A peek into the complex realm of histone phosphorylation

ABSTRACT

Although discovered long ago, post-translational phosphorylation of histones has been in the spotlight only recently. Information is accumulating almost daily on how histones are phosphorylated and their roles in cellular physiology and human diseases. An extensive crosstalk exists between phosphorylation and other post-translational modifications, which together regulate various biological processes including gene transcription, DNA repair, and cell cycle progression. Recent research on histone phosphorylation has demonstrated that nearly all histone types are phosphorylated at specific residues and these modifications act as a critical intermediate step in chromosome condensation during cell division, transcriptional regulation and DNA damage repair. As with all young fields, apparently conflicting and sometimes controversial observations about histone phosphorylations and their true functions in different species are available in published literature. Accumulating evidence suggest that instead of functioning strictly as part of a general code, histone phosphorylation probably functions by establishing crosstalk with other histone modifications and serving as a platform for recruitment or release of effector proteins, leading to downstream cascade of events. Here we extensively review published information on complexities of histone phosphorylation, the roles of proteins recognizing these modifications and physiologic output and importantly future challenges and opportunities in this fast moving field.