Matsuo Hirotaka, Kondo Yoshiyuki, Kawasaki Takashi, Tokuyama Shinji, Imamura Nobutaka
Graduate School of Science and Engineering, Ritsumeikan University.
Biol Pharm Bull. 2015;38(10):1504-11. doi: 10.1248/bpb.b15-00257.
An inhibitor of 3T3-L1 adipocyte differentiation was isolated from Streptomyces sp. TK08330 and identified by spectroscopy as the 18-membered macrolide borrelidin. Treatment with 1.0 μM borrelidin suppressed intracellular lipid accumulation by 80% and inhibited the expression of adipocyte-specific genes. Borrelidin suppressed the mRNA expression of two master regulators of adipocyte differentiation, peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer binding protein (C/EBPα). Studies on well-known upstream regulators of PPARγ revealed that borrelidin down-regulated C/EBPδ mRNA expression but did not affect expression of C/EBPβ. Borrelidin increased mRNA expression of negative regulators of differentiation such as GATA-binding protein (GATA) 3, Krüppel-like factor (KLF) 3 and KLF7, as well as positive regulators, KLF4, KLF6 and KLF15, at early stages of differentiation. To elucidate a primary mediator of borrelidin differentiation inhibitory activity, small interfering RNA (siRNA) transfection experiments were performed. The mRNA expression of PPARγ, which was down-regulated by borrelidin, was not changed by KLF3 and KLF7 siRNA treatment. In contrast, expression of PPARγ in GATA-3 siRNA-treated cells was not significantly different from that of control siRNA-treated cells. Borrelidin significantly inhibited lipid accumulation in control siRNA-treated cells, and treatment with GATA-3 siRNA slightly reduced the inhibitory effect of borrelidin. These results indicate that borrelidin inhibited adipocyte differentiation partially via GATA-3.
从链霉菌属TK08330中分离出一种3T3-L1脂肪细胞分化抑制剂，经光谱鉴定为18元大环内酯类抗生素博来霉素。用1.0μM博来霉素处理可使细胞内脂质积累减少80%，并抑制脂肪细胞特异性基因的表达。博来霉素抑制脂肪细胞分化的两个主要调节因子过氧化物酶体增殖物激活受体γ（PPARγ）和CCAAT/增强子结合蛋白（C/EBPα）的mRNA表达。对PPARγ已知上游调节因子的研究表明，博来霉素下调C/EBPδ mRNA表达，但不影响C/EBPβ的表达。在分化早期，博来霉素增加了分化负调节因子如GATA结合蛋白（GATA）3、Krüppel样因子（KLF）3和KLF7以及正调节因子KLF4、KLF6和KLF15的mRNA表达。为了阐明博来霉素分化抑制活性的主要介质，进行了小干扰RNA（siRNA）转染实验。博来霉素下调的PPARγ mRNA表达在KLF3和KLF7 siRNA处理后未发生变化。相反，GATA-3 siRNA处理细胞中PPARγ的表达与对照siRNA处理细胞的表达无显著差异。博来霉素显著抑制对照siRNA处理细胞中的脂质积累，GATA-3 siRNA处理略微降低了博来霉素的抑制作用。这些结果表明，博来霉素部分通过GATA-3抑制脂肪细胞分化。
