Endothelin (ET)-1 regulates adipogenesis and the endocrine activity of fat cells. However, relatively little is known about the ET-1 signaling pathway in preadipocyte growth. We used 3T3-L1 preadipocytes to investigate the signaling pathways involved in ET-1 modulation of preadipocyte proliferation. As indicated by an increased number of cells and greater incorporation of BrdU, the stimulation of preadipocyte growth by ET-1 depends on concentration and timing. The concentration of ET-1 that increased preadipocyte number by 50-70% was approximately 100 nM for approximately 24-48 h of treatment. ET-1 signaling time-dependently stimulated phosphorylation of ERK, c-JUN, STAT3, AMPK, and PKCα/βII proteins, but not AKT, JNK, or p38 MAPK. Treatment with an ET_AR antagonist, such as BQ610, but not ET_BR antagonist BQ788, blocked the ET-1-induced increase in cell proliferation and phosphorylated levels of ERK, c-JUN, STAT3, AMPK, and PKCα/βII proteins. In addition, pretreatment with specific inhibitors of ERK1/2 (U0126), JNK (SP600125), JAK2/STAT-3 (AG490), AMPK (Compound C), or PKC (Ro318220) prevented the ET-1-induced increase in cell proliferation and reduced the ET-1-stimulated phosphorylation of ERK1/2, c-JUN, STAT-3, AMPK, and PKCα/β. Moreover, SphK antagonist suppressed ET-1-induced cell proliferation and ERK, c-JUN, STAT3, AMPK, and PKC phosphorylation, and SMase2 antagonist suppressed ET-1-induced cell proliferation. However, neither p38 MAPK antagonist nor CerS inhibitor altered the effect of ET-1. The results indicate that ET_AR, JAK2/STAT3, ERK1/2, JNK/c-JUN, AMPK, PKC, SphK, and SMase2, but not ET_BR, p38 MAPK, or CerS, are necessary for the ET-1 stimulation of preadipocyte proliferation.

中文翻译：

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内皮素-1通过PKC，STAT3，AMPK，c-JUN，ERK，鞘氨醇激酶和鞘磷脂酶途径刺激前脂肪细胞的生长。

内皮素（ET）-1调节脂肪细胞的脂肪形成和内分泌活性。然而，关于前脂肪细胞生长中的ET-1信号通路的了解相对较少。我们使用3T3-L1前脂肪细胞来调查参与前脂肪细胞增殖的ET-1调节的信号通路。如细胞数量增加和BrdU掺入量增加所表明，ET-1对前脂肪细胞生长的刺激取决于浓度和时间。在大约24-48小时的治疗中，使前脂肪细胞数量增加50-70％的ET-1浓度约为100 nM。ET-1信号转导时间依赖性刺激ERK，c-JUN，STAT3，AMPK和PKCα/βII蛋白的磷酸化，但不刺激AKT，JNK或p38 MAPK。用ET _A R拮抗剂（例如BQ610）治疗，但不使用ET _B治疗R拮抗剂BQ788阻止ET-1诱导的细胞增殖增加以及ERK，c-JUN，STAT3，AMPK和PKCα/βII蛋白的磷酸化水平。此外，用ERK1 / 2（U0126），JNK（SP600125），JAK2 / STAT-3（AG490），AMPK（化合物C）或PKC（Ro318220）的特异性抑制剂进行预处理可防止ET-1诱导的细胞增加增殖并减少ERK1 / 2，c-JUN，STAT-3，AMPK和PKCα/β的ET-1刺激的磷酸化。此外，SphK拮抗剂抑制ET-1诱导的细胞增殖和ERK，c-JUN，STAT3，AMPK和PKC磷酸化，而SMase2拮抗剂抑制ET-1诱导的细胞增殖。但是，p38 MAPK拮抗剂和CerS抑制剂均不能改变ET-1的作用。结果表明，ET _AR，JAK2 / STAT3，ERK1 / 2，JNK / c-JUN，AMPK，PKC，SphK和SMase2，而不是ET _B R，p38 MAPK或CerS，对于ET-1刺激前脂肪细胞增殖是必需的。