Sylvain Meylan

Dr. Sylvain Meylan

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Research Focus & Metrics

Academic Career Length

19Years (2008-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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5 March 2010 in PLOS Genetics
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AGAnna C Groner
Anna C Groner
SMSylvain Meylan
Sylvain Meylan
Angela CiuffiAngela Ciuffi
Angela Ciuffi
NZNadine Zangger
Nadine Zangger
GAGiovanna Ambrosini
Giovanna Ambrosini
DTDidier Trono
Didier Trono
Krüppel-associated box domain-zinc finger proteins (KRAB–ZFPs) are tetrapod-specific transcriptional repressors encoded in the hundreds by the human genome. In order to explore their as yet ill-defined impact on gene expression, we developed an ectopic repressor assay, allowing the study of KRAB–mediated transcriptional regulation at hundreds of different transcriptional units. By targeting a drug-controllable KRAB–containing repressor to gene-trapping lentiviral vectors, we demonstrate that KRAB and its corepressor KAP1 can silence promoters located several tens of kilobases (kb) away from their DNA binding sites, with an efficiency which is generally higher for promoters located within 15 kb or less. Silenced promoters exhibit a loss of histone H3-acetylation, an increase in H3 lysine 9 trimethylation (H3K9me3), and a drop in RNA Pol II recruitment, consistent with a block of transcriptional initiation following the establishment of silencing marks. Furthermore, we reveal that KRAB–mediated repression is established by the long-range spreading of H3K9me3 and heterochromatin protein 1 β (HP1β) between the repressor binding site and the promoter. We confirm the biological relevance of this phenomenon by documenting KAP1–dependent transcriptional repression at an endogenous KRAB–ZFP gene cluster, where KAP1 binds to the 3′ end of genes and mediates propagation of H3K9me3 and HP1β towards their 5′ end. Together, our data support a model in which KRAB/KAP1 recruitment induces long-range repression through the spread of heterochromatin. This finding not only suggests auto-regulatory mechanisms in the control of KRAB–ZFP gene clusters, but also provides important cues for interpreting future genome-wide DNA binding data of KRAB–ZFPs and KAP1. The regulation of gene activity by transcription factors is crucial to the function of all cells. Here, we studied the mechanisms of action of the largest family of gene regulators encoded by the human genome, the so-called KRAB–containing zinc finger proteins (KRAB–ZFPs), which in concert with their universal cofactor KAP1 act as transcriptional repressors. For this, we used two parallel approaches. First, by targeting an ectopic KRAB domain to hundreds of different genes, we found that KRAB/KAP1 can repress promoters located several tens of kilobases from the repressor DNA docking site. We further could show that KRAB induces such long-range effects by mediating the spread of repressive chromatin marks along the body of the gene, resulting in a block of transcriptional initiation at the promoter. In a second set of experiments, we analyzed an endogenous KRAB–ZFP gene cluster, where we could also document KAP1–dependent heterochromatin spreading and transcriptional repression. Together, these results support a model whereby KRAB–ZFPs and KAP1 can mediate long-range transcriptional repression through the spread of silencing chromatin marks. This study thus provides insight into KRAB/KAP1–induced gene regulation at KRAB–ZFP gene clusters, and will further help interpret genome-wide studies of KRAB–ZFPs and KAP1 DNA binding patterns.

1 February 2017 in Cell Chemical Biology
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Journal Article
Closed access
SMSylvain Meylan
Sylvain Meylan
CPCaroline B.M. Porter
Caroline B.M. Porter
JYJason H. Yang
Jason H. Yang
PBPeter Belenky
Peter Belenky
AGArnaud GUTIERREZ
Arnaud GUTIERREZ
JCJames J. Collins
James J. Collins

1 June 2021 in Hypertension
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SMSylvain Meylan
Sylvain Meylan
FLFrançoise Livio
Françoise Livio
MFMaryline Foerster
Maryline Foerster
PGPatrick James Genoud
Patrick James Genoud
FMFrancois Marguet
Francois Marguet
GWGrégoire Wuerzner
Grégoire Wuerzner

20 December 2022 in BMJ Open
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AKAntigone Kotsaki
Antigone Kotsaki
PPPeter Pickkers
Peter Pickkers
MBMichael Bauer
Michael Bauer
TCThierry Calandra
Thierry Calandra
MLMihaela Lupse
Mihaela Lupse
EGEvangelos J Giamarellos-Bourboulis
Evangelos J Giamarellos-Bourboulis
Introduction Sepsis is a major cause of death among hospitalised patients. Accumulating evidence suggests that immune response during sepsis cascade lies within a spectrum of dysregulated host responses. On the one side of the spectrum there are patients whose response is characterised by fulminant hyperinflammation or macrophage activation-like syndrome (MALS), and on the other side patients whose immune response is characterised by immunoparalysis. A sizeable group of patients are situated between the two extremes. Recognising immune endotype is very important in order to choose the appropriate immunotherapeutic approach for each patient resulting in the best chance to improve the outcome. Methods and analysis ImmunoSep is a randomised placebo-controlled phase 2 clinical trial with a double-dummy design in which the effect of precision immunotherapy on sepsis phenotypes with MALS and immunoparalysis is studied. Patients are stratified using biomarkers. Specifically, 280 patients will be 1:1 randomly assigned to placebo or active immunotherapy as adjunct to standard-of-care treatment. In the active immunotherapy arm, patients with MALS will receive anakinra (recombinant interleukin-1 receptor antagonist) intravenously, and patients with immunoparalysis will receive subcutaneous recombinant human interferon-gamma. Τhe primary endpoint is the comparative decrease of the mean total Sequential Organ Failure Assessment score by at least 1.4 points by day 9 from randomisation. Ethics and dissemination The protocol is approved by the German Federal Institute for Drugs and Medical Devices; the National Ethics Committee of Greece and by the National Organization for Medicines of Greece; the Central Committee on Research Involving Human Subjects and METC Oost Netherland for the Netherlands; the National Agency for Medicine and Medical Products of Romania; and the Commission Cantonale d’éthique de la recherche sur l’être human of Switzerland. The results will be submitted for publication in peer-reviewed journals. Trial registration number NCT04990232.


31 October 2022 in Antibiotics
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DDDimitri Durr
Dimitri Durr
TNTapio Niemi
Tapio Niemi
JDJérémie Despraz-Ryan
Jérémie Despraz-Ryan
STSelin Tusgul
Selin Tusgul
FDFabrice Dami
Fabrice Dami
SMSylvain Meylan
Sylvain Meylan
Background: Prompt recognition of sepsis is critical to improving patients’ outcomes. We compared the performance of NEWS and qSOFA scores as sepsis detection tools in patients admitted to the emergency department (ED) with suspicion of sepsis. Methodology: A single-center 12-month retrospective study comparing NEWS using the recommended cut-off of ≥5 and qSOFA as sepsis screening tools in a cohort of patients transported by emergency medical services (EMS) to the Lausanne University Hospital (LUH). We used the Sepsis-3 consensus definition. The primary study endpoint was the detection of sepsis. Secondary endpoints were ICU admission and 28-day all-cause mortality. Results: Among 886 patients admitted to ED by EMS for suspected infection, 556 (63%) had a complete set of vital parameters panel enabling the calculation of NEWS and qSOFA scores, of whom 300 (54%) had sepsis. For the detection of sepsis, the sensitivity of NEWS > 5 was 86% and that of qSOFA ≥ 2 was 34%. Likewise, the sensitivities of NEWS ≥ 5 for predicting ICU admission and 28-day mortality were higher than those of qSOFA ≥ 2 (82% versus 33% and 88% versus 37%). Conversely, the specificity of qSOFA ≥ 2 for sepsis detection was higher than that of NEWS ≥ 5 (90% versus 55%). The negative predictive value of NEWS > 5 was higher than that of qSOFA ≥ 2 (77% versus 54%), while the positive predictive value of qSOFA ≥ 2 was higher than that of NEWS ≥ 5 (80% versus 69%). Finally, the accuracy of NEWS ≥ 5 was higher than that of qSOFA ≥ 2 (72% versus 60%). Conclusions: The sensitivity of NEWS ≥ 5 was superior to that of qSOFA ≥ 2 to identify patients with sepsis in the ED and predict ICU admission and 28-day mortality. In contrast, qSOFA ≥ 2 had higher specificity and positive predictive values than NEWS ≥ 5 for these three endpoints.