| Objective:The aim of this study is to investigate regulatory effect of carboxymethylysine (CML) on intracellular lipid metabolism and endoplasmic reticulum stress (ERS) in lipid-loaded RAW264.7 macrophages.Methods:RAW264.7 cells were incubated with or without 50μg/mL oxLDL plus various concentration of CML for 48 hours. Oil red O staining and quantitative intracellular cholesterol assay were used to assess the effect of CML on intracellular lipids accumulation and intracellular cholesterol contents. Flow cytometry was used to measure the expression of proteins involved in reverse cholesterol transport (ABCA1) and responsible for uptake of modified lipids (CD36). RT-PCR was performed to detect the mRNA expression of the protein kinase R-like ER kinase (PERK) and C/EBP homologous protein (CHOP) which are associated with endoplasmic reticulum stress.Results:Oil red O staining and cholesterol assay kit demonstrated that the treatment of CML could dramatically increased the cellular levels of cholesterol in RAW264.7 cells, which led to promoted oxLDL-induced macrophage-derived foam cell formation. Significantly augmented expression of CD36 was observed in experimental groups but ABCA1 expression was significantly reduced. Furthermore, Lipd-loaded RAW264.7 macrophages were found to have increased mRNA expressions of PERK and CHOP, which were also augmented by CML treatment.Conclusion:It was demonstrated that CML could significantly increase the cellular cholesterol and promote oxLDL-induced macrophage-derived foam cell formation by oil red 0 staining and cholesterol assay kit. It was observed that significantly increased expression of CD36 and decreased ABCA1 expression in the group which incubated oxLDL plus CML. Furthermore, It was shown the mRNA expression of PERK and CHOP increased compared to the control when lipd-loaded RAW264.7 macrophages were administrated with CML. |
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