Characterization and functional consequences of underexpression of clusterin in rheumatoid arthritis
Characterization and functional consequences of underexpression of clusterin in rheumatoid arthritis
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DOI：
10.4049/jimmunol.177.9.6471
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发表时间：
2006-11-01
影响因子：
4.4
通讯作者：
Chiocchia, Gilles
中科院分区：
文献类型：
--
作者：
Devauchelle, Valerie;Essabbani, Abdellatif;Chiocchia, Gilles
我们先前比较了基因芯片分析基因表达在类风湿性关节炎（RA）和骨关节炎（OA）组织。在被鉴定为RA的分子标记的一组基因中，clusterin（clu）是最差异表达的基因之一。在本研究中，我们试图评估CLU（mRNA和蛋白质）在受影响的关节和培养的成纤维细胞样滑膜细胞（FLS）中的表达和作用，并确定其功能作用。采用定量RT-PCR、北方印迹、原位杂交、免疫组化和Western印迹等方法对CLU在离体滑膜组织中的表达进行定量分析。在滑膜组织中，该蛋白主要由滑膜细胞表达，并在滑液中检测到。与OA和健康滑膜相比，RA组织中全长和剪接异构体CLU mRNA的表达水平均较低。在滑膜和培养的FLS中，CLU的过度表达涉及OA中的所有蛋白亚型，而在RA中，细胞内形式的蛋白几乎检测不到。CLU基因在RA FLS中的过表达在24 h内促进细胞凋亡。我们观察到用小干扰RNA敲低CLU促进IL-6和IL-8的产生。CLU与磷酸化I κ B α相互作用。OA和RA FLS的CLU差异表达似乎是细胞的固有特性。CLU的细胞内亚型的表达在OA和RA之间差异调节。我们认为在RA关节中，细胞外CLU的高水平和细胞内CLU的低表达可能增强NF-κ B的活化和滑膜细胞的存活。
We previously compared by microarray analysis gene expression in rheumatoid arthritis (RA) and osteoarthritis (OA) tissues. Among the set of genes identified as a molecular signature of RA, clusterin (clu) was one of the most differentially expressed. In the present study we sought to assess the expression and the role of CLU (mRNA and protein) in the affected joints and in cultured fibroblast-like synoviocytes (FLS) and to determine its functional role. Quantitative RT-PCR, Northern blot, in situ hybridization, immunohistochemistry, and Western blot were used to specify and quantify the expression of CLU in ex vivo synovial tissue. In synovial tissue, the protein was predominantly expressed by synoviocytes and it was detected in synovial fluids. Both full-length and spliced isoform CLU mRNA levels of expression were lower in RA tissues compared with OA and healthy synovium. In synovium and in cultured FLS, the overexpression of CLU concerned all protein isoforms in OA whereas in RA, the intracellular forms of the protein were barely detectable. Transgenic overexpression of CLU in RA FLS promoted apoptosis within,24 h. We observed that CLU knockdown with small interfering RNA promoted IL-6 and IL-8 production. CLU interacted with phosphorylated I kappa B alpha. Differential expression of CLU by OA and RA FLS appeared to be an intrinsic property of the cells. Expression of intracellular isoforms of CLU is differentially regulated between OA and RA. We propose that in RA joints, high levels of extracellular CLU and low expression of intracellular CLU may enhance NF-kappa B activation and survival of the synoviocytes.