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Raghida Kamal Damaj

Associate professor
Life & Earth Sciences department - Section I - Hadath
Speciality: Biology
Specific Speciality: Physiologie et Génétique Moléculaire

Education
B.S.C

Lebanese University
Biology

good

master1

Lebanese University
General Biology

good

DEA

Institute of Cellular and Molecular Biology, University Louis Pasteur-Strasbourg I
Cellular and Molecular Biology, Option Developement

good, rank 35/132

PHD

(University Blaise Pascal, Clermont-Ferrand), France
Physiology and Molecular Genetics

tres favorable

post-doctoral position

University of Rennes I, Faculty of medicine, France
morphogenesis, signaling pathway and membrane trafficking in C. elegans

Publications 4 publications
Gillard G1, Shafaq-Zadah M1, Nicolle O1, Damaj R1, Pécréaux J1, Michaux G2. Control of E-cadherin apical localisation and morphogenesis by a SOAP-1/AP-1/clathrin pathway in C. elegans epidermal cells. Development 2015

E-cadherin (E-cad) is the main component of epithelial junctions in multicellular organisms, where it is essential for cell-cell adhesion. The localisation of E-cad is often strongly polarised in the apico-basal axis. However, the mechanisms required for its polarised distribution are still largely unknown. We performed a systematic RNAi screen in vivo to identify genes required for the strict E-cad apical localisation in C. elegans epithelial epidermal cells. We found that the loss of clathrin, its adaptor AP-1 and the AP-1 interactor SOAP-1 induced a basolateral localisation of E-cad without affecting the apico-basal diffusion barrier. We further found that SOAP-1 controls AP-1 localisation, and that AP-1 is required for clathrin recruitment. Finally, we also show that AP-1 controls E-cad apical delivery and actin organisation during embryonic elongation, the final morphogenetic step of embryogenesis. We therefore propose that a molecular pathway, containing SOAP-1, AP-1 and clathrin, controls the apical delivery of E-cad and morphogenesis.

Aubusson-Fleury A1, Bricheux G, Damaj R, Lemullois M, Coffe G, Donnadieu F, Koll F, Viguès B, Bouchard P. 3- Epiplasmins and Epiplasm in Paramecium: The Building of a Submembraneous Cytoskeleton : 2013

In ciliates, basal bodies and associated appendages are bound to a submembrane cytoskeleton. In Paramecium, this cytoskeleton takes the form of a thin dense layer, the epiplasm, segmented into regular territories, the units where basal bodies are inserted. Epiplasmins, the main component of the epiplasm, constitute a large family of 51 proteins distributed in 5 phylogenetic groups, each characterized by a specific molecular design. By GFP-tagging, we analyzed their differential localisation and role in epiplasm building and demonstrated that: 1) The epiplasmins display a low turnover, in agreement with the maintenance of an epiplasm layer throughout the cell cycle; 2) Regionalisation of proteins from different groups allows us to define rim, core, ring and basal body epiplasmins in the interphase cell; 3) Their dynamics allows definition of early and late epiplasmins, detected early versus late in the duplication process of the units. Epiplasmins from each group exhibit a specific combination of properties. Core and rim epiplasmins are required to build a unit; ring and basal body epiplasmins seem more dispensable, suggesting that they are not required for basal body docking. We propose a model of epiplasm unit assembly highlighting its implication in structural heredity in agreement with the evolutionary history of epiplasmins.

Viguès B1, Damaj R. 2- The adhesive disc in the mobilid ciliate Trichodina pediculus: evidence for centrin-related, calcium-sensitive filaments. 2012

The adhesive disc is a highly complex apparatus that allows mobilid ciliates to attach to the tissues of a variety of aquatic invertebrates and vertebrates. The disc comprises concentric rings of rigid skeletal pieces interconnected by filamentous material. This study explored the biochemical properties of the filamentous disc material in the trichodinid Trichodina pediculus. Calcium sensitivity of this material was suggested in vitro by the appearance of transverse cross-striation along bundles of filaments following calcium shock, and complete solubilization of the filamentous material in the presence of EGTA. A 23-kDa immunoanalog of centrins was immunoprecipitated from the EGTA extract. The protein binds calcium as indicated by (45) Ca(2+) blot overlay and Ca(2+) -induced shifts in electrophoretic mobility. Using Ca(2+) /EGTA buffers, we demonstrated a direct relationship between extraction of the filaments and solubilization of the protein. Immunofluorescence and immunoelectron microscopy confirmed that the protein localized to the filamentous disc material and revealed cross-reactivity with the spasmoneme, which is the prototype of ion-sensitive, centrin-like contractile systems in ciliates. The possibility that the filamentous disc material may be a novel example of Ca(2+) -sensitive, centrin-based systems found in ciliates is discussed.

Raghida Damaj, Sébastien Pomel, Geneviève Bricheux, Gérard Coffe, Bernard Viguès, Viviane Ravet and Philippe Bouchard* 1- Cross-study analysis of genomic data defines the ciliate multigenic epiplasmin family: strategies for functional analysis in Paramecium tetraurelia. 2009

Background The sub-membranous skeleton of the ciliate Paramecium, the epiplasm, is composed of hundreds of epiplasmic scales centered on basal bodies, and presents a complex set of proteins, epiplasmins, which belong to a multigenic family. The repeated duplications observed in the P. tetraurelia genome present an interesting model of the organization and evolution of a multigenic family within a single cell. Results To study this multigenic family, we used phylogenetic, structural, and analytical transcriptional approaches. The phylogenetic method defines 5 groups of epiplasmins in the multigenic family. A refined analysis by Hydrophobic Cluster Analysis (HCA) identifies structural characteristics of 51 epiplasmins, defining five separate groups, and three classes. Depending on the sequential arrangement of their structural domains, the epiplasmins are defined as symmetric, asymmetric or atypical. The EST data aid in this classification, in the identification of putative regulating sequences such as TATA or CAAT boxes. When specific RNAi experiments were conducted using sequences from either symmetric or asymmetric classes, phenotypes were drastic. Local effects show either disrupted or ill-shaped epiplasmic scales. In either case, this results in aborted cell division. Using structural features, we show that 4 epiplasmins are also present in another ciliate, Tetrahymena thermophila. Their affiliation with the distinctive structural groups of Paramecium epiplasmins demonstrates an interspecific multigenic family. Conclusion The epiplasmin multigenic family illustrates the history of genomic duplication in Paramecium. This study provides a framework which can guide functional analysis of epiplasmins, the major components of the membrane skeleton in ciliates. We show that this set of proteins handles an important developmental information in Paramecium since maintenance of epiplasm organization is crucial for cell morphogenesis.

Languages
English

Full professional proficiency

French

Full professional proficiency