ATP-dependent accumulation and inositol trisphosphate- or cyclic ADP-ribose-mediated release of Ca2+ from the nuclear envelope.
Uptake and release of Ca2+ from isolated liver nuclei were studied with fluorescent probes. We show with the help of digital imaging and confocal microscopy that the Ca(2+)-sensitive fluorescent probe Fura 2 is concentrated in or around the nuclear envelope and that the distribution of Fura 2 fluorescence is similar to that of an endoplasmic reticulum marker. The previously demonstrated ATP-dependent uptake of Ca2+ into isolated nuclei and release of the accumulated Ca2+ by inositol 1,4,5-trisphosphate (IP3) are therefore due to transport of Ca2+ into and out of the nuclear envelope and not the nucleoplasm. Dextrans labeled with fluorescent Ca2+ indicators (calcium-Green 1 and Fura 2) are distributed uniformly in the nucleoplasm and can be used to show that changes in the external Ca2+ concentration produce rapid changes in the nucleoplasmic Ca2+ concentration. Nevertheless, IP3 and cyclic ADP-ribose evoke transient intranuclear Ca2+ elevations. The release from the Ca2+ stores in or around the nuclear envelope appears to be directed into the nucleoplasm from where it can diffuse out through the permeable nuclear pore complexes.
Physiological Laboratory, University of Liverpool, England.
O V
OV
Gerasimenko
J V
JV
Gerasimenko
A V
AV
Tepikin
O H
OH
Petersen
D000246:Adenosine Diphosphate Ribose / Q000031:analogs & derivatives* / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D002232:Carbocyanines; D036563:Cyclic ADP-Ribose; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005456:Fluorescent Dyes; D016257:Fura-2; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology*; D017136:Ion Transport / Q000187:drug effects; D008099:Liver / Q000166:cytology / Q000378:metabolism; D018613:Microscopy, Confocal; D008954:Models, Biological; D009685:Nuclear Envelope / Q000378:metabolism*; D012433:Ryanodine / Q000494:pharmacology
D002232:Carbocyanines; D005456:Fluorescent Dyes; D036563:Cyclic ADP-Ribose; D012433:Ryanodine; D000246:Adenosine Diphosphate Ribose; C007392:3,3'-dihexyl-2,2'-oxacarbocyanine; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D002118:Calcium; D016257:Fura-2