Supplementary Material for: Fiber Type-Specific Expression of Low-Density Lipoprotein Receptor-Related Protein 6 in Human Skeletal Muscles

<b><i>Objective:</i></b> Gene expression patterns differ in the two types of skeletal muscle fiber. The Wnt signaling pathway, which includes low-density lipoprotein receptor-related protein 6 (LRP6), has been associated with cell differentiation and glucose metabolism in skeletal muscles. We examined the relationships between muscle fiber types and LRP6 expression. <b><i>Methods:</i></b> Adenosine triphosphatase was assayed histochemically, and the levels of expression of LRP6 and myosin were analyzed immunohistochemically, in frozen sections of muscle fiber obtained from 16 muscle biopsy samples. The expression pattern of LRP6 in C2C12 cells was assayed by immunocytochemistry. <b><i>Results:</i></b> LRP6 was expressed only in type II fibers. Type IIc fibers showed variations in LRP6 expression. Expression of LRP6 was observed at the stage of myoblast differentiation. <b><i>Conclusion:</i></b> Antibody to LRP6 may be useful for identifying type II skeletal muscle fibers. LRP6 may influence glucose metabolism in type II fibers of human skeletal muscles.

<b><i>研究目的：</i></b> 两种骨骼肌纤维类型的基因表达模式存在差异。包含低密度脂蛋白受体相关蛋白6（low-density lipoprotein receptor-related protein 6，LRP6）的Wnt信号通路，已被证实与骨骼肌细胞分化及葡萄糖代谢相关。本研究探讨了骨骼肌纤维类型与LRP6表达之间的关联。<b><i>研究方法：</i></b> 对16份肌肉活检样本获取的肌纤维冰冻切片进行组织化学腺苷三磷酸酶检测，并通过免疫组织化学法分析LRP6与肌球蛋白的表达水平；同时采用免疫细胞化学法，检测C2C12细胞中LRP6的表达模式。<b><i>研究结果：</i></b> LRP6仅在II型肌纤维中表达。IIc型肌纤维的LRP6表达存在差异。LRP6的表达可在成肌细胞分化阶段被检测到。<b><i>研究结论：</i></b> LRP6抗体可用于鉴定人类骨骼肌II型肌纤维。LRP6或可影响人类骨骼肌II型肌纤维的葡萄糖代谢。