TRANSFORMING GROWTH-FACTOR (TYPE-BETA) PROMOTES THE ADDITION OF CHONDROITIN SULFATE CHAINS TO THE CELL-SURFACE PROTEOGLYCAN (SYNDECAN) OF MOUSE MAMMARY EPITHELIA
TRANSFORMING GROWTH-FACTOR (TYPE-BETA) PROMOTES THE ADDITION OF CHONDROITIN SULFATE CHAINS TO THE CELL-SURFACE PROTEOGLYCAN (SYNDECAN) OF MOUSE MAMMARY EPITHELIA
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DOI：
10.1083/jcb.109.5.2509
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发表时间：
1989-11-01
影响因子：
7.8
通讯作者：
RAPRAEGER, A
中科院分区：
文献类型：
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作者：
RAPRAEGER, A
培养的单层NMuMG小鼠乳腺上皮细胞在转化生长因子-β中培养时，细胞表面硫酸软骨素糖胺聚糖(GAG)的数量增加。(转化生长因子-β)，可能是因为它们的细胞表面蛋白多糖(称为Syndecan)合成增加，以前被证明含有硫酸软骨素和硫酸乙酰肝素GAG。这种增加发生在整个单层，如使用可溶性凝血酶原蛋白作为结合探针所示。然而，比较Gag链和Syndecan核心蛋白的染色强度表明，细胞之间在Gag链与核心蛋白的附着方面存在差异。纯化的Syndecan的表征证实了在转化生长因子-β中添加硫酸软骨素的增强作用：(A)在该蛋白多糖部分中，硫酸软骨素的放射性硫酸盐掺入增加了6.2倍，硫酸乙酰肝素增加了1.8倍，尽管每细胞的核心蛋白数量没有明显增加，以及(B)蛋白多糖的大小和密度增加了，但通过去除硫酸软骨素而减少。这在一定程度上可以通过用0.5 mM的木糖苷处理细胞而阻止硫酸软骨素的加成，而不影响硫酸肝素。较高的木糖苷浓度也会阻止硫酸乙酰肝素，并且Syndecan以核心蛋白的形式出现在细胞表面，没有Gag链。Syndecan上GAG含量的增加部分归因于链长的增加。虽然这解释了额外的硫酸乙酰肝素合成，但这不足以解释硫酸软骨素的总增加；通过评估核心蛋白上由硫酸软骨素ABC裂解酶(ABCase)产生的硫酸软骨素连接短桩，也发生了大约三倍的硫酸软骨素链增加。转化生长因子-β的作用之一。胚胎期间组织间的相互作用很可能是增强了细胞表面硫酸软骨素链的合成蛋白多糖。
Cultured monolayers of NMuMG mouse mammary epithelial cells have augmented amounts of cell surface chondroitin sulfate glycosaminoglycan (GAG) when cultured in transforming growth factor-.beta. (TGF-.beta.), presumably because of increased synthesis on their cell surface proteoglycan (named syndecan), previously shown to contain chondroitin sulfate and heparan sulfate GAG. This increase occurs throughout the monolayer as shown using soluble thrombospondin as a binding probe. However, comparison of staining intensity of the GAG chains and syndecan core protein suggests variability among cells in the attachment of GAG chains to the core protein. Characterization of purified syndecan confirms the enhanced addition of chondroitin sulfate in TGF-.beta.: (a) radiosulfate incorporation into chondroitin sulfate is increased 6.2-fold in this proteoglycan fraction and heparan sulfate is increased 1.8-fold, despite no apparent increase in amount of core protein per cell, and (b) the size and density of the proteoglycan are increased, but reduced by removal of chondroitin sulfate. This is shown in part by treatment of the cells with 0.5 mM xyloside that blocks the chondroitin sulfate addition without affecting heparan sulfate. Higher xyloside concentrations block heparan sulfate as well and syndecan appears at the cell surface as core protein without GAG chains. The enhanced amount of GAG on syndecan is partly attributed to an increase in chain length. Whereas this accounts for the additional heparan sulfate synthesis, it is insufficient to explain the total increase in chondroitin sulfate; an approximately three-fold increase in chondroitin sulfate chain addition occurs as well, confirmed by assessing chondroitin sulfate ABC lyase (ABCase)-generated chondroitin sulfate linkage stubs on the core protein. One of the effects of TGF-.beta. during embryonic tissue interactions is likely to be the enhanced synthesis of chondroitin sulfate chains on this cell surface proteoglycan.