Litwack E D, Ivins J K, Kumbasar A, Paine-Saunders S, Stipp C S, Lander A D
Department of Biology, Massachusetts Institute of Technology, Cambridge, USA.
Dev Dyn. 1998 Jan;211(1):72-87. doi: 10.1002/(SICI)1097-0177(199801)211:1<72::AID-AJA7>3.0.CO;2-4.
The glypicans are a family of glycosylphosphatidylinositol (GPI)-anchored proteoglycans that, by virtue of their cell-surface localization and possession of heparan sulfate chains, may regulate the responses of cells to numerous heparin-binding growth factors, cell adhesion molecules, and extracellular matrix components. Mutations in one glypican cause a syndrome of human birth defects, suggesting important roles for these proteoglycans in development. Glypican-1, the first-discovered member of this family, was originally found in cultured fibroblasts, and later shown to be a major proteoglycan of the mature and developing brain. Here we examine the pattern of glypican-1 mRNA and protein expression more widely in the developing rodent, concentrating on late embryonic and early postnatal stages. High levels of glypican-1 expression were found throughout the brain and skeletal system. In the brain, glypican-1 mRNA was widely, and sometimes only transiently, expressed by zones of neurons and neuroepithelia. Glypican-1 protein localized strongly to axons and, in the adult, to synaptic terminal fields as well. In the developing skeletal system, glypican-1 was found in the periosteum and bony trabeculae in a pattern consistent with expression by osteoblasts, as well as in the bone marrow. Glypican-1 was also observed in skeletal and smooth muscle, epidermis, and in the developing tubules and glomeruli of the kidney. Little or no expression was observed in the developing heart, lung, liver, dermis, or vascular endothelium at the stages examined. The tissue-, cell type-, and in some cases stage-specific expression of glypican-1 revealed in this study are likely to provide insight into the functions of this proteoglycan in development.
磷脂酰肌醇蛋白聚糖是一类糖基磷脂酰肌醇（GPI）锚定的蛋白聚糖，由于其在细胞表面的定位以及硫酸乙酰肝素链的存在，可能会调节细胞对多种肝素结合生长因子、细胞粘附分子和细胞外基质成分的反应。一种磷脂酰肌醇蛋白聚糖的突变会导致人类出生缺陷综合征，这表明这些蛋白聚糖在发育过程中具有重要作用。磷脂酰肌醇蛋白聚糖-1是该家族中最早发现的成员，最初在培养的成纤维细胞中发现，后来被证明是成熟和发育中的大脑中的一种主要蛋白聚糖。在这里，我们更广泛地研究了发育中的啮齿动物中磷脂酰肌醇蛋白聚糖-1 mRNA和蛋白质的表达模式，重点关注胚胎后期和出生后早期阶段。在整个大脑和骨骼系统中发现了高水平的磷脂酰肌醇蛋白聚糖-1表达。在大脑中，磷脂酰肌醇蛋白聚糖-1 mRNA在神经元和神经上皮区域广泛表达，有时只是短暂表达。磷脂酰肌醇蛋白聚糖-1蛋白强烈定位于轴突，在成体中也定位于突触终末区域。在发育中的骨骼系统中，在骨膜和骨小梁中发现了磷脂酰肌醇蛋白聚糖-1，其模式与成骨细胞的表达一致，在骨髓中也有发现。在骨骼肌和平滑肌、表皮以及发育中的肾小管和肾小球中也观察到了磷脂酰肌醇蛋白聚糖-1。在所检查的阶段，在发育中的心脏、肺、肝脏、真皮或血管内皮中几乎没有或没有观察到表达。本研究中揭示的磷脂酰肌醇蛋白聚糖-1的组织、细胞类型以及在某些情况下的阶段特异性表达，可能有助于深入了解这种蛋白聚糖在发育中的功能。
