Peterson Richard E, Hoffman Stanley, Kern Michael J
Medical University of South Carolina, Department of Cell Biology and Anatomy, Charleston, South Carolina, USA.
Dev Dyn. 2005 Jul;233(3):811-21. doi: 10.1002/dvdy.20412.
The Prx1 homeobox gene is critical for cartilage and bone development as suggested by previous expression studies and demonstrated by gene targeting. However, neither approach assessed the individual roles of the two isoforms Prx1a and Prx1b. In this study, Western blot analysis demonstrates that, in the early stages of chondrogenesis, during mesenchymal condensation, only Prx1a is expressed. Higher level Prx1b expression is concomitant with the formation of a defined perichondrium. Prx1a overexpression in limb micro mass cultures results in an increase in the number of prechondrogenic condensations and cartilage nodules, whereas overexpression of Prx1b results in a decrease. Prx1a increases the percentage of proliferating cells in micro mass cultures and decreases apoptosis. The Prx1b isoform does not alter proliferation, but it does increase apoptosis, which is opposite of Prx1a. These results suggest that the Prx1a:Prx1b ratio and the alternative splicing mechanism that generates these two isoforms are critical in controlling chondrogenesis.
如先前的表达研究所表明并经基因靶向验证，Prx1同源框基因对软骨和骨骼发育至关重要。然而，这两种方法均未评估两种亚型Prx1a和Prx1b的各自作用。在本研究中，蛋白质印迹分析表明，在软骨形成的早期阶段，即间充质凝聚过程中，仅表达Prx1a。较高水平的Prx1b表达与明确的软骨膜形成同时出现。肢体微团培养中Prx1a的过表达导致软骨前凝聚物和软骨结节数量增加，而Prx1b的过表达则导致数量减少。Prx1a增加了微团培养中增殖细胞的百分比并减少了细胞凋亡。Prx1b亚型不改变增殖，但确实增加了细胞凋亡，这与Prx1a相反。这些结果表明，Prx1a:Prx1b比率以及产生这两种亚型的可变剪接机制在控制软骨形成中至关重要。
