抄録
The effect of extracellular ATP on adipogenesis was investigated using 3T3-L1 cell line. Incubation of cells with ATP (1-100 μM) for 5 min induced membrane ruffling and migration (chemokinesis). In this cell line, growth arrest is required before initiation of differentiation, and growth-arrested post-confluent cells can be converted to adipocytes by the presence of the adipogenic hormones dexamethasone, 3-isobutyl-1-methylxanthine and insulin. On the other hand, those hormones alone do not trigger differentiation in proliferating cells. ATP did not induce differentiation when applied alone to either proliferating or post-confluent cells. In contrast, proliferating cells (density<50%) preincubated with ATP for 5 min and subsequently given the adipogenic hormones in the continued presence of ATP underwent adipocyte differentiation mediated through phospholipase C-coupled P2Y receptors. These adipocytes were found to show very similar characteristics, including morphology and intracellular triglyceride accumulation, compared with adipocytes differentiated from post-confluent preadipocytes with those adipogenic hormones. When proliferating cells were preincubated with ATP prior to the addition of the adipogenic hormones, gene expression of adipose protein 2 was markedly increased in 6 days, while the expression level stayed very low without ATP pretreatment. These results suggest that extracellular ATP renders preadipocytes responsive to the adipogenic hormones during the growing phase. [J Physiol Sci. 2006;56 Suppl:S67]
