Regulation and mechanism of mannan-binding lectin (MBL) on adipogenic differentiation of 3T3-L1 preadipocytes
Objective 
To investigate the regulatory effects and mechanism of mannan-binding lectin (MBL) on adipogenic differentiation of 3T3-L1 preadipocytes. 
 
 
Methods 
3T3-L1 preadipocytes were induced to differentiate into adipocytes in vitro, and stimulated with different concentrations of MBL (0, 1, 10, 20 μg/ml). Firstly, changes in cell proliferation ability were detected by CCK-8. Then lipid accumulation was analyzed by Oil red O staining and intracellular triglyceride content determination. Further, the expression of adipogenic differentiation-related factors PPARγ and C/EBPα at protein and mRNA levels were detected by Western blot and qRT-PCR, respectively. Finally, Western blot was used to analyze the expression and phosphorylation of Akt, a signal molecule related to adipogenic differentiation. 
 
 
Results 
MBL at the concentrations of 0, 1, 10 and 20 μg/ml had no effect on the proliferation of 3T3-L1 preadipocytes. The level of triglyceride in MBL treatment groups decreased in a dose-dependent manner on 3 d after 3T3-L1 preadipocyte differentiation. Results of Oil red O staining showed that the number of lipid droplets in MBL treatment groups reduced significantly, and the absorbance values also decreased significantly in a concentration-dependent manner. Western blot and qRT-PCR results showed that the expression of PPARγ and C/EBPα at both protein and mRNA levels in MBL treatment groups decreased significantly in a dose-dependent manner, and the phosphorylation level of Akt was significantly down-regulated as well. 
 
 
Conclusions 
MBL regulates the adipogenic differentiation of 3T3-L1 preadipocytes via Akt signaling pathway. 
 
 
Key words: 
Mannan-binding lectin; 3T3-L1 preadipocyte; Akt; Adipogenic differentiation