title: Prostaglandin receptor EP2 mediates PGE2 stimulated hypercalcemia in mice in vivo.
abstract: Prostaglandin E2 (PGE2) can stimulate bone resorption by a cyclic AMP-dependent pathway. Two PGE2 receptors, EP2 and EP4 have been shown to play a role in PGE2 stimulation of osteoclast formation. In primary osteoblastic cell cultures from EP2 wild type (EP2 +/+) mice, PGE2 (0.1 microM) increased cyclic AMP production 3.5-fold, but PGE2 had no effect on cells from mice in which the EP2 receptor had been deleted (EP2 -/-). To examine the role of the EP2 receptor in the resorption response in vivo we injected PGE2 in EP2 -/- mice, and compared them with EP2 +/+ mice. Injection of PGE2 (3 mg/kg, four times daily for three days) in 9- to 12-month-old male mice on a 129 SvEv background increased serum calcium from 9.8 +/- 0.5 to 10.7 +/- 0.3 mg/dl (P < 0.01) in EP2 +/+ mice but not in EP2 -/- mice (10.1 +/- 0.3 vs. 10.2 +/- 0.3 mg/dl). PGE2 injection (6 mg/kg twice a day for three days) in 3-4 month old male mice on a C57 BL/6 X 129 SvEv background increased calcium from 8.2 +/- 0.1 to 9.0 +/- 0.3 mg/dl (P < 0.05) in EP2 +/+ mice but had no effect in EP2-/- mice (8.4 +/- 0.1 vs. 8.3 +/- 0.2 mg/dl). Injection of PGE2 over the calvariae of EP2 +/+ and EP2-/- mice increased the expression of receptor activator of nuclear factor kappaB ligand (RANKL) both locally and in the tibia, but RANKL responses were lower in EP2 -/- mice. We conclude that EP2 receptor plays a role in the hypercalcemic response to PGE2. This impaired response in EP2 -/- mice may be due to decreased ability to stimulate cyclic AMP and in part, to a smaller increase in the expression of RANKL mRNA.
authors.affiliation: Department of Medicine, University of Connecticut Health Center, Farmington 06030, USA.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Li
authors.forename: Masato
authors.initials: M
authors.lastname: Tomita
authors.forename: Carol C
authors.initials: CC
authors.lastname: Pilbeam
authors.forename: Richard M
authors.initials: RM
authors.lastname: Breyer
authors.forename: Lawrence G
authors.initials: LG
authors.lastname: Raisz
mesh_terms: D000199:Actins / Q000378:metabolism; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D015152:Blotting, Northern; D001842:Bone and Bones / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002118:Calcium / Q000097:blood; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D000242:Cyclic AMP / Q000096:biosynthesis; D015232:Dinoprostone / Q000097:blood / Q000378:metabolism / Q000494:pharmacology*; D024581:Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating) / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism; D006934:Hypercalcemia / Q000097:blood / Q000139:chemically induced / Q000378:metabolism*; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010006:Osteoblasts / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects; D053244:Osteoprotegerin; D053245:RANK Ligand; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D018078:Receptors, Prostaglandin E / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D058307:Receptors, Prostaglandin E, EP2 Subtype; D018124:Receptors, Tumor Necrosis Factor
chemical_list: D000199:Actins; D002352:Carrier Proteins; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D053244:Osteoprotegerin; C545645:Ptger2 protein, mouse; D053245:RANK Ligand; D012333:RNA, Messenger; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; D018078:Receptors, Prostaglandin E; D058307:Receptors, Prostaglandin E, EP2 Subtype; D018124:Receptors, Tumor Necrosis Factor; C505687:Tnfrsf11a protein, mouse; C506031:Tnfrsf11b protein, mouse; C505689:Tnfsf11 protein, mouse; D000242:Cyclic AMP; D024581:Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating); D000262:Adenylyl Cyclases; D015232:Dinoprostone; D002118:Calcium