前胶原酶的激活是软骨胶原降解中的关键控制点：丝氨酸和金属蛋白酶途径的相互作用。
Activation of procollagenases is a key control point in cartilage collagen degradation: interaction of serine and metalloproteinase pathways.
作者信息
Milner J M, Elliott S F, Cawston T E
机构信息
Department of Rheumatology, The Medical School, University of Newcastle-upon-Tyne, England, UK.
出版信息
Arthritis Rheum. 2001 Sep;44(9):2084-96. doi: 10.1002/1529-0131(200109)44:9<2084::AID-ART359>3.0.CO;2-R.
OBJECTIVE
Bovine and human cartilages in explant culture respond to proinflammatory cytokines with the up-regulation of procollagenases. In stimulated bovine nasal cartilage (BNC), >90% of collagen is released by day 14 of culture, but collagen release is rarely seen before day 7. The aim of this study was to investigate if activation of procollagenases is a rate-limiting step in cartilage collagen breakdown.
METHODS
BNC and human articular cartilage explants were cultured with interleukin-1alpha (IL-1alpha) and/or oncostatin M (OSM) with or without test reagents. Collagen levels were determined by assay of hydroxyproline. Collagenase activity was measured using the diffuse fibril assay.
RESULTS
The addition of procollagenase activators, matrix metalloproteinase 3 (MMP-3), and APMA to IL-1alpha/OSM-stimulated BNC resulted in early release of collagen. The release with APMA was completely blocked by the addition of tissue inhibitor of metalloproteinases 1. This shows that procollagenases are present early in the culture period, but cartilage collagen breakdown does not happen until activation occurs. The addition of plasminogen to IL-1alpha/OSM-stimulated cartilage produced early collagen release in bovine and a significant increase in human cartilage. Thus, plasminogen activators (PAs) are present and convert plasminogen to plasmin, a known activator of several MMPs, including collagenases. Addition of alpha1-proteinase inhibitor or a urokinase-type PA inhibitor, 7-amino-4-chloro-3-(3-isothiureidopropoxy) isocoumarin, partially blocked the breakdown of collagen from IL-1alpha/OSM-treated bovine cartilage. This suggests that serine proteinases are involved in the activation cascades of procollagenases that result in cartilage collagen breakdown.
CONCLUSION
The activation of procollagenases is a key control point in cartilage collagen breakdown, and serine proteinase pathways activate MMPs.
目的
外植体培养中的牛和人软骨会对促炎细胞因子产生反应，导致前胶原酶上调。在受刺激的牛鼻软骨（BNC）中，培养至第14天时超过90%的胶原蛋白会释放出来，但在第7天之前很少见到胶原蛋白释放。本研究的目的是调查前胶原酶的激活是否是软骨胶原蛋白分解中的限速步骤。
方法
将BNC和人关节软骨外植体与白细胞介素-1α（IL-1α）和/或制瘤素M（OSM）一起培养，添加或不添加测试试剂。通过羟脯氨酸测定来确定胶原蛋白水平。使用弥散纤维测定法测量胶原酶活性。
结果
向IL-1α/OSM刺激的BNC中添加前胶原酶激活剂、基质金属蛋白酶3（MMP-3）和APMA会导致胶原蛋白早期释放。添加金属蛋白酶组织抑制剂1可完全阻断APMA引起的释放。这表明在前胶原酶在培养早期就已存在，但直到激活发生才会出现软骨胶原蛋白分解。向IL-1α/OSM刺激的软骨中添加纤溶酶原会使牛软骨中胶原蛋白早期释放，并使人软骨中胶原蛋白显著增加。因此，纤溶酶原激活剂（PAs）存在并将纤溶酶原转化为纤溶酶，纤溶酶是几种基质金属蛋白酶（包括胶原酶）的已知激活剂。添加α1-蛋白酶抑制剂或尿激酶型PA抑制剂7-氨基-4-氯-3-（3-异硫脲基丙氧基）异香豆素可部分阻断IL-1α/OSM处理的牛软骨中胶原蛋白的分解。这表明丝氨酸蛋白酶参与了导致软骨胶原蛋白分解的前胶原酶激活级联反应。
结论
前胶原酶的激活是软骨胶原蛋白分解的关键控制点，丝氨酸蛋白酶途径激活基质金属蛋白酶。
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