Thrombospondin-2 facilitates assembly of a type-I collagen-rich matrix in marrow stromal cells undergoing osteoblastic differentiation.
Thrombospondin-2 facilitates assembly of a type-I collagen-rich matrix in marrow stromal cells undergoing osteoblastic differentiation.
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DOI：
10.3109/03008207.2013.811236
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发表时间：
2013
影响因子：
2.9
通讯作者：
Reddy AB
中科院分区：
文献类型：
--
作者：
Alford AI;Golicz AZ;Cathey AL;Reddy AB
我们研究了TSP 2缺乏对原代骨髓间充质基质细胞（MSC）成骨分化过程中胶原细胞外基质（ECM）组装的影响。30天后，野生型细胞积累和矿化的胶原丰富的不溶性基质，而TSP 2-null文化含有显着较低的量的基质胶原和显示减少mineral. Differences在基质胶原被视为早在第9天，在这个时候野生型文化含有更多的总胶原每细胞比TSP 2-null细胞。胶原蛋白在两种细胞类型的不同细胞外区室中分布不均匀。野生型细胞条件培养基中的胶原蛋白水平高于TSP 2无效细胞，但在酸溶性，新交联的基质中大致相当。相反，成熟的，交联的酸不溶性基质层的野生型细胞含有约两倍的胶原蛋白的TSP 2无效细胞衍生的基质。洗涤剂可溶性和不溶性基质组分中I型胶原蛋白的Western印迹分析支持这样的前提，即在体外进行成骨分化的TSP 2-null MSC中基质胶原蛋白水平降低。Western blot和免疫荧光分析表明，TSP 2缺陷不影响纤维连接蛋白组装成基质。相反，条件培养基的蛋白质印迹显示在不存在TSP 2的情况下成熟的、完全加工的I型胶原显著减少。我们的数据表明，在成骨细胞分化的背景下，TSP 2通过促进前胶原蛋白加工促进I型胶原蛋白丰富的基质的组装。
We examined the effects of TSP2 deficiency on assembly of collagenous extracellular matrix (ECM) by primary marrow-derived mesenchymal stromal cells (MSC) undergoing osteoblast differentiation in culture. After 30 days, wild-type cells had accumulated and mineralized a collagen-rich insoluble matrix, whereas the TSP2-null cultures contained markedly lower amounts of matrix collagen and displayed reduced mineral. Differences in matrix collagen were seen as early as day 9, at which time wild-type cultures contained more total collagen per cell than did TSP2-null cells. Collagen was unevenly distributed amongst different extracellular compartments in the two cell-types. Collagen levels in conditioned medium of wild-type cells were higher than those of TSP2-null cells, but were roughly equivalent in the acid-soluble, newly cross-linked matrixes. Conversely, the mature, cross-linked acid-insoluble matrix layer of wild-type cells contained about twice as much collagen as TSP2-null cell-derived matrix. Western blot analysis of type I collagen in detergent-soluble and insoluble matrix fractions supported the premise that matrix collagen levels were reduced in TSP2-null MSC undergoing osteoblastic differentiation in vitro. Western blot and immunofluorescent analysis suggested that assembly of fibronectin into matrix was not affected by TSP2 deficiency. Instead, western blots of conditioned medium demonstrated a marked reduction in mature, fully processed type I collagen in the absence of TSP2. Our data suggest that, in the context of osteoblast differentiation, TSP2 promotes the assembly of a type I collagen-rich matrix by facilitating pro-collagen processing.