Urita Atsushi, Matsuhashi Tomoya, Onodera Tomohiro, Nakagawa Hiroaki, Hato Megumi, Amano Maho, Seito Naoki, Minami Akio, Nishimura Shin-Ichiro, Iwasaki Norimasa
Hokkaido University Graduate School of Medicine, Sapporo, Japan.
Arthritis Rheum. 2011 Nov;63(11):3428-38. doi: 10.1002/art.30584.
The process of N-glycosylation is involved in the pathogenesis of various diseases. However, little is known about the contribution of changes in N-glycans in osteoarthritis (OA). The aim of this study was to identify the alterations in N-glycans in human OA cartilage, to characterize the messenger RNA (mRNA) expression of N-glycan biosynthesis enzyme genes (N-glycogenes) in mouse articular chondrocytes during cartilage degradation, and to analyze the relationship between altered N-glycan patterns and mechanisms of cartilage degradation.
Alterations in N-glycans were analyzed in human OA cartilage and degraded mouse cartilage by high-performance liquid chromatography and mass spectrometry. N-glycogene mRNA expression in mouse chondrocytes was measured using reverse transcription-polymerase chain reaction. To assess the relationship between the altered N-glycans and degradation of mouse cartilage, experiments involving either knockdown or overexpression of N-glycogenes were performed in mouse articular chondrocytes.
Alterations in high-mannose type N-glycans were observed in both human OA cartilage and degraded mouse cartilage. The expression of β1,2N-acetylglucosaminyltransferase I (GlcNAc-TI) mRNA, which converts high-mannose type N-glycans, was significantly increased in degraded mouse cartilage. Mouse chondrocytes with suppressed GlcNAc-TI expression had reduced levels of matrix metalloproteinase 13 (MMP-13) and ADAMTS-5 (aggrecanase 2) mRNA following stimulation with interleukin-1α (IL-1α). In contrast, mouse chondrocytes overexpressing GlcNAc-TI had increased levels of MMP-13 and ADAMTS-5 mRNA following stimulation with IL-1α.
These findings indicate that alterations in high-mannose type N-glycans and N-glycogenes in chondrocytes correlate with the release of MMP-13 and ADAMTS-5 during cartilage degradation. These findings suggest that N-glycans play a crucial role in the initiation and progression of OA.
N-糖基化过程参与多种疾病的发病机制。然而，关于骨关节炎（OA）中N-聚糖变化的作用知之甚少。本研究的目的是确定人类OA软骨中N-聚糖的改变，表征小鼠关节软骨细胞在软骨降解过程中N-聚糖生物合成酶基因（N-糖基因）的信使核糖核酸（mRNA）表达，并分析N-聚糖模式改变与软骨降解机制之间的关系。
通过高效液相色谱和质谱分析人类OA软骨和降解的小鼠软骨中N-聚糖的变化。使用逆转录-聚合酶链反应测量小鼠软骨细胞中N-糖基因的mRNA表达。为了评估N-聚糖改变与小鼠软骨降解之间的关系，在小鼠关节软骨细胞中进行了涉及敲低或过表达N-糖基因的实验。
在人类OA软骨和降解的小鼠软骨中均观察到高甘露糖型N-聚糖的改变。在降解的小鼠软骨中，将高甘露糖型N-聚糖转化的β1,2-N-乙酰葡糖胺基转移酶I（GlcNAc-TI）mRNA的表达显著增加。用白细胞介素-1α（IL-1α）刺激后，GlcNAc-TI表达受抑制的小鼠软骨细胞中基质金属蛋白酶13（MMP-13）和ADAMTS-5（聚糖酶2）mRNA水平降低。相反，过表达GlcNAc-TI的小鼠软骨细胞在用IL-1α刺激后MMP-13和ADAMTS-5 mRNA水平升高。
这些发现表明，软骨细胞中高甘露糖型N-聚糖和N-糖基因的改变与软骨降解过程中MMP-13和ADAMTS-5的释放相关。这些发现表明N-聚糖在OA的发生和发展中起关键作用。
