The Role And Mechanism Of Preadipocyte Derived IL-33 In The Adipogenic Differentiation Process Of The 3T3-L1 Cells

Objective: We aim to explore the role of the pre-adipocyte derived IL-33 in the adipogenic differentiation process of the 3T3-L1 cells,and provide a new perspective for exploring the specific effect of IL-33 in the pathogenesis of obesity,inflammation and metabolic diseases.Methods:(1)A mouse model of obesity with metabolic syndrome was established by feeding a high-fat diet,and mesenteric adipose tissue was collected to detect the transcription and expression levels of IL-33 in the tissue;(2)The 3T3-L1 preadipocytes were routinely induced for adipogenic differentiation,and treated with oleic acid for hyper-adipogenic differentiation.The cells and culture medium were collected at the Day 0,D2,D4,D6,D8,D10,and D12 after induction,and the transcription,protein expression,and secretion levels of IL-33 were detected;(3)The expression level of IL-33 in 3T3-L1 preadipocytes was knocked down by the lentiviral gene interference vector,and the cells were subjected to conventional induction of adipogenic differentiation and oleic acid-treated excessive adipogenic differentiation.The cell samples were collected on D10 after induction to detect the aggregation of lipid droplets and the expression of transcription factors related to adipogenic differentiation and fat catabolism;(4)The 3T3-L1 preadipocytes with knockdown of IL-33 expression were subjected to conventional induction of adipogenic differentiation and oleic acid-treated over-adipogenic differentiation,and mouse recombinant IL-33 protein was added during the induction process.After 10 days of induction,cell samples were collected to detect the accumulation of lipid droplets in cells and the expression of transcription factors related to adipogenic differentiation and lipolysis;(5)The 3T3-L1 preadipocytes with knockdown of IL-33 expression were subjected to conventional induction of adipogenic differentiation and oleic acid-treated excessive adipogenic differentiation.The cell samples were collected on D10 after induction,and the key proteins in the Wnt/β-Catenin pathway were detected by WB to evaluate whether the Wnt/β-Catenin canonical pathway was involved in the process of IL-33 regulating adipogenic differentiation.Results:(1)In the mesenteric adipose tissue of the obese mice,the transcription and expression levels of IL-33 were significantly increased,however,the level of IL-33 in the serum shows no difference;(2)During the process of conventional adipogenic differentiation and excessive adipogenic differentiation of 3T3-L1 preadipocytes,the transcription,protein expression and secretion levels of IL-33 were significantly increased,and the expression level of IL-33 in the hyper-adipogenic differentiation group was significantly higher than the conventional induced differentiation group;(3)The knocking down of IL-33 in 3T3-L1 preadipocytes significantly increased the degree of lipid droplet aggregation during adipogenic differentiation.And the transcription and expression levels of the adipogenesis-related factors PPAR-γ,C/EBP-α,Fabp-4 and the lipolysis-related factors ATGL,HSL,LPL were significantly elevated;(4)Knocking down of the IL-33 in 3T3-L1 preadipocytes significantly inhibited the expression of the β-Catenin and Cyclin D1 of the Wnt/β-Catenin canonical pathway.Conclusion:(1)The transcription and expression levels of IL-33 in mouse mesenteric adipose tissue are elevated during obesity.(2)Preadipocyte-derived IL-33 inhibited the adipogenic differentiation of3T3-L1 cells.(3)The Wnt/β-Catenin canonical pathway is involved in the regulation of adipogenesis by preadipocyte-derived IL-33.