Priming chromatin for segregation: functional roles of mitotic histone modifications.

Posttranslational modifications (PTMs) of histone proteins are important for various cellular processes including regulation of gene expression and chromatin structure, DNA damage response and chromosome segregation. Here we comprehensively review mitotic histone PTMs, in particular phosphorylations, and discuss their interplay and functions in the control of dynamic protein-protein interactions as well as their contribution to centromere and chromosome structure and function during cell division. Histone phosphorylations can create binding sites for mitotic regulators such as the chromosomal passenger complex, which is required for correction of erroneous spindle attachments and chromosome bi-orientation.

ULK1/2 Restricts the Formation of Inducible SINT-Speckles, Membraneless Organelles Controlling the Threshold of TBK1 Activation.

Membraneless organelles (MLOs) are liquid-like subcellular compartments providing spatiotemporal control to biological processes. This study reveals that cellular stress leads to the incorporation of the adaptor protein SINTBAD (TBKBP1) into membraneless, cytosolic speckles. Determination of the interactome identified >100 proteins forming constitutive and stress-inducible members of an MLO that we termed SINT-speckles.

CDK1-mediated phosphorylation at H2B serine 6 is required for mitotic chromosome segregation.

Faithful mitotic chromosome segregation is required for the maintenance of genomic stability. We discovered the phosphorylation of histone H2B at serine 6 (H2B S6ph) as a new chromatin modification site and found that this modification occurs during the early mitotic phases at inner centromeres and pericentromeric heterochromatin. This modification is directly mediated by cyclin B1-associated CDK1, and indirectly by Aurora B, and is antagonized by PP1-mediated dephosphorylation.