Co-expressions of casein kinase 2 (CK2) subunits restore the down-regulation of tubulin levels and disruption of microtubule structures caused by PrP mutants.

CK2 shows disease-associated alteration in the scrapie experimental rodents and human prion diseases. In this study, mammalian expressing plasmids for human CK2 subunits, CK2α and CK2β, were generated. Immunoprecipitation assays revealed stronger signals of PrP-CK2α complexes in the HEK293 cells co-transfected with plasmids expressing CK2α and various PrP constructs, including PG5, CytoPrP, PG9, and PG12. Meanwhile, obviously weaker signals of PrP-CK2β complexes were also observed in the cells co-expressing CK2β and PrPs. Tubulin-specific Western blots and immunofluorescence assays revealed that similar as the observations in the presences of PrP-specific siRNA, the abnormal PrPs-induced reductions of tubulin and disruptions of microtubule structures were completely restored in the cells when co-expressing CK2α and CK2β. Moreover, co-expressions of CK2α and PrPs induced phosphorylation on p53 at the position of serine 6 (p53-Ser6), although much weaker than that in the cells expressing CK2α and CK2β, while expressions of either PrPs or CK2 subunits did not change the cellular p53 level or induce phosphorylation on p53 at Ser9. Our data here verify again the molecular interaction between CK2 and PrP. Co-presences of CK2 subunits restore the down-regulated tubulin and disrupted microtubule structures caused by expressions of the abnormal PrP proteins in HEK293 cells.