Chernousov M A, Stahl R C, Carey D J
Sigfried and Janet Weis Center for Research, Geisinger Clinic, Danville, Pennsylvania 17822, USA.
J Biol Chem. 1996 Jun 7;271(23):13844-53. doi: 10.1074/jbc.271.23.13844.
A heparin-binding glycoprotein was purified from conditioned medium of cultured rat Schwann cells. The protein, p200, which has an apparent molecular mass of approximately 200 kDa, was identified by its ability to bind the cell surface heparan sulfate proteoglycan N-syndecan (syndecan-3) in a membrane overlay assay. Soluble heparin but not chondroitin sulfate inhibited the binding, suggesting the involvement of heparan sulfate chains of proteoglycan in the interaction. Purified p200 promoted the attachment and spreading of Schwann cells. Adhesion to p200 was blocked by heparin, suggesting that heparan sulfate proteoglycans are cell surface receptors for p200. The tissue distribution of p200 was determined by immunoblot analysis with anti-p200 antibodies. Among neonatal rat tissues examined p200 was detected only in sciatic nerve and, at lower levels, in skeletal muscle. p200 expression in sciatic nerve was detectable only during the first 2-3 weeks of postnatal development and was not detected in adult rats. Immunofluorescent staining of rat sciatic nerve showed that p200 was localized in the extracellular matrix surrounding individual Schwann cells-axon units. Two tryptic peptides from p200 were purified and sequenced. These contained multiple GXX collagen-like repeats. Bacterial collagenase digestion of p200 produced a product with an apparent molecular mass of approximately 90 kDa. These data suggest that Schwann cells secrete an apparently novel collagen-like adhesive protein that interacts with cells through cell surface heparan sulfate proteoglycans.
从培养的大鼠雪旺氏细胞的条件培养基中纯化出一种肝素结合糖蛋白。该蛋白p200的表观分子量约为200 kDa，通过在膜覆盖分析中结合细胞表面硫酸乙酰肝素蛋白聚糖N-联蛋白聚糖（联蛋白聚糖-3）的能力得以鉴定。可溶性肝素而非硫酸软骨素可抑制这种结合，这表明蛋白聚糖的硫酸乙酰肝素链参与了该相互作用。纯化的p200可促进雪旺氏细胞的黏附和铺展。肝素可阻断细胞与p200的黏附，这表明硫酸乙酰肝素蛋白聚糖是p200的细胞表面受体。用抗p200抗体通过免疫印迹分析确定了p200的组织分布。在所检测的新生大鼠组织中，仅在坐骨神经中检测到p200，在骨骼肌中的含量较低。p200在坐骨神经中的表达仅在出生后发育的前2至3周可检测到，成年大鼠中未检测到。大鼠坐骨神经的免疫荧光染色显示，p200定位于单个雪旺氏细胞-轴突单元周围的细胞外基质中。纯化并测序了来自p200的两个胰蛋白酶肽段。这些肽段含有多个GXX胶原样重复序列。用细菌胶原酶消化p200产生了一种表观分子量约为90 kDa的产物。这些数据表明，雪旺氏细胞分泌一种明显新颖的胶原样黏附蛋白，该蛋白通过细胞表面硫酸乙酰肝素蛋白聚糖与细胞相互作用。
