التفاصيل البيبلوغرافية
| العنوان: |
Nucleoplasmic Ca2+loading is regulated by mobilization of perinuclear Ca2+ |
| المؤلفون: |
Abrenica, B., Gilchrist, J.S.C. |
| المصدر: |
Cell Calcium; August 2000, Vol. 28 Issue: 2 p127-136, 10p |
| مستخلص: |
Regulation of nucleoplasmic calcium (Ca2+) concentration may occur by the mobilization of perinuclear luminal Ca2+pools involving specific Ca2+pumps and channels of both inner and outer perinuclear membranes. To determine the role of perinuclear luminal Ca2+, we examined freshly cultured 10 day-old embryonic chick ventricular cardiomyocytes. We obtained evidence suggesting the existence of the molecular machinery required for the bi-directional Ca2+fluxes using confocal imaging techniques. Embryonic cardiomyocytes were probed with antibodies specific for ryanodine-sensitive Ca2+channels (RyR2), sarco/endoplasmic reticulum Ca2+ATPase (SERCA2)-pumps, and fluorescent BODIPY derivatives of ryanodine and thapsigargin. Using immunocytochemistry techniques, confocal imaging showed the presence of RyR2 Ca2+channels and SERCA2-pumps highly localized to regions surrounding the nucleus, referable to the nuclear envelope. Results obtained from Fluo-3, AM loaded ionomycin-perforated embryonic cardiomyocytes demonstrated that gradual increases of extranuclear Ca2+from 100 to 1600 nM Ca2+was localized to the nucleus. SERCA2-pump inhibitors thapsigargin and cyclopiazonic acid showed a concentration-dependent inhibition of nuclear Ca2+loading. Furthermore, ryanodine demonstrated a biphasic concentration-dependence upon active nuclear Ca2+loading. The concomitant addition of thapsigargin or cyclopiazonic acid with ryanodine at inhibitory concentrations caused an significant increase in nuclear Ca2+loading at low concentrations of extranuclear added Ca2+. Our results show that the perinuclear lumen in embryonic chick ventricular cardiomyocytes is capable of autonomously regulating nucleoplasmic Ca2+fluxes. |
| قاعدة البيانات: |
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