Protein kinase ck2 association with nucleosomes in relation to their state of activity

Protein kinase CK2 (casein kinase 2) has been implicated in cell growth and proliferation. Since nucleosome is the subunit of chromatin structure and its organization on nuclear matrix is associated with transcriptional activity, we have examined if CK2 plays a role in nucleosome function in relation to its state of transcriptional activity. We employed the paradigm of androgenic regulation of genomic activity in the rat prostate, and fractionated the nucleosomes on the basis of their transcriptional activity from this tissue. Normal rat prostate nucleosomes demonstrated higher level of CK2 in the AN compared with IN. On androgen deprivation, loss of CK2 was observed from both the AN and IN; however, the decline in CK2 from the AN was slower than that from IN, reflecting the transcribing of the androgen-repressed genes following castration (e.g., clustcrin gene). On androgen administration, a larger increase was observed in CK2 associated with the AN relative to that in the IN fraction concordant with the expression of androgen-stimulated genes (e.g., C3 gene). However, continued androgenic stimulation resulted in an increase in CK2 in the IN fraction also. This suggests that CK2 association with IN may be required for promoting the conversion of IN to AN, to accord with the progressive temporal expression of many genes under these conditions. Several proteins associated with the prostatic nucleosomes were phosphorylated by the intrinsic CK2 in an androgen dependent manner. These data suggest a potential role of CK2 in nucleosome organization and function.