Transforming growth factor alpha controls the transition from hypertrophic cartilage to bone during endochondral bone growth

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• 作者：Shirine E. Usmani^a ; ^{susmani@uwo.ca} ; Michael A. Pest^a ; ^mpest@uwo.ca ; Gunwoo Kim^b ; ^{gunwoo@fatima.or.kr} ; Sara N. Ohora^a ; ^{sohora@uwo.ca} ; Ling Qin^c ; ^{qinling@mail.med.upenn.edu} ; Frank Beier^a ; ^{fbeier@uwo.ca}
• 关键词：Growth plate ; Chondrocytes ; Transforming growth factor alpha ; Endochondral ossification ; Osteoclasts
• 刊名：Bone
• 出版年：2012
• 期刊代码：39_87563282
• 类别：med
• 出版时间：July, 2012
• 卷：51
• 期：1
• 页码：131-141
• 文件大小：2490 K

摘要

We have recently identified transforming growth factor alpha (TGF伪) as a novel growth factor involved in the joint disease osteoarthritis. The role of TGF伪 in normal cartilage and bone physiology however, has not been well defined.

Purpose

The objective of this study was to determine the role of TGF伪 in bone development through investigation of the Tgfa knockout mouse.

Methods

The gross skeletons as well as the cartilage growth plates of Tgfa knockout mice and their control littermates were examined during several developmental stages ranging from newborn to ten weeks old.

Results

Knockout mice experienced skeletal growth retardation and expansion of the hypertrophic zone of the growth plate. These phenotypes were transient and spontaneously resolved by ten weeks of age. Tgfa knockout growth plates also had fewer osteoclasts along the cartilage/bone interface. Furthermore, knockout mice expressed less RUNX2, RANKL, and MMP13 mRNA in their cartilage growth plates than controls did.

Conclusions

Tgfa knockout mice experience a delay in bone development, specifically the conversion of hypertrophic cartilage to true bone. The persistence of the hypertrophic zone of the growth plate appears to be mediated by a decrease in MMP13 and RANKL expression in hypertrophic chondrocytes and a resulting reduction in osteoclast recruitment. Overall, TGF伪 appears to be an important growth factor regulating the conversion of cartilage to bone during the process of endochondral ossification.