Integrated mechanobiology of integrin-mediated phagocytosis

Integrated mechanobiology of integrin-mediated phagocytosis

By In PhD proposals 2019 On March 7, 2019

Project: Integrated mechanobiology of integrin-mediated phagocytosis

Laboratory: Team Biology of Phagocytes

Affiliation: Institut Cochin (Inserm U1016, CNRS UMR8104, Université Paris Descartes)
Address: 22, rue Méchain 75014 Paris

LAB Director
Name: Florence Niedergang, team leader; Pierre-Olivier Couraud, director of Institut Cochin
Phone number: 33 (0)140516421

Name: Florence Niedergang and Anna Mularski (post-doctoral researcher with a physics/chemisty background)
Phone number: 33 (0)140516421

Subject Keywords: Actin
Traction force microscopy

Summary of lab’s interests: The laboratory has a long time interest in phagocytosis, the mechanism of uptake and degradation of invading microorganisms or debris that is crucial for bacterial clearance and the resolution of inflammation. Our first goal is to dissect the mechanisms used by phagocytes, in particular the coordinated activities of signaling pathways, membrane trafficking and cytoskeleton dynamics. Second, we analyze how viral infections of macrophages impair their phagocytic functions and hence promote the development of bacterial superinfections. We have recently developed transdisciplinary approaches to better define the mechanical aspects of the phagocytic process.
Project summary: During phagocytosis, actin polymerization drives membrane deformation and phagosome cup formation, which is further modulated by the mechanics of the particle itself.
The main objective is to generate an integrated mechanochemical model of integrin-mediated phagosome formation in macrophages. More specifically, the objectives are: i) to build on a novel traction force microscopy-based experimental model of phagocytosing cells that has already been developed in the host laboratory, in order to analyse mechanotransduction in cells undergoing phagocytosis; ii) to create a novel ‘4D’ microscopy, including an innovative traction force microscopy element. This will allow us to report on spatial-temporal localization of the key players and the force distribution around the phagosome in macrophages; iii) to determine the importance of key actin binding proteins and new talin-associated proteins that were recently identified in the host laboratory, based on a pull-down approach coupled to mass spectrometry and biochemistry. The relative contribution of these factors to phagocytosis will also be assessed by functional inhibition or expression of mutants.
This work will bring novel insights into the overlooked force-dependent integrin-mediated phagocytosis, a cellular function crucial for remodelling of tissues and bacteria clearance.

Interdisciplinary aspect of the project: The project is performed in collaboration with Christophe Le Clainche (I2BC, Gif-sur-Yvette) who developed an elegant in vitro microscopy assay to reconstitute and characterise the actomyosin-dependent mechanosensitive machineries with pure proteins on geometrically-defined micropatterned surfaces. This collaboration has enabled the identification of previously unknown actin binding partners active during integrin-mediated phagocytosis. The host lab has started to develop an original traction force microscopy method to analyse phagocytosis by macrophages, in collaboration with Martial Balland (LiPhy, Grenoble), to go beyond classical cell biology approaches. The project is part of an ambitious project that includes theoretical modeling of integrin-mediated phagocytosis by Jian Liu (NIH, USA).
Funding: ANR