Expression of Vitamin D Receptor and Local Vitamin D Metabolism at the Different Stages of Skeletal Muscle Growth

Abstract

Vitamin D metabolism is an important regulatory process for vitamin D3 action on the target cells. Nevertheless, expression of vitamin D receptor (VDR) and its association with the local regulation of vitamin D metabolism in skeletal muscle at the different stages of growth are currently unknown. In this study, hindlimb muscle of male C57BL/6 mice at the different growth stages including development (1‐month‐old), maturation (6‐month‐old), and aging (18‐month‐old) were investigated. Histological features of skeletal muscle were examined to evaluate an alteration of skeletal muscle plasticity across ages. Protein expression levels of VDR and vitamin D metabolizing enzymes (CYP24A1 and CYP27B1) at all ages were analyzed. Serum 25(OH)D3 was quantified to determine its relationship with VDR, CYP24A1, and CYP27B1 protein expression in skeletal muscle. The results revealed a significant increase of muscle fiber cross‐sectional area but not fiber number during developmental to maturation stage of skeletal muscle growth. In contrast, aging muscle presented a significant increase of centronucleated muscle fibers. These changes of skeletal muscle plasticity in mature and aged muscles were accompanied with the increase of serum 25(OH)D3 and VDR protein expression, respectively. In contrast, CYP24A1 and CYP27B1 protein expression in skeletal muscle were not changed at any age investigated. Collectively, these findings demonstrated the associations of 25(OH)D3 and VDR protein expression levels with the stages of skeletal muscle growth. However, the alterations of circulating 25(OH)D3 and VDR protein expression did not affect local vitamin D metabolism in skeletal muscle.Support or Funding InformationThis work was supported by grants(to RS) from the Thailand Research Fund and Office of the Higher Education Commission (MRG6080090) and the Faculty of Science, Mahidol University.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.