Hayashi T, Abe E, Jasin H E
University of Arkansas for Medical Sciences, Little Rock, 72205, USA.
Arthritis Rheum. 1996 Apr;39(4):567-73. doi: 10.1002/art.1780390405.
To study the distribution and synthesis of fibronectin (FN) in superficial and deep layers of normal articular cartilage.
Superficial and deep bovine and human articular cartilage slices were used to extract and quantitate FN by radioimmunoassay. Chondrocytes were also isolated by collagenase digestion for FN extraction and culture. Superficial and deep cartilage explants were cultured with and without stimulation by cytokines. Quantitation of newly synthesized FN was carried out by incubation with 35S-methionine. FN was purified on gelatin-agarose columns and further characterized by polyacrylamide gel electrophoresis. FN messenger RNA (mRNA) was quantitated by Northern blot analysis.
Freshly isolated bovine chondrocytes from deep cartilage contained 2.3 +/- 0.2 times more FN than was found in superficial cells (P < 0.025). Deep cartilage explants contained 1.2 times more FN than was found in superficial tissue. Explants obtained from deep cartilage synthesized 2.4 times more FN per cell than did superficial tissues (P < 0.01). FN synthesis as a fraction of total protein synthesis was significantly greater in deep explants (P < 0.01) compared with superficial tissues. Isolated deep chondrocytes in culture synthesized 1.89 +/- 0.33-fold more FN than did superficial cells (P < 0.05). Cytokine-stimulated superficial cartilage explants failed to respond in terms of FN synthesis. FN mRNA quantitation showed no significant differences between superficial and deep populations.
Since FN plays a major role in cell adhesion to damaged cartilage surfaces, our results suggest that modulation of FN synthesis near the articular surface of cartilage may be one of the factors that impede pannus invasion following an inflammatory insult to the joint.
研究纤连蛋白（FN）在正常关节软骨表层和深层的分布及合成情况。
采用牛和人的关节软骨表层及深层切片，通过放射免疫分析法提取并定量FN。还通过胶原酶消化分离软骨细胞以提取和培养FN。对表层和深层软骨外植体进行有无细胞因子刺激的培养。通过与35S - 蛋氨酸孵育对新合成的FN进行定量。FN在明胶 - 琼脂糖柱上纯化，并通过聚丙烯酰胺凝胶电泳进一步鉴定。通过Northern印迹分析对FN信使核糖核酸（mRNA）进行定量。
从深层软骨新鲜分离的牛软骨细胞所含FN比表层细胞多2.3±0.2倍（P < 0.025）。深层软骨外植体所含FN比表层组织多1.2倍。从深层软骨获得的外植体每个细胞合成的FN比表层组织多2.4倍（P < 0.01）。与表层组织相比，深层外植体中FN合成占总蛋白合成的比例显著更高（P < 0.01）。培养中分离的深层软骨细胞合成的FN比表层细胞多1.89±0.33倍（P < 0.05）。细胞因子刺激的表层软骨外植体在FN合成方面无反应。FN mRNA定量显示表层和深层群体之间无显著差异。
由于FN在细胞黏附于受损软骨表面中起主要作用，我们的结果表明，软骨关节表面附近FN合成的调节可能是炎症损伤关节后阻碍血管翳侵入的因素之一。
