Soutenance de thèse: Pauline NAUROY

Le 2 novembre 2017 Pauline NAUROY de l'équipe de Florence RUGGIERO ("Biologie et Pathologie des matrices extracellulaires")  soutiendra sa thèse intitulée : 

Matrice extracellulaire et régénération :

Une étude utilisant le modèle de la nageoire caudale du poisson zèbre

L'évènement aura lien en amphi Bio (ENS de Lyon) et la thèse se déroulera en anglais.

Résumé:

In addition to their structural role in tissues, extracellular matrix (ECM) proteins are implicated in various biological events and signaling pathways. Surprisingly, their implication in regeneration remains poorly documented. My PhD project aimed at filling this gap.

To determine the ECM players of regeneration, I thus took advantage of the adult zebrafish caudal fin model for it shows unique advantages. To explore the ECM landscape and its dynamics during regeneration, I first performed a time-course transcriptomic analysis using RNA-seq. Because no list was available to comprehensively annotate ECM genes in zebrafish, I first characterized the zebrafish matrisome, defined as the list of ECM and ECM-related genes. For that, we developed an in silico orthology-based method and validated the robustness of our approach using various independent strategies.

Bioinformatics analyses of RNA-seq data revealed that among the 4,000 genes differentially expressed during regeneration, the most enriched gene sets are related to ECM. I then analyzed epidermal basement membrane (BM) gene expression profiles during regeneration, a specialized ECM structure that provides tissues with structural cohesion and serves as a signaling platform. In addition to “BM master components”, other ECM genes of the BM zone whose function remains elusive were found in our transcriptome. Among them was col14a1a, encoding collagen XIV-A protein, whose expression was shown to be restricted to embryos. Collagen XIV-A is re-expressed by epidermal basal cells and progressively deposited in the BM zone as the fin regenerates. Using atomic force microscopy, we showed that vivo-morpholino knockdown of collagen XIV-A resulted in a thinner and stiffer BM. These results were confirmed in a zebrafish collagen XIV-A knockout line that I have generated using the CRISPR/Cas9 technology. Altogether our results indicated that collagen XIV-A is a new regulator of the BM biomechanics probably by acting as a molecular spacer that is transiently but specifically required for the proper three-dimensional organization of the BM during regeneration.

My PhD work represents the first documentation of ECM gene expression profiles of regeneration and underscores the importance of collagen XIV-A in the epidermal BM regeneration. As such, our findings will certainly open new avenues of investigation in regenerative and reconstructive medicine.

Mots-clés:

zebrafish, regeneration, matrisome, extracellular matrix, basement membrane, collagen XIV