biostudies-literatureUnknown12(1)Mita YSumitomo Pharma Co., Ltd. for Partnership to Realize Innovative Seeds and MedicinesMuscle fibres are broadly categorised into types I and II; the fibre-type ratio determines the contractile and metabolic properties of skeletal muscle tissue. The maintenance of type I fibres is essential for the prevention of obesity and the treatment of muscle atrophy caused by type 2 diabetes or unloading. Some reports suggest that myokines are related to muscle fibre type determination. We thus explored whether a myokine determines whether satellite cells differentiate to type I fibres. By examining the fibre types separately, we identified R-spondin 3 (Rspo3) as a myokine of interest, a secreted protein known as an activator of Wnt signalling pathways. To examine whether Rspo3 induces type I fibres, primary myoblasts prepared from mouse soleus muscles were exposed to a differentiationScientific reports13020https://www.ebi.ac.uk/biostudies/studies/S-EPMC9338073biostudies-literatureR-spondin3 is a myokine that differentiates myoblasts to type I fibres.PMC9338073Mita YManabe YFujii NLHamaguchi HZhu HFuruichi YfalseR-spondin3 is a myokine that differentiates myoblasts to type I fibres.Muscle fibres are broadly categorised into types I and II; the fibre-type ratio determines the contractile and metabolic properties of skeletal muscle tissue. The maintenance of type I fibres is essential for the prevention of obesity and the treatment of muscle atrophy caused by type 2 diabetes or unloading. Some reports suggest that myokines are related to muscle fibre type determination. We thus explored whether a myokine determines whether satellite cells differentiate to type I fibres. By examining the fibre types separately, we identified R-spondin 3 (Rspo3) as a myokine of interest, a secreted protein known as an activator of Wnt signalling pathways. To examine whether Rspo3 induces type I fibres, primary myoblasts prepared from mouse soleus muscles were exposed to a differentiation2022-01-01T00:00:00Z2022 Jul2025-04-27T01:16:14.381Z2025-04-06T18:08:52.841ZS-EPMC93380733590636310.1038/s41598-022-16640-2