Found programs: National Natural Science Foundation of China ( No . 81774083) ; Clinical Specialty Project of Shanghai Putuo District Health System (No . 2020tszk01) ; Scientific Research Project of Shanghai Health Commis- sion ( No . 202240309) ; Technology Innovation Project of Shanghai Putuo District Health System ( Nos . ptkw- ws202003 , ptkwws202302)
Authors：Cai Xinghua1 , 2 , Gao Jie3 , Xu Yuanying3 , Zhang Huihui3 , Maireyanmu Rouzi3 , Sha Wenjun3 , Lu Jun1 , 2 , 3 , Lei Tao1 , 2 , 3
Keywords：BCAA; 3T3-L1 ; adipocyte differentiation; Stat3 ; adipogenesis; obesity
DOI：10.19405/j.cnki.issn1000-1492.2025.03.015
〔Abstract〕 Abstract Objective To investigate the effects of branched-chain amino acid ( BCAA) on the differentiation of 3T3-L1 preadipocytes and its potential mechanism . Methods 3T3-L1 preadipocytes were divided into the Control , differentiation medium ( DM) , low-concentration BCAA , and high-concentration BCAA groups . A CCK-8 assay was utilized to evaluate pre-adipocyte survival under various BCAA concentrations . Oil-red O staining was used to observe the formation of lipid droplets in adipocytes . Intracellular triglyceride ( TG) and total cholesterol ( TC) were detected by enzymatic method . RT-qPCR and Western blot were used to detect the mRNA and protein expres- sion of Stat3 and adipocyte differentiation-related genes . Results CCK-8 results showed that the viability of 3T3 - L1 cells was not affected when the BCAA concentration was ≤ 10 mmol/L. Compared with the DM group , the low- concentration BCAA groups (0. 5 and 1 . 0 mmol/L) had significantly larger intracellular lipid droplets , increased number of lipid droplets , and elevated levels of the intracellular TC (0. 88 vs 0. 68 mmol/g; 0. 83 vs 0. 68 mmol/ g , P < 0. 01) and TG (0. 77 vs 0. 40 mmol/g; 0. 62 vs 0. 40 mmol/g , P < 0. 01) . Nevertheless , the cell differen- tiation in the high-concentration group (5 . 0 and 10 mmol/L) significantly decreased compared with that in the DM group . Further , levels of PPARγ, C/EBPα, Adiponectin , and FABP4 mRNA and protein expression significantly increased in the low-concentration group , but significantly decreased in the high-concentration group than that in the DM group (P < 0. 01) . In addition , low concentrations of BCAA promoted stat3 phosphorylation , while high concentrations inhibited its phosphorylation ( P < 0. 01) . Conclusion BCAA have a dual role in regulating the differentiation of preadipocytes through Stat3 , i . e . low concentrations of BCAA induce cell differentiation by pro- moting Stat3 phosphorylation; whereas high concentrations of BCAA inhibit Stat3 phosphorylation and cell differen- tiation .