GROWTH STIMULUS-MEDIATED DIFFERENTIAL TRANSLOCATION OF CASEIN KINASE-2 TO THE NUCLEAR MATRIX - EVIDENCE BASED ON ANDROGEN ACTION IN THE PROSTATE

Recently, we documented that a significant amount of nuclear casein ki nase 2 (CK2) (a ubiquitous multipotential messenger-independent serine /threonine protein kinase) is associated with the nuclear matrix (NM), where it may be involved in the phosphorylation of several intrinsic proteins (Tawfic, S., and Ahmed, K. (1994) J. Biol. Chem. 269, 7489-74 93). Both CK2 and NM have been implicated in cell growth and prolifera tion. To examine whether CK2 in the NM was regulated in relation to a growth stimulus, we employed androgen action in the prostate as a mode l of growth control. In rats, androgen deprivation leads to a differen tial loss of CK2 activity and protein from the NM fraction in the pros tate. At 24 h after androgen deprivation, the NM-associated CK2 activi ty as well as immunoreactive protein decline by about 80%. By comparis on, total nuclear CK2 activity decreased by only 37%. Androgen adminis tration to the castrated rats evokes a rapid differential increase in CK2 activity in the NM, so that within 1 h following the androgenic st imulus, the CK2 activity increases by 110% in the NM fraction versus 4 5% in the total nuclei. We propose that the stimulus-mediated differen tial translocation of CK2 to NM may play a role in the transduction of growth signal.