Birch M A, Skerry T M
Department of Biology, University of York, UK.
Bone. 1999 Jun;24(6):571-8. doi: 10.1016/s8756-3282(99)00088-5.
Bone cells are regulated by interactions with both growth factors and components of the extracellular matrix (ECM). Syndecans are cell-surface heparan sulfate proteoglycans known to play a role in cell adhesion and migration, and binding of growth factors. This study was performed to investigate the expression of syndecans by osteoblasts. Reverse transcription-linked polymerase chain reaction (RT-PCR) and Northern analysis detected syndecan transcripts in the human osteosarcoma cell lines MG-63, TE-85, SaOS-2, and U2OS; human osteoblast-like cells; rat calvarial osteoblasts; and in human bone. Western blot analysis of proteoglycans from MG-63 and TE-85 cells detected multiple heparan sulfate proteoglycan core proteins consistent with syndecan expression. Regulation of syndecan-1, -2, and -4 expression was investigated in TE-85, MG-63, and SaOS-2 cells, in response to interleukin (IL)-1beta, and IL-6, parathyroid hormone [PTH(1-34)], and 1,25(OH)2-vitamin D3. Northern analysis demonstrated that in the osteosarcoma cell lines there was no regulation of syndecan transcript levels in response to PTH(1-34) or 1,25(OH)2-vitamin D3 for 24 or 48 h. In contrast, when MG-63 and SaOS-2 cells were incubated with IL-1beta (0.01-10 ng/mL) and IL-6 (0.1-50 ng/mL) there was a dose-dependent decrease in mRNA levels for syndecan-1 and -2 at 24 and 48 h, but in response to IL-1beta upregulation in the levels of syndecan-4 transcripts. In addition, Northern analysis was performed on RNA isolated from neonatal rat calvarial osteoblasts cultured under conditions that promote osteogenesis for 0, 5, 13, 21, and 35 days. Syndecan-1 expression was observed to decrease during the culture period, syndecan-2 transcript levels increased, and there appeared to be no overall change in syndecan-4 levels. Controlled expression of syndecans by cells of the osteoblast lineage may be important in the regulation of osteoblastic proliferation and differentiation.
骨细胞受到与生长因子和细胞外基质（ECM）成分相互作用的调节。Syndecans是细胞表面硫酸乙酰肝素蛋白聚糖，已知在细胞黏附、迁移以及生长因子结合中发挥作用。本研究旨在调查成骨细胞中syndecans的表达情况。逆转录聚合酶链反应（RT-PCR）和Northern分析在人骨肉瘤细胞系MG-63、TE-85、SaOS-2和U2OS；人成骨样细胞；大鼠颅骨成骨细胞以及人骨中检测到syndecan转录本。对MG-63和TE-85细胞的蛋白聚糖进行Western印迹分析，检测到与syndecan表达一致的多种硫酸乙酰肝素蛋白聚糖核心蛋白。在TE-85、MG-63和SaOS-2细胞中，研究了syndecan-1、-2和-4表达对白细胞介素（IL）-1β、IL-6、甲状旁腺激素[PTH(1-34)]和1,25(OH)2-维生素D3的反应。Northern分析表明，在骨肉瘤细胞系中，PTH(1-34)或1,25(OH)2-维生素D3作用24或48小时后，syndecan转录水平没有受到调节。相反，当MG-63和SaOS-2细胞与IL-1β（0.01 - 10 ng/mL）和IL-6（0.1 - 50 ng/mL）孵育时，24和48小时后syndecan-1和-2的mRNA水平呈剂量依赖性下降，但对IL-1β的反应是syndecan-4转录本水平上调。此外，对在促进成骨的条件下培养0、5、13、21和35天的新生大鼠颅骨成骨细胞分离的RNA进行Northern分析。观察到在培养期间syndecan-1表达下降，syndecan-2转录水平升高，并且syndecan-4水平似乎没有总体变化。成骨细胞系细胞对syndecans的可控表达可能在成骨细胞增殖和分化的调节中起重要作用。
