Effects of Physical Loading on Adipogenic Differentiation in 3T3-L1 Preadipocytes

Abstract

Adipose tissue is subjected to various types of physical loading. Previous studies show that adipocytes have mechanosensitive properties and are affected by mechanical stimulation. In this study, we investigated the effects of fluid shear stress on adipogenic differentiation using 3T3-L1 preadipocytes. The study included 3 groups: (1) No Loading, (2) Loading-Immediate harvest, and (3) Loading-Post 2 day harvest. In the loading groups, dynamic fluid shear stress of maximum 1 Pa at 1 Hz was applied to the preadipocytes for 30 mins. GAPDH, ERK, p-ERK, C/EBPβ, PPARγ proteins were assessed by Western blot analysis. Loading resulted in increased p-ERK and reduced C/EBPβ expressions compared to the No Loading group. These changes were more significant when the cells were harvested post 2 day loading. However, loading did not result in significant changes in PPARγ expression. C/EBPβ plays a major role in promoting the differentiation process of preadipocytes and also induces PPARγ which shows enhanced expressions in the terminal differentiation stage of adipocytes. These results indicate that fluid shear stress may suppress adipogenic differentiation through C/EBPβ inhibition. Greater decrease in C/EBPβ when cells were harvested post 2 day loading suggests that changes in C/EBPβ are not immediate with loading and therefore longer duration may be necessary to observe changes in PPARγ expression. Further experiments with increased harvest time as well as experiments using 3T3-L1 preadipocytes of more advanced differentiation stage are underway.