PCID2 assists in the nuclear export of nucleophosmin (NPM) in HeLa cells

Abstract

PCI‐domain containing protein 2 (PCID2) plays a key role in facilitating the nuclear export of various proteins. PCID2 further functions by localizing to the centrosome, where it likely helps to regulate the process of centrosome duplication. Nucleophosmin (NPM) is a nucleolar protein that undergoes Crm1‐dependent nuclear export and also associates with centrosomes to prevent premature cell division. Other proteins reliant on Crm1 for nuclear export, including BRCA1, further require the presence of PCID2 for efficient nuclear export and subsequent centrosomal localization. Here, we show that NPM is also reliant on PCID2 for its nuclear export through the use of siRNA knockdown on HeLa cells. Immunofluorescence revealed a 34% increase in nuclear fluorescence of NPM without PCID2, while centrosomal localization of NPM exhibited no direct impact due to removal of PCID2. These results identify a supporting role for PCID2 in the regulation of centrosome duplication through the facilitation of NPM nuclear export to the cytoplasm. Ongoing studies seek to identify NPM and PCID2 complexes via immunoprecipitation as well as exploring the possible effects of PCID2 knockdown on the structure or composition of the nucleolus and on NPM subnuclear localization. Our research has identified a role for PCID2 in the regulation of NPM nuclear export, providing potential insight into the development of tumorigenesis due to centrosome amplification and possible changes to nucleolar structure and composition.