Vitamin D modulates gene expression in four major muscle tissues in Atlantic salmon

Vitamin D is essential to muscle health but could affect different muscle tissues in distinct ways. In humans, vitamin D is primarily synthesized in the skin via sun exposure but can also be obtained through ingesting foods that are fortified (e.g., milk) or naturally high in vitamin D (e.g., salmon). Like humans, salmon vitamin D titers vary considerably and can be altered through biofortification. We experimentally determined how vitamin D manipulation alters gene expression in four salmon muscles tissues: skeletal, craniofacial, smooth, and cardiac. Vitamin D changes in expression were exceptionally profound in the heart, where there were also several gene duplicates expressed unidirectionally. Six genes were differentially expressed in multiple muscles and many genes impacted by our vitamin D treatments in salmon show extensive evolutionary conservation as they are influenced by vitamin D titers in mammals, including humans. Salmon could provide a powerful model for understanding how variation in vitamin D impacts all vertebrates.