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Ca 2+ is released from the nuclear tubular structure into nucleoplasm in C6 glioma cells after stimulation with phorbol ester
Author(s) -
Lui P.P.Y.,
Lee C.Y.,
Tsang D.,
Kong S.K.
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)00838-2
Subject(s) - nucleoplasm , cytosol , cell nucleus , microbiology and biotechnology , phorbol , cytoplasm , nucleus , nuclear membrane , intracellular , nuclear localization sequence , biophysics , chemistry , biology , biochemistry , signal transduction , protein kinase c , nucleolus , enzyme
It is well established that cellular Ca 2+ is an important messenger that controls many nuclear functions but the source of nuclear Ca 2+ is far from clear. It has long been thought that Ca 2+ is translocated from the cytosol over a long distance to activate the nuclear transcription machinery. However, this model is at best an incomplete one. With the aid of confocal microscopy, we observed tubules extended deep inside the nucleus of C6 cells in agreement with previous studies (Fricker et al. (1997) J. Cell Biol. 136, 531–544). When cells were stimulated with phorbol 12‐myristate 13‐acetate or phorbol 12,13‐diacetate, Ca 2+ was released from these tubules. DiOC6(3), a vital marker for intracellular membranes, stained the tubule in the nucleus of the same cell used for Ca 2+ imaging. Moreover, results from labelling the cells with rhodamine 123 further indicate that the tubule was formed by a double‐membraned invagination with mitochondria inside. Studies with acridine orange showed that chromatin was excluded from the tubules. Taken together, our results demonstrate that the nuclear tubule is a structural entity responsible for the release of Ca 2+ into the nucleoplasm after stimulation with phorbol ester.