title: [Effects of ursolic acid on c-Cbl-associated protein expression in 3T3-L1 adipocytes with insulin resistance].
abstract: OBJECTIVE
  To observe the effects of ursolic acid (UA) on insulin resistance and cell differentiation in 3T3-L1 adipocytes and to explore the mechanisms.
  
  
  METHODS
  3T3-L1 adipocytes were cultured in Dulbecco's modified Eagle's medium (DMEM) supplemented with glucose (25 mmol/L) and insulin (10(-6) mol/L) to induce insulin resistance. After culture, glucose consumption of the adipocytes was detected by glucose oxidase method and glucose uptake was detected by using tritium-marked glucose. Drug concentration for following test was determined through detecting the effects of different concentrations of UA on the activity of 3T3-L1 adipocytes with insulin resistance by methyl thiazolyl tetrazolium (MTT) staining. 3T3-L1 adipocytes with insulin resistance were cultured with DMEM, rosiglitazone, and low- and high-dose UA, and then, glucose uptake and differentiation of 3T3-L1 adipocytes were detected. Finally, real-time fluorescence quantitative polymerase chain reaction and Western blot methods were used to detect the effects of UA on expressions of adipocyte lipid binding protein (aP2), c-Cbl-associated protein (CAP) and matrix metalloproteinase-1 (MMP-1) in 3T3-L1 cells with insulin resistance.
  
  
  RESULTS
  After dealing with high glucose/hyperinsulin for 24 h, insulin resistance was induced successfully in the 3T3-L1 adipocytes. The concentrations of UA were defined to be 4 to 20 μmol/L. Compared with the model group, the glucose uptake was significantly increased in the rosiglitazone group and groups treated with low- and high-dose UA (P<0.01). The differentiation levels of 3T3-L1 adipocytes in the UA groups were lower than those in the control group and the rosiglitazone group. Effects of UA on the expressions of aP2 and MMP-1 were not obvious, but UA could up-regulate expression of CAP both in mRNA and protein levels (P<0.01).
  
  
  CONCLUSIONS
  Low- and high-dose UA can improve the glycometabolism and differentiation of 3T3-L1 adipocytes with insulin resistance by up-regulating the expression of CAP.
authors.affiliation: Department of Traditional Chinese Medicine, Changhai Hospital, Second Military Medical University, Shanghai 200433, China.
authors.forename: Di
authors.initials: D
authors.lastname: Li
authors.forename: Guan-liang
authors.initials: GL
authors.lastname: Wang
authors.forename: Meng-ya
authors.initials: MY
authors.lastname: Shan
authors.forename: Jia-han
authors.initials: JH
authors.lastname: Liu
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.forename: De-zeng
authors.initials: DZ
authors.lastname: Zhu
mesh_terms: D041721:3T3-L1 Cells / Q000187:drug effects; D017667:Adipocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D000818:Animals; D002454:Cell Differentiation; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance; D053509:Matrix Metalloproteinase 13 / Q000378:metabolism; D051379:Mice; D014315:Triterpenes / Q000494:pharmacology*; D000097245:Ursolic Acid
chemical_list: D007328:Insulin; D053509:Matrix Metalloproteinase 13; D014315:Triterpenes; D000097245:Ursolic Acid; C507081:Mmp13 protein, mouse