Department of Biological Sciences, College of Natural Sciences, Kongju National University, Gongju 314-701, Korea.
Exp Mol Med. 2010 Jul 31;42(7):503-13. doi: 10.3858/emm.2010.42.7.051.
2-deoxy-D-glucose (2DG) is known as a synthetic inhibitor of glucose. 2DG regulates various cellular responses including proliferation, apoptosis and differentiation by regulation of glucose metabolism in cancer cells. However, the effects of 2DG in normal cells, including chondrocytes, are not clear yet. We examined the effects of 2DG on dedifferentiation with a focus on the beta-catenin pathway in rabbit articular chondrocytes. The rabbit articular chondrocytes were treated with 5 mM 2DG for the indicated time periods or with various concentrations of 2DG for 24 h, and the expression of type II collagen, c-jun and beta-catenin was determined by Western blot, RT-PCR, immunofluorescence staining and immunohistochemical staining and reduction of sulfated proteoglycan synthesis detected by Alcain blue staining. Luciferase assay using a TCF (T cell factor)/LEF (lymphoid enhancer factor) reporter construct was used to demonstrate the transcriptional activity of beta-catenin. We found that 2DG treatment caused a decrease of type II collagen expression. 2DG induced dedifferentiation was dependent on activation of beta-catenin, as the 2DG stimulated accumulation of beta-catenin, which is characterized by translocation of beta-catenin into the nucleus determined by immunofluorescence staining and luciferase assay. Inhibition of beta-catenin degradation by inhibition of glycogen synthase kinase 3-beta with lithium chloride (LiCl) or inhibition of proteasome with z-Leu-Leu-Leu-CHO (MG132) accelerated the decrease of type II collagen expression in the chondrocytes. 2DG regulated the post-translational level of beta-catenin whereas the transcriptional level of beta-catenin was not altered. These results collectively showed that 2DG regulates dedifferentiation via beta-catenin pathway in rabbit articular chondrocytes.
2-脱氧-D-葡萄糖（2DG）是一种葡萄糖的合成抑制剂。2DG 通过调节癌细胞中的葡萄糖代谢来调节各种细胞反应，包括增殖、凋亡和分化。然而，2DG 在正常细胞中的作用，包括软骨细胞，尚不清楚。我们研究了 2DG 在兔关节软骨细胞去分化中的作用，重点关注β-catenin 通路。兔关节软骨细胞用 5mM 2DG 处理指定时间或用不同浓度的 2DG 处理 24 小时，通过 Western blot、RT-PCR、免疫荧光染色和免疫组织化学染色检测 II 型胶原、c-jun 和β-catenin 的表达，通过 Alcian blue 染色检测硫酸软骨素蛋白聚糖合成的减少。使用 TCF（T 细胞因子）/LEF（淋巴增强因子）报告基因构建体进行的荧光素酶测定用于证明β-catenin 的转录活性。我们发现 2DG 处理导致 II 型胶原表达减少。2DG 诱导的去分化依赖于β-catenin 的激活，因为 2DG 刺激β-catenin 的积累，这通过免疫荧光染色和荧光素酶测定确定为β-catenin 易位到核内。用氯化锂（LiCl）抑制糖原合酶激酶 3-β或用 Z-Leu-Leu-Leu-CHO（MG132）抑制蛋白酶体抑制β-catenin 降解加速软骨细胞中 II 型胶原表达的减少。2DG 调节β-catenin 的翻译后水平，而β-catenin 的转录水平没有改变。这些结果共同表明，2DG 通过兔关节软骨细胞中的β-catenin 通路调节去分化。
