Identification of Structural Elements of the Lysine Specific Demethylase 2B CxxC Domain Associated with Replicative Senescence Bypass in Primary Mouse Cells.

Background: Lysine specific demethylase 2B, KDM2B, regulates genes that participate in cellular development, morphogenesis, differentiation and metabolism as a component of the polycomb repressive complex 1 (PRC1). The CxxC finger of KDM2B is responsible for the DNA binding capacity of this epigenetic regulator, acting as a sampling mechanism across chromatin for gene repression OBJECTIVES: The molecular determinants of the CxxC-DNA interaction remain largely unknown, revealing a significant knowledge gap to be explored. Our goal was to elucidate the key residues of the CxxC domain that contribute to its function as well as to further elaborate on the significance of this domain in the KDM2B role METHODS: By using electrophoresis mobility swift assay, we identified structural elements of CxxC domain that participate in the DNA recognition. We created mouse embryonic fibroblasts overexpressing different truncated and point-mutated mouse KDM2B variants to examine the contribution of the KDM2B domains in replicative senescence bypass RESULTS: In this study, we show that only the CxxC finger is essential for the ability of mKDM2B to bypass replicative senescence in primary cells by ink4A-Arf-ink4B locus repression, and that this is mediated by specific interactions of residues R585, K608 and K616 with non-methylated CpG containing DNA CONCLUSIONS: These results provide new structural insights into the molecular interactions of CxxC and could serve as a stepping-stone for developing domain-specific inhibitors for KDM2B.