Fabienne PAYEN (Micromechanics)

Hôte: R. Debret

 

Une présentation du dispositif Pavone. Il s'agit d'une solution permettant de mesurer à haut débit les propriétés mécaniques de cellules, biomatériaux et modèles 3D par nano-indentation, facilitant ainsi les études mécanobiologiques.

 

 

Pavan RAMDYA (EPFL Lausanne, Switzerland) 

Hôte : Anne Laurençon-Loviton

Dr. Sadhan DAS  (Indian Institute of Science Education and Research (IISER) Mohali)                                   

Host : Emiliano Ricci

 

His research team works on elucidating the role of epigenetic regulators (enhancers/super-enhancers and lncRNAs) in vascular smooth muscle cell and macrophage function, that are critical cell types associated with major diabetic vascular complications (you can check his laboratory website for more information: https://sites.google.com/view/sadhandaslab/home).

 

Florian STENGEL (University of Konstanz, mass spectrometry, stuctural and systems biology)            

Host : Riccardo Pellarin

 

Cells need to control an almost infinite number of processes and biochemical reactions in time and space. A key concept is the organization of the cellular space into functional units and compartments. Cellular compartmentalization scales from single molecules over protein complexes of varying complexity to large membrane surrounded organelles. On the protein and protein complex level posttranslational modifications lead to the generation of functional proteoforms which confer both complexity and dynamics of the system.The emerging concept of liquid-liquid phase separation is increasingly identified as a mechanism to organize the cellular space into functional units via the formation of biomolecular condensates. Biomolecular condensates offer a confined space where specific protein protein interactions (PPIs) can take place in order to facilitate distinct biochemical reactions. As the formation and maturation of biomolecular condensates appears to be of fundamental relevance to biology and a disease-associated process, it is critical to understand the underlying molecular interactions. During my talk I will describe how mass spectrometry-based proteomics can be used to study PPIs and protein dynamics within molecular condensates, focusing on stress granules and in particularly the role of chaperones in organizing and maintaining these specific molecular condensates.

Bio: Florian Stengel studied biochemistry at the FU Berlin and Harvard University. After completing his diploma thesis as a DAAD foreign exchange scholar with Pamela Silver in functional genomics at Harvard Medical School, he went to the University of Cambridge to earn his PhD with Carol Robinson. In 2011 he joined the laboratory of Ruedi Aebersold at ETH Zurich as an Sir Henry Wellcome Fellow. Since 2015 he heads his own laboratory at the University of Konstanz, first as an Assistant Professor and Emmy-Noether Group Leader and since 2022 as Full Professor and Heisenberg Professor of Biochemistry. He is the recipient of the 2020 Manfred-Fuchs Prize of the Heidelberg Academy of Sciences and Humanities.

 

Jan ERZBERGER (UT southwestern Texas, CryoEM of Ribosome biogenesis) 

Host : Riccardo Pellarin

 

ATPases of the DEAD-box family are ubiquitous, highly conserved enzymes that play essential roles in ribosome assembly. ATPase activity is proposed to drive the remodeling of secondary and tertiary RNA structures, facilitating the ordered addition of proteins to form functional ribonucleoprotein (RNP) modules. Because of the transient nature of their interactions, we have little understanding of how DEAD-box proteins engage and remodel their rRNP assembly substrates. We used genetic manipulation of yeast strains to trap and enrich transient complexes of DEAD-box ATPases bound to large ribosomal (60S) assembly intermediates. Cryo-EM reconstructions of three distinct pre-60S states, at resolutions ranging from 2.3 to 2.8 Å, reveal a critical function for DEAD-box proteins in the proper assembly of core RNA elements during 60S maturation.

Bio: Dr. Erzberger received his undergraduate degree in Biological Chemistry from Harvard University and his Ph.D. Molecular and Cell Biology in the lab of James Berger at the University of California, Berkeley, studying DNA replication initiation in bacteria. During his postdoctoral training in the laboratory of Nenad Ban at the ETH Zürich, Dr. Erzberger focused on studies of the eukaryotic translation initiation machinery, developing a novel hybrid structural approach, combining x-ray crystallography, cryo-electron microscopy and mass-spectrometry to investigate the role of eIF3, a large, multiprotein initiation factor. Since joining the faculty of UT Southwestern in 2015, Dr. Erzberger has using integrative methodologies centered on cryo-electron microscopy to elucidate the assembly mechanism of the large (60S) ribosomal subunit, in particular the role of ATPases, GTPases and methyltransferases in carrying out RNA modification reactions to guide the accurate biogenesis of 60S subunits.                                                                                                                                                                        

Pr. Michael YU (University of Utah) 

Hôte: J-D Malcor

Veronika KRCHLIKOVA (Mechanisms of Innate Antiviral Immunity, Institute for Medical Virology and Epidemiology of Viral Diseases, University Hospital Tübingen, Elfriede-Aulhorn Str.6, 72076 Tübingen, Germany) 

Hôte : Lucie Etienne

 

Syncytin 1 and syncytin 2 are envelope glycoproteins encoded by human endogenous retroviruses. They have been exapted for the fusion of cytotrophoblast cells into syncytiotrophoblasts during placenta development. Interestingly, pregnancy complications have been associated with altered expression of syncytins or aberrant expression of interferons and interferon-stimulated genes such as antiviral restriction factors. In our study, we show that the antiviral activity of guanylate-binding protein 5 (GBP5) can be misdirected against syncytin 1. GBP5 inhibits the proteolytic activity of furin, thereby supressesing the cleavage and fusogenic activity of syncytin 1. In contrast, GBP5 does not inhibit syncytin 2 cleavage. Mechanistic analyses revealed that syncytin 2 cannot only be activated by furin, but also by its paralog PCSK7, which is resistant to GBP5. In line with this, we observed that the fusogenic activity of syncytin 1 can by partially compensated by syncytin 2. In summary, we here describe a mechanism of innate auto-immunity during pregnancy that impairs the activity of a co-opted retroviral envelope protein.