(-) Epigallocatechin gallate suppresses the differentiation of 3T3-L1 preadipocytes through transcription factors FoxO1 and SREBP1c.

Tea catechin is one of the compounds that are closely related to obesity and insulin sensitivity. In order to determine the effect of catechin on adipocyte differentiation, we treated 3T3-L1 preadipocytes with different kinds of catechins. Our results showed that catechins, especially epigallocatechin gallate (EGCG), significantly reduced intracellular lipid accumulation and repressed the activity of glycerol-3-phosphate dehydrogenase, an enzyme involved in lipid synthesis.

Mouse 3T3-L1 cells acquire resistance against oxidative stress as the adipocytes differentiate via the transcription factor FoxO.

Repression of excessive increase and enlargement of adipocytes that is closely associated with obesity is effective in the prevention and treatment of metabolic syndrome. Generally, apoptosis is induced in cells via a wide variety of intracellular or extracellular substances, and recently, it has been suggested that the FoxO subfamily is involved in the induction of apoptosis. We aimed to elucidate the mechanism of FoxO-mediated apoptosis-induction in the adipocytes under the reactive oxygen species (ROS) stimulus.

P53 negatively regulates the transcriptional activity of FOXO3a under oxidative stress.

Transcription factors P53 and FOXO are both activated in response to stresses via protein-protein interactions, leading to events such as cell survival or apoptosis. To clarify the mechanisms that regulate FOXO activity, we analyzed the intermolecular interaction of FOXO3a and P53. FOXO3a and P53 interacted in COS-7 cells, and transcriptional activity of FOXO3a was suppressed by P53, but P53 was not affected by FOXO3a.