Asymmetric expression of GPR126 in the convex/concave side of the spine is associated with spinal skeletal malformation in adolescent idiopathic scoliosis population.

Abstract

To determine the relationship between the bone formation-related functions of GPR126 and the structural asymmetry of spine in adolescent idiopathic scoliosis (AIS). Vertebral body samples were obtained from 51 AIS patients during spinal surgery between October 2014 and November 2017, and the expression pattern of GPR126 in the convex/concave sides of AIS spine was identified by RT-qPCR. Next, we explored the bone formation-related functions of GPR126 by knocking down and overexpressing GPR126 in human mesenchymal stem cells (hMSC) and further performing osteogenic differentiation. We also applied overexpression of N-terminal fragments derived from GPR126 (GPR126-NTFs) and osteogenic differentiation experiments to determine the functional part of GPR126 in skeletal development. We provided evidence that GPR126 showed a marked convex/concave asymmetric expression in the spine of AIS. Further RNA detection found that exon6-included transcripts of GPR126 (GPR126-exon6in) were significantly higher expressed in the convex side of AIS patients. Knocking down of GPR126 accelerated ossification of hMSCs during osteogenic differentiation, and overexpression of GPR126-exon6in delayed this process. Overexpression of GPR126-NTFs revealed that NTF is a functional fragment and exon6-included NTF (NTF-exon6in) delayed ossification of hMSCs. Our findings indicated that GPR126-NTFs play a role in skeletal development, and the inclusion/exclusion of exon6 may regulate the bone formation-related functions of GPR126. The convex/concave asymmetric expression of GPR126-exon6in may be an important factor in abnormal bone formation of AIS. These slides can be retrieved under Electronic Supplementary Material.