Differential control of free calcium and free zinc levels in isolated bovine liver nuclei.
Modulation of intracellular signal transduction by Ca2+ and possibly Zn2+ is based on an effective homoeostatic control of the corresponding free ion concentrations. We used the fluorescent indicator fura-2 to monitor concentrations of free Ca2+ and free Zn2+ in nuclei isolated from bovine liver. The nuclei showed an ATP-stimulated accumulation of intranuclear free Ca2+, which was inhibited in the presence of the Ca(2+)-pump inhibitor thapsigargin. Furthermore, uptake and intranuclear levels of free Zn2+ were measured after incubation with different extranuclear Zn2+ concentrations. There was no stimulating effect of ATP on Zn2+ uptake. Our data suggest that the levels of intranuclear free Ca2+ and free Zn2+ are controlled differentially. A distinct regulation of free ion levels in the nucleus may contribute to the specific control of nuclear events associated with gene transcription and cell differentiation.
Universität Bremen, Fachbereich Biologie/Chemie, Germany.
S
S
Hechtenberg
D
D
Beyersmann
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002417:Cattle; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002474:Cell-Free System; D016257:Fura-2; D008099:Liver / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013347:Subcellular Fractions / Q000378:metabolism; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin; D014220:Trialkyltin Compounds / Q000494:pharmacology; D014638:Vanadates / Q000494:pharmacology; D015032:Zinc / Q000378:metabolism*
D015220:Calcium Channels; D013729:Terpenes; D014220:Trialkyltin Compounds; D014638:Vanadates; C011559:tributyltin; D019284:Thapsigargin; D000255:Adenosine Triphosphate; D000252:Calcium-Transporting ATPases; D015032:Zinc; D002118:Calcium; D016257:Fura-2