Multiple functions of the von Willebrand Factor A domain in matrilins: secretion, assembly, and proteolysis.
Multiple functions of the von Willebrand Factor A domain in matrilins: secretion, assembly, and proteolysis.
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DOI：
10.1186/1749-799x-3-21
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发表时间：
2008-06-02
影响因子：
2.6
通讯作者：
Chen Q
中科院分区：
文献类型：
--
作者：
Zhang Y;Wang ZK;Luo JM;Kanbe K;Chen Q
冯维勒布兰德因子 A (vWF A) 结构域是整合素和细胞外基质蛋白等细胞基质粘附分子中分布最广泛的结构模块之一。 matrilin-3 vWF A 结构域的突变会导致多发性骨骺发育不良 (MED)，但其病理机制仍有待确定。之前我们表明，matrilin-1 中的 vWF A 结构域通过结构域中金属离子依赖性粘附位点介导丝状基质网络的形成。在这里，我们展示了软骨特异性基质蛋白中 vWF A 结构域的两个新功能（1 和 3）。首先，vWF A 结构域调节母体蛋白的寡聚化。将vWF A结构域插入matrilin-3中，将matrilin-3四聚体、三聚体和二聚体的混合物的形成转化为仅四聚体，而从matrilin-1中删除vWF A结构域，将天然matrilin-1三聚体的形成转化为三聚体和二聚体的混合物。其次，vWF A 结构域可保护 matrilin-1 免受蛋白水解。我们在 matrilin-1 中的 vWF A2 结构域旁边发现了一个潜在的蛋白水解位点，该位点对基质蛋白酶抑制剂敏感。邻接的 vWF A 结构域的删除会导致 matrilin-1 降解，可能是通过暴露相邻的蛋白水解位点来实现的。此外，我们还证实了vWF A结构域对于matrilin-3的分泌至关重要。在 MED 患者中，vWF A 结构域内含有点突变的突变型 matrilin-3 的分泌显着减少和延迟，这是由于突变型 matrilin-3 的细胞内滞留所致。综上所述，我们的数据表明，由于 vWF A 结构域的多种功能，母体蛋白中 vWF A 结构域的不同突变/缺失可能导致不同的病理机制。
The von Willebrand Factor A (vWF A) domain is one of the most widely distributed structural modules in cell-matrix adhesive molecules such as intergrins and extracellular matrix proteins. Mutations in the vWF A domain of matrilin-3 cause multiple epiphyseal dysplasia (MED), however the pathological mechanism remains to be determined. Previously we showed that the vWF A domain in matrilin-1 mediates formation of a filamentous matrix network through metal-ion dependent adhesion sites in the domain. Here we show two new functions of the vWF A domain in cartilage-specific matrilins (1 and 3). First, vWF A domain regulates oligomerization of matrilins. Insertion of a vWF A domain into matrilin-3 converts the formation of a mixture of matrilin-3 tetramer, trimer, and dimer into a tetramer only, while deletion of a vWF A domain from matrilin-1 converts the formation of the native matrilin-1 trimer into a mixture of trimer and dimer. Second, the vWF A domain protects matrilin-1 from proteolysis. We identified a latent proteolytic site next to the vWF A2 domain in matrilin-1, which is sensitive to the inhibitors of matrix proteases. Deletion of the abutting vWF A domain results in degradation of matrilin-1, presumably by exposing the adjacent proteolytic site. In addition, we also confirmed the vWF A domain is vital for the secretion of matrilin-3. Secretion of the mutant matrilin-3 harbouring a point mutation within the vWF A domain, as occurred in MED patients, is markedly reduced and delayed, resulting from intracellular retention of the mutant matrilin-3. Taken together, our data suggest that different mutations/deletions of the vWF A domain in matrilins may lead to distinct pathological mechanisms due to the multiple functions of the vWF A domain.