Mycobacterium tuberculosis (Mtb), the etiologic agent of tuberculosis (TB), is one of the deadliest human pathogen. Despite existing chemotherapy, Mtb has been responsible for the death of 1.4 million people and about 10 million new infections in 2015 (WHO report on TB, 2016). This concerns not only developing countries since 5000 new cases are reported yearly in France. The current problems in TB eradication are: lengthy treatments, co-infection with HIV and emergence of multidrug-resistant strains of Mtb. During the last 50 years, very few antitubercular drugs have been discovered and put on the market. Therefore, identifying new molecules targeting mycobacteria is urgent although highly challenging. Most mycobacteria are naturally resistant to antibiotics for which the highly hydrophobic cell wall represents an impermeable barrier. Mycolic acids (MA) are very long lipids made of 90 carbon atoms that are essential components of the mycomembrane and contribute to the high hydrophobicity of the cell wall. MA are synthesized in the cytoplasm and then transported to the periplasm by a specific transporter, MmpL3, which belongs to the superfamily of Resistance-Nodulation-Division permeases. To date, our knowledge about the mechanism by which MA are transported by MmpL3 remains very limited, due to the lack of both in vitro characterization and structural information. The fact that MmpL3 is essential for mycobacterial growth makes it an extremely attractive drug target for future translational applications. Recent whole-cell-based screening conducted by several independent teams, including ours, led to the identification of various chemical entities exhibiting potent antitubercular activity. The mode of action of all these chemotypes involves the inhibition of MA transport to the bacterial surface. In most studies, MmpL3 was designated as the primary target based on the presence of mutations occurring in mmpL3 in spontaneous resistant strains. Among them, some have already reached phases II or III of clinical trials and/or have shown to exhibit synergetic effects with existing antitubercular drugs. Despite these exciting promises, concerns have recently been raised regarding the real implication of MmpL3 as the target of many of these compounds as well as their mechanism of action. Therefore, describing, at a molecular and structural level, the MmpL3-mediated transport mechanism might help to understand how MA are translocated to the cell surface and to validate the importance of MmpL3 in cell wall assembly. This may also greatly help to describe the mode of action of some of the recently identified MmpL3 inhibitors. The objectives of MyTraM consists of the 1) expression and purification of large amounts of recombinant MmpL3; 2) implementation of hybrid structural biology approaches including X-ray crystallography and cryo-electron microscopy to determine the three-dimensional structure(s) of MmpL3; 3) development of an innovative biochemical in vitro assay to assess MA transport and to investigate the mode of action of several MmpL3 inhibitors; and 4) determination of the binding constants of MmpL3 substrates and inhibitors in solution using microscale thermophoresis. We anticipate that this 3-year project should add important breakthroughs in our understanding of MmpL structure-function relationships and lead to a more precise description of the mode of inhibition of a family of promising anti-TB compounds. On a longer term, these studies should also aid in the future improvement of already existing MmpL3 inhibitors and in the conception of new generations of MmpL3-based drugs for the treatment of TB and other mycobacterial infections.

The nucleoporin RanBP2 is a component of the cytoplasmic filaments of the nuclear pore complex known to regulate the nuclear export of RNA molecules, and the post-translational modification of proteins during nucleocytoplasmic trafficking. Mutations in the N-terminal domain of RanBP2 are associated with a rare genetic predisposition in otherwise healthy individuals to deleterious inflammation and Acute Necrotizing Encephalopathy (ANE) following viral infection, frequently by Influenza A virus (IAV). We found that loss of RanBP2 leads to increased expression of some pro-inflammatory cytokines in cell lines and primary immune cells, suggesting that some inflammatory pathways are regulated by RanBP2 and that this control is lost with mutant ANE-associated RanBP2. To uncover the mechanisms linking RanBP2 to deleterious inflammation following IAV infection, we will study both cells lacking RanBP2, and ANE cells that contain the prevalent RanBP2 mutation T585M (c. 1880C/T). Our project aims to establish how RanBP2 regulates the inflammatory response to infection in genetically edited cell lines and mouse models, as well as samples from ANE patients, focusing on (i) the Impact of viral infection, cell type and mutations on RanBP2 localisation and dynamics, (ii) the effect of RanBP2 on cytokine production, and (iii) the CNS-specific role of RanBP2 and brain susceptibility of ANE. The project leverages our diverse expertise in virus/host cell interaction and neuroinflammation. Thus, this collaboration will foster exchange of knowledge, and will help understand how alterations in the nuclear pore complex contribute to disease development following viral infection.

Bacterial effector proteins manipulating host cell functions play a key role in virulence. Our consortium identified sub-nuclear associated proteins (SNAPs) translocated by the stealth bacterial pathogens Brucella abortus and Coxiella burnetii, that localize at promyelocytic leukemia nuclear bodies (PML-NB) and nucleoli and interfere with the host stress response, suggesting that this pathway plays a relevant role in infection. Indeed, nucleoli and PML-NB are essential for maintaining cellular homeostasis. Together, they coordinate the cellular abiotic stress response by modulating transcription and sequestering proteins away from their site of action. Emerging evidence suggest that nucleoli and PML-NBs can also mount a cellular response against viral and bacterial infections. With this project we aim at thoroughly characterizing the nuclear response to bacterial infection and investigate how bacterial effector proteins co-opt this cellular mechanism.

SESASA aims at developing a “system of systems (SoS)” for assessing agricultural land-use-and-management-change scenarios and provide adaptive feed-back. SESASA will connect farmer responses to social, economic and climate changes at local scale with planning and policy instruments at national scale. SESASA will explore spatio-temporal opportunities to harmonize conflicts between arable farming, grazing and pastoralism. Our theoretical framework builds on social-ecological systems and considers systemic properties such as emergence effects that arise from a non-predictable amplification of management impacts on the availability of natural resources. Research/ innovation questions the project intends to address: 1. How can social-ecological-systems be operationalized in terms of smart modelling approaches and architectures to enable a highly flexible and low data demanding assessment of the performance of agro-ecological systems? 2. Which adaptation opportunities for arable farming, grazing and pastoralism – using scenarios – are most recommendable in different agro-ecological zones to minder food and water insecurity? 3. How can we transfer such an approach into decision making and consulting? Accounting local land-management practices in large scale simulations is indispensable for understanding complex social-ecological interactions and requires a highly integrative knowledge processing approach based, for instance, on graph-node theories to reflect the complexity of drivers, agents and nature-human interactions of agro-ecosystems. We suggest implementing a multi-disciplinary SoS including the models ECOSERV (France), GISCAME (Germany) and MOWASIA (Burkina Faso) + research on planning and management practices (Burkina Faso, Ghana), environmental assessment (Ghana, Germany) and perceptions of local experts and actors (Burkina Faso, Ghana). This ensemble will be implemented to explore multiple trajectories of agro-ecosystems at nested scales.

Viruses evolved strategies to disseminate by hiding into immune cells and enhance their migrating properties. Viruses induce drastic subcellular rearrangements that may lead to particular types of migratory behavior, but the underlying mechanisms remain poorly understood. We aim at unravelling the molecular determinants induced by Zika virus (ZIKV) responsible for the increased migrating properties of monocytes and dendritic cells. We recently showed that ZIKV promotes transmigration of monocytes and we are now proposing to investigate the impact of ZIKV on cell migration in a broader range of assays, including microchannels, cerebral organoids and mouse lymphatic vessels. The molecular partners promoting ZIKV-induced cell migration will be identified by proteomics, CRISPR and pharmacological approaches. Our work should offer seminal bases for the development of antiviral and/or anti-inflammatory therapeutic strategies through the specific prevention/induction of immune cell migration.