David G, Bai X M, Van der Schueren B, Marynen P, Cassiman J J, Van den Berghe H
Center for Human Genetics, University of Leuven, Belgium.
Development. 1993 Nov;119(3):841-54. doi: 10.1242/dev.119.3.841.
Fibroglycan (syndecan-2) is a member of a family of cell surface heparan sulfate proteoglycans that interact with adhesion molecules, growth factors and a variety of other effector systems that support the shaping, maintenance and repair of an organism. To investigate this apparent redundancy of proteoglycans at the cell surface, we have studied the expression of fibroglycan in the mouse embryo and compared this expression with that of syndecan-1. The characterisation of mouse embryo cDNA clones that crosshybridized to human fibroglycan-cDNA predicted that murine and human fibroglycan were highly similar in structure. Consistently, the analysis of transfectant cells, murine cell lines and embryo extracts indicated that the murine proteoglycan reacted specifically with monoclonal antibody 10H4 developed against the human protein. Fibroglycan, as detected by monoclonal antibody 10H4 in sections of embryonic tissues, occurred exclusively on mesenchymal cells that represented the putative precursors of the hard and connective tissue cells. No fibroglycan was detected in epithelia or in muscle cells. Areas where fibroglycan was particularly abundant were sites of high morphogenetic activity where intense cell-cell and cell-matrix interactions are known to occur (e.g. the epithelial-mesenchymal interfaces, the prechondrogenic and preosteogenic mesenchymal condensations). The expression of fibroglycan was weak in the early embryo, culminated during the morphogenetic phase and at the moment of cell lineage differentiation, and persisted in the perichondrium, periosteum and connective tissue cells. Syndecan-1, in contrast, was primarily detected in epithelia, and transiently in some mesenchymal cells, with mesenchymal localisations that did not or only partially overlap with those of fibroglycan. In situ hybridization analyses confirmed these expression patterns at the transcriptional level, identifying mesenchymal cells as the major source of fibroglycan production. These data indicate that the expression of fibroglycan occurs along unique and developmentally regulated patterns, and suggest that fibroglycan and syndecan-1 may have distinctive functions during tissue morphogenesis and differentiation.
纤维聚糖（syndecan - 2）是细胞表面硫酸乙酰肝素蛋白聚糖家族的成员，该家族与黏附分子、生长因子以及多种其他效应系统相互作用，这些效应系统支持生物体的形态塑造、维持和修复。为了研究细胞表面蛋白聚糖这种明显的冗余现象，我们研究了纤维聚糖在小鼠胚胎中的表达，并将其与syndecan - 1的表达进行了比较。与人类纤维聚糖 - cDNA交叉杂交的小鼠胚胎cDNA克隆的特征预测，小鼠和人类纤维聚糖在结构上高度相似。一致地，对转染细胞、小鼠细胞系和胚胎提取物的分析表明，小鼠蛋白聚糖与针对人类蛋白开发的单克隆抗体10H4发生特异性反应。在胚胎组织切片中，用单克隆抗体10H4检测到的纤维聚糖仅出现在间充质细胞上，这些间充质细胞代表硬组织和结缔组织细胞的假定前体。在上皮细胞或肌肉细胞中未检测到纤维聚糖。纤维聚糖特别丰富的区域是高形态发生活性的部位，已知在这些部位会发生强烈的细胞 - 细胞和细胞 - 基质相互作用（例如上皮 - 间充质界面、软骨形成前和骨形成前的间充质凝聚）。纤维聚糖在早期胚胎中的表达较弱，在形态发生阶段和细胞谱系分化时达到高峰，并在软骨膜、骨膜和结缔组织细胞中持续存在。相比之下，syndecan - 1主要在上皮细胞中检测到，在一些间充质细胞中短暂出现，其在间充质中的定位与纤维聚糖的定位不重叠或仅部分重叠。原位杂交分析在转录水平证实了这些表达模式，确定间充质细胞是纤维聚糖产生的主要来源。这些数据表明纤维聚糖的表达沿着独特的、受发育调控的模式发生，并表明纤维聚糖和syndecan - 1在组织形态发生和分化过程中可能具有独特的功能。
