Crosstalk Between Histone Modifications Integrates Various Signaling Inputs to Fine-Tune Transcriptional Output

Gene transcription requires the complex association of several factors, such as histone-modifying complexes, transcription factors, and chromatin remodeling factors. Among them, histone marks coordinate with each other extensively to modulate transcription. These marks can crosstalk with adjacent marks in cis or with marks present on other histones in trans to promote transcriptional activation or repression. In this chapter, we describe various crosstalk mechanisms potentiated by different histone marks, mainly histone lysine methylation, acetylation, monoubiquitination, phosphorylation, and arginine methylation. We also explain the role of chromatin-associated complexes that contain subunits with different functions and their coordination to modulate a single transcriptional response. These crosstalk mechanisms overall function as a cascade of events to help in the activation or repression of gene expression. Deregulation of these mechanisms result in pathological conditions like cancers, and understanding these pathways may greatly help in the development of specific therapeutic targets to cure diseases.