Cell Biology of Parasitism - INSERM – U786  


  HEADDr. GUILLEN-AGHION, Nancy, DR1 – CNRS / nguillen@pasteur.fr
  MEMBERSDr. BANSAL, Devendra, Post-Doctorant, IP / Dr. FAUST, Daniela, CR-IP / Dr. GIRARD-MISGUICH, Fabienne, MCU
Dr. LABRUYERE, Elisabeth, CR-IP / Dr. SOLIS, Carlos, Post-doctorant FRM / M. WEBER, Christian, Engineer-II-IP
SYAN Sylvie, Technician IP / SANTI-ROCCA, Julien, graduate student, MARQUAY MARKIEWICZ, Jacques, graduate student
LAMBRECH, Régine, secretary


  Annual Report

Amoebiasis, a human infection developped by 50 million persons every year, is caused by the protozoan parasite, Entamoeba histolytica. The parasite invades the intestinal mucosa where it causes dysentery, in some cases liver abscesses are formed too. Two major processes sustain amoebiasis: (i) amoebic motilitysupported by the interaction with the extracellular matrix and the reorganization of the amoebic cytoskeleton, and (ii) adhesionto human cells that is a consequence of the activity of surface receptors and cytoskeleton dynamics of both the amoeba and the host cell. Our project aims to :

  1. Elucidate the cytoskeletal changes necessary for motility as well as the signaling pathways triggered by the interactions between the parasite and the external environment.

  2. Identify the parasite molecules necessary for amoebic interaction with human cells and their role in the cross-talk between amoeba and human cells leading to cell death and inflammation.

  3. Analyze amoebiasis by pathophysiology and by biotechnology developments.

Cellular analysis of cytoskeleton activities during chemotaxis and phagocytosis

E. Labruyère, S. Blazquez, S. Marion and S. Syan, with the Pasteur ImagoPole. Granted by European union- INCO-DEV.

Entamoeba histolyticahas remarkably adapted its very simple cytoskeleton to motility, infection and phagocytosis of human cells. Capital actors of the cytoskeleton dynamics, such as myosins and PAK kinase contribute to the infectious process. Myosins sustain the mechanical and visco-elastic properties of its versatile cytoskeleton. A proteomic high-resolution analysis of phagosomes provided a first global view of their composition revealing new cytoskeleton components and signaling molecules associated to myosins. Mobility of E. histolytica is enhanced by gradients of pro-inflammatory molecules such as TNF. Like cancer cells, amoebic chemotaxis induces transcription of genes encoding α-actinin, Arp2 and cofilin.

Pathophysiology of amoebiasis.

E. Labruyère, D. Faust, D. Bansal with the Pasteur ImagoPole and Genopole (PF2). Granted by PTR 178 and DARRI

We had set up and validated a human ex vivo model based on human colon explants. To imaging the infectious process in real time we used two photons laser microscopy, scanning electron microscopy and histology. Read out of interaction includes the kinetic of mucus degradation, the human cells lyse and the pattern of secreted cytokines.

After disruption of intestinal barrier, liver infection start with the destruction of sinusoidal endothelial cells. We analyse changes occurring in these celles upon contact with the parasite by a transcriptome approach; key regulators and signalling cascades modified by the interaction were identified.

Expression analysis of genes involved in Entamoeba histolytica pathogenic process.

C. Weber, F. Misguich-Girard, C. Solis, J. Santi-Rocca and S. Syan, with the Pasteur Genopole (PF1, PF2, PF4, PF5 and PF8), D. Mirelman (Weizmann Institute, Rehovot, Israel). Granted the Pasteur-Weizmann Research Council and the PTR 179.

Blockage of transcripts by RNA interference, enabling down regulation of gene expression, has been developed with a large success. Thanks to the completion of a genome project, we have set up a microarray with E. histolytica transcripts. Using them, we conclude that infection relies on a stress response and epigenetic trancriptional changes in the parasite. Transcripts encoding new lysine rich proteins have been revealed as relevant pathogenic factors. One of them, KERP1, plays a role in the early steps of liver infection and has been evaluated as an efficient candidate for diagnosis of the infection. Other lysine rich factors are concentrated along with calreticulin (an ER component) in the uropod and may participates to cytotoxic effects of E. histolytica.

Keywords: Amoebiasis, Entamoeba, motility, phagocytosis, microarrays, inflammation

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  Publications

Marion, S. , Laurent, C. and Guillen , N. (2005).. Signalization and cytoskeleton Activity through myosin IB during the early steps of phagocytosis in Entamoeba histolytica: a proteomic approach. Cell Microbiol. 7 : 1504-18.

Blazquez S, Zimmer C, Guigon G, Olivo-Marin JC, Guillen N, Labruyere E. (2006). Human tumor necrosis factor is a chemoattractant for the parasite Entamoeba histolytica. Infect Immun. 74:1407-11.

Weber C, Guigon G, Bouchier C, Frangeul L, Moreira S, Sismeiro O, Gouyette C, Mirelman D, Coppee JY andGuillen N. (2006). Stress by heat shock induces massive down regulation of genes and allows differential allelic expression of the Gal/GalNAc lectin in Entamoeba histolytica Euk. Cell, 5: 871–875

Blazquez S, Rigothier MC, Huerre M, Guillen N. (2007). Initiation of inflammation and cell death during liver abscess formation by Entamoeba histolytica depends on activity of the galactose/N-acetyl-D-galactosamine lectin. Int J Parasitol. 37:425-33.

Santi-Rocca J, Weber C, Guigon G, Sismeiro O, Coppée JY, Guillén N. (2007). The lysine- and glutamic acid-rich protein KERP1 plays a role in Entamoeba histolytica liver
abscess pathogenesis.Cell Microbiol. Aug 17 doi:10.1111/j.1462-5822.2007.01030.x



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Activity Reports 2007 - Institut Pasteur
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