In this study, researchers used plasmid recombinant technology to generate HMGB1, p53, and P. HMGB1 is a growth factor, p53 is a tumor suppression factor that is enhanced through binding with HMGB1, and P is a 24-kDA phosphoprotein found in bornaviruses that inhibits HMGB1. The study aimed to determine the mechanism by which P inhibits HMGB1, with the hypothesis that P interferes with the binding between p53 and HMGB1.
The hypothesis was confirmed using a variety of techniques and assays, including recombinant plasmid technology to generate proteins, p53 deficient cells, and a Far Western blot. p53 and P was found to competitively bind with HMGB on the A box domain. P also decreased p53-mediated activation of cyclin G promoters, and p53 failed to upregulate cell-cycle inhibitor p21wafl in infected cells.
Development of this mechanism provides an understanding of not only the roles of HMGB1, but also that of P in vitro and how their interactions through p53 result in the virus’s neuropathogenicity. The study also established P as unique for its competitive binding with p53, for most viruses interfere with p53 by binding directly; a common mechanism found in oncogenic viruses.