Investigation of the role of a ciliopathy gene in familial idiopathic scoliosis: from zebrafish to human
Idiopathic Scoliosis (IS) is a human pathology characterised by a severe curvature of the axial skeleton without any obvious ossification defect, which affects 3% of the population, mainly girls, before puberty. Because its etiology remains mysterious, no genetic test or medication is available to either predict or stop its progression. Similar scoliotic phenotypes have been recently described in zebrafish mutant for a ciliary motility gene “Curly” and for the Wnt signalling co-receptor PTK7 suggesting links between cilia, the Wnt-pathway and scoliosis (1). Cilia are cellular antennae that support many functions: fluid propulsion and transduction of light, chemical and mechanical signals.
To achieve a better understanding of cilia function during morphogenesis, we produced a zebrafish mutant with a complete deletion of the Rpgrip1llocus. Rpgrip1l encodes a ciliary protein required for tissue-specific ciliogenesis and for primary cilia signalling. We have previously uncovered its crucial function in Hedgehog transduction in a murine model and its implication in Wnt-PCP establishment both in mice and zebrafish (2, 3). Mutations of the human RPGRIP1L gene lead to severe ciliopathies, Meckel and Joubert syndromes (4). Surprisingly, zebrafish rpgrip1l null mutants present only subtle defects in ciliary content and ciliary motility at larval stages and a high proportion of mutants develop until juvenile stages, displaying a severe scoliosis phenotype without presenting major defects in ossification or locomotion.
Thus, zebrafish rpgrip1l mutant is a novel animal model to study the etiology of IS. We favor the hypothesis that this phenotype originates from a defect within the nervous system, ie from abnormal postural control or asymmetric locomotor comand, but it could also arise from non-isotropic growth of cartilage and tendons at puberty or intervertebral disk degeneration.To determine in which tissue(s) and at which stages Rpgrip1l and cilia are required between larval stage and puberty we plan to rescue the scoliosis phenotype of rpgrip1l mutants by reintroducing Rpgrip1l function by transgenesis using tissue-specific promoters. In parallel, we will analyse the presence and activity of motoneurons and ciliated (KA) interneurons in mutants before the appearance of scoliosis because their dysfunction could trigger asymmetric muscle contraction (5). As a non-biaised approach and more long-term project, we will prepare material for a transcriptomic analysis to compare juvenile trunks of wild-type animals versus mutants in order to identify the deregulated molecular pathways at the onset of the disease.
These studies will help uncover novel functions of cilia that directly or indirectly affect skeletal morphogenesis at puberty. They should help improve IS patients care on a long-term basis.
1: Boswell, TIGS, 2017. 2: Besse, Dvpt, 2011. 3: Mahuzier, JCB, 2012. 4: Delous, Nat. Gen, 2007. 5: Djenoune, Sci. Rep. 2017 6: Oliazadeh, Sci. Rep. 2017.
Master-2 Project 2018-2019 : Functional analysis of Shroom proteins during pronephros morphogenesis
Chronic kidney disease (CKD) affects
750 million people around the world. Mutation of Shroom 3 has been
identified in Human and mice associated with CKD but also neural tube closure
defect. Shroom3 encodes an
intracellular protein located at adherent junctions where it generates
contractile forces by controlling the distribution of Myosin II downstream of
the PCP pathway. [...]
Stage Master : Modélisation de la dynamique temporelle des
divisions des cellules précurseurs neurales au sein de l'épithélium dorsal de la drosophile. Responsable: Michel Gho
Les soies mécanosensorielles qui couvrent la partie dorsale du thorax de la drosophile sont formées au sein de l'épithélium à partir de cellules précurseurs. Ces dernières sont organisées en rangées, s’étendant sur toute la longueur, parallèles à la ligne médiane. Ces cellules précurseurs restent arrêtées environ 10 heures en phase-G2 puis entrent en division pour générer les cellules formant chaque soie sensorielle. [...]
Projet thèse équipe Breau
qui vient de créer une jeune équipe affiliée au Laboratoire de Biologie du
Développement à l’IBPS et au Laboratoire Jean Perrin (Physique) et Alain
Trembleau (Lab. Neuroscience Paris Seine, IBPS) recherchent un(e) très
bon(ne) candidat(e) à présenter au concours de l'Ecole Doctorale Complexité du
Master 1 and 2 on Mitochondrial Heredity in C. elegans
For 2018-19, if you are interested in using C.elegans to study mitochondrial maternal inheritance using genetics and live imaging, join our team : send your CV and motivations by e-mail to email@example.com
Exploring the function of an RNA methyl transferase (RMT) involved in non-coding RNA silencing pathways (mi, si &piRNA).
Three classes of small non-coding RNAs (sncRNA) emerged as a vast silencing framework in metazoan. They are involved in numerous biological processes including development, defense against pathogens and transposable element as well as chromatin dynamics. Precursors of these three types of small RNAs, namely miRNAs (microRNA), siRNAs (small interfering RNA) and piRNAs (piwi interacting RNA) are all transcribed by RNA polymerase II. After distinct biogenesis processes, si, pi and miRNAs are all loaded inside Argonaute proteins and guide them to target RNAs with sequence complementarity. The post-transcriptional repression that will take place using these ribonucleoprotein complexes (RNA-Induced Silencing Complexes, RISC) can operate through endonucleolytic cleavage or translational repression of the target RNA. Argonaute proteins loaded with si or piRNA are also involved in transcriptional repression by recruiting, at nascent RNAs, complexes that are able to modify DNA or histone proteins. These varieties of functional and mechanistic outputs explain why misregulation of RNA silencing pathways has been correlated to the emergence of cancer, neurodegenerative diseases and infertility troubles. [...]
Molecular interactions between
fibroblasts and muscle cells in order to build a full muscular system
Muscle development is a coordinated
process that requires the integration of different cell types. Skeletal muscles
are formed of myogenic cells and fibroblasts from connective tissues (reviewed in Nassari et al., 2017). Classical
surgical experiments in chicken embryos have shown that fibroblasts (and not
myogenic cells) contain the positional information to drive the correct spatial
organisation of limb muscles. This project aims to identify the molecular
signature underlying connective tissue specification and differentiation during
development and the molecular interactions between fibroblasts and myogenic
cells that impact on muscle differentiation and spatial organisation during
Nassari S., Duprez
D. and Fournier Thibault C. (2017) Non-myogenic Contribution to Muscle
Development and Homeostasis: The Role of Connective Tissues Frontiers in Cell Dev. Biol. 5:22. doi:
Mechanobiology underlying the formation of skeletal muscle
The absence of movement during
development leads to severe developmental defects that mostly affect the
musculoskeletal system. Similar symptoms are also observed in congenital
myasthenic syndrome due to mutations in genes coding for proteins involved in
the function of neuromuscular junction. We recently showed that the absence of
muscle contraction leads to a deficit of muscle progenitors and a switch
towards differentiation (Esteves de Lima
et al., 2016). With this project
based on the chicken model, we aim to determine the signalling pathways that
act downstream of mechanical activity and regulate developmental myogenesis. This
will provide us with molecular tools to rescue muscle function in the absence
of muscle activity observed in pathological situations
Esteves de Lima J.,
Bonnin MA, Birchmeier C and Duprez
D (2016) Muscle contraction is required to maintain the pool of muscle
progenitors via YAP and NOTCH during fetal myogenesis Elife. Aug24;5. pii: e15593. doi: 10.7554/eLife.15593.
Mechanical and molecular signals that regulate stem cell differentiation
and ligament (T/L) injuries have clinical importance since they can lead to disability
affecting patient’s activities (reviewed in Nourissat et al., 2015). T/L repair remains a clinical challenge. One of the reasons of our
inability to fully repair T/L is the lack of understanding of molecular aspects
underlying tendon biology (reviewed in
Gaut and Duprez, 2016). The objective of this project is to identify the link between
mechanical and molecular signals that regulate tendon cell differentiation. T/L mechanobiology
will be studied in vitro using
mesenchymal stem cells or primary T/L cells in a 3-dimensional (3D) culture system mimicking in vitro T/L formation (Guerquin et al., 2013). With this project, we will identify the molecular sensors of mechanical
forces during tendon and ligament cell differentiation.
Gaut L and Duprez
D (2016) Tendon development and diseases. Wiley
Interdiscip Rev Dev Biol. 2016 Jan-Feb;5(1):5-23. Review.
Guerquin MJ, Charvet B, Nourissat G, Havis E, Ronsin
O, Bonnin MA, Ruggiu M, Olivera I, Robert N, Lu Y, Kadler KE, Baumberger T,
Doursounian L, Berenbaum F and Duprez
D. (2013) Transcription factor Egr1
directs tendon differentiation and promotes tendon repair. Journal of Clinical Investigation
Nourissat G., Berenbaum F. and Duprez D. (2015).
Tendon injury: from biology to tendon repair Nature Reviews Rheumatology Apr;11(4):223-233. Review.
Projet Master-2 (équipe Labouesse)
Nous étudions dans l’équipe comment deux tissus différents, les muscles et l’épithélium extérieur, coopèrent pour entraîner l’extension de l’embryon du nématode C. elegans dans une configuration où les muscles induisent une déformation mécanique de l’épithélium en se contractant. L’objectif du stage sera de créer par une approche CRISPR des mutants conditionnels de la myosine musculaire pour ensuite relier potentiel contractile des muscles au degré d’extension de l’embryon. Les résultats seront essentiels pour produire un modèle physique de l’extension.Approches utilisées: CRISPR/Cas9, génétique moléculaire, imagerie, modélisation