Laboratory for Molecular Oncology, University of Leuven, Belgium.
Prohormone convertases are involved in the tissue-specific endoproteolytic processing of prohormones and neuropeptide precursors within the secretory pathway. In the present study, we have isolated genomic clones comprising the 5'-terminal region of the human prohormone convertase 1 (PC1) gene and identified and characterized the PC1 promoter region. We found multiple transcription start sites located within a 15-base pair region, 205 base pairs upstream of the translation start codon. The promoter region is not G+C-rich and does not contain a canonical TATA box nor a CAAT box. Transient expression assays with a set of human PC1 gene fragments containing progressive 5' deletions demonstrate that the proximal promoter region is capable of directing high levels of neuroendocrine-specific expression of reporter gene constructs. In addition, the proximal promoter region confers both basal and hormone-regulated promoter activity. Site-specific mutagenesis experiments demonstrate that two closely spaced cAMP response elements within the proximal promoter region direct cAMP-mediated hormonal regulation of transcription of the PC1 gene.