ERK2-mediated C-terminal Serine Phosphorylation of p300 Is Vital to the Regulation of Epidermal Growth Factor-induced Keratin 16 Gene Expression

Department of Pharmacology, Institute of Basic Medical Sciences, College of Medicine, Center for Gene Regulation and Signal Transduction Research, National Cheng Kung University, Tainan 701, Taiwan.
Journal of Biological Chemistry (Impact Factor: 4.57). 10/2007; 282(37):27215-28. DOI: 10.1074/jbc.M700264200
Source: PubMed


We previously reported that the epidermal growth factor (EGF) regulates the gene expression of keratin 16 by activating the extracellular signal-regulated kinase 1 and 2 (ERK1/2) signaling which in turn enhances the recruitment of p300 to the keratin 16 promoter. The recruited p300 functionally cooperates with Sp1 and c-Jun to regulate the gene expression of keratin 16. This study investigated in detail the molecular events incurred upon p300 whereby EGF caused an enhanced interaction between p300 and Sp1. EGF apparently induced time- and dose-dependent phosphorylation of p300, both in vitro and in vivo, through the activation of ERK2. The six potential ERK2 phosphorylation sites, including three threonine and three serine residues as revealed by sequential analysis, were first identified in vitro. Confirmation of these six sites in vivo indicated that these three serine residues (Ser-2279, Ser-2315, and Ser-2366) on the C terminus of p300 were the major signaling targets of EGF. Furthermore, the C-terminal serine phosphorylation of p300 stimulated its histone acetyltransferase activity and enhanced its interaction with Sp1. These serine phosphorylation sites on p300 controlled the p300 recruitment to the keratin 16 promoter. When all three serine residues on p300 were replaced by alanine, EGF could no longer induce the gene expression of keratin 16. Taken together, these results strongly suggested that the ERK2-mediated C-terminal serine phosphorylation of p300 was a key event in the regulation of EGF-induced keratin 16 expression. These results also constituted the first report identifying the unique p300 phosphorylation sites induced by ERK2 in vivo.

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    • "Active ERK1/2 directly binds DNA, controls RNA polymerase II, and works in concert with TFs such as ELK1 to modulate gene expression (Gö ke et al., 2013; Hu et al., 2009; Tee et al., 2014). ERK1/2 indirectly impinges on chromatin by controlling the activity of MSK1/2, which is responsible for histone 3 serine 10 and serine 28 phosphorylation (H3S10ph and H3S28ph), and p300 (Chen et al., 2007; Soloaga et al., 2003). The Ras-Raf axis also activates the INK4A-ARF locus through upregulation of the histone demethylase JMJD3, leading to loss of histone 3 lysine 27 tri-methylation (H3K27me3) (Agger et al., 2009; Barradas et al., 2009). "
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    • "For example, while protein kinase C (PKC) and salt inducible kinase 2 mediated phosphorylation at serine-89 was reported to inhibit the HAT activity [38,39], Akt mediated phosphorylation at serine-1834, serine-2279, serine-2315, and serine-2366 was shown to enhance the HAT activity of p300 [40-42]. Along those lines, Akt and ERK2 mediated phosphorylation was shown to stabilize p300 protein levels, but phosphorylation by mitogen activated protein kinase (MAPK) resulted in degradation of the p300 protein [11,12,36,40,43]. However, none of the studies have so far focused on the effect of phosphorylation on intracellular distribution of p300. "
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    • "The stability of p300 protein is believed to be regulated by its phosphorylation [Reviewed in (37)]. Multiple site-specific serine/threonine phosphorylations have been identified in p300 and are linked to its pleiotropic potential (15,19,38–41). To discern the underlying basis of p300 phosphorylation in response to UV damage, we irradiated NHF cells and analyzed p300 phosphorylations at serine 89 and serine 1834 by western blots with antibodies against site-specifically phosphorylated p300. "
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