Casein kinase II is required for transition of G0/G1, early G1, and G1/S phases of the cell cycle.

摘要: Casein kinase II (CKII) is a ubiquitous serine/threonine protein with many cellular functions, including participation in mitogenic signaling by cytoplasmic nuclear translocation (Lorenz, P., Pepperkok, R., Ansorge, W., and Pyerin, W. (1993) J. Biol. Chem. 268, 2733-2739). To examine whether cell compartment-specific availability requirement for CKII function during cycle progression, antibodies against beta, the regulatory subunit of CKII, were microinjected into cytoplasm or nucleus G0-synchronized human primary fibroblasts (IMR-90) at time stimulation various intervals thereafter. Significant inhibition was obtained both injections. The reversible, not observed control antibodies, abolished co-injection purified holoenzyme. differed, however, extent, duration, phase between After injection, reached 45-50% effective two within first 2 h 12-16 post-stimulation, i.e. G0/G1 transition G1/S boundary cycle. injection nucleus, considerably stronger, reaching 80-85%, 6 adjoining part G1 phase. Cytoplasmic injections S affected neither DNA synthesis nor division. data suggest that from G0 to requires presence certain functional level defined times locations as follows: cytoplasm, early cytoplasm.