G. An et al., ISOLATION AND CHARACTERIZATION OF THE HUMAN SPR1 GENE AND ITS REGULATION OF EXPRESSION BY PHORBOL ESTER AND CYCLIC-AMP, The Journal of biological chemistry, 268(15), 1993, pp. 977-982
The small proline-rich protein gene (spr1) is a marker whose expressio
n is frequently associated with squamous cell differentiation. We obse
rved that the expression of the spr1 gene is strongly induced by phorb
ol 12-myristate 13-acetate (PMA). Both the time course result and the
nuclear run-on transcriptional assay suggested that the regulation of
spr1 expression by PMA is controlled at the transcriptional level. To
understand the nature of this regulation, human genomic clones of the
spr1 gene were isolated. DNA sequence analysis revealed that the human
spr1 gene contains two exons and a single intron located within the 5
'-untranslated region. An AP-1 binding site (TGAGTCA) is found at -142
, and a putative cyclic AMP-responsive element (TGAGGTCA) at -597 base
pairs upstream of the transcription start site. A chimeric construct
containing the 5'-flanking region of the spr1 gene and the chloramphen
icol acetyltransferase (CAT) reporter gene was used to transfect HeLa
cells or monkey primary TBE cells. The CAT activity in transfected cel
ls is stimulated 7.5-11-fold by PMA, and the stimulation is inhibited
by a protein kinase C inhibitor or by pretreating cells with PMA to do
wn-regulate the protein kinase C activity. The CAT activity is also st
imulated 3.5-fold by dibutyryl cyclic AMP, a protein kinase A activato
r. The stimulations by PMA and cAMP are additive. These results sugges
t that protein kinase C and probably protein kinase A play important r
oles in regulating the transcription of the spr1 gene.