Wu Y, Zhang Y, Cao L, Chen L, Lee V, Zheng P S, Kiani C, Adams M E, Ang L C, Paiwand F, Yang B B
Sunnybrook & Women's College Health Sciences Centre and Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario M4N 3M5, Canada.
J Biol Chem. 2001 Apr 27;276(17):14178-86. doi: 10.1074/jbc.M100618200. Epub 2001 Jan 31.
This study was designed to investigate the mechanisms by which mutant versican constructs play a dominant-negative effect on astrocytoma cell proliferation. Although a mini-versican or a versican G3 construct promoted growth of U87 astrocytoma cells, a mini-versican lacking epidermal growth factor (EGF) motifs (versicanDeltaEGF) and a G3 mutant (G3DeltaEGF) exerted a dominant-negative effect on cell proliferation. G3DeltaEGF-transfected cells formed smaller colonies, arrested cell cycle at G(1) phase, inhibited expression of cell cycle proteins cdk4 and cyclin D1, and contained multiple nucleoli. In cell surface binding assays, G3 products expressed in COS-7 cells and bacteria bound to U87 cell surface. G3DeltaEGF products exhibited decreased binding activity, but higher levels of G3DeltaEGF products were able to inhibit the binding of G3 to the cell surface. G3DeltaEGF expression inhibited secretion of endogenous versican in astrocytoma cells and also inhibited the secretion of mini-versican in COS-7 cells co-transfected with the mini-versican and G3DeltaEGF constructs. The effect seems to depend on the expression efficiency of G3DeltaEGF, and it occurred via the carbohydrate recognition domain.
本研究旨在探究突变型多功能蛋白聚糖构建体对星形细胞瘤细胞增殖产生显性负效应的机制。尽管一种小型多功能蛋白聚糖或多功能蛋白聚糖G3构建体促进了U87星形细胞瘤细胞的生长，但缺乏表皮生长因子（EGF）基序的小型多功能蛋白聚糖（多功能蛋白聚糖ΔEGF）和G3突变体（G3ΔEGF）对细胞增殖发挥了显性负效应。转染G3ΔEGF的细胞形成较小的集落，使细胞周期停滞在G1期，抑制细胞周期蛋白cdk4和细胞周期蛋白D1的表达，并含有多个核仁。在细胞表面结合试验中，在COS-7细胞和细菌中表达的G3产物与U87细胞表面结合。G3ΔEGF产物表现出降低的结合活性，但较高水平的G3ΔEGF产物能够抑制G3与细胞表面的结合。G3ΔEGF的表达抑制了星形细胞瘤细胞中内源性多功能蛋白聚糖的分泌，也抑制了与小型多功能蛋白聚糖和G3ΔEGF构建体共转染的COS-7细胞中小型多功能蛋白聚糖的分泌。这种效应似乎取决于G3ΔEGF的表达效率，并且是通过碳水化合物识别结构域发生的。
