TOPGAL mice show that the canonical Wnt signaling pathway is active during bone development and growth and is activated by mechanical loading in vitro
TOPGAL mice show that the canonical Wnt signaling pathway is active during bone development and growth and is activated by mechanical loading in vitro
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DOI：
10.1359/jbmr.050210
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发表时间：
2005-07-01
影响因子：
6.2
通讯作者：
Wysolmerski, JJ
中科院分区：
文献类型：
--
作者：
Hens, JR;Wilson, KM;Wysolmerski, JJ
我们在骨骼中发现了典型Wnt信号的细胞靶点，包括生长骨骼中的软骨细胞、成骨细胞和骨细胞，但只有成熟骨骼中的骨细胞和软骨细胞。机械变形诱导体外成骨细胞Wnt信号传导。小鼠和人类的遗传证据表明，典型的Wnt信号通路与骨骼发育和骨量的控制有关。然而，我们对体内骨骼中Wnt信号的细节知之甚少。我们使用Wnt指示物TOPGAL小鼠来鉴定在骨骼发育和成熟骨骼中哪些细胞激活了这一途径。材料和方法：我们检测了TOPGAL小鼠胚胎和新生儿骨发育过程中的典型Wnt信号。TOPGAL转基因由T细胞因子(TCF) β -连环蛋白响应启动子驱动的β -半乳糖苷酶基因组成，因此可以通过X-gal染色检测典型Wnt活性。RT-PCR检测了Writ信号组分在初代颅骨细胞培养中的表达。机械变形对Writ信号传导的影响在胶原I上生长的初代颅骨细胞中进行了研究，并使用Flexercell Tension Plus进行拉伸。系统fx - 4000 t。免疫组织化学用于检测-连环蛋白在软骨、骨和体外培养的变形颅骨细胞中的定位。结果和结论：典型Wnt信号在胎儿和新生儿骨骼的几种细胞类型中活跃，包括软骨细胞、成骨细胞和骨细胞。随着年龄的增长，Wnt信号的激活变得不那么突出，但在软骨细胞和骨细胞中持续存在。虽然培养的成骨细胞表达了许多不同的Wnt和Wnt受体，但TOPGAL转基因在这些细胞中基线时没有活性。然而，Wnt信号在这些细胞中通过物理变形被激活。结合在体内观察到的骨细胞中典型Wnt信号的激活，这些数据表明Wnt信号可能参与了骨骼中机械力与合成代谢活性的耦合。
We identified cellular targets of canonical Wnt signaling within the skeleton, which included chondrocytes, osteoblasts, and osteocytes in growing bone, but only osteocytes and chondrocytes in the mature skeleton. MEchanical deformation induced Wnt signaling in osteoblasts in vitro.Introduction: Genetic evidence in mice and humans has implicated the canonical Wnt signaling pathway in the control of skeletal development and bone mass. However, little is known of the details of Wnt signaling in the skeleton in vivo. We used Wnt indicator TOPGAL mice to identify which cells activated this pathway during bone development and in the mature skeleton.Materials and Methods: We examined canonical Wnt signaling during embryonic and neonatal bone development in TOPGAL mice. The TOPGAL transgene consists of a beta-galactosidase gene driven by a T cell factor (TCF)beta-catenin responsive promoter so that canonical Wnt activity can be detected by X-gal staining. Expression of Writ signaling components was examined in primary calvarial cell cultures by RT-PCR. The effect of mechanical deformation on Writ signaling was examined in primary calvarial cells grown on collagen I and stretched using Flexercell Tension Plus. System FX-4000T. Immunohistochemistry was used to examine the localization of beta-catenin in cartilage, bone, and cultured calvarial cells exposed to physical deformation.Results and Conclusions: Canonical Wnt signaling was active in several cell types in the fetal and neonatal skeleton, including chondrocytes, osteoblasts, and osteocytes. With age, activation of Wnt signaling became less prominent but persisted in chondrocytes and osteocytes. Although osteoblasts in culture expressed many different individual Wnt's and Wnt receptors, the TOPGAL transgene was not active in these cells at baseline. However, Wnt signaling was activated in these cells by physical deformation. Together with the activation of canonical Wnt signaling in osteocytes seen in vivo, these data suggest that Wnt signaling may be involved in the coupling of mechanical force to anabolic activity in the skeleton.