Bj. Desai et Jm. Burrin, PACAP-38 POSITIVELY REGULATES GLYCOPROTEIN HORMONE ALPHA-GENE EXPRESSION IN PLACENTAL CELLS, Molecular and cellular endocrinology, 99(1), 1994, pp. 31-37
The human glycoprotein hormone alpha-gene is transcriptionally activat
ed by cAMP in placental cells. We have shown that the novel hypothalam
ic peptide, pituitary adenylate cyclase activating polypeptide, PACAP-
38, significantly stimulates intracellular cAMP levels (12-fold increa
se; P < 0.001) in JEG-3 choriocarcinoma cells. Regulation of alpha-pro
moter activity was assessed using both the chloramphenicol acetyl tran
ferase (CAT) and the luciferase (LUC) reporter gene systems. alpha-CAT
activity was significantly stimulated by PACAP-38 (4-fold increase; P
< 0.05) at 24 h with a similar stimulation being seen with a LUC expr
ession vector. The kinetics of stimulation of the alpha-promoter by PA
CAP-38 were similar to those seen with 8-Br-cAMP and vasoactive intest
inal polypeptide (VIP), a peptide which shares 68% homology with PACAP
-38. PACAP-38 also stimulated the production of IL-6 from JEG-3 cells
with a time course of response similar to that of alpha-promoter trans
cription. We conclude that human placental choriocarcinoma cells posse
ss functional receptors for PACAP-38, whose activation enhances cAMP f
ormation, alpha-subunit gene transcription and interleukin-6 (IL-6) pr
oduction.