Histone modifications and mitosis: countermarks, landmarks, and bookmarks

The roles of post-translational histone modifications in regulating transcription and DNA damage have been widely studied and discussed. Although mitotic histone marks, particularly phosphorylation, were discovered four decades ago, their roles in mitosis have been outlined only in the past few years. Here we aim to provide an integrated view of how histone modifications act as ‘countermarks’, ‘landmarks’, and ‘bookmarks’ to displace, recruit, and ‘remember’ the location of regulatory proteins during and shortly after mitosis. These capabilities allow histone marks to help downregulate interphase functions such as transcription during mitosis, to facilitate chromatin events required to accomplish chromosome segregation, and to contribute to the maintenance of epigenetic states through mitosis.