Downregulation of collagen IV deposition and ITGB1-FAK signaling pathway to inhibit adipogenesis: A novel mechanism of swertiamarin in treating type 2 diabetes mellitus.

Extracellular matrix (ECM) and integrins are important biological macromolecules. ECM especially collagen IV (COLIV) deposition modulates the integrin-FAK signaling pathway involved in adipogenesis and is strongly associated with insulin resistance. Type 2 diabetes mellitus (T2DM) mice were given swertiamarin (STM) by intragastric administration. STM reduced body weight, blood glucose, and lipid levels and enhanced insulin sensitivity in diabetic mice. The lipid accumulation in liver, gastrocnemius muscle, and inguinal subcutaneous white adipose tissue (igSWAT) were significantly reduced by STM. Bioinformatics analysis revealed a connection between ECM, ITGB1/FAK, and PI3K/Akt signaling pathways. STM downregulated the adipogenesis, IRβ expression, COLIV deposition, ITGB1/FAK, and PI3K/Akt signaling pathways in igSWAT of diabetic mice. In vitro, STM inhibited the glucose uptake and differentiation of adipocytes, and downregulated adipogenesis-related gene and protein expression. STM is bound to ITGB1 and downregulated COLIV deposition, ITGB1/FAK, and PI3K/Akt signaling pathways. When we overexpressed FAK, the effects of STM on downstream PI3K/Akt signaling pathway and adipogenesis were attenuated. In conclusion, STM reduced COLIV deposition and binding with ITGB1 to downregulate ITGB1/FAK signaling pathway, further the downstream PI3K/Akt signaling pathway was inhibited to reduce adipogenesis and ameliorated T2DM. Thus, these signals may be a novel mechanism of STM in treating T2DM.