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Updated: Aug 14, 2026
11:11
Identification of Novel CK2 Kinase Substrates Using a Versatile Biochemical Approach
Published on: February 21, 2019
B23 is a downstream target of polyamine-modulated CK2
Kathryn Lawson1, Laura Larentowicz, Lisa Laury-Kleintop
1Lankenau Institute for Medical Research, 100 Lancaster Avenue, Wynnewood, PA 19096, USA.
Molecular and Cellular Biochemistry
|December 14, 2005
Summary
Overexpression of ornithine decarboxylase (ODC) increases casein kinase 2 (CK2) activity, leading to elevated levels and phosphorylation of nucleolar phosphoprotein B23. This suggests B23 is a downstream effector of polyamines via CK2 signaling.
Area of Science:
- Cell Biology
- Biochemistry
- Molecular Biology
Background:
- Ornithine decarboxylase (ODC) is the rate-limiting enzyme in polyamine biosynthesis.
- Overexpression of ODC enhances the activity of the polyamine-responsive enzyme casein kinase 2 (CK2).
- CK2 associates with the nuclear matrix in response to trophic stimuli.
Purpose of the Study:
- To investigate the effects of ODC overexpression on CK2 localization.
- To examine the impact of ODC overexpression on CK2-mediated phosphorylation of nucleolar phosphoprotein B23.
- To determine if B23 is a downstream effector of polyamines.
Main Methods:
- Immunofluorescence analysis of CK2 and B23 in primary keratinocytes.
- Utilized K6/ODC transgenic keratinocytes and ODC inhibitor alpha-difluoromethylornithine (DFMO).
- Employed CK2 kinase inhibitors apigenin and 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB).
Main Results:
- ODC overexpression caused CK2 to colocalize with B23 at nucleolar borders.
- CK2 kinase activity at the nuclear matrix increased 2-fold, reversible by DFMO.
- B23 protein levels and phosphorylation increased in ODC-overexpressing cells, independent of mRNA or protein stability.
- Increased B23 phosphorylation was blocked by CK2 inhibitors.
Conclusions:
- ODC overexpression influences CK2 localization and activity.
- B23 is a substrate for CK2, and its levels and phosphorylation are regulated by ODC/polyamine pathway.
- B23 may function as a downstream effector of polyamines through CK2-mediated phosphorylation.
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