Article

RNA polymerase II-mediated transcription at active loci does not require histone H3S10 phosphorylation in Drosophila

Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011, USA.
Development (Impact Factor: 6.27). 10/2008; 135(17):2917-25. DOI: 10.1242/dev.024927
Source: PubMed

ABSTRACT JIL-1 is the major kinase controlling the phosphorylation state of histone H3S10 at interphase in Drosophila. In this study, we used three different commercially available histone H3S10 phosphorylation antibodies, as well as an acid-free polytene chromosome squash protocol that preserves the antigenicity of the histone H3S10 phospho-epitope, to examine the role of histone H3S10 phosphorylation in transcription under both heat shock and non-heat shock conditions. We show that there is no redistribution or upregulation of JIL-1 or histone H3S10 phosphorylation at transcriptionally active puffs in such polytene squash preparations after heat shock treatment. Furthermore, we provide evidence that heat shock-induced puffs in JIL-1 null mutant backgrounds are strongly labeled by antibody to the elongating form of RNA polymerase II (Pol IIoser2), indicating that Pol IIoser2 is actively involved in heat shock-induced transcription in the absence of histone H3S10 phosphorylation. This is supported by the finding that there is no change in the levels of Pol IIoser2 in JIL-1 null mutant backgrounds compared with wild type. mRNA from the six genes that encode the major heat shock protein in Drosophila, Hsp70, is transcribed at robust levels in JIL-1 null mutants, as directly demonstrated by qRT-PCR. Taken together, these data are inconsistent with the model that Pol II-dependent transcription at active loci requires JIL-1-mediated histone H3S10 phosphorylation, and instead support a model in which transcriptional defects in the absence of histone H3S10 phosphorylation are a result of structural alterations of chromatin.

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Available from: Weili Cai, Aug 29, 2015
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    • "have proposed that JIL-1 and histone H3S10 phosphorylation are required for active transcription by the RNA polymerase II machinery (11–13). However, the results of these studies have been controversial because it has been demonstrated that RNA polymerase II mediated transcription occurs at robust levels in the absence of H3S10 phosphorylation in Drosophila (10,14,15). "
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    ABSTRACT: In this study we have determined the genome-wide relationship of JIL-1 kinase mediated H3S10 phosphorylation with gene expression and the distribution of the epigenetic H3K9me2 mark. We show in wild-type salivary gland cells that the H3S10ph mark is predominantly enriched at active genes whereas the H3K9me2 mark is largely associated with inactive genes. Comparison of global transcription profiles in salivary glands from wild-type and JIL-1 null mutant larvae revealed that the expression levels of 1539 genes changed at least 2-fold in the mutant and that a substantial number (49%) of these genes were upregulated whereas 51% were downregulated. Furthermore, the results showed that downregulation of genes in the mutant was correlated with higher levels or acquisition of the H3K9me2 mark whereas upregulation of a gene was correlated with loss of or diminished H3K9 dimethylation. These results are compatible with a model where gene expression levels are modulated by the levels of the H3K9me2 mark independent of the state of the H3S10ph mark, which is not required for either transcription or gene activation to occur. Rather, H3S10 phosphorylation functions to indirectly maintain active transcription by counteracting H3K9 dimethylation and gene silencing.
    Nucleic Acids Research 03/2014; 42(9). DOI:10.1093/nar/gku173 · 9.11 Impact Factor
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    • "Thus, in this study, to overcome such potential difficulties we labeled “smush” preparations with the two H3S28ph antibodies as well as with H3S10ph antibody for comparison (Fig. 2). The smush preparation is a modified whole-mount staining technique where nuclei from dissected salivary glands are gently compressed beneath a coverslip to flatten them before fixation in a standard paraformaldehyde/PBS solution with a physiological pH [2], [12]. As illustrated in Fig. 2A in such preparations there were extensive overlap between H3S10ph and JIL-1 labeling including upregulation on the male X chromosome whereas there was no discernable labeling above background by either H3S28ph antibody (Figs 2B, 2C). "
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    ABSTRACT: JIL-1 is the major kinase controlling phosphorylation of histone H3S10 and has been demonstrated to function to counteract heterochromatization and gene silencing. However, an alternative model has been proposed in which JIL-1 is required for transcription to occur, additionally phosphorylates H3S28, and recruits 14-3-3 to active genes. Since these findings are incompatible with our previous demonstration that there are robust levels of transcription in the complete absence of JIL-1 and that JIL-1 is not present at developmental or heat shock-induced polytene chromosome puffs, we have reexamined JIL-1's possible role in H3S28 phosphorylation and 14-3-3 recruitment. Using two different H3S28ph antibodies we show by immunocytochemistry and immunoblotting that in Drosophila the H3S28ph mark is not present at detectable levels above background on polytene chromosomes at interphase but only on chromosomes at pro-, meta-, and anaphase during cell division in S2 cells and third instar larval neuroblasts. Moreover, this mitotic H3S28ph signal is also present in a JIL-1 null mutant background at undiminished levels suggesting that JIL-1 is not the mitotic H3S28ph kinase. We also demonstrate that H3S28ph is not enriched at heat shock puffs. Using two different pan-specific 14-3-3 antibodies as well as an enhancer trap 14-3-3ε-GFP line we show that 14-3-3, while present in salivary gland nuclei, does not localize to chromosomes but only to the nuclear matrix surrounding the chromosomes. In our hands 14-3-3 is not recruited to developmental or heat shock puffs. Furthermore, using a lacO repeat tethering system to target LacI-JIL-1 to ectopic sites on polytene chromosomes we show that only H3S10ph is present and upregulated at such sites, not H3S28ph or 14-3-3. Thus, our results argue strongly against a model where JIL-1 is required for H3S28 phosphorylation and 14-3-3 recruitment at active genes.
    PLoS ONE 04/2013; 8(4):e62484. DOI:10.1371/journal.pone.0062484 · 3.23 Impact Factor
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    • "Although the direct involvement of JIL-1 in the transcription process has been brought into question due to the failure to observe recruitment of JIL-1 to heat shock genes in polytene chromosomes (Cai et al. 2008), results presented here clearly indicate that JIL-1 affects transcription at different steps in the transcription cycle. At the promoter region, phosphorylation of H3S10 by JIL-1 results in the recruitment of 14-3-3 and, subsequently, histone acetyltransferases Elp3 and MOF (Karam et al. 2010). "
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    ABSTRACT: Transcription regulation is mediated by enhancers that bind sequence-specific transcription factors, which in turn interact with the promoters of the genes they control. Here, we show that the JIL-1 kinase is present at both enhancers and promoters of ecdysone-induced Drosophila genes, where it phosphorylates the Ser10 and Ser28 residues of histone H3. JIL-1 is also required for CREB binding protein (CBP)-mediated acetylation of Lys27, a well-characterized mark of active enhancers. The presence of these proteins at enhancers and promoters of ecdysone-induced genes results in the establishment of the H3K9acS10ph and H3K27acS28ph marks at both regulatory sequences. These modifications are necessary for the recruitment of 14-3-3, a scaffolding protein capable of facilitating interactions between two simultaneously bound proteins. Chromatin conformation capture assays indicate that interaction between the enhancer and the promoter is dependent on the presence of JIL-1, 14-3-3, and CBP. Genome-wide analyses extend these conclusions to most Drosophila genes, showing that the presence of JIL-1, H3K9acS10ph, and H3K27acS28ph is a general feature of enhancers and promoters in this organism.
    Genome Research 04/2012; 22(6):1081-8. DOI:10.1101/gr.136929.111 · 13.85 Impact Factor
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