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 kinase 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, 7489-7493). Both CK2 and NM have been implicated in cell growth and proliferation. To examine whether CK2 in the NM was regulated in relation to a growth stimulus, we employed androgen action in the prostate as a model of growth control. In rats, androgen deprivation leads to a differential loss of CK2 activity and protein from the NM fraction in the prostate. At 24 h after androgen deprivation, the NM-associated CK2 activity as well as immunoreactive protein decline by about 80%. By comparison, total nuclear CK2 activity decreased by only 37%. Androgen administration to the castrated rats evokes a rapid differential increase in CK2 activity in the NM, so that within 1 h following the androgenic stimulus, the CK2 activity increases by 110% in the NM fraction versus 45% in the total nuclei. We propose that the stimulus-mediated differential translocation of CK2 to NM may play a role in the transduction of growth signal.