Poly(ADP-Ribosyl)ation Affects Histone Acetylation and Transcription

Poly(ADP-ribosyl) ation (PARylation) is a posttranslational protein modification catalyzed by members of the poly(ADP-ribose) polymerase (PARP) enzyme family. PARylation regulates a wide variety of biological processes in most eukaryotic cells including energy metabolism and cell death, maintenance of genomic stability, chromatin structure and transcription. Inside the nucleus, cross-talk between PARylation and other epigenetic modifications, such as DNA and histone methylation, was already described. In the present work, using PJ34 or ABT888 to inhibit PARP activity or over-expressing poly(ADP-ribose) glycohydrolase (PARG),we show decrease of global histone H3 and H4 acetylation. This effect is accompanied by a reduction of the steady state mRNA level of p300, Pcaf, and Tnf alpha, but not of Dnmt1. Chromatin immunoprecipitation (ChIP) analyses, performed at the level of the Transcription Start Site (TSS) of these four genes, reveal that changes in histone acetylation are specific for each promoter. Finally, we demonstrate an increase of global deacetylase activity in nuclear extracts from cells treated with PJ34, whereas global acetyltransferase activity is not affected, suggesting a role for PARP in the inhibition of histone deacetylases. Taken together, these results show an important link between PARylation and histone acetylation regulated transcription

Social selection within aggregative multicellular development drives morphological evolution

Aggregative multicellular development is a social process involving complex forms of cooperation among unicellular organisms. In some aggregative systems, development culminates in the construction of spore-packed fruiting bodies and often unfolds within genetically and behaviourally diverse conspecific cellular environments. Here, we use the bacterium Myxococcus xanthus to test whether the character of the cellular environment during aggregative development shapes its morphological evolution. We manipulated the cellular composition of Myxococcus development in an experiment in which evolving populations initiated from a single ancestor repeatedly co-developed with one of several non-evolving partners-a cooperator, three cheaters and three antagonists. Fruiting body morphology was found to diversify not only as a function of partner genotype but more broadly as a function of partner social character, with antagonistic partners selecting for greater fruiting body formation than cheaters or the cooperator. Yet even small degrees of genetic divergence between distinct cheater partners sufficed to drive treatment-level morphological divergence. Co-developmental partners also determined the magnitude and dynamics of stochastic morphological diversification and subsequent convergence. In summary, we find that even just a few genetic differences affecting developmental and social features can greatly impact morphological evolution of multicellular bodies and experimentally demonstrate that microbial warfare can promote cooperation.ISSN:0962-8452ISSN:1471-295

Hidden paths to endless forms most wonderful: ecology latently shapes evolution of multicellular development in predatory bacteria

International audienceEcological causes of developmental evolution, for example from predation, remain much investigated, but the potential importance of latent phenotypes in eco-evo-devo has received little attention. Using the predatory bacterium Myxococcus xanthus , which undergoes aggregative fruiting body development upon starvation, we tested whether adaptation to distinct growth environments that do not induce development latently alters developmental phenotypes under starvation conditions that do induce development. In an evolution experiment named MyxoEE-3, growing M. xanthus populations swarmed across agar surfaces while adapting to conditions varying at factors such as surface stiffness or prey identity. Such ecological variation during growth was found to greatly impact the latent evolution of development, including fruiting body morphology, the degree of morphological trait correlation, reaction norms, degrees of developmental plasticity and stochastic diversification. For example, some prey environments promoted retention of developmental proficiency whereas others led to its systematic loss. Our results have implications for understanding evolutionary interactions among predation, development and motility in myxobacterial life cycles, and, more broadly, how ecology can profoundly shape the evolution of developmental systems latently rather than by direct selection on developmental features

DamID profiling of dynamic Polycomb-binding sites in Drosophila imaginal disc development and tumorigenesis

Background: Tracking dynamic protein–chromatin interactions in vivo is key to unravel transcriptional and epigenetic transitions in development and disease. However, limited availability and heterogeneous tissue composition of in vivo source material impose challenges on many experimental approaches. Results: Here we adapt cell-type-specific DamID-seq profiling for use in Drosophila imaginal discs and make FLP/FRT-based induction accessible to GAL driver-mediated targeting of specific cell lineages. In a proof-of-principle approach, we utilize ubiquitous DamID expression to describe dynamic transitions of Polycomb-binding sites during wing imaginal disc development and in a scrib tumorigenesis model. We identify Atf3 and Ets21C as novel Polycomb target genes involved in scrib tumorigenesis and suggest that target gene regulation by Atf3 and AP-1 transcription factors, as well as modulation of insulator function, plays crucial roles in dynamic Polycomb-binding at target sites. We establish these findings by DamID-seq analysis of wing imaginal disc samples derived from 10 larvae. Conclusions: Our study opens avenues for robust profiling of small cell population in imaginal discs in vivo and provides insights into epigenetic changes underlying transcriptional responses to tumorigenic transformation.ISSN:1756-893

Correction to: DamID profiling of dynamic Polycomb-binding sites in Drosophila imaginal disc development and tumorigenesis

Unfortunately, the original version of this article contained a typographical error in one of the author names. The name of the author Alexey Pindyurin was incorrectly spelt as Alexey Pinduyrin. The correct spelling is included here and has been updated in the original article

Inhibition of PARP activity affects transcription and promoter histone acetylation level of <i>p300</i> and <i>PCAF</i>.

<p>(A) Real time qRT-PCR analysis of mRNA accumulation for two acetyltransferases, <i>p300</i> and <i>Pcaf</i>. Histograms indicate mRNA level of cells treated with PJ34 for 1 h (black), relative to untreated cells (grey, value ~1). Values were normalized with <i>Actβ</i> or <i>Hprt</i>. (B) Real time qRT-PCR analysis of histone H3 and H4 acetylation of <i>p300</i> and <i>Pcaf</i> promoter regions. Histograms indicate acetylation level of cells treated with PJ34 for 1 h (black), relative to untreated cells (grey, value ~1). Values were normalized with an internal region of <i>Actβ</i>. Primers used were described in Materials and Methods. Error bars indicate the standard deviation of data obtained from three independent experiments. NT: control cells, no treatment. *p ≤ 0.05; **p ≤ 0.01.</p

Transcriptional modulation of a human monocytic cell line exposed to PM(10) from an urban area.

Insight into the mechanisms by which ambient air particulate matter mediates adverse health effects is needed to provide biological plausibility to epidemiological studies demonstrating an association between PM(10) exposure and increased morbidity and mortality. In vitro studies of the effects of air pollution on human cells help to establish conditions for the analysis of cause-effect relationships. One of the major challenges is to test native atmosphere in its complexity, rather than the various components individually. We have developed an in vitro system in which human monocyte-macrophage U937 cells are directly exposed to filters containing different amounts of PM(10) collected in the city of Rome. Transcriptional profiling obtained after short exposure (1h) of cells to a filter containing 1666μg PM(10) (77.6μg/cm(2)) using a macroarray panel of 1176 genes reveals a significant change in the mRNA level (>2 fold) for 87 genes relative to cells exposed to a control filter. Overall, 9 out of 87 modulated genes were annotated as "lung cancer". qRT-PCR confirmed the induction of relevant genes involved in DNA repair and apoptosis, specifically: ERCC1, TDG, DAD1 and MCL1. In cells exposed for 10min, 1h and 3h to different amounts of PM(10), transcription of TNFα and TRAP1, which code for a key pro-inflammatory cytokine and a mitochondrial protein involved in cell protection from oxidative stress, respectively, was shown to be modulated in a time-dependent, but not a dose-dependent manner. Taken together, these data indicate that it is possible to analyze the effects of untreated particulate matter on human cells by the direct-exposure approach we have developed, possibly providing new clues to traffic-related health hazard. Copyright © 2011 Elsevier Inc. All rights reserved