G protein subunit β1 is an important mediator of the late stage of endochondral ossification.

Abstract G protein signaling plays important roles in skeletal development. G protein subunit β1 (GNB1) is a component of the G protein complex and is associated with G protein signaling. In humans, GNB1 mutations cause global developmental and persistent growth delays and severe neurodevelopmental disability. Similarly, Gnb1-knockout (KO) mice display growth retardation with neural tube defects. These genetic studies raise the possibility that GNB1 regulates skeletal development. This study was designed to investigate the role of GNB1 in skeletal development using Gnb1-KO mice. Gnb1-KO mice showed dwarfism, shortening of limbs, and a decreased ossifying zone of long bones. In situ hybridization and RT-qPCR analyses revealed that Col10a1 and Mmp13 expression was reduced in long bones of Gnb1-KO mice, while Runx2, Osterix, Ihh, and Ppr expression levels were similar to those in wild-type littermates. Gnb1-KO-derived osteoblasts maintained calcification abilities and the expression levels of osteoblast marker genes were unaltered, indicating that osteoblast differentiation and function were not affected in Gnb1-KO mice. Taken together, our results show that GNB1 is required for the late stage of endochondral bone formation by regulating Col10a1 and Mmp13 expression.