SOX9 is a potent activator of the chondrocyte-specific enhancer of the pro alpha 1(II) collagen gene
SOX9 is a potent activator of the chondrocyte-specific enhancer of the pro alpha 1(II) collagen gene
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DOI：
10.1128/mcb.17.4.2336
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发表时间：
1997-04-01
影响因子：
5.3
通讯作者：
deCrombrugghe, B
中科院分区：
文献类型：
--
作者：
Lefebvre, V;Huang, WD;deCrombrugghe, B
在患有肢端发育不良（一种严重的骨骼畸形综合征）的患者中鉴定出SRY相关的SOX 9基因突变，以及在胚胎发育过程中Sox 9在小鼠软骨祖细胞和完全分化的软骨细胞中的丰富表达，这表明SOX 9可能在软骨形成中发挥作用的假设。我们先前对II型胶原基因（Col2a1）（软骨细胞分化的早期和丰富的标志物）的实验，在内含子1中鉴定了指导转基因小鼠中软骨细胞特异性表达的最小DNA元件，该元件在瞬时转染实验中也是强的软骨细胞特异性增强子，我们在这里表明，Col2a1表达与软骨细胞中高水平的SOX 9 RNA和蛋白密切相关。我们的实验表明，最小的Col2a1增强子是Sox 9的直接靶点。SOX 9与软骨细胞中活性所必需的最小Col2a1增强子的序列结合，并且SOX 9在非软骨细胞中的共转染实验中充当该增强子的有效激活剂。防止SOX 9结合的增强子中的突变消除软骨细胞中的增强子活性并抑制SOX 9在非软骨细胞中的增强子激活。缺乏反式激活结构域但保留DNA结合活性的截短的SOX 9蛋白的表达干扰成纤维细胞中全长SOX 9的增强子激活，并抑制软骨细胞中的增强子活性。我们的研究结果强烈表明，SOX 9参与控制软骨细胞中COL2A1的细胞特异性激活的模型，这是这些细胞分化程序的重要组成部分。我们推测，在Campomelic发育不良中，SOX 9活性的降低将抑制II型胶原蛋白的产生，并最终抑制其他软骨基质蛋白的产生，导致主要的骨骼异常。
The identification of mutations in the SRY-related SOX9 gene in patients with campomelic dysplasia, a severe skeletal malformation syndrome, and the abundant expression of Sox9 in mouse chondroprogenitor cells and fully differentiated chondrocytes during embryonic development have suggested the hypothesis that SOX9 might play a role in chondrogenesis. Our previous experiments with the gene (Col2a1) for collagen II, an early and abundant marker of chondrocyte differentiation, identified a minimal DNA element in intron 1 which directs chondrocyte-specific expression in transgenic mice, This element is also a strong chondrocyte-specific enhancer in transient transfection experiments, We show here that Col2a1 expression is closely correlated with high levels of SOX9 RNA and protein in chondrocytes, Our experiments indicate that the minimal Col2a1 enhancer is a direct target for Sox9, Indeed, SOX9 binds to a sequence of the minimal Col2a1 enhancer that is essential for activity in chondrocytes, and SOX9 acts as a potent activator of this enhancer in cotransfection experiments in nonchondrocytic cells, Mutations in the enhancer that prevent binding of SOX9 abolish enhancer activity in chondrocytes and suppress enhancer activation by SOX9 in nonchondrocytic cells, Other SOX family members are ineffective, Expression of a truncated SOX9 protein lacking the transactivation domain but retaining DNA-binding activity interferes with enhancer activation by full-length SOX9 in fibroblasts and inhibits enhancer activity in chondrocytes. Our results strongly suggest a model whereby SOX9 is involved in the control of the cell-specific activation of COL2A1 in chondrocytes, an essential component of the differentiation program of these cells, We speculate that in campomelic dysplasia a decrease in SOX9 activity would inhibit production of collagen II, and eventually other cartilage matrix proteins, leading to major skeletal anomalies.