Background

The obesity epidemic has forced efforts to understand the mechanisms controlling adipocytes differentiation and adiposetissue development. Adipose tissue, primarily composed of mature adipocytes and stromal vascular fraction (SVF)cells, goes through a series of changes in its quantity and composition during the onset and development of obesity and plays a key role in maintaining both whole body energy homeostasis and endocrine function. Adipose tissue macrophages (ATMs)accumulation has been reported to participate in inflammatory pathways that are activated in adipose tissues of obese individual. This study were designed to understand the roles that SVF cells and ATMs play in adipogenic differentiation and explore its detailed signal transduction mechanisms.

Methods

Obese mice model were established by high-fat diet. We purified the SVF derived from adipose tissue of obese or lean mice and CD11b+, which presented macrophage. The SVF and ATMs were used to stimulate 3T3-L1 preadipocyte differentiation. Immunoblotting and real-time PCR were conducted to assess the expression of genes and protein involved in differentiation of adipocytes. Oil red O staining were used to observe directly the differentiation degree.

Results

SVF cells and ATMs of obese mice inhibited adipocyte differentation.The expression of FasL on ATMs increased in obese mice. Fas signaling inhibited the adipocytes difference by reducing Akt and deficiency of Fas/FasL pathway attenuates the inhibitation of ATMs on adipocyte differentiation

Conclusions

Macrophage of adipose tissue from obese mice inhibits adipocyte differentation through Fas signaling down regulating on Akt.