β-连环蛋白在骨折愈合期间的信号传导作用及其机制

Mechanism of intracellular signaling transduction through β-catenin during fracture healing

目的观察β-连环蛋白在骨折愈合期间变化，探讨其在骨折愈合期间发挥信号传导作用机制。方法对32只鼠进行随机分组，制作胫骨骨折模型。应用Westernbtot分析对骨折愈合不同时间点β-连环蛋白水平进行测定，逆转录-聚合酶链反应（RT—PCR）技术检测骨折愈合期间Wnts和它们受体表达，组织形态学测量观察β-连环蛋白信号传导拮抗剂Dkk．1对骨折愈合影响。结果β-连环蛋白在骨折愈合期间高表达。Dkk-1腺病毒处理骨痂样本显示β-连环蛋白水平低于未用Dkk1骨痂样本。Wnt-4、Wnt5b以及受体Fz-1和Lrp-6骨折愈合期间呈高表达。Ad—Dkk1组和对照组的骨和软骨占整个骨痂组织量比例、小梁骨直径（μm）、数量（每毫米）、小梁骨间隔（μm）分另0为（11．33±2．52）％／（35．67±3．06）％、（14．33±2．51）％／（47．33±4．04）％、（720．00±77．70）μm／（189．33±83．36）pm、13．67±2．05／32．33±2．62、（1．25±0．96）μm／（4．00±0．82）μm。两组差异有统计学意义（P〈0．01）。结论β-连环蛋白在骨折愈合中发挥重要作用，激活β-连环蛋白的治疗措施可能有助于骨折的愈合。

Objective To observe the changes of β-catenin during fracture repair and explore the mechanism of signaling transduetion through β-eatenin during fracture repair. Methods Mice were randomly divided into three groups, and the animal models of tibia fracture were established. Western blot analysis was employed for detecting the β-catenin expression at different time points during fracture repair. Quantitative RT-PCR was used to detect Wnt ligmants and their receptors during fracture repair to understand whether signaling transduction through β-catenin during fracture healing was directly regulated by Wnts. Histomorphometrie measurements were used to observe the effect of Dkk-1 on fracture repair for further understanding function of β-catenin. Results β-catenin level was low in intact bone tissue,but highly expressed during the entire period of fracture repair. Callus samples from animals treated with Ad-Dkkl exhibited a greater reduction of β-catenin level. Wnt-4, WntSb and their receptors Fz-1 and Lrp-6 were upregulated during fracture healing. In Dkk-1 and eontror groups, using histomorphometric measurements, there was substantial reduction of callus parameters. Bone and cartilage volume as a percentage of total callus tissue volume, trabecular thickness, trabecular number （ per ram） and trabecular separation （OLin） in Dkk-1 and contror groups were （ 11.33± 2.52 ） %/（ 35.67 ± 3.06 ） %, （ 14.33 ± 2 51 ） %/（ 47.33 ± 4.04） %, （720.00 ± 77.70） μm/（ 189.33 ± 83.36） μm, 13.67 ± 2.05/32.33 ± 2.62, （ 1.25 e 0.96 ） μm/（ 4.130 ± 0.82） μm respectively （ P 〈 0.01 ）. Conclusion β-catenin may play a key signaling role during fracture healing. The therapy to activate β-catenin could be used to enhance fracture repair.