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Skeletal muscle consists of muscle fibres formed during embryonic and foetal development. With the exception of muscle regeneration following injury, fibre formation (hyperplasia) ceases around birth in mammals and shortly after hatching in zebrafish. Muscle hyperplasia requires the proliferation and differentiation of muscle stem cells, also called satellite cells, located in a distinct niche between the basal lamina and the plasma membrane of the fibre. Once differentiated, these cells either fuse with existing fibres to generate larger cells (hypertrophy) or together to form new fibres (hyperplasia). Fish of agronomic interest have continuous post-larval muscle growth, associated with the persistent formation of new muscle fibres from muscle stem cells (satellite cells). Nevertheless, hyperplastic muscle growth declines at the end of the exponential growth phase, the molecular and cellular mechanisms of muscle hyperplasia arrest are still unexplored. Given that hyperplasia level determines the muscle growth potential, the aim of this project is to analyse the cellular and molecular dynamics of muscle stem cells during the decline of muscle hyperplasia in trout. To achieve this objective we will study during the decline of hyperplasia, (i) the evolution of the characteristics of satellite cell populations using a single cell RNAseq approach, (ii) the evolution of the number of satellite cells using a 3D reconstruction of the muscle and (iii) the myogenic capacity of satellite cells using a stem cell transplantation method.

Partners:

• INRAE - LPGP – Coordinateur JC Gabillard
• INRAE - Oniris UMR703 PAnTher, Nantes, France. (Resp. K Rouger)