Induction of the Sry-related factor SOX6 contributes to bone morphogenetic protein-2-induced chondroblastic differentiation of C3H10T1/2 cells
Induction of the Sry-related factor SOX6 contributes to bone morphogenetic protein-2-induced chondroblastic differentiation of C3H10T1/2 cells
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DOI：
10.1210/me.2002-0254
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发表时间：
2003-07-01
影响因子：
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通讯作者：
Ventura, F
中科院分区：
文献类型：
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作者：
Fernández-Lloris, R;Viñals, F;Ventura, F
软骨发生导致成熟软骨的形成，并产生作为软骨内骨形成模板的初始骨骼元素。骨形态发生蛋白（BMPs）参与多种发育和器官发生过程，并已被确定为软骨形成的关键调节因子。在本研究中，我们试图确定BMP-2诱导软骨形成标志物的转录机制。BMP-2刺激的C3 H10 T1/2细胞的时程研究显示，阿尔西安蓝阳性物质的剂量依赖性外观和II型胶原mRNA的上调表达。这最后的效果需要新的蛋白质合成，因为放线菌酮的加入完全阻断了II型胶原mRNA的诱导。包含软骨细胞特异性增强子的区域位于II型胶原α 1链（Col 2a 1）基因的内含子I中，足以赋予II型胶原基因表达的BMP-2依赖性转录诱导。软骨形成Sry型高迁移率族（HMG）盒蛋白（SOX）转录因子的表达水平的分析表明，Sox 6的表达与BMP-2诱导的蛋白复合物结合到软骨细胞特异性增强子的外观相关的BMP-2诱导的时间依赖性诱导。用SOX 6和SOX 9抗体预孵育核提取物显著降低了这些条带的强度。SOX 6的强制表达模拟了BMP-2的作用，而SOX 9的共表达促进了软骨细胞特异性增强子转录中两种因子之间的协同相互作用。此外，过表达的SOX 6突变形式，缺乏其高迁移率族结构域，足以防止软骨细胞特异性增强BMP-2的转录诱导。总之，这些结果表明，SOX 6是软骨形成中BMP-2信号传导的重要下游介质。
Chondrogenesis leads to the formation of mature cartilage and generates initial skeletal elements that serve as templates for endochondral bone formation. Bone morphogenetic proteins (BMPs) are involved in several developmental and organogenetic processes and have been identified as key regulators in chondrogenesis. In the present study we sought to determine the transcriptional mechanisms contributing to the induction of chondrogenic markers by BMP-2. Time-course studies with BMP-2-stimulated C3H10T1/2 cells showed a dose-dependent appearance of Alcian-blue-positive material and up-regulated expression of type-II collagen mRNA. This last effect required new protein synthesis because addition of cycloheximide completely blocked the induction of type-II collagen mRNA. A region encompassing the chondrocyte-specific enhancer, localized in intron I of type-II collagen alpha1 chain (Col2a1) gene, is sufficient to confer BMP-2-dependent transcriptional induction of type-II collagen gene expression. Analysis of the expression levels of chondrogenic Sry-type high-mobility group (HMG) box proteins (SOX) transcription factors demonstrated a time-dependent induction of Sox6 expression by BMP-2 that correlated with the appearance of BMP-2-induced protein complexes bound to the chondrocyte-specific enhancer. Preincubation of nuclear extracts with SOX6 and SOX9 antibodies markedly reduced the intensity of these bands. Forced expression of SOX6 mimicked the BMP-2 effect, whereas coexpression of SOX9 promoted a synergistic interaction between both factors in transcription from the chondrocyte-specific enhancer. Moreover, overexpression of a SOX6 mutated form, devoid of its high-mobility group domain, was sufficient to prevent transcriptional induction of the chondrocyte-specific enhancer by BMP-2. Taken together, these results indicate that SOX6 is an important downstream mediator of BMP-2 signaling in chondrogenesis.