The protooncogene MYC regulates a variety of cellular processes, including proliferation and metabolism. Maintaining MYC at homeostatic levels is critical to normal cell function; overexpression drives many cancers. MYC stability is regulated through phosphorylation: phosphorylation at Thr58 signals degradation while Ser62 phosphorylation leads to its stabilization and functional activation. The bromodomain protein 4 (BRD4) is a transcriptional and epigenetic regulator with intrinsic kinase and histone acetyltransferase (HAT) activities that activates transcription of key protooncogenes, including MYC . We report that BRD4 phosphorylates MYC at Thr58, leading to MYC ubiquitination and degradation, thereby regulating MYC target genes. Importantly, BRD4 degradation, but not inhibition, results in increased levels of MYC protein. Conversely, MYC inhibits BRD4’s HAT activity, suggesting that MYC regulates its own transcription by limiting BRD4-mediated chromatin remodeling of its locus. The MYC stabilizing kinase, ERK1, regulates MYC levels directly and indirectly by inhibiting BRD4 kinase activity. These findings demonstrate that BRD4 negatively regulates MYC levels, which is counteracted by ERK1 activation.

The bromodomain protein 4 (BRD4) is an atypical kinase and histone acetyl transferase (HAT) that binds to acetylated histones and contributes to chromatin remodeling and early transcriptional elongation. During transcription, BRD4 travels with the elongation complex. Since most alternative splicing events take place co-transcriptionally, we asked if BRD4 plays a role in regulating alternative splicing. We report that distinct patterns of alternative splicing are associated with a conditional deletion of BRD4 during thymocyte differentiation in vivo. Similarly, the depletion of BRD4 in T cell acute lymphoblastic leukemia (T-ALL) cells alters patterns of splicing. Most alternatively spliced events affected by BRD4 are exon skipping. Importantly, BRD4 interacts with components of the splicing machinery, as assessed by both immunoprecipitation (IP) and proximity ligation assays (PLAs), and co-localizes on chromatin with the splicing regulator, FUS. We propose that BRD4 contributes to patterns of alternative splicing through its interaction with the splicing machinery during transcription elongation.

cspD , a member of cspA family of cold shock genes in Escherichia coli , is not induced during cold shock. Its expression is induced during stationary phase. CspD inhibits DNA replication, and a high level of the protein is toxic to cells. Recently, CspD was proposed to be associated with persister cell formation in E. coli . Here, we show that cyclic AMP receptor protein (CRP) upregulates cspD transcription. Sequence analysis of the cspD upstream region revealed two tandem CRP target sites, CRP site-I (the proximal site centered at −83.5 with respect to the transcription start) and CRP site-II (the distal site centered at −112.5). The results from electrophoretic mobility shift assays showed that CRP indeed binds to these two target sites in P cspD . The promoter-proximal CRP target site was found to play a major role in P cspD activation by CRP, as studied by transcriptional fusions carrying mutations in the target sites. The results from in vitro transcription assays demonstrated that CRP activates P cspD transcription in the absence of additional factors other than RNA polymerase. The requirement for activating region 1 of CRP in P cspD activation, along with the involvement of the 287, 265, and 261 determinants of the α-CTD, suggest that CRP activates by a class I-type mechanism. However, only moderate activation in vitro was observed compared to high activation in vivo , suggesting there might be additional activators of P cspD . Overall, our findings show that CRP, a global metabolic regulator in E. coli , activates a gene potentially related to persistence.

Bismuth vanadate (BiVO₄) is a promising photoactive material for the design of photoelectrochemical (PEC) analytical devices for the non-enzymatic detection of glucose.