Stage M2- Mécanotransduction dans les chondrocytes

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Stage M2- Mécanotransduction dans les chondrocytes

Titre du sujet de stage :

Role of α10β1integrin in chondrocyte mechanotransduction.

Nom, adresse de l’Unité d’accueil / Nom du responsable de l’unité :

Laboratoire de biologie Tissulaire et Ingénierie thérapeutique (LBTI – CNRS UMR 5305)

7 passage du Vercors

69007 LYON Cedex 07

Nom du responsable d’unité : Dr Bernard VERRIER

Nom, adresse de l’Equipe d’accueil / Nom du responsable d’équipe :

Groupe : « Biologie et Ingénierie du Cartilage »

Responsable d’équipe : Dr Frédéric MALLEIN-GERIN

Nom, tel, adresse e-mail de l’encadrant de stage :

Encadrant de stage : Dr Emeline PERRIER-GROULT

emeline.groult@ibcp.fr

Tél: 04 72 72 26 17

Sujet de stage :

Context:

Although osteoarthritis (OA) can be initiated by multiple factors at multiple sites, mechanical overloading remains a key feature of OA pathogenesis. OA may result from excessively aberrant or physiologically normal mechanical stresses on initially healthy or pathologically-impaired articular cartilage, bone and ligaments. There is thus a need to decipher the mechanotransduction pathways involved in these tissues since alterations in these pathways likely increase the risk of OA. Our project focuses on the mechanotransduction in cartilage. Chondrocytes exposed to mechanical forces transmit the signals via various mechanotransducers including stretch-activated ion channels, receptor tyrosine kinases, the hyaluronan receptor CD44 and integrins. Integrins are transmembrane proteins consisting of a and β subunits and almost all cartilage proteins bind to integrins. Chondrocytes primarily use β1 integrins for adhesion to the cartilage matrix but the participation of the individual β1 integrin heterodimers in articular cartilage mechanotransduction is not clearly defined. While most literature data propose the fibronectin receptor a5β1 integrin as a critical mechanotransducer, the role of the prominent collagen-binding integrins such as a10β1 is unknown. The prominent expression of a10β1 integrin in articular chondrocytes and the partially overlapping chondrodysplasia phenotype of Itga10 null mice and mice with cartilage-specific deletion of Itgb1 makes us think that a10β1 is an integrin heterodimer which plays pivotal roles for functional and mechanical integrity of the joint tissue.

Internship project:

Our specific objective is to determine the role of α10β1 in chondrocytes mechanotransduction. We will use a cell system consisting of wild-type or Itga10 null chondrocytes embedded within agarose hydrogels and submitted to compression. We will investigate the impact of a10 privation on the phosphorylation state of signaling molecules and transcriptome. This project will bring new insight into how chondrocytes respond to mechanical forces, under the control of a10β1 integrin.

Workflow of the analysis of the effect of compression on gene expression and activation of signaling molecules in presence or absence of α10 integrin.

Technologies utilisées :

Culture de cellules primaires en 3D, Utilisation d’un bioréacteur à compression, Extraction d’ARN, RT-qPCR, Western-blotting, Immunofluorescence

Mots clés : Chondrocytes, Intégrines, Mécanotransduction, Voies de signalisation

Publications d’intérêt :

1- Cueru L, Bougault C, Aszodi A, Berthier Y, Mallein-Gerin F, Sfarghiu AM. Mechanical and physicochemical responses for hyaline cartilage: role of protein β1 integrin in mechanotransduction. Comput Methods Biomech Biomed Engin. 2013;16 Suppl 1:330-1.

2- Bougault C, Cueru L, Bariller J, Malbouyres M, Paumier A, Aszodi A, Berthier Y, Mallein-Gerin F, Trunfio-Sfarghiu AM. Alteration of cartilage mechanical properties in absence of β1 integrins revealed by rheometry and FRAP analyses. J Biomech. 2013 Jun 21;46(10):1633-40.

3- Bougault C, Aubert-Foucher E, Paumier A, Perrier-Groult E, Huot L, Hot D, Duterque-Coquillaud M, Mallein-Gerin F. Dynamic compression of chondrocyte-agarose constructs reveals new candidate mechanosensitive genes. PLoS One. 2012;7(5):e36964.

4- Gouttenoire J, Bougault C, Aubert-Foucher E, Perrier E, Ronzière MC, Sandell L, Lundgren-Akerlund E, Mallein-Gerin F. BMP-2 and TGFbeta1 differentially control expression of type II procollagen and alpha 10 and alpha 11 integrins in mouse chondrocytes. Eur J Cell Biol. 2010 Apr;89(4):307-14.

5- Bougault C, Paumier A, Aubert-Foucher E, Mallein-Gerin F. Investigating conversion of mechanical force into biochemical signaling in threedimensional chondrocyte cultures. Nat Protoc. 2009;4(6):928-38.