CV Science

Jean-Louis Martiel PhD, Biophysics

Course and current status

Institut National Agronomique Paris-Grignon, competitive engineering school in the field of life sciences.

Present position. Chargé de Recherche, permanent position, Inserm (French National Institute of Health and Medical Research),

Laboratoire TIMC-IMAG, Domaine de la Merci, F38706 La Tronche

Scientific summary

In silico study of actin-based force generation during cell movement or morphogenesis.

 We are interested in the understanding of actin-based force production during cell motility or cell morphogenesis. In the “Physics of the cytoskeleton and morphology” team (CEA/iRTSV/LPVC) (head Dr. L. Blanchoin), we use (i)  biomimetic systems (purified proteins), (ii) patterned surface or objects and (iii) in silico approaches to study the dynamic of actin cytoskeleton of moving cells.

In vitro cell motility. Towards the reconstitution of lamellipodia-like structures.

in vitro biomimetic systems have been a valuable tool to dissect the many aspects of actin-based force production during cell motility or morphogenesis (Loisel, Boujemaa et al. 1999; Bernheim-Groswasser, Wiesner et al. 2002; Boukellal, Campas et al. 2004; Achard, Martiel et al. 2010). However, the spherical shape of the objects used so far (hard beads or lipid droplets) imposes a cylindrical symmetry to the comet of actin filaments. This situation is relevant for the movement of Listeria bacteria or the propulsion of cytoplasmic vesicles in cell cytoplasm. But, this cylindrical symmetry is not pertinent for a wide range of cellular processes, particularly the formation of lamellipodia, actin sheet-like structures of a few hundreds of nanometers of thickness and which extend over several microns (Pollard and Borisy 2003).

The use of new surface patterning techniques (Reymann, Martiel et al. 2010) allows us to generate layered actin-filament network mimicking lamellipodia with different thickness, curvature, density and extension. This project began on both the experimental side (C. Suarez, R. Boujemaa-Paterski, L. Blanchoin and M. Théry) and on the modeling side (JL Martiel, A. Kawska). Modeling approach: we combine a microscopic model, like the one already developed in (Achard, Martiel et al. 2010) and a macroscopic model of the gel of actin filaments. 

We also developed tools (ImageJ) to analyze the force production of cells moving on/attached to  elastic substratum (Martiel et al., 2015).

Mesoscopic model for actin filaments.

We developed a mesoscopic model to study the mechanics of polymers at a mesoscopic scale (De La cruz et al., 2010). This study renews preexistent studies for actin filament severing (De La cruz, 2015) and brings new insights in polymers mechanics (Schramm et al., 2017).

Artery behavior

We have developed models for the active and passive properties of coronary arteries (Ohayon et al., 2017). Now, with J. Ohayon I will study the mechanical aspects of initiation, growth, and rupture of atherosclerotic plaques in coronaries. This study is developed in collaboration with medical doctors (G. Finet, Lyon) and biologists (L. Riou, Grenoble).

 Selected publications (2007-2017) 

Berro, J., Michelot, A., Blanchoin, L., Kovar, D., and Martiel, J. L. 2007. Attachment conditions control actin filament buckling and the production of forces. Biophys J. 92: 2546-2558.

Michelot A., Berro J., Guérin C., Boujemaa-Paterski R., Staiger C., Martiel JL, Blanchoin L. 2007. Actin-filaments Stochastic dynamics Mediated by ADF/cofilin. Curr. Biol., 17:825-833.

Hamès C., Ptchelkine D., Grimm C., Thevenon E., Moyroud E., Gérard F., Martiel JL, Benlloch R., Parcy F. and Muller C. Structural basis for LEAFY floral switch function and similarity with helix-turn-helix proteins. EMBO J, 27:2628-37, 2008.

McCullough B, Blanchoin L., Martiel JL, De La Cruz E. 2008. Cofilin Increases the Bending Flexibility of Actin Filaments : Implications for Severing and Cell Mechanics. J. Mol. Biol., 381:550-558.

Roland J., Berro J., Michelot A., Blanchoin L., Martiel JL. 2008. Stochastic severing of actin filaments by ADF/cofilin controls the emergence of a steady dynamical regime. Biophys. J. 94:2082-2094.

De La Cruz EM, Roland J, McCullough BR, Blanchoin L, Martiel JL. Origin of twist-bend coupling in actin filaments. Biophys J. 2010;99:1852-60.

Reymann AC, Martiel JL, Cambier T, Blanchoin L, Boujemaa-Paterski R, Théry M. Nucleation geometry governs ordered actin networks structures. Nat Mater. 2010 9:827-32.

Achard V, Martiel JL, Michelot A, Guérin C, Reymann AC, Blanchoin L, Boujemaa-Paterski R. A "primer"-based mechanism underlies branched actin filament network formation and motility, Curr Biol. 2010 20:423-8.

McCullough BR, Grintsevich E, Chen CK, Kang H, Hutchison AL, Henn A, Cao W, Suarez C, Martiel JL, Blanchoin L.  Reisler E and De La Cruz E. Cofilin-Linked Changes in Actin Filament Flexibility Promote Severing, Biophys. J., 2011, (in press).

Reymann AC, Suarez C, Guérin C, Martiel JL, Staiger CJ, Blanchoin L, Boujemaa-Paterski R. Turnover of Branched Actin Filament Networks by Stochastic Fragmentation with ADF/cofilin. Mol Biol Cell. 2011, 22:2541-2550.

Suarez C, Roland J, Boujemaa-Paterski R, Kang H, McCullough BR, Reymann AC, Guérin C, Martiel JL, De La Cruz EM, Blanchoin L. Cofilin tunes the nucleotide state of actin filaments and severs at bare and decorated segment boundaries. Curr Biol. 2011; 21:862-8.

Reymann AC, Boujemaa-Paterski  R,  Martiel JL, Guerin C, Cao W, Chin H, DeLaCruz E, Théry M, Blanchoin L.  Actin network architecture determines myosin motor activity. Science , 2012, 336:1310-1314.

Kawska A., Carvalho K., Manzi J., Boujemaa-Paterski R., Blanchoin L., Martiel JL., Sykes C.How actin network dynamics control the onset of actin-based motility. PNAS, 2012, 109:14440-14445.

Stoppin-Mellet V., Fache V., Portran D., Martiel JL., Vantard M. MAP65 Coordinate microtubule growth during bundle formation. Plos One., 2013, 8:e56808.

Portran D., Zoccoler M., Gaillard J. Stoppin-Mellet V., Neumann E., Arnal I. Martiel JL and Vantard M. MAP65/Ase1 promote microtubule flexibility. Mol. Biol. Cell, 2013, doi:10.1091/mbc.E13-03-0141.

De La Cruz EM, Martiel JL, Blanchoin L. Mechanical heterogeneity favors fragmentation of strained actin filaments. Biophys J. 2015;108(9):2270-81.

Martiel JL, Leal A, Kurzawa L, Balland M, Wang I, Vignaud T, Tseng Q, Théry M. Measurement of cell traction forces with ImageJ. Methods Cell Biol. 2015;125:269-87.

Ennomani H, Letort G, Guérin C, Martiel JL, Cao W, Nédélec F, De La Cruz EM, Théry M, Blanchoin L. Architecture and Connectivity Govern Actin Network Contractility. Curr Biol. 2016, 26(5):616-26.

Leal-Egaña A, Letort G, Martiel JL, Christ A, Vignaud T, Roelants C, Filhol O, Théry M. The size-speed-force relationship governs migratory cell response to tumorigenic factors. Mol Biol Cell. 2017;28(12):1612-1621.

Schramm AC, Hocky GM, Voth GA, Blanchoin L, Martiel JL, De La Cruz EM. Actin Filament Strain Promotes Severing and Cofilin Dissociation. Biophys J. 2017 20;112(12):2624-2633.

Ohayon J., Ambrosi D., Martiel JL. Hyperelastic models for contractile tissues : application to cardiovascular mechanics. In Biomechanics of living organs, Y. Payan and J. Ohayon editors, Elsevier, 2017, SBN 978-0-12-804009-6