Mechanical Sensitive Molecule MACF1 Promotes Osteoblast Differentiation

The decreased osteoblast differentiation associated with reduced bone formation is one main cause of microgravityinduced bone loss.Our previous studies have demonstrated that microtubule actin crosslinking factor 1(MACF1)is downregulated in association with the decreased osteoblast differentiation and bone formation under simulated microgravity conditions.These findings suggest that MACF1 is sensitive to mechanical condition and may be critical for osteoblast differentiation and bone formation.To verify this hypothesis,current study investigates the role and mechanism of MACF1 in regulatingosteoblast differentiation by adopting MACF1 knockdown(MACF1-KD)osteoblasts.The results showed that MACF1 knockdown suppressed mineralized nodules formation,alkaline phosphatase(ALP)activity,osteogenic gene expression andβ-catenin signaling transduction.Moreover,we used RNA sequencing(RNA-seq)and chromatin immunoprecipitation sequencing(ChIP-seq)to investigate further mechanism.Interestingly,we found that MACF1 sequesterd repressors of osteoblast differentiation in cytoplasm.In conclusion,MACF1 is sensitive to mechanical condition and plays key role in activatingβ-catenin signaling transduction and sequestering repressors of osteoblast differentiation,which further promotes osteoblast differentiation.