Intracellular calcium levels can regulate Importin-dependent nuclear import

We previously showed that increased intracellular calcium can modulate Importin (Imp)beta 1-dependent nuclear import of SRY-related chromatin remodeling proteins. Here we extend this work to show for the first time that high intracellular calcium inhibits Imp alpha/beta 1- or Imp beta 1-dependent nuclear protein import generally. The basis of this relates to the mislocalisation of the transport factors Imp beta 1 and Ran, which show significantly higher nuclear localization in contrast to various other factors, and RCC1, which shows altered subnuclear localisation. The results here establish for the first time that intracellular calcium modulates conventional nuclear import through direct effects on the nuclear transport machinery. (C) 2014 Elsevier Inc. All rights reserved.