Skeletogenesis in Xenopus tropicalis: Characteristic bone development in an anuran amphibian
Skeletogenesis in Xenopus tropicalis: Characteristic bone development in an anuran amphibian
复制标题
DOI：
10.1016/j.bone.2008.07.005
复制
发表时间：
2008-11-01
期刊：
影响因子：
4.1
通讯作者：
Togashi, Shin
中科院分区：
文献类型：
--
作者：
Miura, Shinichirou;Hanaoka, Kazunori;Togashi, Shin
在哺乳动物和鸟类中，大多数骨骼是通过软骨内成骨发育起来的。软骨原中的软骨细胞经历了肥大、钙化和凋亡等成熟过程。伴随而来的是成骨细胞以骨基质逐渐替代软骨支架，成为松质骨中的骨细胞。在骨骼的连续发育过程中，已有几种基因产物被确认为调控骨骼发育的分子机制的组成部分。转录因子SOX9在未分化间充质细胞向增生性软骨细胞的发育过程中发挥重要作用，同时抑制增殖性软骨细胞向肥大转化。其他转录因子RUNX2和OSTERIX在成骨细胞分化中起关键作用，RUNX2也是软骨细胞成熟所必需的，如肥大和基质矿化。GDF5是一种属于转化生长因子β超家族的蛋白质，参与关节形成和软骨形成。无尾两栖动物的四肢骨骼也是通过软骨板向骨骼发育的，但与哺乳动物和鸟类相比，它们的骨骼发育具有一些独特的特征。无尾两栖动物的发育和生长具有较少的骨小梁和较差的骨痂生长板，其软骨内成骨被发现是一个延迟的过程。为了解决无尾两栖动物骨骼发育的特点，我们克隆了热带非洲爪哇RUNX2(XT-Runx2)、OSTERIX(XT-Osterix)和GDF5(XT-gdf5)同源物，并与XT-Sox9一起观察了表达模式。组织学观察和切片原位杂交分析表明，XT-SOX9参与软骨形成，XT-RUNX2和XT-OSTERIX参与成骨，XT-GDF5参与关节形成。在软骨原中，XT-Runx2在软骨膜和未成熟软骨细胞中表达，与其他脊椎动物相同。然而，XT-Runx2在增大的软骨细胞中的表达很弱，与普通的肥大软骨细胞不同。这些观察结果表明，在成熟的软骨细胞中，XT-Runx2的弱表达影响了热带X线虫长骨的特征骨发育。(C)2008 Elsevier Inc.保留所有权利。
In mammals and birds, most of the skeletal bones develop via endochondral ossification. Chondrocytes in the cartilaginous anlagen undergo processes Of Maturation such as hypertrophy, calcification and apoptosis. Concomitantly, osteoblasts are recruited to replace the cartilage scaffold gradually with bone matrix and become osteocytes in the trabecular bones. Throughout the Successive development of bones, several gene products have been identified as being the components of the molecular mechanism regulating bone development. Transcription factor SOX9 plays essential roles during developmental Steps from Undifferentiated mesenchymal cells to proliferating chondrocytes, meanwhile, it inhibits transition of proliferating chondrocytes to hypertrophy. Other transcription factors RUNX2 and OSTERIX are critical in osteoblast differentiation, and RUNX2 is also essential for chondrocyte maturation such as hypertrophy and matrix mineralization. GDF5, a protein belonging to the transforming growth factor beta superfamily, is involved in joint formation and chondrogenesis. The limb skeleton of one of the ancestral tetrapod, anuran amphibians also develops through cartilaginous anlagen to bones, but their skeletogenesis has some unique characteristics compared with that of mammals and birds. Anuran amphibians develop and grow with less bone trabeculae and poor epiphyseal growth plates, and its endochondral ossification was found to be a delayed process. In order to address the characteristic skeletal development of anuran amphibians, we cloned Xenopus tropicalis RUNX2 (Xt-runx2), OSTERIX (Xt-osterix) and GDF5 (Xt-gdf5) homologue, and observed expression patterns together with Xt-sox9. In X tropicalis limbs, histological observation and section ill situ hybridization analysis Suggest that Xt-SOX9 is involved in chondrogenesis, Xt-RUNX2 and Xt-OSTERIX are involved in osteogenesis, and Xt-GDF5 is involved in joint formation. In the cartilaginous anlagen, Xt-runx2 expression was found in perichondrium and immature chondrocytes as seen in other vertebrates. However, Xt-runx2 expression in enlarged chondrocytes was weak and dissimilar to common hypertrophic chondrocytes. These observations suggest that weak Xt-runx2 expression in Maturing chondrocytes affects characteristic bone development in X. tropicalis long bones. (c) 2008 Elsevier Inc. All rights reserved.