Endocytic Trafficking and Intracellular Delivery

Unit :

Chemical Biology of Cancer (U1339 / UMR3666)

LUDGER JOHANNES

Team Leader

Unit :

Chemical Biology of Cancer (U1339 / UMR3666)

Presentation

Staff scientists and staff research engineers of the Endocytic Trafficking and Intracellular Delivery team:

Ludger Johannes (ludger.johannes@curie.fr, +33 1-56246351)

Massiullah Shafaq-Zadah (massiullah.shafaq-zadah@curie.fr, +33 1-56246352)

Christian Wunder (christian.wunder@curie.fr, +33 1-56246358)

Estelle Dransart (estelle.dransart@curie.fr, +33 1-56246352)

Caio Vaz Rimoli (caio.vaz-rimoli@curie.fr, +33 1-56246358)

For all other team members, see Members link.

Team projects

Research in the Endocytic Trafficking and Intracellular Delivery team focuses on the mechanisms by which glycans regulate the cell surface dynamics of plasma membrane proteins and their polarized intracellular distribution, and mediate the cellular entry of pathogens. We further harness these principles to develop intracellular delivery strategies for immunotherapy.

Endocytosis allows for the internalization of extracellular materials and cell surface receptors, using membrane-bound carriers. Our team discovered a mechanism by which tubular endocytic pits are generated through the interaction of oligomeric lectins with glycans on a specific class of glycosylated lipids, the glycosphingolipids (GSLs). Pathogenic lectins exploit this mechanism to drive the GSL-dependent uptake of bacterial toxins (e.g., Shiga toxin and cholera toxin) and animal viruses (e.g., polyomaviruses). Endogenous lectins, known as galectins, in turn mediate the GSL-dependent internalization of glycoprotein cargos, including cell adhesion molecules (e.g., integrins, CD44) and scavenger receptors (e.g., LRP1). In both cases, cargo uptake proceeds independently of the canonical clathrin-mediated endocytic machinery. We coined the term GlycoLipid–Lectin (GL-Lect) driven endocytosis to describe this distinct uptake process.

Research themes

A first major focus of our current research is on the elucidation of structural, molecular, and pathophysiological principles governing GL-Lect driven endocytosis, with a particular emphasis on polarized trafficking across intestinal enterocytes, epithelial–mesenchymal plasticity in breast cancer, and immune checkpoints in head and neck squamous cell carcinoma (HNSCC). To address these questions, we combine state-of-the-art imaging approaches, including lattice light-sheet microscopy, fluorescence orientation microscopy, and spectral imaging, with membrane protein reconstitution, cryogenic electron microscopy, DNA origami, multi-omics analyses, organoid systems, and genetically engineered mouse models.

Figure 1 : Hypothèse GL-Lect pour la construction de fosses endocytaires entraînées par la galectine-3 (Gal3) dans la biogénèse de porteurs indépendants de la clathrine (CLIC). Monomeric Gal3 est recruté sur les membranes en se liant aux protéines glycosylées de la cargaison, telles que CD44 et a5β1-integrin. Le Gal3 lié à la membrane oligomérise et acquiert la capacité de liaison des glycosphingolipides fonctionnels (GSL), conférant aux complexes Gal3/GSL des propriétés actives de courbure, c’est-à-dire la capacité à induire et/ou à détecter la courbure de la membrane. Les cargaisons et les lipides glycosylés sont ensuite regroupés dans des fosses endocytaires tubulaires à partir desquelles des porteurs indépendants de la clathrine (CLIC) sont formés pour l’absorption endocytaire dans les cellules. Tiré de Lakshminarayan et al, 2014, Nature Cell Biology 16 : 595-606

A second major focus of our research program is chemical biology. We identify small-molecule modulators of GSL metabolism as candidate therapeutics for lysosomal storage disorders. We define their cellular targets, elucidate their molecular and cellular mechanisms of action, and evaluate their therapeutic efficacy in mouse models of disease. In parallel, we develop synthetic chemical tools to reconstitute and functionally interrogate GSLs in physiological and pathological contexts, with particular emphasis on cancer and immunity.

A third major research direction exploits GSL ligands to promote the targeted intracellular delivery of antigenic peptides and proteins to professional antigen-presenting cells, namely dendritic cells. Our goal is to induce immune modulation at mucosal surfaces, enabling preventive and durable vaccination against infectious diseases, such as COVID-19, as well as therapeutic vaccination against mucosal malignancies, including lung cancer and gastric cancer. To this end, we develop both mRNA- and protein subunit-based vaccine platforms, including the chemical synthesis of our dendritic cell-targeting vector STxB, a 69-amino-acid protein that we assemble in vitro into its homopentameric structure.