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 モ-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 モ-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 モ-catenin. We found that 2DG
treatment caused a decrease of type II collagen
expression. 2DG induced dedifferentiation was dependent
on activation of モ-catenin, as the 2DG stimulated
accumulation of モ-catenin, which is characterized
by translocation of モ-catenin into the nucleus
determined by immunofluorescence staining and luciferase
assay. Inhibition of モ-catenin degradation by inhibition
of glycogen synthase kinase 3-モ 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
モ-catenin whereas the transcriptional level of
モ-catenin was not altered. These results collectively
showed that 2DG regulates dedifferentiation via
モ-catenin pathway in rabbit articular chondrocytes. |