Nuclear matrix and protein kinase CK2 signaling.

The dynamic functional nature of the nuclear matrix dictates that it provide a locus for molecules involved in nuclear transduction of signals, such as those participating in cell growth control. Protein kinases are key elements in a variety of signaling mechanisms and certain of these enzymes have been shown to associate with the NM. Among these, the protein ser/thr kinase CK2 has attracted considerable attention because of its involvement in cell growth. NM appears to be a preferential locus for CK2, as evidenced from its rapid modulation in the NM in response to hormonal and growth factor signals. Differential regulation of CK2 is also noted in the transcriptionally active and inactive nucleosomes. A number of potential substrates for CK2 are localized to the NM. Likewise, distinct substrates for CK2 are noted in the transcriptionally active compared with inactive nucleosomes. The dynamics of phosphorylation of these substrates and that of the association of CK2 activity to these fractions suggests that CK2 may play a role in the functional activities of NM and provide a link between the NM and nucleosomes by serving as a factor in promoting the transition of inactive to active nucleosome.