Dodge G R, Boesler E W, Jimenez S A
Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
Lab Invest. 1995 Nov;73(5):649-57.
Perlecan is a heparan sulfate proteoglycan that has a core protein of 466 kDa and is composed of five modules, four of which share a high degree of homology with a variety of biologically important molecules including the low-density lipoprotein receptor, laminin, and the neural cell adhesion molecule. Previously, this specialized proteoglycan, characteristic of the basement membrane, was not identified as a constitutive extracellular component of human synovium.
Using human synovium and cultured human synovial cells, we examined perlecan gene expression in human synovium, a tissue lacking a classic basement membrane. The modulation of gene expression of the perlecan core protein by transforming growth factor-beta (TGF-beta) and basic fibroblast growth factor (FGF) was examined in cultures of normal human synovial cells, and by metabolic labeling using radioactive sodium sulfate, the question of whether this specialized protein is produced by synovial cells as a proteoglycan was addressed.
Cultures of normal human synovial cells were shown to contain the large 14.5 kb perlecan mRNA and produced substantial amounts of perlecan core protein as shown by immunohistochemistry employing specific human perlecan Ab. Immunohistochemical detection showed intense staining in the intimal and subintimal layers of human synovial membrane. Moreover, the perlecan core protein was shown to be up-regulated by TGF-beta and down-regulated by basic FGF. In addition, a sizable portion (approximately 25%) of the synovial cell-produced proteoglycan was shown to contain heparan sulfate, providing evidence that synovial cell perlecan is produced as a proteoglycan.
The presence of perlecan in human synovium and the modulation of the biosynthesis of its core protein by TGF-beta and FGF suggest that, in addition to its structural role, this unique heparan sulfate proteoglycan may be involved in normal synovial membrane function and in the pathogenesis of arthritis.
基底膜聚糖是一种硫酸乙酰肝素蛋白聚糖，其核心蛋白为466 kDa，由五个结构域组成，其中四个结构域与多种生物学重要分子具有高度同源性，包括低密度脂蛋白受体、层粘连蛋白和神经细胞黏附分子。此前，这种基底膜特有的特殊蛋白聚糖并未被鉴定为人类滑膜的组成性细胞外成分。
利用人类滑膜组织和培养的人类滑膜细胞，我们检测了在缺乏经典基底膜的人类滑膜组织中基底膜聚糖基因的表达。在正常人滑膜细胞培养物中，研究了转化生长因子-β（TGF-β）和碱性成纤维细胞生长因子（FGF）对基底膜聚糖核心蛋白基因表达的调节作用。通过使用放射性硫酸钠进行代谢标记，探讨了这种特殊蛋白是否由滑膜细胞作为蛋白聚糖产生的问题。
正常人滑膜细胞培养物显示含有14.5 kb的大型基底膜聚糖mRNA，并产生大量基底膜聚糖核心蛋白，这通过使用特异性人类基底膜聚糖抗体的免疫组织化学得以证实。免疫组织化学检测显示在人类滑膜内膜和内膜下层有强烈染色。此外，基底膜聚糖核心蛋白被证明受TGF-β上调，受碱性FGF下调。另外，滑膜细胞产生的蛋白聚糖中有相当一部分（约25%）被证明含有硫酸乙酰肝素，这证明滑膜细胞基底膜聚糖是以蛋白聚糖形式产生的。
基底膜聚糖在人类滑膜中的存在以及其核心蛋白生物合成受TGF-β和FGF调节，表明这种独特的硫酸乙酰肝素蛋白聚糖除了其结构作用外，可能还参与正常滑膜功能及关节炎的发病机制。
