MicroRNA-185 inhibits the growth and proliferation of osteoblasts in fracture healing by targeting PTH gene through down-regulating Wnt/ß -catenin axis: In an animal experiment.

Fracture healing is a repair process of a mechanical discontinuity loss of force transmission, and pathological mobility of bone. Increasing evidence suggests that microRNA (miRNA) could regulate chondrocyte, osteoblast, and osteoclast differentiation and function, indicating miRNA as key regulators of bone formation, resorption, remodeling, and repair. Hence, during this study, we established a right femur fracture mouse model to explore the effect microRNA-185 (miR-185) has on osteoblasts in mice during fracture healing and its underlying mechanism. After successfully model establishment, osteoblasts were extracted and treated with a series of mimics or inhibitors of miR-185, or siRNA against PTH. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot analysis were performed to determine the levels of miR-185, PTH, ß-catenin and Wnt5b. Cell viability, cycle distribution and apoptosis were detected by means of MTT and flow cytometry assays. Dual luciferase reporter gene assay verified that PTH is a target gene of miR-185. Osteoblasts transfected with miR-185 mimics or siRNA against PTH presented with decreased levels of PTH, ß-catenin and Wnt5b which indicated that miR-185 blocks the Wnt/ß -catenin axis by inhibiting PTH. Moreover, miR-185 inhibitors promoted the osteoblast viability and reduced apoptosis with more cells arrested at the G1 stage. MiR-185 mimics were observed to have inhibitory effects on osteoblasts as opposed to those induced by miR-185 inhibitors. Above key results indicated that suppression of miR-185 targeting PTH could promote osteoblast growth and proliferation in mice during fracture healing through activating Wnt/ß -catenin axis.

METTL3-mediated m6A modification of SOX4 regulates osteoblast proliferation and differentiation via YTHDF3 recognition.

N6-methyladenosine (m6A), the most prevalent internal modification in mRNA, is related to the pathogenesis of osteoporosis (OP). Although methyltransferase Like-3 (METTL3), an m6A transferase, has been shown to mitigate OP progression, the mechanisms of METTL3-mediated m6A modification in osteoblast function remain unclear. Here, fluid shear stress (FSS) induced osteoblast proliferation and differentiation, resulting in elevated levels of METTL3 expression and m6A modification. Through Methylated RNA Immunoprecipitation Sequencing (MeRIP-seq) and Transcriptomic RNA Sequencing (RNA-seq), SRY (Sex Determining Region Y)-box 4 (SOX4) was screened as a target of METTL3, whose m6A-modified coding sequence (CDS) regions exhibited binding affinity towards METTL3. Further functional experiments demonstrated that knockdown of METTL3 and SOX4 hampered osteogenesis, and METTL3 knockdown compromised SOX4 mRNA stability. Via RNA immunoprecipitation (RIP) assays, we further confirmed the direct interaction between METTL3 and SOX4. YTH N6-Methyladenosine RNA Binding Protein 3 (YTHDF3) was identified as the m6A reader responsible for modulating SOX4 mRNA and protein levels by affecting its degradation. Furthermore, in vivo experiments demonstrated that bone loss in an ovariectomized (OVX) mouse model was reversed through the overexpression of SOX4 mediated by adeno-associated virus serotype 2 (AAV2). In conclusion, our research demonstrates that METTL3-mediated m6A modification of SOX4 plays a crucial role in regulating osteoblast proliferation and differentiation through its recognition by YTHDF3. Our research confirms METTL3-m6A-SOX4-YTHDF3 as an essential axis and potential mechanism in OP.

[Comparative study on posterior cruciate ligament reconstruction with autologous hamstring tendon and LARS artificial ligament in the treatment of KD-â ¢-M knee dislocation].

OBJECTIVE: To observe the curative effect of one-stage reconstruction of anterior cruciate ligament(ACL), posterior cruciate ligament (PCL) and medial collateral ligament (MCL) in patients with KD-Ⅲ-M knee injury, and to compare the operation time, hospitalization cost and curative effect after arthroscopic reconstruction of PCL with LARS artificial ligament and autogenous hamstring tendon, ACL reconstruction with autogenous hamstring tendon and MCL repair combined with limited incision. METHODS: From March 2016 to January 2019, a total of 36 patients met the criteria of this study. Twenty patients in group A were treated with autogenous hamstring tendon reconstruction of ACL and PCL and repair of MCL, including 17 males and 3 females, with an average age of (34.7±9.2) years old. Sixteen patients in group B with LARS artificial ligament reconstruction of PCL, with an autogenous hamstring tendon reconstruction of PCL and MCL repair as before as group B, including 15 males and 1 female, with an average age of (36.8±8.6) years old. The operation time, hospitalization time and total hospitalization cost were compared between the two groups. The preoperative and postoperative functions of the two groups were evaluated by Hospital for Sepcial Surgery (HSS) score and Lysholm score respectively, and the curative effects were compared within and between groups. RESULTS: All the patients in the two groups were followed up for at least 1 year. There were no complications such as infection and poor wound healing in both groups. There was significant difference in operation time between (120.25±9.55) min in group A and (106.63±8.85) min in group B (P<0.01). The average hospitalization days in group A was (10.60±1.64) days, while that in group B was (10.38±1.59) days. There was no significant difference between the two groups (P>0.05). The HSS score of group A increased from preoperative 32.95±5.03 to postoperative 84.70±5.72 (P<0.01), and that of group B increased from preoperative 33.81±4.10 to postoperative 85.00±5.25 (P<0.01). The Lyshlom score in group A increased from preoperative 21.10±3.46 to postoperative 80.25±5.75 (P<0.01), and in group B increased from preoperative 21.56±3.01 to postoperative 80.00±4.30(P<0.01). There was no significant difference in preoperative and postoperative scores between the two groups(P>0.05). CONCLUSION: There was no significant difference in the average hospitalization days between the two groups, but the operation time in group A was longerthan that in group B, and the hospitalization cost in group B was higher than that in group A. There was no difference in HSS score and Lysholm score before and follow-up for a certain period of time after operation.