Dai Sheng-Ming, Shan Zheng-Zheng, Nakamura Hiroshi, Masuko-Hongo Kayo, Kato Tomohiro, Nishioka Kusuki, Yudoh Kazuo
St. Marianna University School of Medicine, Kawasaki, Kanagawa, Japan.
Arthritis Rheum. 2006 Mar;54(3):818-31. doi: 10.1002/art.21639.
Articular chondrocyte senescence is responsible, at least in part, for the increased incidence of osteoarthritis (OA) with increased age. Recently, it was suggested that caveolin 1, a 21-24-kd membrane protein, participates in premature cellular senescence. Caveolin 1 is the principal structural component of caveolae, vesicular invaginations of the plasma membrane. This study was undertaken to investigate whether the catabolic factors oxidative stress and interleukin-1beta (IL-1beta) induce features of premature senescence of articular chondrocytes through up-regulation of caveolin 1 expression.
Caveolin 1 expression was investigated in human OA cartilage by real-time polymerase chain reaction and in rat OA cartilage by immunohistologic analysis. We studied whether IL-1beta and H2O2 induce caveolin 1 expression in OA chondrocytes and analyzed the relationship between cellular senescent phenotypes and caveolin 1 expression in human chondrocytes.
In human and rat OA articular cartilage, caveolin 1 positivity was associated with cartilage degeneration. Both IL-1beta and H2O2 up-regulated caveolin 1 messenger RNA and protein levels, and both treatments induced marked expression of senescent phenotypes: altered cellular morphology, cell growth arrest, telomere erosion, and specific senescence-associated beta-galactosidase activity. Caveolin 1 overexpression induced p38 MAPK activation and impaired the ability of chondrocytes to produce type II collagen and aggrecan. In contrast, down-regulation of caveolin 1 with antisense oligonucleotide significantly inhibited the features of chondrocyte senescence induced by catabolic factors. Caveolin 1 induction and stresses with both IL-1beta and H2O2 up-regulated p53 and p21 and down-regulated phosphorylated retinoblastoma (Rb), suggesting that the p53/p21/Rb phosphorylation pathway, as well as prolonged p38 MAPK activation, may mediate the features of chondrocyte senescence induced by stress.
Our findings suggest that IL-1beta and oxidative stress induce features of premature senescence in OA chondrocytes, mediated, at least in part, by stress-induced caveolin 1 expression. This indicates that caveolin 1 plays a role in the pathogenesis of OA via promotion of chondrocyte down-regulation.
关节软骨细胞衰老至少部分地导致骨关节炎（OA）发病率随年龄增长而增加。最近，有人提出小窝蛋白1（一种21 - 24kd的膜蛋白）参与细胞早衰。小窝蛋白1是质膜囊泡内陷小窝的主要结构成分。本研究旨在探讨分解代谢因子氧化应激和白细胞介素-1β（IL-1β）是否通过上调小窝蛋白1的表达来诱导关节软骨细胞早衰特征。
通过实时聚合酶链反应研究人OA软骨中小窝蛋白1的表达，并通过免疫组织学分析研究大鼠OA软骨中小窝蛋白1的表达。我们研究了IL-1β和H2O2是否诱导OA软骨细胞中小窝蛋白1的表达，并分析了人软骨细胞中细胞衰老表型与小窝蛋白1表达之间的关系。
在人和大鼠OA关节软骨中，小窝蛋白1阳性与软骨退变相关。IL-1β和H2O2均上调小窝蛋白1信使核糖核酸和蛋白水平，且两种处理均诱导衰老表型的明显表达：细胞形态改变、细胞生长停滞、端粒侵蚀和特异性衰老相关β-半乳糖苷酶活性。小窝蛋白1过表达诱导p38丝裂原活化蛋白激酶（MAPK）激活，并损害软骨细胞产生Ⅱ型胶原和聚集蛋白聚糖的能力。相反，用反义寡核苷酸下调小窝蛋白1可显著抑制分解代谢因子诱导的软骨细胞衰老特征。IL-1β和H2O2诱导小窝蛋白1表达及应激均上调p53和p21并下调磷酸化视网膜母细胞瘤（Rb），提示p53/p21/Rb磷酸化途径以及p38 MAPK的持续激活可能介导应激诱导的软骨细胞衰老特征。
我们的研究结果表明，IL-1β和氧化应激诱导OA软骨细胞出现早衰特征，至少部分是由应激诱导的小窝蛋白1表达介导的。这表明小窝蛋白1通过促进软骨细胞下调在OA发病机制中起作用。
