| dc.description.abstract | Lipid accumulation reflects the process of preadipocytes differentiating into adipocytes
and such process is regulated by genetic, hormonal (i.e., insulin) and nutritional cues (i.e.,
vitamins). In this study, we examined the effect of green tea catechins, having been
considered as vitamin P, on differentiation of 3T3-L1 preadipocytes and investigated how they
work. We found that green tea EGCG was more effective than structurally-related EC, EGC
or ECG to reduce insulin-dexamethasone-1-methyl-3-isobutylxanthine (IDM)-induced
increases in cell number of preadipocytes during their initial differentiation to adipocytes.
The EGCG effect varied with dose administration and with time course. However, EGCG
altered the protein amount of C/EBPβ, C/EBPα, or PPARγ transcriptional factors, which were
enabling to stimulate adipogenesis of preadipocytes, as well as reduced total triglyceride
accumulation in the cells and medium. Further study showed that treatment of preadipocytes
with MIX alone, but neither insulin nor dexamethasone, caused a significant increase in the
protein amount of PPARγ and such stimulation was decreased by EGCG in the manner of dose
dependency or catechin specificity. H-89, a selective protein kinase A inhibitor, could not
block the EGCG inhibition of MIX-stimulated PPARγ, suggesting that EGCG effect is
independent of protein kinase A-associated pathway. We conclude that green tea EGCG may
modulate differentiation of preadipocytes to adipocytes through altering
adipogenesis-controlling transcriptional factors. | en_US |