The Effects Of Luteolin On Adipogenesis And Macrophage Polarization And The Synthesis Of Associated Molecular Probes

Obesity and related insulin resistance(IR)is becoming a great threat to human health,the differentiation and interaction of adipocytes and macrophages plays an important role in obesity and related IR.As a food-borne natural product,luteolin can improve obesity and related IR,but the details of associated mechanism remains unclear.Therefore,we firstly investigated the effects of luteolin on 3T3-L1 preadipocytes adipogenic differentiation and bone marrow-derived macrophages(BMDMs)inflammatory polarization,and then synthesis 3'-biotinylated luteolin as molecular probe.The results will become an important base of further researches about targets and signaling pathways.Luteolin was added into the medium of 3T3-L1 during differentiation.3T3-L1 preadipocytes differentiation needs 8 days,as shown in this study,the treatment with luteolin for 8 days significantly inhibited lipid droplet generation and adipogenic gene expressions,such as C/EBP?,PPAR?,AP2 and FAS.When 3T3-L1 cells were treated with luteolin for 2,4 or 6 days,the lipid droplet generation was not significantly inhibited,although the expression of adipogenic genes was significantly down-regulated.This study illustrated that luteolin plays an important role during early and terminal differentiation of 3T3-L1 cells.Bone marrow cells differentiate into BMDMs needs 6 days,flow cytometry showed that luteolin could significantly inhibit CD38 and CD274 fluorescence intensity when BMDMs were treated with luteolin for 24 hrs,24hrs+3days or 24hrs+6days.Consistent with the flow cytometry results,RT-PCR results showed that luteolin could significantly reduce the m RNA levels of NOS2,IL-6 and IL-1? when BMDMs were treated for 6hrs,6hrs+3days or 6hrs+6days.The cells treated with luteolin at differentiation or polarization stages both can reduce inflammation.This study showed that luteolin played important roles during differentiation and polarization of BMDMs.On the basis,we synthesized 3'-biotinylated luteolin as molecular probe.The effects of 3'-biotinylated luteolin were detected in 3T3-L1 cells and BMDMs.Compared with unbiotinylated luteolin,the effects of 3'-biotinylated luteolin on inhibiting 3T3-L1 cells differentiation is weaker.However,the effects of 3'-biotinylated luteolin on inhibiting BMDMs inflammation and polarization is similar with unbiotinylated luteolin.So the biotinylated luteolin can be used to study the detail signaling mechanism about luteolin inhibiting BMDMs inflammation and polarization.In conclusion,based on the effects of luteolin improving obesity and related IR,we determined the best conditions for luteolin inhibited associated cell differentiation and synthesized biotinylated s,which will help our further mechanistic study.