Ca2+ Signaling via ς1-Receptors: Novel Regulatory Mechanism Affecting Intracellular Ca2+Concentration1
- 1Cellular Pathobiology Unit, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland (T.H., T.-P.S.); and 2Institut National de la Santé et de la Recherche Médicale, Unité 336-Développement, Vieillissement et Plasticité du Système Nerveux, Montpellier, France (T.M.)
Abstract
The ς1-receptor is a one-transmembrane endoplasmic reticulum protein that binds neurosteroids and dextrorotatory benzomorphans. The roles of ς1-receptors in regulating intracellular Ca2+ in NG108 cells were examined in this study. ς1-Ligands pregnenolone sulfate, (+)-pentazocine, and 2-(4-morpholino)ethyl-1-phenylcyclohexane-1-carboxylate hydrochloride modulate Ca2+ signaling in NG108 cells via two modes of action. First, nanomolar concentrations of the ligands, without effect by themselves, potentiated the bradykinin-induced increase of the cytosolic free Ca2+ concentration in a bell-shaped manner. This effect of ς1-ligands was unaffected by depletion of Ca2+ from perfusion buffer and was blocked by a 21-mer antisense oligodeoxynucleotide against the cloned ς1-receptors. Second, after the cells were depleted of the endoplasmic reticulum Ca2+ stores, the depolarization (75 mM KCl)-induced increase in cytosolic free Ca2+ was potentiated by 2-(4-morpholino)ethyl-1-phenylcyclohexane-1-carboxylate hydrochloride, whereas it was inhibited by pregnenolone sulfate and (+)-pentazocine. These effects, albeit opposite in direction, were blocked by both the 21-mer antisense oligodeoxynucleotide and pertussis toxin. Western blotting indicates that ς1-receptors are increased on the plasma membrane and the nuclear membrane in the presence of ς1-ligand. These results suggest that Ca2+signaling via ς1-receptors may represent a novel mechanism that affects intracellular Ca2+ concentrations.
Footnotes
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Send reprint requests to: Dr. Tsung-Ping Su, Cellular Pathobiology Unit, Molecular Neuropsychiatry Section, Intramural Research Program, National Institute on Drug Abuse/National Institutes of Health, 5500 Nathan Shock Dr., Baltimore, MD 21224. E-mail: TSU{at}intra.nida.nih.gov
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↵1 This study was supported by the Intramural Research Program of the National Institute on Drug Abuse/National Institutes of Health. The partial supports of the Division of Basic Research (Basic Neurobiology and Biological Systems Research Branch), National Institute on Drug Abuse/National Institutes of Health, and the Pharmacopsychiatry Research Foundation of Japan are appreciated.
- Abbreviations:
- ER
- endoplasmic reticulum
- IP3
- inositol 1,4,5-trisphosphate
- NMDA
- N-methyl-d-aspartate
- NE-100
- N,N-dipropyl-2-[4-methoxy-3-(2-phenylethoxy)phenyl]-ethylamine monohydrochloride
- AS ODN
- antisense oligodeoxynucleotide
- PS
- pregnenolone sulfate
- (+)-PTZ
- (+)-pentazocine
- PRE-084
- 2-(4-morpholino)ethyl-1-phenylcyclohexane-1-carboxylate hydrochloride
- PT
- pertussis toxin
- BDK
- bradykinin
- TG
- thapsigargin
- HBSS
- Hanks' balanced salt solution
- MS ODN
- mismatched oligodeoxynucleotide
- TBST
- Tris-buffered saline/Tween 20
- Prog
- progesterone
- GABA
- γ-aminobutyric acid
- T + B + C
- TG + BDK + caffeine
- VDCC
- voltage-dependent Ca2+ channel
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- Received October 6, 1999.
- Accepted February 1, 2000.
- The American Society for Pharmacology and Experimental Therapeutics
