Equipe: Biologie et ingénierie du cartilage
Date: année universitaire 2019-2020
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.