Analysis of Myc-Induced Histone Modifications on Target Chromatin

Abstract

The c-myc proto-oncogene is induced by mitogens and is a central regulator of cell growth and differentiation. The c-myc product, Myc, is a transcription factor that binds a multitude of genomic sites, estimated to be over 10–15% of all promoter regions. Target promoters generally pre-exist in an active or poised chromatin state that is further modified by Myc, contributing to fine transcriptional regulation (activation or repression) of the afferent gene. Among other mechanisms, Myc recruits histone acetyl-transferases to target chromatin and locally promotes hyper-acetylation of multiple lysines on histones H3 and H4, although the identity and combination of the modified lysines is unknown. Whether Myc dynamically regulates other histone modifications (or marks) at its binding sites also remains to be addressed. Here, we used quantitative chromatin immunoprecipitation (qChIP) to profile a total of 24 lysine-acetylation and -methylation marks modulated by Myc at target promoters in a human B-cell line with a regulatable c-myc transgene. Myc binding promoted acetylation of multiple lysines, primarily of H3K9, H3K14, H3K18, H4K5 and H4K12, but significantly also of H4K8, H4K91 and H2AK5. Dimethylation of H3K79 was also selectively induced at target promoters. A majority of target promoters showed co-induction of multiple marks - in various combinations - correlating with recruitment of the two HATs tested (Tip60 and HBO1), incorporation of the histone variant H2A.Z and transcriptional activation. Based on this and previous findings, we surmise that Myc recruits the Tip60/p400 complex to achieve a coordinated histone acetylation/exchange reaction at activated promoters. Our data are also consistent with the additive and redundant role of multiple acetylation events in transcriptional activation.

Identification of a c-Jun N-terminal kinase-2-dependent signal amplification cascade that regulates c-Myc levels in ras transformation

“…This supports a recent model whereby c-Myc identifies transcriptionally engaged genes and associates with specifically modified chromatin (Guccione et al, 2006). Indeed, c-Myc actively regulates acetylation of multiple lysine sites of histones H3 and H4 (Martinato et al, 2008), with a mechanism which is not fully understood. Interestingly, ATF2 possesses histone acetyltransferase activity (Kawasaki et al, 2000), and could therefore be an ideal cooperation partner for c-Myc.…”

Essential Role of p400/mDomino Chromatin-remodeling ATPase in Bone Marrow Hematopoiesis and Cell-cycle Progression

“…We also provide evidence that p400/mDomino plays an essential role in the cell-cycle progression of fibroblasts, probably through its transcriptional activation of cellcycle-regulatory genes, especially the targets of FoxM1 and c-Myc. Because p400/mDomino exerts its chromatin-remodeling function via its H2A.Z-exchange activity, the interaction of p400/mDomino with c-Myc (and possibly with FoxM1) might regulate the deposition and/or eviction of the H2A.Z variant at the promoter nucleosome of cell-cycle-regulatory genes (14,16,44). Future studies on the interaction between transcription factors and the p400/mDomino complex and their role in the H2A.Z-positioning mechanism will provide insight into the biological significance of the H2A.Z-exchanging machinery in cell growth and differentiation.…”

A long noncoding RNA connects c-Myc to tumor metabolism

“…5C), indicating a suppressed transcriptional status of these metabolic genes. c-Myc-mediated transcription in vivo involves several histone modification events at the target promoters (16). In particular, once bound to the target, c-Myc induces local hyperacetylation of both histone H3 and H4, further maintaining the active chromatin status (16,17).…”

“…c-Myc-mediated transcription in vivo involves several histone modification events at the target promoters (16). In particular, once bound to the target, c-Myc induces local hyperacetylation of both histone H3 and H4, further maintaining the active chromatin status (16,17). Given the reduced c-Myc occupancy upon PCGEM1 knockdown, we examined whether the histone hyperacetylation on the target loci is decreased as well.…”