Activin A Suppresses Osteoblast Mineralization Capacity by Altering Extracellular Matrix (ECM) Composition and Impairing Matrix Vesicle (MV) Production
Activin A Suppresses Osteoblast Mineralization Capacity by Altering Extracellular Matrix (ECM) Composition and Impairing Matrix Vesicle (MV) Production
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DOI：
10.1074/mcp.m112.024927
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发表时间：
2013-10-01
影响因子：
7
通讯作者：
van Leeuwen, Johannes P. T. M.
中科院分区：
文献类型：
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作者：
Alves, Rodrigo D. A. M.;Eijken, Marco;van Leeuwen, Johannes P. T. M.
在骨形成过程中，成骨细胞沉积一种细胞外基质（ECM），该基质通过一个涉及高度特化的基质小泡（MVs）产生和分泌的过程而矿化。激活素A是转化生长因子 -β（TGF -β）超家族成员，先前已被证明在人类骨形成模型中通过不明确的机制具有抑制作用。我们研究了激活素A在人骨髓间充质干细胞（hMSC）体外成骨分化过程中引发的这些机制。激活素A对ECM矿化的抑制与细胞外区间、ECM和基质小泡中碱性磷酸酶（ALP(1)）活性的强烈下降同时发生。基于稳定同位素标记氨基酸的细胞培养（SILAC）定量蛋白质组学揭示了激活素A的ECM中复杂的蛋白质组成变化，包括胶原蛋白XII、骨粘连蛋白和几种细胞骨架结合蛋白的表达改变。此外，在激活素A作用下的成骨细胞中，基质小泡产生不足，膜联蛋白表达极低。ECM促进人骨髓间充质干细胞的成骨发育和矿化。当人骨髓间充质干细胞在激活素A处理下产生的ECM上培养时，这种成骨促进作用显著降低。这些发现表明，激活素A作用于成骨细胞分化的ECM成熟阶段，最终导致矿化抑制。受激活素A调节的ECM蛋白不仅对骨矿化起决定性作用，而且具有与骨组织再生相关的骨诱导特性。
During bone formation, osteoblasts deposit an extracellular matrix (ECM) that is mineralized via a process involving production and secretion of highly specialized matrix vesicles (MVs). Activin A, a transforming growth factor-beta (TGF-beta) superfamily member, was previously shown to have inhibitory effects in human bone formation models through unclear mechanisms. We investigated these mechanisms elicited by activin A during in vitro osteogenic differentiation of human mesenchymal stem cells (hMSC). Activin A inhibition of ECM mineralization coincided with a strong decline in alkaline phosphatase (ALP(1)) activity in extracellular compartments, ECM and matrix vesicles. SILAC-based quantitative proteomics disclosed intricate protein composition alterations in the activin A ECM, including changed expression of collagen XII, osteonectin and several cytoskeleton-binding proteins. Moreover, in activin A osteoblasts matrix vesicle production was deficient containing very low expression of annexin proteins. ECM enhanced human mesenchymal stem cell osteogenic development and mineralization. This osteogenic enhancement was significantly decreased when human mesenchymal stem cells were cultured on ECM produced under activin A treatment. These findings demonstrate that activin A targets the ECM maturation phase of osteoblast differentiation resulting ultimately in the inhibition of mineralization. ECM proteins modulated by activin A are not only determinant for bone mineralization but also possess osteoinductive properties that are relevant for bone tissue regeneration.