Regulation of microtubule nucleation

Paul CONDUIT

Nous voulons acquérir une compréhension fondamentale de la manière dont la nucléation des microtubules est régulée spatio-temporellement dans le contexte des animaux pluricellulaires.

Nous sommes particulièrement intéressés par la façon dont les mécanismes régulant la formation et l’organisation des microtubules varient entre les types de cellules, y compris dans les cellules en division et les neurones.

Mots-clés : Microtubules, division cellulaire, neurones, gamma-tubuline, g-TuRC, MTOC, centrosome, drosophile

+33 (0)157278095    paul.conduit(at)ijm.fr     @PaulConduit

Research goal

We want to gain a fundamental understanding of how microtubule nucleation is spatiotemporally regulated within the context of multi-cellular animals. We are particularly interested in how the mechanisms regulating microtubule formation and organisation vary between cell types.

 

 

 

Background

Microtubules are dynamic polymers that make up part of the cell’s cytoskeleton. They form a spectacular variety of arrays across different cell types and developmental stages. For example, during cell division microtubules are arranged into the mitotic spindle, which separates the duplicated chromosomes equally between daughter cells. In mature neurons, however, microtubules are arranged into polarised networks that run through axons and dendrites. These networks are required for structural support, neurite growth, and transport of molecules between the cell body and the neurite terminals. All cells use the same fundamental machinery to generate and organise microtubules, so how do different cells form such different microtubule arrays?

 

Research programme

We are addressing this question by studying the molecular regulation of multi-protein γ-tubulin ring complexes (γ-TuRCs), which template and catalyse de novo microtubule formation. γ-TuRCs are recruited and activated at specific sites within the cells in order to generate new microtubules at the right place and time. These sites include microtubule organising centres (MTOCs), such as centrosomes during mitosis or the Golgi in migrating fibroblasts, the sides of pre-existing microtubules, or specialised regions of cytoplasm, such as the cytosol surrounding mitotic chromatin. Once generated, molecular motors can slide microtubules against one another or even guide the direction of microtubule growth. Microtubules can also be stabilised by post-translational modifications or binding of other proteins. While not a focus of the lab, we are also interested in these post-nucleated processes as collectively they are important for correct microtubule array formation.

 

Main research areas currently within the lab

  • Investigating the molecular mechanisms regulating γ-TuRC recruitment and activation at different MTOCs
  • Understanding how microtubule formation and polarity are regulated within neurons.

 

 

Methodology

We predominantly use Drosophila as an in vivo multi-cellular animal model system. We combine precise manipulation of the genome, fixed and live advanced cell imaging, and biochemical assays to probe the molecular regulation of microtubules and the effect of their mis-regulation within cells.

 

Impact

Our work has implications for cancer and neurodegenerative disease, as γ-TuRCs have been identified as potential anti-cancer targets and microtubules form part of an important response during neuronal stress.

Group Leader :

Paul CONDUIT
phone : +33 (0)157278089
paul.conduit(at)ijm.fr

 

Members:

 

Isabelle BECAM Assistant professor
Adria CHORRO PhD Student
Abir ELFARKOUCHI PhD Student
Léa MAMMRI Technician
Akila MERAH Postdoc
Anaëlle TAIEB Engineer
Berta GARCIA Intern

Publications 

Augmin-ting dendritic branching through microtubule nucleation. (2024). Journal of Cell Science, 137(9), e137_e0901.
Mukherjee, A., Jeske, Y. A., Becam, I., Taïeb, A., Brooks, P., Aouad, J., Monguillon, C., & Conduit, P. T. (2024). γ-TuRCs and Augmin are required for the development of highly branched dendritic arbors in Drosophila. Journal of Cell Science, jcs.261534. https://doi.org/10.1242/jcs.261534
Conduit, P. (2024). Building the centrosome: PLK-1 controls multimerization of SPD-5. Journal of Cell Biology, 223(4), e202403003. https://doi.org/10.1083/jcb.202403003
Zhu, Z., Becam, I., Tovey, C. A., Elfarkouchi, A., Yen, E. C., Bernard, F., Guichet, A., & Conduit, P. T. (2023). Multifaceted modes of γ-tubulin complex recruitment and microtubule nucleation at mitotic centrosomes. Journal of Cell Biology, 222(10), e202212043. https://doi.org/10.1083/jcb.202212043
Cunningham, N. H. J., Bouhlel, I. B., & Conduit, P. T. (2022). Daughter centrioles assemble preferentially towards the nuclear envelope in Drosophila syncytial embryos. Open Biology, 12(1), 210343. https://doi.org/10.1098/rsob.210343
Tovey, C. A., Tsuji, C., Egerton, A., Bernard, F., Guichet, A., de la Roche, M., & Conduit, P. T. (2021). Autoinhibition of Cnn binding to γ-TuRCs prevents ectopic microtubule nucleation and cell division defects. The Journal of Cell Biology, 220(8), e202010020. https://doi.org/10.1083/jcb.202010020
Alvarez-Rodrigo, I., Steinacker, T. L., Saurya, S., Conduit, P. T., Baumbach, J., Novak, Z. A., Aydogan, M. G., Wainman, A., & Raff, J. W. (2019). Evidence that a positive feedback loop drives centrosome maturation in fly embryos. ELife, 8, e50130. https://doi.org/10.7554/eLife.50130
Tovey, C. A., Tubman, C. E., Hamrud, E., Zhu, Z., Dyas, A. E., Butterfield, A. N., Fyfe, A., Johnson, E., & Conduit, P. T. (2018). γ-TuRC Heterogeneity Revealed by Analysis of Mozart1. Current Biology, 28(14), 2314-2323.e6. https://doi.org/10.1016/j.cub.2018.05.044
Conduit, P. T. (2016). Microtubule organization: A complex solution. Journal of Cell Biology, 213(6), 609–612. https://doi.org/10.1083/jcb.201606008

 

Review

Mukherjee, A., Brooks, P. S., Bernard, F., Guichet, A., & Conduit, P. T. (2020). Microtubules originate asymmetrically at the somatic golgi and are guided via Kinesin2 to maintain polarity within neurons. ELife, 9, e58943. https://doi.org/10.7554/eLife.58943
Mukherjee, A., & Conduit, P. T. (2019). γ-TuRCs. Current Biology, 29(11), R398–R400. https://doi.org/10.1016/j.cub.2019.04.013
Tovey, C. A., & Conduit, P. T. (2018). Microtubule nucleation by γ-tubulin complexes and beyond. Essays in Biochemistry, 62(6), 765–780. https://doi.org/10.1042/EBC20180028

 

Preprint

Zhu, Z., Tovey, C. A., Yen, E. C., Bernard, F., Guichet, A., & Conduit, P. T. (2022). Multifaceted modes of γ-tubulin complex recruitment and microtubule nucleation at mitotic centrosomes. bioRxiv. https://doi.org/10.1101/2022.09.23.509043
Mukherjee, A., & Conduit, P. T. (2021). γ-TuRCs are required for asymmetric microtubule nucleation from the somatic Golgi of Drosophila neurons. bioRxiv. https://doi.org/10.1101/2021.09.24.461707

Antoine Guichet, Susan Lea, Emmanuel Derivery, Françoise Ochsenbein

Impulscience, Fondation Bettencourt-Schueller

FRM – team label

ANR project grant

IDex, Université Parix Cité

21.11.2023 : Impulscience prize 2023

We are currently recruiting postdocs to study microtubule nucleation in neurons – please contact Paul Conduit directly.