Best Poster Awards: Friend or Foe — Transcription and RNA Meet DNA Replication and Repair

During the second virtual EMBO | EMBL Symposium of the year three scientists were awarded a prize for their scientific poster. In this blog, we present the winners and their research.

Friend or Foe attracted 336 participants worldwide, discussing transcription and RNA and DNA replication and repair in live sessions and panel discussions. Three poster session rounds gave the opportunity for participants to view 72 digital posters and interact with the poster presenters.

After the sessions, a voting round followed and three presenters were distinguished with a best poster award by popular vote.

  1. Gianluca Sigismondo of the German Cancer Research Center in Heidelberg, Germany.
  2. Tycho Mevissen, Howard Hughes Medical Institute and Harvard Medical School, USA
  3. Sara Luzzi, Newcastle University, UK

Read our blog on how to create a prize-winning digital poster.

Chromatin dynamics during DNA repair investigated via chromatin-directed proteomics

A portrait picture of scientist Gianluca Sigismondo
Gianluca Sigismondo, German Cancer Research Center, Germany. PHOTO: Gianluca Sigismondo

Poster presenter: Gianluca Sigismondo

Authors: Gianluca Sigismondo, Lavinia Arseni, Jeroen Krijgsveld

DNA lesions predispose to genomic instability, a hallmark of cancer; therefore cells have evolved repair pathways to solve those harmful insults.

Double-strand breaks (DSBs) represent the most lethal DNA damage first marked by the phosphorylation of the histone H2A.X (γH2A.X) which triggers the recruitment of sensor proteins belonging to either the error-prone non-homologous end joining (NHEJ) or the efficient homologous recombination (HR) pathway.

It is now established that chromatin has an active role also in DNA repair, thus its characterization at DSB repair foci is essential to better understand the coordinate action of the repair mechanisms and to identify novel players participating in tumor-associated apoptotic resistance and cell survival.

Here we dissect chromatin changes upon exposure to ionizing radiations through multiple proteomics-based approaches. We applied the Selective Isolation of Chromatin-Associated Protein strategy (ChIP-SICAP; Rafiee, 2016) to investigate the interactors of core NHEJ, HR proteins and γH2A.X while bound to the DNA or in the chromatin soluble fraction.

Through a click chemistry-assisted procedure we profiled the configuration of DNA-bound proteins during DSBs repair; finally we analyzed the histone post-translational modifications (hPTMs) cross-talk at mono-nucleosomes marked by γH2A.X.

Our integrated analysis identified the dynamics of expected chromatin determinants during the DNA repair and interestingly suggested the role for new candidates specifically enriched upon DSB formation.

Validation experiments based on monitoring of DSB foci formation and resolution in AID-DIvA cells proficient or knock-down cells provided evidence of a role for novel candidates in DNA repair. FACS-based analysis of Traffic-light Reporter (TLR) isogenic cells upon silencing of proteins identified by MS characterized their functional role in NHEJ, HR or pathway choice. Furthermore, we defined hPTMs associated with γH2A.X-marked mono-nucleosomes and their dynamics during DSB resolution.

This analysis corroborated expected enrichments (e.g. H4K20me1/me2) and provided insights on new modifications specifically enriched at γH2A.X-nucleosomes.

Chromatin dynamics during DNA repair investigated via chromatin-directed proteomics

Towards transcription-coupled DNA repair in Xenopus egg extract

Poster presenter: Tycho Mevissen

A portrait of scientist Tycho Mevissen
Tycho Mevissen, Harvard Medical School, USA. PHOTO: Tycho Mevissen

This poster and abstract contain unpublished data and are not available at this moment.

Tycho Mevissen is a postdoctoral research fellow in Johannes Walter’s lab at Harvard Medical School. He had completed his PhD with David Komander at the MRC Laboratory of Molecular Biology in Cambridge, UK, where he used structural and biochemical tools to elucidate the intricate mechanisms of enzymes in the ubiquitin system, in particular deubiquitinases (DUBs).

His current research interests in the Walter lab revolve around molecular mechanisms at the intersection of DNA transcription, replication and repair.

In particular, he is interested in understanding how elongating RNA polymerase II deals with various types of obstacles – including different DNA lesions – during transcription elongation. To study this, he uses Xenopus egg extract, which is a powerful cell-free system that has been successfully used to recapitulate a wide range of cellular DNA repair pathways.


RBMX enables productive RNA processing of ultra long exons important for genome stability

A portrait picture of scientist Sara Luzzi
Sara Luzzi, Newcastle University, UK. PHOTO: Sara Luzzi

Poster presenter: Sara Luzzi

Authors: Sara Luzzi, Gerald Hysenaj, Chileleko Siachisumo, Kathleen Cheung, Matthew Gazzara, Katherine James, Caroline Dalgliesh, Mahsa Kheirollahi Chadegani, Ingrid Ehrmann, Graham R Smith, Simon J Cockell, Jennifer Munkley, Yoseph Barash, and David J Elliott.

The nuclear RNA binding protein RBMX has a direct role in genome repair and is required for expression of the tumour suppressor BRCA2. Here we report that RBMX controls RNA processing of key genes involved in genome maintenance in breast cancer cells.

Our data demonstrate that RBMX represses a premature polyadenylation site that would truncate BRCA2 protein, and is essential for full-length mRNA expression from other genes important for genome stability. These include ETAA1, which encodes for a key replication fork protein, where RBMX and its protein interaction partner Tra2ß efficiently suppress a weak splice site to enable ETAA1 protein expression.

More generally, we propose that RBMX facilitates correct inclusion of unusually long exons within mature mRNAs by repressing cryptic RNA processing. Our data provide new molecular insights explaining the role of RBMX in DNA repair and genome maintenance.

Poster RBMX enables productive RNA processing of ultra-long exons important for genome stability

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Best Poster Awards – In Situ Structural Biology Workshop

The EMBO Workshop: In Situ Structural Biology: From Cryo-EM to Integrative Modelling was our final virtual conference of 2020, but there was no trace of Zoom fatigue amongst the 466 participants who joined us from 6 – 8 December!

80 international researchers presented their posters during the two posters sessions on the following topics:

  • Biophysical analysis in cells
  • COVID-19
  • Imaging across scales
  • Integrative modelling
  • Molecular sociology
  • Structural analysis in situ
  • Structural biology

Each of the participants had the chance to vote for their favourite poster, resulting in two posters winning the Best Poster Award kindly sponsored by EMBO Press.  Here are the winners:

New insights on the catalytic mechanism of arsenite oxidase

PHOTO: Filipa Engrola

Authors: Filipa Engrola, Márcia Correia, Teresa Santos-Silva, Maria Romao, (UCIBIO@FCT-NOVA, Portugal)

Arsenic (As) and antimony (Sb) are two metalloids that, due to anthropogenic and natural causes, pose an environmental  threat, considered as priority pollutants by the World Health Organisation and the United States Environmental Protection Agency. Although the safety guards recommend a maximum of 10 μg/L of As and Sb in drinking water, these values are exceeded in many regions worldwide, with no remediation approach that is simultaneously effective, clean and economically sustainable [1,2]. The ancient bioenergetic enzyme arsenite oxidase (Aio), from microorganisms Rhizobium sp. NT-26 (NT-26 Aio) and Alcaligenes faecalis (A.f. Aio), is currently being studied for its use as a biosensor and in bioremediation processes. Both Aio enzymes contain a large subunit (AioA) that harbours a molybdenum centre and a [3Fe-4S] cluster, and a small subunit (AioB) that possess a Rieske [2Fe-2S] cluster and have demonstrated to oxidise AsIII, as well as SbIII, into the easier to remove and less toxic forms of AsV and SbV, respectively [3,4]. Aiming to elucidate the catalysis mechanism of the enzymes, a combination of expression and purification of the proteins, crystallisation, structural analysis, enzyme kinetics and affinity tests were conducted. X-ray structures of the ligand-free form of the enzyme had been previously determined (PDB: 4AAY, 5NQD and 1G8K [3,5,6]). In our work, Aio crystals in complex with two different forms of the substrate analogue – Sb oxyanions, with a reaction kinetic 6500 times slower than AsIII [6] – diffracted up to ca 1.8 Å resolution. The structures show the reaction intermediates bound at the active site, with a μ-oxo bridge binding Sb to the Mo atom. Analysis of bond lengths and geometry of the ligands at the Mo active site allowed us to revisit the catalytic mechanism of As oxidation [7], contributing to the understanding and future biotechnological application of this family of enzymes in water treatment.

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Allosteric hotspot in the main protease of SARS-CoV-2

PHOTO: Léonie Ströhmich

Authors: Léonie Strömich, Sophia N Yaliraki, (Imperial College London, UK)

Since the beginning of 2020 we have seen the coronavirus SARS-CoV-2 causing a global pandemic with almost 34 million cases and over 1 million deaths worldwide [as of 01.10.2020] [1.] As a result, we have seen a surge in research efforts to develop effective treatments for the underlying disease, COVID-19. One approach is to target the main protease (Mpro) of SARS-CoV-2 as it is essential for virus replication in an early step of the viral life cycle [2.] Most efforts are centred on inhibiting the orthosteric binding site of the enzyme. However, considering allosteric sites on the protein allows for more selective drug design and widens the chemical search space. Here, we report an allosteric hotspot in the SARS-CoV-2 Mpro dimer by using novel atomistic graph theoretical methods: Markov transient analyses follow the propagation of a random walker on a graph and have been shown to successfully identify allosteric communication in catalytic proteins [3.] We further score the so identified allosteric hotspots against random sites in similar distances and thus identify a statistically significant putative allosteric site in the SARS-CoV-2 Mpro. We then simulate a binding event at this hotspot region using data from a recent XChem fragment screen by the Diamond Light Source [4.] which provides a starting point for rational drug design. This study uses highly efficient network theoretical models to shed light on allosteric communication and uncovers putative allosteric sites in the SARS-CoV-2 main protease. This provides a valuable contribution to the ongoing efforts to find a cure against COVID-19 by broadening the horizon for drug discovery efforts.

Image: Léonie Ströhmich

References:
[1.] Official World Health Organization COVID-19
dashboard: https://covid19.who.int (Accessed: 01.10.2020).
[2.] Hilgenfeld, R. (2014). FEBS Journal, 281(18), 4085-4096.
[3.] Amor, B., Yaliraki, S. N., Woscholski, R., & Barahona, M. (2014) Molecular BioSystems, 10(8), 2247-2258.
[4.] Douangamath, A., Fearon, D., Gehrtz, P., Krojer, T., Lukacik, P., Owen, C. D., … Walsh, M. A. (2020) Nature Communications, 11, 5047.

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Best Poster Awards – Target Validation Using Genomics and Informatics

Meet Giovanni Spirito and Borja Gomez Ramos – the two poster prize winners at the recent EMBL – Wellcome Genome Campus Conference: Target Validation Using Genomics and Informatics (8 – 10 Dec 2019).

Identification and prioritization of candidate causal genomic variations from individuals affected by ASD

PHOTO: Giovanni Spirito

Authors: Giovanni Spirito (1), Diego Vozzi (2), Martina Servetti (3), Margherita Lerone (3), Maria Teresa Divizia (3), Giulia Rosti (3), Livia Pisciotta (4), Lino Nobili (4), Irene Serio (4), Stefano Gustincich (2), Remo Sanges (1)

Next generation sequencing (NGS) technologies enabled the extensive study of the genomics underlying human diseases. Namely whole exome sequencing (WES) represents a cost-efficient method which can lead to the detection of multiple classes of genomic variants and the discovery of novel disease-associated genes. One of the drawbacks of this approach however, is the large number of genomic variants detected in each analysis. Automated variant prioritization strategies are therefore required. This is particularly important in the case of complex disease such as ASD, whose genetic etiology is still poorly understood. To this aim we built a custom computational framework capable, from raw WES data, to automatically detect four classes of genomic variants (SNPs, indels, copy number variants and short tandem repeat variants) and prioritize them in regards to their relevance to a specific phenotype. We tested this framework on a selection of 29 trios including probands affected by severe and undiagnosed rare phenotypes and a small cohort of 10 trios all featuring healthy parents and one offspring affected by autism spectrum disorder (ASD). We were able to successfully detect rare and de novo high penetrance variants which have been validated and confirmed as causative among the undiagnosed probands. In the specific case of the ASD cohort we could highlight several genes which are not implicated in autism susceptibility, but nevertheless whose connections to genes relevant for ASD could suggest a possible involvement in the phenotype. Furthermore, our approach enabled us to detect several instances characterized by the presence of multiple candidate variants within genes belonging to the same canonical pathway in one proband. Our workflow allows to detect and prioritize multiple classes of genomic variants in order to both highlight rare high penetrance disease-causative mutation, and possibly reconstruct the genomics at the basis of complex ASD phenotypes.

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(1) SISSA, Italy, (2) IIT, Italy, (3) Gaslini Institute, Italy, (4) University of Genova, Italy


Omics data integration for the identification of cell-type-specific gene regulatory networks and regulatory variants in Parkinson’s disease

PHOTO: Borja Gomez Ramos

Authors: Borja Gomez Ramos (1,2), Jochen Ohnmacht (1,2), Nikola de Lange (2), Aurélien Ginolhac (1), Aleksandar Rakovic (5), Christine Klein (5), Roland Krause (2) , Marcel H. Schulz (6), Thomas Sauter (1), Rejko Krüger (2,3,4) and Lasse Sinkkonen (1)

Genome-Wide Association Studies (GWAS) have identified many variants associated with different diseases. However, it is still a challenge to make sense of this data as the majority of genetic variants are located in non-coding regions, complicating the understanding of their functionality. In the last few years, it has been found that non-coding genetic variants concentrate in regulatory regions in the genome, which are cell type and cell-stage specific. In this project, we seek to identify functional Parkinson’s disease GWAS non-coding genetic variants that could make carriers more prone to developing PD. To do so, we are using induced pluripotent stem cell (iPSC) technology to differentiate somatic cells into midbrain dopaminergic (mDA) neurons, astrocytes and microglia. Assessing their chromatin accessibility, active chromatin regions and transcriptome, we can identify crucial regulatory regions in the genome, key transcription factors and derive the gene regulatory networks for the three different cell types. Then, we will map the non-coding genetic variants to the different regulatory regions and predict their effect in silico for the subsequent validation in vitro. This innovative approach will also identify novel factors controlling cell fate and cell identity.

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(1) Life Sciences Research Unit, University of Luxembourg, Luxembourg, (2) Luxembourg Centre for Systems Biomedicine (LCSB), University of Luxembourg, Luxembourg, (3) Centre Hospitalier de Luxembourg (CHL), Luxembourg, (4) Luxembourg Institute of Health (LIH), Luxembourg, (5) Institute of Neurogenetics, University of Lübeck, Germany, (6) Institute for Cardiovascular Regeneration, Uniklinikum and Goethe University Frankfurt, Germany


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Best Poster Awards – Cancer Genomics

The 4th EMBL Conference: Cancer Genomics (4 – 6 November 2019) brought together over 240 scientists in the field of cancer research to present the latest findings in cancer functional genomics, systems biology, cancer immunogenomics and epigenomics, as well as their translation and clinical impact.

123 posters were presented at the two poster sessions, out of which two were selected as the winners by popular vote. 

Infinite sites violations during tumour evolution reveal local mutational determinants

Jonas Demeulemeester is a postdoctoral researcher at the Francis Crick Insitute in UK. PHOTO: Jonas Demeulemeester

Authors: Jonas Demeulemeester (1), Stefan C. Dentro (2), Moritz Gerstung (2), Peter Van Loo (1)

The infinite sites model of molecular evolution requires that every base in the genome is mutated at most once. It is a cornerstone of (tumour) phylogenetic analysis, and is often implied when calling, phasing and interpreting variants or studying the mutational landscape as a whole. It is unclear however, whether this assumption holds in practice for bulk tumour samples. Here we provide frameworks to model and detect infinite sites violations, identifying 24,459 in total, including 6 candidate biallelic driver events, in 700 bulk tumour samples (26.3%) from the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes project. Violations generally occur at mutational hotspots and their frequency and type can accurately be predicted from the overall mutation spectrum. In melanoma, their local sequence context evidences how not only ETS, but also NFAT-family transcription factor binding creates hotspots for UV-induced cyclobutane pyrimidine dimer formation. In colorectal adenocarcinoma, violations reveal hypermutable special cases of the trinucleotide mutational contexts identified in POLE-mutant tumours. Taken together, we reveal the infinite sites model breaks down at the bulk level for a considerable fraction of tumours. These results warrant a careful evaluation of current pipelines relying on the validity of the infinite sites assumption, especially when scaling up to larger sets of mutations and lineages in the future.

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(1) The Francis Crick Institute, United Kingdom, (2) EMBL-EBI, United Kingdom


The other award-winning poster was:

Understanding the early impact of activating PIK3CA mutation on cellular and genetic heterogeneity presented by Evelyn Lau, UCL Cancer Institute, United Kingdom


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Best Poster Awards – The Non-Coding Genome

Taking place for the third time,  the EMBO|EMBL Symposium: The Non-Coding Genome (16 – 19 October 2019) brought together 305 RNA experts to discuss the roles of non-coding RNAs in both prokaryotes and eukaryotes, gene regulation and function. 

A total of 189 posters were presented, from which two were singled out as the winners by popular vote.

Characterization of the genomic and splicing features of long non-coding RNAs using bioinformatics approaches

Monah Abou Alezz is a Ph.D student in genetics, molecular and cellular biology at the University of Pavia, Italy. PHOTO: Monah Abou Alezz

Authors: Monah Abou Alezz, Ludovica Celli, Giulia Belotti, Silvia Bione, Institute of Molecular Genetics L. L Cavalli-Sforza – National Research Council, Italy

Recent developments in deep sequencing approaches have simulated the continuous discovery of a significantly large number of novel long non-coding RNA (lncRNA) genes loci in the genomes. Long non-coding RNAs are recognized as a new class of regulatory molecules despite very little is known about their functions in the cellular processes. Due to their overall low expression level and tissue-specificity, the identification and annotation of lncRNA genes still remains challenging. The characterization of lncRNAs’ features is crucial to understand and get functional insights on their mechanisms of action. We exploited recent annotations by the GENCODE compendium to characterize the genomic and splicing features of long non-coding genes, in comparison to protein-coding ones, in the human and mouse genome by using bioinformatics approaches. Our analysis highlighted differences between the two classes of genes in terms of gene architecture regarding exons and introns length, GC-content, and the combinatorial patterns of chromatin marks and states. Moreover, significant differences in the splice sites usage were observed between long non-coding and protein-coding genes. While the frequency of non-canonical GC-AG splice junctions represents about 0.8% of total splice sites in protein-coding genes, we identified a remarkable enrichment of the GC-AG splice sites in long non-coding genes, both in human (3.0%) and mouse (1.9%). In addition, we identified peculiar characteristics of the GC-AG introns in terms of donor and acceptor splice sites strength, poly-pyrimidine tract, intron length, and a positional bias of GC-AG junctions being enriched in the first intron. Genes containing at least one GC-AG intron were found conserved in many species across large evolutionary distances, more prone to alternative splicing and a functional analysis pointed toward their enrichment in specific biological processes such as
DNA repair.

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MirGeneDB 2.0: The metazoan microRNA complement

Bastian Fromm is a Senior Researcher at Science for Life Laboratory, Stockholm University, Sweden. PHOTO: Bastian Fromm

Authors: Bastian Fromm (1), Diana Domanska (2), Eirik Hoye (3), Vladimir Ovchinnikov (4), Wenjing Kang (5), Ernesto Aparicio-Puerta (6), Morten Johansen (7), Kjersti Flatmark (3), Anthony Mathelier (8), Hovig
Eivind (3), Michael Hackenberg (6), Marc Friedländer (5), Kevin Peterson (9)

Non-coding RNAs (ncRNA) have gained substantial attention due to their roles in human disorders and animal development. microRNAs (miRNAs) are unique within this class as they are the only ncRNAs with individual gene sequences conserved across the animal kingdom. Bona fide miRNAs can be clearly distinguished from the myriad small RNAs generated in cells by a set of unique criteria. Unfortunately, recognition and utilization of these clear and mechanistically well understood features is not a  common practice. We addressed this by extensively expanding our curated miRNA gene database MirGeneDB to 45 organisms that represent the breadth of Metazoa. By consistently annotating and naming more than 11,000 miRNA genes in these organisms, we show that previous miRNA annotations contained not only many false positives, but surprisingly many false negatives as well. Indeed, curated miRNA complements of closely related organisms are very similar and can be used to reconstruct evolution of miRNA genes, families and biogenesis across more than 1 billion years of evolution. MirGeneDB represents a robust platform for providing deeper and more significant insights into the biology of miRNAs, possible sources of mis-regulation, and evolutionary mechanisms. MirGeneDB is publicly and freely available under http://mirgenedb.org/.

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Fromm, B. et al. MirGeneDB 2.0: the metazoan microRNA complement. Nucleic Acids Research, gkz885, (2019), https://doi.org/10.1093/nar/gkz885

(1) Science for Life Laboratory, Sweden
(2) Department of Informatics, University of Oslo, Oslo, Norway
(3) Department of Tumor Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
(4) School of Life Sciences, Faculty of Health and Life Sciences, University of Nottingham, United Kingdom
(5) Stockholm University, SciLifeLab, Sweden
(6) Department of Genetics, Faculty of Sciences, University of Granada, Granada, Spain
(7) Institute for Medical Informatics, The Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
(8) Centre for Molecular Medicine Norway (NCMM), Nordic EMBL Partnership, University of Oslo, Oslo, Norway
(9) Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, United States of America


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