The role of the plasminogen system in bone resorption in vitro
The role of the plasminogen system in bone resorption in vitro
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DOI：
10.1359/jbmr.1999.14.6.946
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发表时间：
1999-06-01
影响因子：
6.2
通讯作者：
Carmeliet, G
中科院分区：
文献类型：
--
作者：
Daci, E;Udagawa, N;Carmeliet, G
纤溶酶原/纤溶酶蛋白水解级联在细胞外基质重塑中起重要作用。骨细胞中存在两种纤溶酶原激活剂（PA），组织型纤溶酶原激活剂（tPA）和尿激酶型纤溶酶原激活剂（uPA），以及它们的抑制剂1型（派-1），表明它们在骨吸收的一个或多个方面发挥作用，如破骨细胞形成、矿物质溶解和有机基质降解。使用来自tPA（tPA-/-）、uPA（uPA-/-）、派-1（派-1-/-）失活或联合失活（tPA-/-：uPA-/-）的小鼠的细胞在体外测定这些不同的过程，并与野生型小鼠（WT）进行比较。首先，破骨细胞的形成，通过调查的数量和特性的抗酒石酸酸性磷酸酶阳性多核细胞形成的原代成骨细胞和骨髓细胞的共培养物与1 α，25-二羟维生素D-3的评估，是没有不同的细胞类型之间的差异。第二，牙本质吸收，破骨细胞活性的测定，不受tPA和uPA的组合缺陷。最后，与WT细胞相比，tPA-/-：uPA-/-细胞降解非矿化骨样基质的能力显著降低（分别为28.1 +/-0.6%，n = 6 vs. 56.4 +/-3.1%，n = 6，p < 0.0001）。令人惊讶的是，骨细胞的胶原蛋白水解是不依赖于纤溶酶的存在下，所建议的I型H-3-胶原膜上进行的降解试验。两者合计，这些数据表明，纤溶酶原激活剂/纤溶酶系统是不需要破骨细胞的形成，也不为矿物质相的吸收，但参与去除非胶原蛋白存在于非矿化骨基质。
The plasminogen/plasmin proteolytic cascade plays an important role in extracellular matrix remodeling. The presence of the two plasminogen activators (PAs), tissue-type plasminogen activator (tPA), and urokinase-type plasminogen activator (uPA), and their inhibitor type 1 (PAI-1) in bone cells, suggests a role in one or more aspects of bone resorption such as osteoclast formation, mineral dissolution, and degradation of the organic matrix. These different processes were assayed in vitro using cells derived from mice with either tPA (tPA-/-), uPA (uPA-/-), PAI-1 (PAI-1-/-) inactivation or with a combined inactivation (tPA-/-:uPA-/-) and compared with wild-type mice (WT). First, osteoclast formation, assessed by investigating the number and characteristics of tartrate-resistant acid phosphatase-positive multinucleated cells formed in cocultures of primary osteoblasts and bone marrow cells treated with 1 alpha,25-dihydroxyvitamin D-3, was not different between the different cell types. Second, dentine resorption, an assay for osteoclast activity, was not affected by the combined deficiency of both tPA and uPA. Finally, the ability to degrade nonmineralized bone-like matrix,vas however, significantly reduced in tPA-/-:uPA-/- cells compared with WT cells (28.1 +/- 0.6%, n = 6 vs. 56.4 +/- 3.1%, n = 6, respectively, p < 0.0001). Surprisingly, collagen proteolysis by bone cells was not dependent on the presence of plasmin as suggested by degradation assays performed on type I H-3-collagen films. Taken together, these data suggest that the plasminogen activator/plasmin system is not required for osteoclast formation, nor for the resorption of the mineral phase, but is involved in the removal of noncollagenous proteins present in the nonmineralized bone matrix.