Linda KOHL

Scientific background

1990/95:     PhD in Biomedical Sciences (supervisor: P. Michels) UCL, Belgium,

1995/00:    Postdoctoral fellow (supervisor: K. Gull) Manchester University, United Kingdom

2001/03:    Postdoctoral fellow (supervisor: P. Bastin) USM503, Muséum National d’Histoire Naturelle, Paris.

2004-now:   Lecturer MNHN, UMR7245, MNHN/CNRS, team PPL  (Parasites and Free-living protists)

2010:          Habilitiation à Diriger des Recherches , Université Pierre et Marie Curie, Paris

Research activities:  1. Tubulin in filarial parasites

Recently I decided to change the direction of my research: from unicellular organisms, like Trypanosomes and Plasmodium (see below), I moved to the study of multicellular parasites, in particluar filariae. This work is done in collaboration with Prof Coralie Martin, in our research unit, who has been studying filariae for many years.

Among neglected tropical diseases (NTDs), infections with nematodes constitute the largest proportion, with an estimated 1.5 billion infections. There is a wide consensus in the scientific, donor, non-governmental organisations and most importantly endemic country governmental expert groups that elimination of these NTDs will be not achieved by 2030, the major milestone in the roadmap of the Sustainable Development Goals from the WHO, and that new drugs are needed with better activity. In filariasis, drugs need to either kill or sterilise the long-lived (10-15 years) adult worms. This way, transmission can be stopped and the diseases can be eliminated by mass administration and by targeting the remaining infected population by test-and-treat methods. Global efforts to eliminate helminth infections or to provide individual care for patients are hampered by the absence of effective, affordable and accessible medicines.

We are interested in determining the mode of action of Oxfendazole (OXF), a benzimidazole anthelmintic which is used in oral and topical formulations and has been approved for veterinary use in the United States (US) and the European Union (EU) since the early 1990s. Repurposing of an existing veterinary drug allows to shortcut overall development costs and timelines. OXF is a promising alternative to the limited portfolio of anthelmintics available to treat worm infections also in humans. We can use a mouse model for filariae ( Litomosoides sigmodontis) for which we dispose of the complete life cycle in the laboratory.

Benzimidazoles are known to be tubulin inhibitors, they display a marked selectivity towards helminth tubulin vs mammalian tubulin. My project is to study the mode of action of Oxfendazole on parasite tubulin and the consequences of a disrupture in the tubulin network in the parasites are not known. It is also unclear why OXF shows no activity against microfilaria.This work will provide a more complete picture of the mode of action of the inhibitor, aiding in the decision making and the development of this lead compound.

Research activities:  2. Flagellar diversity in unicellular organisms

For many years, I was mainly interested in the flagella of two unicellular parasites: Trypanosoma brucei, responsible for sleeping sickness in Afrika, and Plasmodium, the causative agent of malaria, as well as in the molecular mechanisms that rule their cellular morphogenesis. Both parasites are subject to very strong environmental constraints, as they must develop within two host organisms : the tsetse fly for T. brucei, the Anopheles mosquito for Plasmodium, and the mammalian host. The challenge is even greater because the parasites must transit through different tissues within the hosts.

Flagella have important roles in eukaryotic organisms, such as motility, signalling and cell morphogenesis, particularly in unicellular organisms. They have a central structure, the axoneme: 9 doublets of microtubules positioned in a cylinder surrounding a central pair of single microtubules, as well as the radial spokes that link the outer doublets to the central pair. Trypanosoma brucei keeps a flagellum throughout its life cycle and it is assembled on a cell protrusion by a transport mechanism, the “intraflagellar transport”. In Plasmodium, only one life stage is flagellated, the male gamete, and its assembly, independent of intraflagellar transport and extremely rapid, takes place in the cytoplasm of the mother cell.

1. Study of molecular motors: kinesins

Kinesins are molecular motors that move on microtubules using ATP as energy. They are involved in organelle and vesicle transport, cell division, cell motility and flagellum construction. Several kinesins have been studied and we have shown for example that a specific kinesin (KIF9B)  is responsible for the construction of the extra-axonal structure in T. brucei (Demonchy et al., 2009, J. Cell Bio 187 (5): 615-22). The absence of this protein leads to structural changes in the paraflagellar rod, defects in cell motility, and finally to cell death. Other kinesins are also essential for cell survival and their absence leads to the appearance of abnormal cells. A different role can be seen with kinesin KIN5, which is necessary for the attachment of the flagellum to the cell body.

Recently, in collaboration with Derrick Robinson and Mélanie Bonhivers from the University of Bordeaux, we identified the first kinesin located at the basal body, an organelle at the base of the flagellum. This protein plays an essential role in the survival of the parasite in the mammalian bloodstream. The absence of TbKINX1B kinesin is lethal, as it leads to a global disruption of the endomembrane network (Perdomo et al., 2022, Parasite. 29:14).

In Plasmodium, kinesin KIN8B is essential for the formation of male gametes and in its absence, the parasites can no longer infect mosquitoes and the parasite cycle is interrupted (Depoix et al., 2020, Cell Microbiol. 22(3):e13121.).

2. Comparative study in Trypanosoma, Leishmania and Plasmodium

Despite the structural conservation of axonemes, there are many differences in assembly and function, particularly in unicellulars. Few studies compare flagella assembled by transport systems on cellular protrusions, such as Trypanosoma and Leishmania, and those assembled by polymerisation in mother cells, such as Plasmodium.

We have undertaken the study of radial bridges, the central structures of the axoneme, which play an essential role in the regulation and control of motility (collaboration with the teams of R. Wheeler (University of Oxford) and Dr Sara Marques (Imperial College, London) and Dr Chandra Ramakrishnan (Universität Zürich, Switzerland). This work helps us to better understand the diversification of flagella and how they function.

Collaborations

• Institut Pasteur, Unit ‘Cell biology of Trypanosomes’ - Dr Philippe Bastin.
• Université de Bayreuth (Allemagne) – Dr Klaus Ersfeld.
• Université de Bordeaux – Dr. Derrick Robinson, Dr. Mélanie Bonhivers
• Laboratoire de Biologie du Développement de Villefranche sur mer (UMR7009 CNRS/UPMC)
• Imperial College, Londres – Dr S. Marques.
• Universität Zurich – Dr C. Ramakrishnan.
• University of Oxford – Dr Richard Wheeler.
• University of Brasilia (Brazil) – Dr Izabella Bastos.

Publications (from 2000)

Depoix D, Marques SR, Ferguson DJP, Chaouch S, Duguet T, Sinden RE, Grellier P, Kohl L.(2019) Vital role for Plasmodium berghei Kinesin8B in axoneme assembly during male gamete formation and mosquito transmission. Cell Microbiol. 2019 Oct 21:e13121.

Fort C, Bonnefoy S, Kohl L, Bastin P. (2016) Intraflagellar transport is required for the maintenance of the trypanosome flagellum composition but not its length. J Cell Sci.;129(15):3026-41.

Benmerah A, Durand B, Giles RH, Harris T, Kohl L, Laclef C, Meilhac SM, Mitchison HM, Pedersen LB, Roepman R, Swoboda P, Ueffing M, Bastin P. (2015) The more we know, the more we have to discover: an exciting future for understanding cilia and ciliopathies. Cilia. Mar 31;4:5.

Gallet C, Demonchy R, Koppel C, Grellier P, Kohl L. (2013) A Protein Phosphatase 1 involved in correct nucleus positioning in trypanosomes. Mol Biochem Parasitol. 2013 Nov-Dec;192(1-2):49-54.

Travers MA, Florent I, Kohl L, Grellier P. (2011) Probiotics for the control of parasites: an overview. J Parasitol Res. 2011:610769. Review

Marande W, Kohl L. (2011) Flagellar kinesins in protists. Future Microbiol. 6(2):231-46. Invited Review

Berg M, Kohl L, Van der Veken P (2010) Evaluation of nucleoside hydrolase inhibitors in the treatment of African trypanosomiasis. Antimicrob Agents Chemother, 54, 1900-8.

Demonchy R, Blisnick T, Deprez C, Toutirais G, Loussert C, Marande W, Grellier P, Bastin P, Kohl L. (2009) Kinesin 9 family members perform separate functions in the trypanosome flagellum. J. Cell Biol, 187(5), 615-622.

Depoix D, Kohl L, Florent I. (2008) L’analyse fonctionnelle des gènes chez les protozoaires parasites. Biofutur, 289 : 46-51. Revue

Absalon S, Blisnick T, Bonhivers M, Kohl L, et al. (2008) Flagellum elongation is required for correct structure, orientation and function of the flagellar pocket in Trypanosoma brucei. J. Cell Sci. 121:3704-16 + front cover.

Absalon S, Blisnick T, Kohl L, Toutirais G, et al. (2008). Intraflagellar transport and functional analysis of genes required for flagellum formation in trypanosomes. Mol Biol Cell. 19(3):929-944.

Vaughan S*, Kohl L*, Ngai I, Wheeler RJ, Gull K. (2008). A repetitive protein essential for the flagellum attachment zone filament structure and function in Trypanosoma brucei. Protist. 159(1): 127-36. *equal co-autors

Absalon S*, Kohl L*, Branche C, Blisnick T, et al. (2007). Basal body positioning is controlled by flagellum formation in Trypanosoma brucei. PLoS ONE. May 9; 2(5):e437. *equal co-autors

Branche C, Kohl L, Toutirais G, Buisson J, Cosson J, Bastin P. (2006) Conserved and specific functions of axoneme components in trypanosome motility. J Cell Sci. 119 3443-55.

Kohl L., Robinson D.R. & P. Bastin (2003). Novel roles for the flagellum in cell morphogenesis and cytokinesis of trypanosomes. EMBO J. 22, 5336-46 + front cover.

Durand-Dubief M., Kohl L. & Bastin P. (2003). Efficiency and specificity of RNA interference generated by intra- and intermolecular double stranded RNA in Trypanosoma brucei. Mol. Biochem. Parasitol. 129, 11-21.

Moreira-Leite F.F., Sherwin T., Kohl L. & Gull, K. (2001). A trypanosome structure involved in transmitting cytoplasmic information during cell division. Science, 294, 610-612.

Bastin P., Ellis K., Kohl L. & Gull, K. (2000). Flagellum ontogeny in trypanosomes studied via an inherited and regulated RNA interference system. J Cell Sci. 113, 3321-332

Responsabilities et collective activities

Responsabilities in the MCAM unit

• 2009-… :       Evacuation guide of the building 52 (61, rue Buffon, MNHN)
• 2012-2017:   Co-editor of MCAM-news ( internal unit magazine, published every 3 month)
• 2015-…:       Webmaster for the PPL team web site

Responsabilities outside the MCAM unit

• 2022-… :       Elected member of the AVIV Department

Collective activities

• Expert for ECOS-Sud , FWO (Research Foundation Flanders, Belgique), BBSRC (Biotechnology and Biological Sciences Research Council, Grande-Bretagne)
• Reviewer for international scientific journals:  Journal of Biological Chemistry, PloS Pathogens, Experimental Parasitology, Biochimica et Biophysica Acta - Molecular Cell Research, PLoS One
• Membre of the GDR Cils
• Member of the selection comity of the National Fund for research of the Grand-Duchy of Luxembourg (domain: biology) for the attribution of PhD and post-doctoral fellowships (2008-2012)
• Appointed member of the Section 27 (Host Pathogen Interactions, Immunity and Inflammation) of the CNRS (2012-2016)
• Representative of the doctoral school ED227 (2015 - 2018, 2021-…)

Current Teaching activities

• ES5 : Diversité et biologie fonctionnelle des micro-organismes
• ES20 : Biodiversité et Ecologie Fonctionnelle des micro-organismes
• TC5 : Anatomie comparée « Mobilité des micro-organismes »
• Contrôle de l’expression génique par les acides nucléiques (SU-MNHN&UP+ Paris-Diderot)
• From 2018 : TC2 : Anglais scientifique (2 groupes)
• From 2021 : Cours d’anglais au personnel (1,5H/semaine, 4 membres du personnel

    In charge of teaching module TC5 : Anatomie comparée

Student Supervision

PhD students

• Clément Cormerais (2022-…)
• Estelle REMION (Co-supervision with Dr. C. Martin, 2017-2021)
• Luz IRAZAZABAL (Co-supervision with Dr. I. Bastos, University of Brasilia, 2012)
• Raphaël DEMONCHY (2006-2008).

- Post-doctorate and visiting scientists

• 2009-2011: W. MARANDE, William was recruited at the French Plant Genomic Resource Center in Toulouse.
• 2014 : Dr. Carla Nunes de Araujo, University of Brasilia, Brazil

Etudiants en thèse étrangère ou en Master 2

• Maya BERG (2007, 4 month training period, PhD from the Antwerp University, Belgium)
• Luz IRAZAZABAL (2011, Master 2)
• Cécile PHILIPPOTEAUX (2012, Master 2 & Doctor of Pharmacy, University of Reims)
• Lysiane Pao ( M2-Pro – University Paul Sabatier, Toulouse, 2014)
• Ons Ben Aissa (M2 University Versailles St Quentin en Yvelines, 2015)
• Nour Chamseddine (M2, Rouen University)
• Estelle Remion ( M2, EPHE, Paris, 2016)

 Students for short term training periods (Master 1, Graduats, BTS) : 11 students from 2010