Expression and subcellular distribution of imp13 are regulated in brain development.

Imp13, a member of importin-β superfamily, is found to be one of two bidirectional transport receptors in many nuclear transport activities in mammals. Several cargoes of imp13 have been identified; most of these are essential factors involved in cell cycle and development. The expression and localization of imp13 may influence its cargoes in playing their roles in appropriate time and space. To gain insight into the role of imp13 in brain development, we generated an anti-imp13 polyclonal antibody and investigated the expressions of imp13 in mouse embryonic brains during development, including E13.5, E15.5, E17.5, P0, and adult, at both transcriptional and translational levels. In addition, we performed immunohistochemical analysis and revealed that imp13 tends to be localized in the cytoplasm at the early stages and relocates into the nucleus at the late stages in neuronal cells of mouse brains. These findings suggested that the expression and localization of imp13 in brain tissues are regulated developmentally, which extends our knowledge of the dynamic presence of imp13. These observations also imply that imp13 contributes to the neural cell-specific cargo trafficking and potentially to other functions during brain development.