Phosphorylation of serines 287/288 in DEK regulates cell-type-specific chromatin occupancy and compaction [ATAC-seq]

Using multi-omics and biochemical approaches, we find that while DEK predominantly occupies promoter-proximal regions in HeLa cells and primary melanocytes, its chromatin binding is dramatically reduced in melanoma cell lines—despite DEK overexpression.

We attributed this to CK2-mediated phosphorylation, which governs DEK chromatin association and transcriptional output in a cell-type-specific manner. Phosphoproteomics identified 34 phosphorylation sites, including S287 and S288 within the DEK C-terminal DNA-binding domain. Strikingly, CK2 inhibition and concomitant loss of phosphorylation at S287/S288 triggered DEK redistribution to promoter regions, coinciding with transcriptional repression of oncogenic pathways and global chromatin compaction.