Protein kinase CK2alpha may induce gene expression but unlikely acts directly as a DNA-binding transcription-activating factor.

The gene-inducing property ofCK2alpha, a Ser/Thr protein kinase that appears normally to be complexed to a CK2beta protein controlling activity and substrate selectivity, has been unclear. We show here that CK2alpha induces in human JEG-3 cells the expression of Aromatase, an estrogen-synthesis key enzyme, which is regulated at transcriptional level. Electrophoretic mobility shift assays indicate that CK2alpha binds to the Aromatase gene promoter. To test for CK2alpha's transactivating ability as a DNA-binding protein, a CK2alpha binding site was cloned in front of indicator genes. The constructs were used to transform a yeast-based one-hybrid system. Overexpression of activation-domain fused CK2alpha in this system, i.e., CK2alpha in its native configuration, failed to activate the transcription machinery. The data indicate CK2alpha to affect gene expression at the level of transcription via an indirect as yet unknown mechanism rather than directly as a DNA-binding transcription-activating protein.