Fiber type-specific expression of low-density lipoprotein receptor-related protein 6 in human skeletal muscles.

OBJECTIVE 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. METHODS 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. RESULTS 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. CONCLUSION 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.