ASSOCIATION OF CASEIN KINASE-2 WITH NUCLEAR CHROMATIN IN RELATION TO ANDROGENIC REGULATION OF RAT PROSTATE

Casein kinase 2 (CK-2) is a ubiquitous messenger-independent protein s erine/threonine kinase that has been implicated in growth control. We have studied the activity and subcellular location of CK-2 in adult ra t ventral prostate in relation to androgen withdrawal and administrati on. Androgen deprivation by castration results in a faster decline in CK-2 activity associated with prostatic nuclei than that in the cytoso l. Nuclear CK-2 associated with chromatin is reduced at an even greate r rate than that in the total nucleus. Reversal of these events by adm inistration of a single dose of 5alpha-dihydrotestosterone to adult ra ts castrated 144 hr previously was accompanied by a differential early enhancement of chromatin-associated CK-2 activity, with a concomitant decrease in the CK-2 activity present in the cytosol. Changes in the nuclear CK-2 activity correlated with the immunostainable enzyme prote in in the nucleus. We propose that androgens evoke translocation of CK -2 from the cytoplasm to the nucleus (nucleoplasm) where its enhanced association with the chromatin constituents takes place. Conversely, w ithdrawal of circulating androgens due to castration evokes a dissocia tion of CK-2 from chromatin and eventual translocation of nucleoplasmi c CK-2 to the cytoplasm. Modulations in the association of CK-2 with n uclear chromatin may represent an important mechanism of post-transcri ptional regulation of nuclear CK-2 in relation to androgen action in t he prostate.