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Reduced miR-9 and miR-181a expression down-regulates Bim concentration and promote osteoclasts survival
Shilong Wang1, Chaoliang Tang1, Quan Zhang1
1Department of Orthopedics, Huashan Hospital Affiliated to Fudan University Shanghai 200040, China.
Abstract:
Tibial plateau fractures are often the result of blunt trauma and are associated with severe soft-tissue injury. Operative management of high-energy fractures remains difficult and challenging because the injuries often associated with serious complications. MicroRNAs (miRNAs) are the class of short noncoding single-stranded RNA molecules that negatively regulate gene expression. miRNAs contribute to every step of osteogenesis from embryonic bone development to maintenance of adult bone tissue, and disturbed miRNAs expression are identified related to osteoporosis, osteosarcoma, post-traumatic arthritis and bone remodeling. But our understandings about the roles of miRNAs in tibial plateau fractures repairing process are rare. In this study, we first detect seven candidate miRNAs expression in the SF cells of the mouse model. The results indicated that miR-9 and miR-181a were down-regulated significantly five days after injury. By using dual luciferase assay and western blot, we confirmed that the expression of Cbl is repressed by miR-9 and miR-181a. Meanwhile, the amount of ubiquitinated Bim was raised and the total Bim was reduced by miRNA inhibitors. Further functional study indicated that reduced miR-9 and miR-181a expression can active RAW264.7 cells migration ability and raise the primary mouse osteoclasts survival rate in vitro. To our understood, this is the first study about the function of disturbed miRNAs in the tibial plateau fracture mouse model, and may expand our understanding about post tibial plateau fracture recover and post-traumatic sequelae generation.
Insights
This study reveals that miR-9 and miR-181a are downregulated after tibial plateau fractures in mice. Reduced levels of these microRNAs (miRNAs) impact bone healing by affecting cell migration and survival.
Area of Science:
- Orthopedics
- Molecular Biology
- Biochemistry
Background:
- Tibial plateau fractures result from blunt trauma and often involve severe soft-tissue injury, posing challenges for operative management.
- MicroRNAs (miRNAs) are crucial regulators of gene expression involved in osteogenesis and bone remodeling, with altered expression linked to various bone diseases.
- The specific roles of miRNAs in the repair process following tibial plateau fractures are not well understood.
Purpose of the Study:
- To investigate the expression patterns of candidate microRNAs (miRNAs) in a mouse model of tibial plateau fracture.
- To elucidate the functional roles of specific miRNAs, namely miR-9 and miR-181a, in the context of tibial plateau fracture repair.
- To explore the molecular mechanisms by which these miRNAs influence cellular processes relevant to bone healing.
Main Methods:
- Expression analysis of seven candidate miRNAs in synovial fluid (SF) cells from a mouse tibial plateau fracture model.
- Dual luciferase assay and Western blot to confirm miRNA-mediated repression of target gene expression (Cbl).
- In vitro functional assays using miRNA inhibitors to assess effects on RAW264.7 cell migration and osteoclast survival.
Main Results:
- Downregulation of miR-9 and miR-181a was observed five days post-injury in the mouse model.
- miR-9 and miR-181a were confirmed to repress the expression of Cbl.
- Reduced miR-9 and miR-181a expression enhanced RAW264.7 cell migration and increased primary mouse osteoclast survival in vitro.
Conclusions:
- This study provides the first insights into the function of dysregulated miRNAs in a mouse model of tibial plateau fracture.
- Downregulated miR-9 and miR-181a play a role in regulating cellular responses post-fracture, potentially influencing bone healing and the development of post-traumatic complications.
- Findings may contribute to a better understanding of fracture recovery and sequelae following tibial plateau injuries.
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