Nucleocytoplasmic shuttling of SOX14A and SOX14B transcription factors.

The nucleocytoplasmic shuttling of SOX transcription factors play a crucial role in the regulation of SOX protein functions during development. In this study, we have demonstrated two nuclear localization signals in the HMG box of Eriocheir sinensis SOX14A and SOX14B. These two conserved nuclear localization signals mediate nuclear transport. The N-termini nuclear localization signal mediates the calmodulin-dependent pathway and the C-termini nuclear localization signal interacts with the importin-β pathway. The targeted deletion of nuclear localization signals of SOX14A/B dramatically inhibits the nuclear accumulation. We have first time revealed a non-classic nuclear export signal in the HMG box of E. sinensis SOX14A/B proteins is responds to leptomycin B. E. sinensis SOX14A/B is transported from the nucleus to the cytoplasm via a CRM1-dependent nuclear export pathway. And E. sinensis SOX14A/B are not belong to the subgroup E SOX proteins. Furthermore, these findings could shed a light on the mechanisms involved in the nuclear export of SOX proteins. The imperfect nuclear export signal on other SOX proteins, rather than just those of the SOXE group, may also be functional for nuclear export.