Oxygen tension regulates chondrocyte differentiation and function during endochondral ossification
Oxygen tension regulates chondrocyte differentiation and function during endochondral ossification
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DOI：
10.1074/jbc.m602296200
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发表时间：
2006-10-13
影响因子：
4.8
通讯作者：
Myoui, Akira
中科院分区：
文献类型：
--
作者：
Hirao, Makoto;Tamai, Noriyuki;Myoui, Akira
软骨在比大多数其他组织更低的氧张力下发挥作用。为了确定氧张力在软骨细胞分化和功能中的作用，我们研究了氧张力对多能间充质细胞系C3H10T1/2和14.5E小鼠胚胎前肢器官培养物的影响。在重组人骨形态发生蛋白2存在下，在常氧（20% O-2）或缺氧（5% O-2）下培养10T1/2细胞和胚胎前肢。为了阐明氧张力影响软骨细胞分化的机制，使用Smad6过表达腺病毒和Smad6转基因小鼠胚胎前肢检查了Smad通路。使用显性失活 MKK3 和 FR167653（一种特定的 p38 MAPK 抑制剂）检查 p38 MAPK 通路。还研究了 Sox9 和 Runx2 的转录活性。缺氧促进骨形态发生蛋白 2 诱导的糖胺聚糖产生，并抑制碱性磷酸酶活性和 C3H10T1/2 矿化。因此，缺氧促进软骨细胞分化而不是成骨细胞分化。在小鼠胚胎前肢器官培养中，缺氧增加了软骨基质的合成。这些作用主要由 p38 MAPK 激活介导，与 Sox9 无关。缺氧通过 Smad 抑制和组蛋白脱乙酰酶 4 激活下调 Runx2 活性，从而抑制 Col10a1（X 型胶原蛋白 α 1）表达。总之，缺氧促进软骨细胞分化和软骨基质合成，并抑制终末软骨细胞分化。这些缺氧引起的现象可能作用于软骨细胞，以在软骨细胞分化和软骨内骨化过程中增强和保持其表型和功能。
Cartilage functions at a lower oxygen tension than most other tissues. To determine the role of oxygen tension in chondrocyte differentiation and function, we investigated the influence of oxygen tension in the pluripotent mesenchymal cell line C3H10T1/2 and 14.5E mice embryo forelimb organ culture. 10T1/2 cells and embryo forelimbs were cultured under normoxia (20% O-2) or hypoxia (5% O-2) in the presence of recombinant human bone morphogenetic protein 2. To elucidate the mechanism by which oxygen tension influences chondrocyte differentiation, the Smad pathway was examined using Smad6 overexpression adenovirus and Smad6 transgenic mice embryo forelimbs. The p38 MAPK pathway was examined using dominant-negative MKK3 and FR167653, a specific p38 MAPK inhibitor. The transcriptional activities of Sox9 and Runx2 were also investigated. Hypoxia promoted bone morphogenetic protein 2-induced glycosaminoglycan production and suppressed alkaline phosphatase activity and mineralization of C3H10T1/2. Thus, hypoxia promoted chondrocytic commitment rather than osteoblastic differentiation. In the mice embryo forelimb organ culture, hypoxia increased cartilaginous matrix synthesis. These effects were primarily mediated by p38 MAPK activation, independent of Sox9. Hypoxia inhibited Col10a1 (type X collagen alpha 1) expression via down-regulation of Runx2 activity by Smad suppression and histone deacetylase 4 activation. In conclusion, hypoxia promotes chondrocytic differentiation and cartilage matrix synthesis and suppresses terminal chondrocyte differentiation. These hypoxia-induced phenomena may act on chondrocytes to enhance and preserve their phenotype and function during chondrocyte differentiation and endochondral ossification.