Prostaglandin E2 activates outwardly rectifying Cl(-) channels via a cAMP-dependent pathway and reduces cell motility in rat osteoclasts.
We examined changes in electrical and morphological properties of rat osteoclasts in response to prostaglandin (PG)E(2). PGE(2) (>10 nM) stimulated an outwardly rectifying Cl(-) current in a concentration-dependent manner and caused a long-lasting depolarization of cell membrane. This PGE(2)-induced Cl(-) current was reversibly inhibited by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), and tamoxifen. The anion permeability sequence of this current was I(-) > Br(-) approximately Cl(-) > gluconate(-). When outwardly rectifying Cl(-) current was induced by hyposmotic extracellular solution, no further stimulatory effect of PGE(2) was seen. Forskolin and dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP) mimicked the effect of PGE(2). The PGE(2)-induced Cl(-) current was inhibited by pretreatment with guanosine 5'-O-2-(thiodiphosphate) (GDPbetaS), Rp-adenosine 3',5'-cyclic monophosphorothioate (Rp-cAMPS), N-(2-[p-bromocinnamylamino]ethyl)-5-isoquinolinesulfonamide dihydrochloride (H-89), and protein kinase A inhibitors. Even in the absence of nonosteoclastic cells, PGE(2) (1 microM) reduced cell surface area and suppressed motility of osteoclasts, and these effects were abolished by Rp-cAMPS or H-89. PGE(2) is known to exert its effects through four subtypes of PGE receptors (EP1-EP4). EP2 and EP4 agonists (ONO-AE1-259 and ONO-AE1-329, respectively), but not EP1 and EP3 agonists (ONO-DI-004 and ONO-AE-248, respectively), mimicked the electrical and morphological actions of PGE(2) on osteoclasts. Our results show that PGE(2) stimulates rat osteoclast Cl(-) current by activation of a cAMP-dependent pathway through EP2 and, to a lesser degree, EP4 receptors and reduces osteoclast motility. This effect is likely to reduce bone resorption.
Okamoto
Fujio
F
Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan 814-0193. fujipi@college.fdcnet.ac.jp
Kajiya
Hiroshi
H
Fukushima
Hidefumi
H
Jimi
Eijiro
E
Okabe
Koji
K
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000494:pharmacology; D000818:Animals; D000838:Anions / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism*; D015232:Dinoprostone / Q000819:agonists / Q000494:pharmacology / Q000502:physiology*; D004553:Electric Conductivity; D007425:Intracellular Membranes / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D009579:Nitrobenzoates / Q000494:pharmacology; D009995:Osmosis; D010010:Osteoclasts / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D010539:Permeability / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D011982:Receptors, Prostaglandin / Q000819:agonists / Q000378:metabolism; D015398:Signal Transduction
D000838:Anions; D018118:Chloride Channels; D009579:Nitrobenzoates; D011982:Receptors, Prostaglandin; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D000242:Cyclic AMP; D015232:Dinoprostone; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid