Nucleophosmin 1 (NPM1)
The NPM1(B23.1) protein derived from the main transcription form and the
longest transcript of the NPM gene, is mainly located in the granular
region of nucleolus. It has several functional domains responsible for
various actions, such as oligomerization, chaperone activity, histone
binding, ribonuclease activity (H. K, A, & MO, 2000). As a nuclear
shuttle protein, NPM1 plays multiple roles in the nucleolus including
centrosome duplication, ribosome biogenesis, intracellular transport,
apoptosis and mRNA splicing (MS, 2011). Importantly, a series of
evidence have demonstrated the interaction/interplay of the PEDV N
protein with the NPM1 protein, as well as their contribution to PEDV
infection. Firstly, the interaction and co-localization of those two
proteins has been confirmed by both immunoprecipitation (IP) and
GST-pull down assay, as well as confocal microscopy, respectively.
Moreover, the region of aa147-294 of the PEDV N protein and the region
of aa189-294 of NPM1 was verified to be essential for their interaction.
Secondly, the infection of PEDV was found to cause considerable
upregulation of the NPM1 expression. Especially, the NPM1 overexpression
of could promote the expression of the N protein and the proliferation
of PEDV, while its downregulation led to converse consequences. Thirdly,
mechanically the interaction between the N and NPM1 proteins could
prevent the cells from being cut off, increase the cell resistance to
apoptosis, avoid premature cell death, thus enhancing virus replication
(Shi D et al., 2017).