A Common Clathrin-Mediated Machinery Co-ordinates Cell-Cell Adhesion and Bacterial Internalization.

INRA, USC2020, Paris, F-75015, France
Traffic (Impact Factor: 4.71). 09/2012; DOI: 10.1111/tra.12009
Source: PubMed

ABSTRACT Invasive bacterial pathogens often target cellular proteins involved in adhesion as a first event during infection. For example, Listeria monocytogenes uses the bacterial protein InlA to interact with E-cadherin, hijack the host adherens junction (AJ) machinery and invade non-phagocytic cells by a clathrin-dependent mechanism. Here, we investigate a potential role for clathrin in cell-cell adhesion. We observed that the initial steps of AJ formation trigger the phosphorylation of clathrin, and its transient localization at forming cell-cell contacts. Furthermore, we show that clathrin serves as a hub for the recruitment of proteins that are necessary for the actin rearrangements that accompany the maturation of AJs. Using an InlA/E-cadherin chimera, we show that adherent cells expressing the chimera form AJs with cells expressing E-cadherin. We demonstrate that non-adherent cells expressing the InlA chimera, as bacteria, can be internalized by E-cadherin-expressing adherent cells. Together these results reveal that a common clathrin-mediated machinery may regulate internalization and cell adhesion and that the relative mobility of one of the interacting partners plays an important role in the commitment to either one of these processes.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The bacterial pathogen Listeria monocytogenes induces internalization into mammalian cells and uses actin-based motility to spread within tissues. Listeria accomplishes this intracellular life cycle by exploiting or antagonizing several host GTPases. Internalization into human cells is mediated by the bacterial surface proteins InlA or InlB. These two modes of uptake each require a host actin polymerization pathway comprised of the GTPase Rac1, nucleation promotion factors, and the Arp2/3 complex. In addition to Rac1, InlB-mediated internalization involves inhibition of the GTPase Arf6 and participation of Dynamin and septin family GTPases. After uptake, Listeria is encased in host phagosomes. The bacterial protein GAPDH inactivates the human GTPase Rab5, thereby delaying phagosomal acquisition of antimicrobial properties. After bacterial-induced destruction of the phagosome, cytosolic Listeria uses the surface protein ActA to stimulate actin-based motility. The GTPase Dynamin 2 reduces the density of microtubules that would otherwise limit bacterial movement. Cell-to-cell spread results when motile Listeria remodel the host plasma membrane into protrusions that are engulfed by neighboring cells. The human GTPase Cdc42, its activator Tuba, and its effector N-WASP form a complex with the potential to restrict Listeria protrusions. Bacteria overcome this restriction through two microbial factors that inhibit Cdc42-GTP or Tuba/N-WASP interaction.
    Cellular Microbiology 06/2014; 16(9). DOI:10.1111/cmi.12324 · 4.82 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Clathrin-mediated endocytosis (CME) is a fundamental property of eukaryotic cells. Classical CME proceeds via the formation of clathrin-coated pits (CCP) at the plasma membrane that invaginate to form clathrin-coated vesicles; a process that is well understood. However, clathrin also assembles into flat clathrin lattices (FCL); these structures remain poorly described and their contribution to cell biology is unclear. We have used quantitative imaging to provide the first comprehensive description of FCL and explore their influence on plasma membrane organization. Ultrastructural analysis by electron and super-resolution microscopy revealed two discrete populations of clathrin structures. CCP were typified by their sphericity, small size and homogeneity. FCL were planar, large and heterogeneous, and present on both the dorsal and ventral surfaces of cells. Live microscopy demonstrated that CCP are short-lived and culminate in a peak of dynamin recruitment, consistent with classical CME. In contrast, FCL were long-lived with sustained association with dynamin. We investigated the biological relevance of FCL using the chemokine receptor CCR5 as a model system. Agonist activation leads to sustained recruitment of CCR5 to FCL. Quantitative molecular imaging indicated that FCL partitioned receptors at the cell surface. Our observations suggest that FCL provide stable platforms for the recruitment of endocytic cargo.
    Molecular Biology of the Cell 08/2014; 25(22). DOI:10.1091/mbc.E14-06-1154 · 4.55 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The roles of clathrin, its regulators, and the ESCRT (endosomal sorting complex required for transport) proteins are well defined in endocytosis. These proteins can also participate in intracellular pathways that are independent of endocytosis and even independent of the membrane trafficking function of these proteins. These nonendocytic functions involve unconventional biochemical interactions for some endocytic regulators, but can also exploit known interactions for nonendocytic functions. The molecular basis for the involvement of endocytic regulators in unconventional functions that influence the cytoskeleton, cell cycle, signaling, and gene regulation are described here. Through these additional functions, endocytic regulators participate in pathways that affect infection, glucose metabolism, development, and cellular transformation, expanding their significance in human health and disease.
    Cold Spring Harbor perspectives in biology 09/2014; 6(9). DOI:10.1101/cshperspect.a017004 · 8.23 Impact Factor


Available from
May 30, 2014