Interleukin-6 (IL-6) and/or soluble IL-6 receptor down-regulation of human type II collagen gene expression in articular Chondrocytes requires a decrease of Sp1•Sp3 ratio and of the binding activity of both factors to the COL2A1 promoter
Interleukin-6 (IL-6) and/or soluble IL-6 receptor down-regulation of human type II collagen gene expression in articular Chondrocytes requires a decrease of Sp1•Sp3 ratio and of the binding activity of both factors to the COL2A1 promoter
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DOI：
10.1074/jbc.m706387200
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发表时间：
2008-02-22
影响因子：
4.8
通讯作者：
Galera, Philippe
中科院分区：
文献类型：
--
作者：
Poree, Benoit;Kypriotou, Magdalini;Galera, Philippe
II型胶原蛋白由COL 2A 1基因编码的α 1（II）链组成。这种软骨标志物的改变是骨关节炎的常见特征。白细胞介素-6（IL-6）是一种促炎细胞因子，在某些细胞模型中需要一种称为sIL-6 R的可溶性受体才能发挥其作用。在这种情况下，sIL-6 R发挥激动作用。这种机制可以弥补某些细胞类型（如软骨细胞）中膜锚定IL-6受体的部分或全部缺失。我们的研究表明，IL-6，sIL-6 R，或两者通过转录调控抑制兔关节软骨细胞II型胶原的产生。细胞因子和/或sIL-6 R通过结合Sp1中心点Sp3的-63/-35序列抑制COL 2A 1转录。事实上，IL-6和/或sIL-6 R抑制Sp1和Sp3的表达及其与63-bp启动子的结合活性。在染色质免疫沉淀实验中，IL-6中心点sIL-6 R诱导Sp3募集增加，损害Sp1。通过小干扰RNA和诱饵策略敲低Sp1中心点Sp3被发现可以防止IL-6和/或sIL-6 R诱导的COL 2A 1转录抑制，这表明这些Sp蛋白中的每一个都是下调靶基因所必需的，并且涉及异型Sp1中心点Sp3复合物。此外，Sp1被证明与Sp3和HDAC 1相互作用。事实上，全长Sp3 cDNA的过表达阻断了Sp1对63-bp COL 2A 1启动子活性的上调，并且其本身抑制COL 2A 1转录。我们可以得出结论，IL-6，sIL-6 R，或两者的组合降低Sp1中心点Sp3的比例和DNA结合活性，从而抑制COL 2A 1转录。
Type II collagen is composed of alpha 1( II) chains encoded by the COL2A1 gene. Alteration of this cartilage marker is a common feature of osteoarthritis. Interleukin-6 (IL-6) is a pro-inflammatory cytokine that needs a soluble form of receptor called sIL-6R to exert its effects in some cellular models. In that case, sIL-6R exerts agonistic action. This mechanism can make up for the partial or total absence of membrane-anchored IL-6 receptors in some cell types, such as chondrocytes. Our study shows that IL-6, sIL-6R, or both inhibit type II collagen production by rabbit articular chondrocytes through a transcriptional control. The cytokine and/or sIL-6R repress COL2A1 transcription by a -63/-35 sequence that binds Sp1 center dot Sp3. Indeed, IL-6 and/ or sIL-6R inhibit Sp1 and Sp3 expression and their binding activity to the 63-bp promoter. In chromatin immunoprecipitation experiments, IL-6 center dot sIL-6R induced an increase in Sp3 recruitment to the detriment of Sp1. Knockdown of Sp1 center dot Sp3 by small interference RNA and decoy strategies were found to prevent the IL-6- and/ or sIL-6R- induced inhibition of COL2A1 transcription, indicating that each of these Sp proteins is required for down-regulation of the target gene and that a heterotypic Sp1 center dot Sp3 complex is involved. Additionally, Sp1 was shown to interact with Sp3 and HDAC1. Indeed, overexpression of a full-length Sp3 cDNA blocked the Sp1 up-regulation of the 63-bp COL2A1 promoter activity, and by itself, inhibits COL2A1 transcription. We can conclude that IL-6, sIL-6R, or both in combination decrease both the Sp1 center dot Sp3 ratio and DNA-binding activities, thus inhibiting COL2A1 transcription.