Hypothermia-induced RNA-binding motif protein 3 (RBM3) stimulates osteoblast differentiation via the ERK signaling pathway.

The RNA-binding motif protein 3 (RBM3) belongs to a small group of proteins whose synthesis increases during hypothermia while global protein production is slowed down. Bone homeostasis is maintained by a balance between bone resorption and bone formation. Osteoblasts are key components of the bone and have an important role in bone remodeling cycle. However, hypothermia-induced RBM3 between osteoblasts remains unclear. At 32°C, expression of RBM3 and Runx2 was increased in a time-dependent manner and mineralization was also increased. RBM3 was also increased in a time-dependent manner under osteogenic conditions. Overexpression of RBM3 increased the expression of osteogenic genes such as Runx2 and OC. The osteogenic condition-induced expressions of RBM3, Runx2 and OC gene were decreased by RBM3 siRNA. Moreover, RBM3 promoted ERK and p38 phosphorylation. The inhibitor of ERK decreased the expression of Runx2 but did not affect the expression of RBM3. Taken together, these results demonstrate that RBM3 stimulates osteoblast differentiation via the ERK signaling pathway.