Identification and analysis of the promoter region of the human PLC-delta4 gene.

The delta4 isoform of phospholipase C (PLC-delta4) is thought to be associated with various cellular functions and disease status. However, little is known about how its function is controlled in cells, particularly in terms of the regulation of its expression. To understand the regulation mechanisms of the PLC-delta4 gene transcription, the 5'-flanking region (-2046 approximately +5) (the nucleotide sequence data reported in this paper have been submitted to the EMBL/GenBank/DDBJ data bank under accession numbers DQ302751) of the human PLC-delta4 gene was isolated from human genomic DNA. It was a TATA-less promoter with very GC-rich sequences near the transcription start site. The activity of the PLC-delta4 promoter was shown in various human and mouse cell lines by luciferase reporter assay. Serial deletion analysis identified the core promoter region as being between -402 and -67, in which an E-box and an AP-1 binding site played important roles in the promoter activity. In addition, we also showed that 12-O-tetradecanoylphorbol-1,3-acetate (TPA), a PKC activator and tumor promoter, induced the activity of the PLC-delta4 promoter via the AP-1 binding site. In summary, this study identified a core promoter region of the hPLC-delta4 gene and the factor binding sites responsible for the promoter activity. These results will provide important new information to further understand the regulatory mechanism of the PLC-delta4 function.