PGE2 stimulates human brain natriuretic peptide expression via EP4 and p42/44 MAPK

Hypertension and Vascular Research Division, Department of Medicine, Henry Ford Hospital, Detroit, Michigan Submitted 23 August 2005 ; accepted in final form 13 January 2006 Brain natriuretic peptide (BNP) produced by cardiac myocytes has antifibrotic and antigrowth properties and is a marker of cardiac hypertrophy. We previously showed that prostaglandin E 2 (PGE 2 ) is the main prostaglandin produced in myocytes treated with proinflammatory stimuli and stimulates protein synthesis by binding to its EP 4 receptor. We hypothesized that PGE 2 , acting through EP 4 , also regulates BNP gene expression. We transfected neonatal ventricular myocytes with a plasmid encoding the human BNP (hBNP) promoter driving expression of a luciferase reporter gene. PGE 2 increased hBNP promoter activity 3.5-fold. An EP 4 antagonist reduced the stimulatory effect of PGE 2 but not an EP 1 antagonist. Because EP 4 signaling can involve adenylate cyclase, cAMP, and protein kinase A (PKA), we tested the effect of H-89, a PKA inhibitor, on PGE 2 stimulation of the hBNP promoter. H-89 at 5 µM decreased PGE 2 stimulation of BNP promoter activity by 100%. Because p42/44 MAPK mediates the effect of PGE 2 on protein synthesis, we also examined the role of MAPKs in the regulation of BNP promoter activity. PGE 2 stimulation of the hBNP promoter was inhibited by a MEK1/2 inhibitor and a dominant-negative mutant of Raf, indicating that p42/44 MAPK was involved. In contrast, neither a p38 MAPK inhibitor nor a JNK inhibitor reduced the stimulatory effect of PGE 2 . Involvement of small GTPases was also studied. Dominant-negative Rap inhibited PGE 2 stimulation of the hBNP promoter, but dominant-negative Ras did not. We concluded that PGE 2 stimulates the BNP promoter mainly via EP 4 , PKA, Rap, and p42/44 MAPK. EP receptor; cardiac myocytes; hypertrophy; signaling pathways Address for reprint requests and other correspondence: M. C. LaPointe, Hypertension and Vascular Research Division, Henry Ford Hospital, 2799 W. Grand Blvd., Detroit, MI 48202-2689 (e-mail: mlapoin1{at}hfhs.org )