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The role of cellular energy levels in the calcium‐mediated regulation of the Ran nuclear transport gradient.
Author(s) -
Batzel Kaci,
Resendes Karen
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.571.1
Subject(s) - ran , gtp' , cytoplasm , nuclear transport , microbiology and biotechnology , thapsigargin , ionomycin , cytosol , intracellular , small gtpase , chemistry , aequorin , biology , biophysics , biochemistry , cell nucleus , signal transduction , enzyme
Nuclear protein transport is regulated by karyopherin receptors and their interaction with the Ran gradient, which regulates their functional directionality. Ran is a small GTPase that can be found either in its GTP‐bound state within in the nucleus or its GDP‐bound state within the cytoplasm. Treatment of HeLa cells with thapsigargin or ionomycin causes cellular stress by increasing intracellular calcium levels, which can cause Ran to accumulate in the cytoplasm in its GDP bound state. Since GTP levels within the cell are inherently dependent to the presence of ATP, this study sought to determine whether the collapse of the Ran gradient was caused by a decrease in cellular ATP levels. We hypothesize that a drop in ATP occurs with drug treatment, which leads to a decrease in the amount of GTP present, thus resulting in the collapse in the overall gradient. Interestingly, localization of the Ran‐independent receptor for mRNA export, Tap (NXF1), is not affected by drug treatment, indicating that the GTP independent export of mRNA is not disrupted under these circumstances. The amount of ATP present within the cells was then quantified in relation to the amount of light produced by using a luciferin‐luciferase assay. Thus, we intend to determine the relationship between increased intracellular calcium levels and the disruption of the Ran gradient in terms of cellular ATP levels.