Protein kinase CK2 and phosphorylated ERK1/2 accumulated in nucleus after serum stimulation of quiescent HepG2 cells. Nonetheless, phospho-ERK1/2 accumulated mainly in the nuclease-extracted fraction (NE) whereas the increases in nuclear CK2 (either CK2α or CK2β) occurred initially in the nuclease-resistant fraction (NR). Transient decreases in CK2 were observed in cytoplasm and NE in the first 3 h but thereafter they either reverted (cytoplasm) or increased above the control (NE). CK2 levels in both NE and NR were high in cells arrested at G1/S. Maximal nuclearaccumulation of CK2 was blocked by cycloheximide but little affected by PD98059, SB203580 or apigenin, all of which affected nuclear phopho-ERK1/2. Thus, nuclear accumulation of CK2 during G1 phase is independent of ERK1/2 pathway. Although this process may initially relay on intracellular redistribution of the preexisting enzyme, active protein synthesis is required to attain maximal nuclear CK2 levels. © 2002 Elsevier Science (USA). All rights reserved.
|Journal||Archives of Biochemistry and Biophysics|
|Publication status||Published - 6 Nov 2002|
- Cell cycle
- HepG2 cells
- Serum stimulation