Cell signaling and estrogens in female rat osteoblasts: A possible involvement of unconventional nonnuclear receptors
| Autor: | Sonia Balsan, Moustapha Kachkache, Michèle Lieberherr, Brigitte Grosse |
|---|---|
| Rok vydání: | 2009 |
| Předmět: |
medicine.medical_specialty
Thapsigargin Inositol Phosphates Endocrinology Diabetes and Metabolism Calcium-Transporting ATPases Biology Pertussis toxin Calcium in biology chemistry.chemical_compound Internal medicine medicine Animals Orthopedics and Sports Medicine Inositol Inositol phosphate Egtazic Acid Cells Cultured Diacylglycerol kinase chemistry.chemical_classification Osteoblasts Estradiol Phospholipase C Terpenes Calcium Channel Blockers Rats Endocrinology chemistry Calcium Female Arachidonic acid |
| Zdroj: | Journal of Bone and Mineral Research. 8:1365-1376 |
| ISSN: | 0884-0431 |
| DOI: | 10.1002/jbmr.5650081111 |
| Popis: | Estrogen deficiency is associated with bone loss, and estrogen replacement is an effective treatment of this osteoporotic process. This study examines the early (5-120 s) effects of 17 beta-estradiol on the intracellular calcium and phospholipid metabolism in confluent female rat osteoblasts. The cytosolic free Ca2+ concentration ([Ca2+]i) was determined using fura-2/AM as Ca2+ probe. Cells were labeled with myo-[2-3H]inositol or [14C]arachidonic acid for inositol or lipid determination. Inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG) production were determined by either mass measurement or anion-exchange chromatography or by thin-layer chromatography, respectively. 17 beta-Estradiol (1 pM to 1 nM) increased [Ca2+]i in a biphasic manner within 10 s via Ca2+ influx from the extracellular milieu, as shown by the effects of the calcium chelator EGTA and the Ca2+ channel blockers nifedipine and verapamil, and via Ca2+ mobilization from the endoplasmic reticulum (ER), as shown by the effects of thapsigargin. 17 beta-Estradiol (1 pM to 1 nM) induced a biphasic and concomitant increase in IP3 and DAG formation. Estradiol immobilized on bovine serum albumin (BSA) [E-(O-carboxymethyl)oxime BSA] and its derivative (O-carboxymethyl)oxime rapidly increased ([Ca2+]i, IP3, and DAG and were full agonists, although they were less potent than the free estradiol. They had the same action time course and acted via Ca2+ influx and Ca2+ mobilization from ER. Tamoxifen, a potent inhibitor of genomic steroid responses, did not block the rapid increase in Ca2+, IP3, and DAG induced by estradiol. Finally, inhibitor of phospholipase C (neomycin) and pertussis toxin abolished the effects of 17 beta-estradiol on IP3 and DAG formation. These results suggest that female rat osteoblasts bear non-genomic unconventional cell surface receptors for estradiol, belonging to the class of the membrane receptors coupled to a phospholipase C via a pertussis toxin-sensitive G protein. |
| Databáze: | OpenAIRE |
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