Myokines Produced by Cultured Bovine Satellite Cells Harvested from 3-and 11-Month-Old Angus Steers

Simple Summary One class of muscle growth regulators known as myokines have been vastly understudied in many livestock species, including cattle. Myokines are proteins produced by muscle that regulate muscle growth and have systemic functions that support whole-body health, as identified in many human and biomedical studies. In cattle, it is unknown how many myokines regulate growth, as very few myokines have been characterized with respect to expression, secretion, and functionality. Therefore, the expression and secretion of interleukin-6 (IL-6), interleukin-15 (IL-15), myonectin (CTRP15), fibronectin type III domain containing protein 5/irisin (FNDC5), and brain-derived neurotrophic factor (BDNF), were evaluated in this study. The results suggest and support that IL-6, IL-15, CTRP15, and BDNF are myokines secreted from bovine satellite cells and that they may contribute to the regulation of muscle stem cell activity in cattle.Abstract The myokines interleukin 6 (IL-6), interleukin 15 (IL-15), myonectin (CTRP15), fibronectin type III domain containing protein 5/irisin (FNDC5), and brain-derived neurotrophic factor (BDNF) are associated with skeletal muscle cell proliferation, differentiation, and muscle hypertrophy in biomedical model species. This study evaluated whether these myokines are produced by cultured bovine satellite cells (BSCs) harvested from 3- and 11-month-old commercial black Angus steers and if the expression and secretion of these targets change across 0, 12, 24, and 48 h in vitro. IL-6, IL-15, FNDC5, and BDNF expression were greater (p <= 0.05) in the differentiated vs. undifferentiated BSCs at 0, 12, 24, and 48 h. CTRP15 expression was greater (p <= 0.03) in the undifferentiated vs. differentiated BSCs at 24 and 48 h. IL-6 and CTRP15 protein from culture media were greater (p <= 0.04) in undifferentiated vs. differentiated BSCs at 0, 12, 24, and 48 h. BDNF protein was greater in the media of differentiated vs. undifferentiated BSCs at 0, 12, 24, and 48 h. IL-6, 1L-15, FNDC5, and BDNF are expressed in association with BSC differentiation, and CTRP15 appears to be expressed in association with BSC proliferation. This study also confirms IL-6, IL-15, CTRP15, and BDNF proteins present in media collected from primary cultures of BSCs.