Irisin enhances osteoblast differentiation in vitro.
It has been recently demonstrated that exercise activity increases the expression of the myokine Irisin in skeletal muscle, which is able to drive the transition of white to brown adipocytes, likely following a phenomenon of transdifferentiation. This new evidence supports the idea that muscle can be considered an endocrine organ, given its ability to target adipose tissue by promoting energy expenditure. In accordance with these new findings, we hypothesized that Irisin is directly involved in bone metabolism, demonstrating its ability to increase the differentiation of bone marrow stromal cells into mature osteoblasts. Firstly, we confirmed that myoblasts from mice subjected to 3 weeks of free wheel running increased Irisin expression compared to nonexercised state. The conditioned media (CM) collected from myoblasts of exercised mice induced osteoblast differentiation in vitro to a greater extent than those of mice housed in resting conditions. Furthermore, the differentiated osteoblasts increased alkaline phosphatase and collagen I expression by an Irisin-dependent mechanism. Our results show, for the first time, that Irisin directly targets osteoblasts, enhancing their differentiation. This finding advances notable perspectives in future studies which could satisfy the ongoing research of exercise-mimetic therapies with anabolic action on the skeleton.
Department of Basic Medical Science, Neuroscience and Sense Organs, University of Bari, 70124 Bari, Italy.
Graziana
0000-0001-8501-5399
G
Colaianni
Department of Basic Medical Science, Neuroscience and Sense Organs, University of Bari, 70124 Bari, Italy.
Concetta
C
Cuscito
Department of Basic Medical Science, Neuroscience and Sense Organs, University of Bari, 70124 Bari, Italy.
Teresa
T
Mongelli
Department of Basic Medical Science, Neuroscience and Sense Organs, University of Bari, 70124 Bari, Italy.
Angela
A
Oranger
Department of Clinical and Experimental Medicine, University of Foggia, 71100 Foggia, Italy.
Giorgio
G
Mori
Department of Basic Medical Science, Neuroscience and Sense Organs, University of Bari, 70124 Bari, Italy.
Giacomina
0000-0002-0681-1432
G
Brunetti
Department of Basic Medical Science, Neuroscience and Sense Organs, University of Bari, 70124 Bari, Italy.
Silvia
S
Colucci
Department of Experimental and Clinical Medicine, Center of Obesity, United Hospitals-University of Ancona, 60020 Ancona, Italy.
Saverio
S
Cinti
Department of Basic Medical Science, Neuroscience and Sense Organs, University of Bari, 70124 Bari, Italy.
Maria
M
Grano