健骨颗粒含药血清调控miR-141对小鼠骨髓间充质干细胞成骨分化的影响

目的观察健骨颗粒含药血清对去卵巢模型小鼠BMSCs成骨分化的影响,并研究其调控miR-141影响BMSCs分化的可能机制。方法流式细胞计数法鉴定BMSCs;含药血清和空白血清分别干预体外培养的BMSCs;显微镜下观察细胞形态结构,碱性磷酸酶染色、定量检测,茜素红染色;RT-PCR检测miR-141及DLx5、Msx2、Runx2的基因表达情况;Western blot检测DLx5、Msx2及Runx2的蛋白表达情况。结果流式细胞计数法鉴定提取细胞符合实验要求;镜下观察发现两组细胞有差异,含药血清组细胞群落间结晶更为密集;ALP染色及定量、茜素红染色结果含药血清组均优于空白血清组;RT-PCR检测Dlx5、Msx2、Runx2及miR-141的基因表达结果:含药血清组miR-141和Msx2基因表达较空白血清组显著降低(P<0.01),而Dlx5、Runx2的基因表达显著升高(P<0.01);Western blot检测DLx5、Msx2、Runx2的蛋白表达结果:含药血清组较空白血清组相比,Msx2的蛋白表达略微下降(P<0.05),而Dlx5、Runx2的蛋白表达相对升高(P<0.01)。结论健骨颗粒可以调低miR-141的表达,进而调高Dlx5的表达,削弱Dlx5的同源异形基因Msx2对Runx2抑制作用,通过miR-141调控Dlx5/Msx2/Runx2信号通路促进BMSCs成骨分化达到预防和治疗绝经后骨质疏松的目的。     

Connexin43 and Runx2 Interact to Affect Cortical Bone Geometry,Skeletal Development,and Osteoblast and Osteoclast Function

The coupling of osteoblasts and osteocytes by connexin43 (Cx43) gap junctions permits the sharing of second messengers that coordinate bone cell function and cortical bone acquisition. However, details of how Cx43 converts shared second messengers into signals that converge onto essential osteogenic processes are incomplete. Here, we use in vitro and in vivo methods to show that Cx43 and Runx2 functionally interact to regulate osteoblast gene expression and proliferation, ultimately affecting cortical bone properties. Using compound hemizygous mice for the Gja1 (Cx43) and Runx2 genes, we observed a skeletal phenotype not visible in wild‐type or singly hemizygous animals. Cortical bone analysis by micro–computed tomography (μCT) revealed that 8‐week‐old male, compound Gja1^+/– Runx2^+/– mice have a marked increase in cross‐sectional area, endosteal and periosteal bone perimeter, and an increase in porosity compared to controls. These compound Gja1^+/– Runx2^+/– mice closely approximate the cortical bone phenotypes seen in osteoblast‐specific Gja1‐conditional knockout models. Furthermore, μCT analysis of skulls revealed an altered interparietal bone geometry in compound hemizygotes. Consistent with this finding, Alizarin red/Alcian blue staining of 2‐day‐old Gja1^+/– Runx2^+/– neonates showed a hypomorphic interparietal bone, an exacerbation of the open fontanelles, and a further reduction in the hypoplastic clavicles compared to Runx2^+/– neonates. Expression of osteoblast genes, including osteocalcin, osterix, periostin, and Hsp47, was markedly reduced in tibial RNA extracts from compound hemizygous mice, and osteoblasts from compound hemizygous mice exhibited increased proliferative capacity. Further, the reduced osteocalcin expression and hyperproliferative nature of osteoblasts from Cx43 deficient mice was rescued by Runx2 expression. In summary, these findings provide evidence that Cx43 and Runx2 functionally intersect in vivo to regulate cortical bone properties and affect osteoblast differentiation and proliferation, and likely contributes to aspects of the skeletal phenotype of Cx43 conditional knockout mice. © 2017 American Society for Bone and Mineral Research     

Cbfb Regulates Bone Development by Stabilizing Runx Family Proteins

Runx family proteins, Runx1, Runx2, and Runx3, play important roles in skeletal development. Runx2 is required for osteoblast differentiation and chondrocyte maturation, and haplodeficiency of RUNX2 causes cleidocranial dysplasia, which is characterized by open fontanelles and sutures and hypoplastic clavicles. Cbfb forms a heterodimer with Runx family proteins and enhances their DNA‐binding capacity. Cbfb‐deficient (Cbfb^?/?) mice die at midgestation because of the lack of fetal liver hematopoiesis. We previously reported that the partial rescue of hematopoiesis in Cbfb^?/? mice revealed the requirement of Cbfb in skeletal development. However, the precise functions of Cbfb in skeletal development still remain to be clarified. We deleted Cbfb in mesenchymal cells giving rise to both chondrocyte and osteoblast lineages by mating Cbfb^fl/fl mice with Dermo1 Cre knock‐in mice. Cbfb^fl/fl/Cre mice showed dwarfism, both intramembranous and endochondral ossifications were retarded, and chondrocyte maturation and proliferation and osteoblast differentiation were inhibited. The differentiation of chondrocytes and osteoblasts were severely inhibited in vitro, and the reporter activities of Ihh, Col10a1, and Bglap2 promoter constructs were reduced in Cbfb^fl/fl/Cre chondrocytes or osteoblasts. The proteins of Runx1, Runx2, and Runx3 were reduced in the cartilaginous limb skeletons and calvariae of Cbfb^fl/fl/Cre embryos compared with the respective protein in the respective tissue of Cbfb^fl/fl embryos at E15.5, although the reduction of Runx2 protein in calvariae was much milder than that in cartilaginous limb skeletons. All of the Runx family proteins were severely reduced in Cbfb^fl/fl/Cre primary osteoblasts, and Runx2 protein was less stable in Cbfb^fl/fl/Cre osteoblasts than Cbfb^fl/fl osteoblasts. These findings indicate that Cbfb is required for skeletal development by regulating chondrocyte differentiation and proliferation and osteoblast differentiation; that Cbfb plays an important role in the stabilization of Runx family proteins; and that Runx2 protein stability is less dependent on Cbfb in calvariae than in cartilaginous limb skeletons. © 2014 American Society for Bone and Mineral Research.