Cell cycle-dependent gene networks for cell proliferation activated by nuclear CK2α complexes

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Nuclear expression of protein kinase CK2α (casein kinase 2 alpha) is elevated in human carcinomas.
• Mechanisms of CK2α's variable cellular localization are poorly understood.

Purpose of the Study:

• To investigate the functional connection between nuclear CK2 and gene expression in cell proliferation.
• To elucidate the role of CK2α phosphorylation in its nuclear localization and activity.

Main Methods:

• Growth stimulation of quiescent human fibroblasts.
• Phospho-proteomic analysis to identify phosphorylated CK2α.
• Chromatin immunoprecipitation-sequencing (ChIP-seq) to profile CK2α recruitment to gene loci.

Main Results:

• A pool of CK2α phosphorylated at serine 7 was identified, essential for nuclear translocation and activity.
• Nuclear CK2 complexes include unique transcription factors and chromatin remodelers during G1 phase.
• CK2α is recruited to active gene loci, particularly histone genes and ribosomal RNAs, in late G1 phase.

Conclusions:

• Nuclear CK2α facilitates cell cycle progression by activating histone gene expression and ribosome biogenesis.
• CK2α's nuclear function is linked to specific transcriptional regulators and chromatin remodeling during the G1 phase.