ABSTRACT
Prostaglandin E2 (PGE2) is elevated during cardiac injury and we have previously shown that mice lacking the PGE2 EP4 receptor display dilated cardiomyopathy (DCM) with increased expression of the membrane type matrix metalloproteinase, MMP-14. We thus hypothesized that PGE2 regulates expression of MMP-14 and also affects fibroblast migration. Primary cultures of neonatal rat ventricular fibroblasts (NVFs) were used to test the effects of PGE2. Gene and protein expression was assessed by real time RT-PCR and Western blot, MMP activity was determined by zymography and migration of NVF was assessed by motility in a transwell system. PGE2 reduced expression of MMP-14 and these effects were antagonized by an EP4 antagonist. An EP4 agonist mimicked the effect of PGE2. PGE2 also increased mRNA and protein levels of plasminogen activator inhibitor-1 (PAI-1), an inhibitor of MMP activation. However, PGE2-stimulation of PAI-1 was mediated by the EP1/EP3 receptor and not EP4. Migration of NVF was assessed by motility in a transwell system. Treatment of NVFs with PGE2 reduced the number of cells migrating toward 10% FCS. Treatment with the EP2 agonist also reduced migration but did not affect MMP-14 expression or PAI-1. Our results suggest that PGE2 utilizes different receptors and mechanisms to ultimately decrease MMP expression and NVF migration.
Subject(s)
Cardiomyopathies/metabolism , Dinoprostone/metabolism , Gene Expression Regulation/physiology , Matrix Metalloproteinase 14/metabolism , Plasminogen Activator Inhibitor 1/metabolism , Receptors, Prostaglandin E, EP4 Subtype/metabolism , Alprostadil/analogs & derivatives , Alprostadil/pharmacology , Animals , Animals, Newborn , Cardiomyopathies/enzymology , Cell Movement/physiology , Dinoprostone/analogs & derivatives , Dinoprostone/pharmacology , Fibroblasts/enzymology , Fibroblasts/metabolism , Male , Matrix Metalloproteinase 14/genetics , Methyl Ethers/pharmacology , Naphthalenes/pharmacology , Phenylbutyrates/pharmacology , Plasminogen Activator Inhibitor 1/genetics , RNA, Messenger/chemistry , RNA, Messenger/genetics , Rats , Real-Time Polymerase Chain Reaction , Receptors, Prostaglandin E, EP4 Subtype/antagonists & inhibitorsABSTRACT
Parathyroid hormone-related protein (PTHrP) increases renin release from isolated perfused kidneys and may act as an autacoid regulator of renin secretion, but its effects on renin in vivo are unknown. In vivo, PTHrP causes hypercalcemia and anorexia, which may affect renin. We hypothesized that chronically elevated PTHrP would increase plasma renin activity (PRA) indirectly via its anorexic effects, reducing sodium chloride (NaCl) intake and causing NaCl restriction. We infused male Sprague-Dawley rats with the vehicle (control) or 125 µg PTHrP/day (PTHrP) via subcutaneous osmotic minipumps for 5 days. To replenish NaCl consumption, a third group of PTHrP-infused rats received 0.3% NaCl (PTHrP + NaCl) in their drinking water. PTHrP increased PRA from a median control value of 3.68 to 18.4 ng Ang I·ml(-1)·h(-1) (P < 0.05), whereas the median PTHrP + NaCl PRA value was normal (7.82 ng Ang I·ml(-1)·h(-1), P < 0.05 vs. PTHrP). Plasma Ca(2+) (median control: 10.2 mg/dl; PTHrP: 13.7 mg/dl; PTHrP + NaCl: 14.1 mg/dl; P < 0.05) and PTHrP (median control: 0.03 ng/ml; PTHrP: 0.12 ng/ml; PTHrP + NaCl: 0.15 ng/ml; P < 0.05) were elevated in PTHrP- and PTHrP + NaCl-treated rats. Body weights and caloric consumption were lower in PTHrP- and PTHrP + NaCl-treated rats. NaCl consumption was lower in PTHrP-treated rats (mean Na(+): 28.5 ± 4.1 mg/day; mean Cl(-): 47.8 mg/day) compared with controls (Na(+): 67.3 ± 2.7 mg/day; Cl(-): 112.8 ± 4.6 mg/day; P < 0.05). NaCl consumption was comparable with control in the PTHrP + NaCl group; 0.3% NaCl in the drinking water had no effect on PRA in normal rats. Thus, our data support the hypothesis that PTHrP increases PRA via its anorexic effects, reducing NaCl intake and causing NaCl restriction.
