Developmental alterations in casein kinase 2 activity during the morphogenesis of quail secondary palate

Abstract

Background During the progression of avian secondary palate morphogenesis, the rate of cell proliferation declines, whereas the production and accumulation of extracellular matrices increases. To investigate the regulation of these events, we examined the quail secondary palate for the activity of casein kinase 2 (CK 2), a pleiotropic serine/threonine second messenger independent enzyme implicated in cell growth and differentiation. Methods Quail palatal shelves were dissected between days 5 and 9 of incubation, which is the period of palate morphogenesis in quail, and prepared either for light microscopic observations or homogenized, cleared by ultracentrifugation, and then subjected to fractionation on a MonoQ column by fast protein liquid chromatography and Western immunoblotting. Results Histological examination showed that the palatal shelves appeared on day 5 of incubation and approximated by day 8 of incubation. Fractionation of palate extract using a Mono‐Q column revealed the presence of a major peak of phosvitin phosphotransferase activity which eluted with 0.5 M NaCl. This activity peak coincided with the presence of a 42 kDa subunit of CK 2 as determined by Western blotting with a CK 2 specific antibody. The CK 2 activity towards phosvitin was elevated on days 5 and 6 and then rapidly declined by day 9. The decrease in CK 2 activity did not correlate with a decrease in CK 2 protein during palate development indicating that the differential activity of the CK 2 enzyme observed during quail palate development may be due to post‐translational modifications of the enzyme. A high positive correlation was found between the CK 2 phosphotransferase activity and both the proliferation index and DNA synthesis during palate development. Conclusion On the basis of literature analysis and the results of the present study, it was suggested that the activity of CK 2 may be regulated along with protein kinase A to coordinate cell proliferation and the synthesis of extracellular matrices during palate development in quail. Anat. Rec. 247:102–108 © 1997 Wiley‐Liss, Inc.

Translated Alu sequence determines nuclear localization of a novel catalytic subunit of casein kinase 2

“…The nucleus is organized by a fibrillar network, the nuclear lamina and the nucleolus that together are referred to as the NM (37). The NM provides the internal scaffolding for nuclear functions related to transcription (35) and cell growth and proliferation (25,49,50), all functions in which CK2 has been implicated to play a significant regulatory role (15,18,28,44,48). It is well documented that the NM is a subnuclear site of CK2 association (14), and it has been suggested that it is this association that provides the physiological relevance to CK2 nuclear localization (3,5,9).…”

“…To date, more than 150 different proteins in various tissues and species have been described as potential phosphorylation targets of CK2 (41). It has become clear that CK2 plays an important role in regulating physiological and pathological cellular processes such as cancer development (44) signal transduction (48), transcriptional control (15), proliferation (18), and cell cycle control (28). Although the three-dimensional structure of CK2 suggests that relatively simple biochemical mechanisms regulate the substrate specificity of this kinase (14), the mechanisms that govern its cellular activity have remained largely unknown.…”