在表达刺鼠蛋白聚糖（Acan）的细胞中，转化生长因子β受体2（Tgfbr2）对于维持椎间关节和胸肋关节是必需的。
Tgfbr2 is required in Acan-expressing cells for maintenance of the intervertebral and sternocostal joints.
作者信息
Alkhatib Bashar, Liu Cunren, Serra Rosa
机构信息
Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama.
出版信息
JOR Spine. 2018 Jun;1(2). doi: 10.1002/jsp2.1025. Epub 2018 Jun 22.
BACKGROUND
Members of the transforming growth factor beta (TGF-β) family are secreted proteins that regulate skeletal development. TGF-β signaling is critical in embryonic development of the annulus fibrosus (AF) of the intervertebral disc (IVD). To address the question of the role of TGF-β signaling in postnatal development and maintenance of the skeleton, we generated mice in which T was deleted at 2-weeks of age in Aggrecan (Acan)-expressing cells using inducible Cre/LoxP recombination.
METHODS
Localization of Cre recombination was visualized by crossing Acan mice to fluorescent mTmG reporter mice. Acan mice were mated to T mice and Cre recombinase was activated by tamoxifen injection at 2-weeks postnatally. Following tamoxifen injection, mice were aged to 3, 6, and 12-months and control mice were compared to the experimental (cKO) group. Mice were initially analyzed using X-ray and skeletal preparations. Sternocostal joints and IVD tissues were further analyzed histologically by hematoxylin and eosin (H&E), Safranin O, and Picrosirius Red staining as well as Col10 immunostaining.
RESULTS
Cre recombination was observed in the IVD and sternocostal joints. X-ray analysis revealed osteophyte formation within the disc space of 12-month-old cKO mice. Skeletal preparations confirmed calcification within the IVD and the sternocostal joints in cKO mice. H&E staining of cKO IVD revealed disorganized growth plates, delay in the formation of the bony endplate, and Col10 staining in the AF indicative of ectopic endochondral bone formation. Furthermore, proteoglycan loss was observed and collagen bundles within the inner AF were thinner and less organized. Alterations in the IVD were apparent beginning at 3 months and were progressively more visible at 6 and 12 months. Similarly, histological analysis of cKO sternocostal joints revealed joint calcification, proteoglycan loss, and disorganization of the collagen architecture at 12 months of age.
CONCLUSIONS
TGF-β signaling is important for postnatal development and maintenance of fibrocartilaginous IVD and sternocostal joints.
背景
转化生长因子β（TGF-β）家族成员是调节骨骼发育的分泌蛋白。TGF-β信号传导在椎间盘（IVD）纤维环（AF）的胚胎发育中至关重要。为了解决TGF-β信号传导在出生后骨骼发育和维持中的作用问题，我们利用诱导型Cre/LoxP重组技术，构建了在表达聚集蛋白聚糖（Acan）的细胞中于2周龄时缺失T的小鼠。
方法
通过将Acan小鼠与荧光mTmG报告基因小鼠杂交，观察Cre重组的定位。将Acan小鼠与T小鼠交配，在出生后2周通过注射他莫昔芬激活Cre重组酶。注射他莫昔芬后，将小鼠饲养至3、6和12个月，并将对照小鼠与实验组（cKO）进行比较。最初使用X射线和骨骼标本对小鼠进行分析。对胸骨肋关节和IVD组织进一步进行苏木精和伊红（H&E）、番红O、天狼星红染色以及Col10免疫染色的组织学分析。
结果
在IVD和胸骨肋关节中观察到Cre重组。X射线分析显示，12月龄cKO小鼠椎间盘间隙有骨赘形成。骨骼标本证实cKO小鼠的IVD和胸骨肋关节有钙化。cKO IVD的H&E染色显示生长板紊乱、骨终板形成延迟，AF中Col10染色表明有异位软骨内骨形成。此外，观察到蛋白聚糖丢失，AF内部的胶原束更细且排列更紊乱。IVD的改变在3个月时开始明显，在6个月和12个月时逐渐更明显。同样，cKO胸骨肋关节的组织学分析显示，在12月龄时有关节钙化、蛋白聚糖丢失和胶原结构紊乱。
结论
TGF-β信号传导对出生后纤维软骨性IVD和胸骨肋关节的发育和维持很重要。
Zotero 插件