The Effection Of Resistin On Lipid Accumulation In RAW264.7 Cells Based On PI3K-AKT-PPAR? Signaling Pathway

Objective: Resistin is an adipocytokine found in Steppan's study of the mechanism of action of insulin sensitizers(thiazolidinediones)in 2001,and is associated with obesity,insulin resistance and type 2 diabetes.Resistin has a pro-inflammatory role in the body's inflammation and immune response,also affect the body's glucose and lipid metabolism through insulin resistance.Resistin promotes the phosphorylation of I?B in monocytes or macrophages and dissociates with NF-?B,activates the NF-?B signaling pathway,releases inflammatory cytokines such as IL-6 and TNF?,and induces inflammatory response.In addition,resistin also can promote macrophage lipid accumulation,but its action mechanism is not clear yet.Previous studies have shown that rohitukine and diosgenin downregulated macrophage LPL expression through PI3K/AKT/ PPAR? signaling pathway and reduce the accumulation of lipids.Resistin play a role in promoting insulin resistance,affecting endothelial NO production,anti-apoptosis and other biological effects through PI3K/AKT/ PPAR? signaling pathway,but whether it can affect LPL expression through this signaling pathway and promote macrophage lipid accumulation remains to be confirmed.Therefore,this study intends to study the effect of resistin on LPL expression and lipid accumulation in RAW264.7 cells based on PI3K/AKT/PPAR? signaling pathway.Results and Analysis:(1)RAW264.7 cells were incubated with resistin at a final concentration of 50ng/mL,100ng/mL,150ng/mL,200ng/mL for 24 h.The expression of LPL mRNA and protein were separately detected by real-time quantitative PCR and western blot analyses.The results showed that the LPL gene level and protein expression were upregulated with the increasing of resistin concentration(50-200 ng/mL)in RAW264.7cells.The RAW264.7 cells were incubated with resistin at a final concentration of 200ng/mL,detected the expression of LPL mRNA and protein at 0h,3h,6h,12 h,24h and 48 h.LPL gene and protein expression also increased with the incubated time of resistin(within24 h).The results indicate that resistin can promote the expression of LPL mRNA and protein in RAW264.7 cells.(2)RAW264.7 cells were incubated with 40?mol/L PI3 K inhibitor LY294002 for 1h,and then added 200 ng/mL resistin incubated for 24 h,detected the mRNA and protein expression of PI3 K,Akt,PPAR? and LPL.After incubation with LY294002,the expression of PI3 K,Akt,PPAR? and LPL,mRNA gene and protein was significantly down-regulated(P<0.01).The results showed that resistin can promote the mRNA and protein expression of LPL by activating PI3 K.(3)RAW264.7 cells were incubated with LPL siRNA for 24 h,then treated with50?mol/mL LDL for 1h,then added 200ng/mL resistin incubated for 24 h,detected the mRNA and protein expression of LPL and the lipid content and cellular level of TG and TC were separately detected by Oil red O staining and standard enzymc proxess in RAW264.7 cells.After incubation with LPL siRNA,the expression of LPL mRNA and protein was significantly down-regulated(P<0.01),and the accumulation of lipid droplets in the cells was significantly reduced,and the intracellular TG and TC contents were significantly reduced(P < 0.01).The results indicate that LPL is a key regulator of resistin-induced macrophage lipid accumulationConclusion:(1)Resistin can promote the expression of LPL mRNA and protein in RAW264.7,and is affected by the concentration and action time of resistin.(2)Resistin promotes the mRNA and protein expression of LPL through activated PI3K/AKT/PPAR?signaling pathway.(3)Resistin promotes RAW264.7 lipid accumulation were closely linked to the increasing of LPL mRNA and protein expression.