Uchida Y, Irie K, Tsukahara F, Ohba K, Ogawa A, Fujii E, Muraki T
Department of Pharmacology, Tokyo Women's Medical College, Japan.
Eur J Pharmacol. 1995 Sep 15;291(1):33-41. doi: 10.1016/0922-4106(95)90186-8.
The effect of endothelins on lipoprotein lipase activity and lipoprotein lipase mRNA levels was studied in brown adipocytes differentiated in culture. Lipoprotein lipase activity was determined in two fractions; lipoprotein lipase released by heparin (10 IU/ml, 1 h) into the medium (heparin-releasable fraction) and lipoprotein lipase activity remaining in cells (extractable fraction). Time-course studies showed that endothelin 1 (10(-7) M) progressively decreased both lipoprotein lipase fractions (heparin-releasable, extractable), until nadir at 24 h. Endothelin-1 reduced both lipoprotein lipase activities (heparin-releasable, extractable) in a concentration-dependent manner, whereas endothelin-3 did not produce any significant changes in either of them. Northern blot analysis revealed that endothelin-1 (10(-7)-10(-11) M) caused a concentration-dependent decrease in lipoprotein lipase mRNA obtained from cells on day 9. Furthermore, pretreatment of brown adipocytes with endothelin ETA receptor antagonist FR139317 antagonized the endothelin-1-induced reduction of lipoprotein lipase activity and lipoprotein lipase mRNA. These results suggest that endothelin-1 decreases lipoprotein lipase activity by inhibiting the lipoprotein lipase gene expression in brown adipocytes differentiated in culture, possibly through endothelin ETA receptors on cell membranes. Because of marked reduction of lipoprotein lipase activity and its mRNA as a marker of adipogenic differentiation, endothelin-1 may have an inhibitory role in the differentiation of brown adipocytes.
在体外分化的棕色脂肪细胞中研究了内皮素对脂蛋白脂肪酶活性和脂蛋白脂肪酶mRNA水平的影响。脂蛋白脂肪酶活性在两个组分中测定：肝素（10IU/ml，1小时）释放到培养基中的脂蛋白脂肪酶（肝素可释放组分）和细胞中残留的脂蛋白脂肪酶活性（可提取组分）。时间进程研究表明，内皮素-1（10^(-7)M）使脂蛋白脂肪酶的两个组分（肝素可释放的、可提取的）逐渐降低，直至24小时达到最低点。内皮素-1以浓度依赖的方式降低了两种脂蛋白脂肪酶活性（肝素可释放的、可提取的），而内皮素-3对两者均未产生任何显著变化。Northern印迹分析显示，内皮素-1（10^(-7)-10^(-11)M）导致第9天从细胞中获得的脂蛋白脂肪酶mRNA呈浓度依赖性降低。此外，用内皮素ETA受体拮抗剂FR139317预处理棕色脂肪细胞可拮抗内皮素-1诱导的脂蛋白脂肪酶活性和脂蛋白脂肪酶mRNA的降低。这些结果表明，内皮素-1可能通过细胞膜上的内皮素ETA受体抑制培养中分化的棕色脂肪细胞中的脂蛋白脂肪酶基因表达，从而降低脂蛋白脂肪酶活性。由于脂蛋白脂肪酶活性及其mRNA作为脂肪生成分化标志物的显著降低，内皮素-1可能在棕色脂肪细胞的分化中起抑制作用。
