around the transcriptional start site is very GC-rich and has no TATA or CAAT boxes. Transient expression of a luciferase reporter gene under the control of serially deleted 5′-flanking sequences revealed that the 160-base-pair region from −622 to −462 upstream of the transcriptional start site includes a positive cis-acting element(s) for the efficient expression of the PLC-δ1 gene. Gel retardation analysis suggests that multiple transcription factors bind to separate sites on the promoter region. Based on these results, our study suggests that the minimal essential region located at −622 to +70 is fully sufficient to confer high-level transcriptional activity and contains high-affinity binding elements for multiple transcription factors.