Characterization of melanocortin receptor subtype expression in murine adipose tissues and in the 3T3-L1 cell line
Characterization of melanocortin receptor subtype expression in murine adipose tissues and in the 3T3-L1 cell line
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DOI：
10.1210/en.137.5.2043
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发表时间：
1996-05-01
期刊：
影响因子：
4.8
通讯作者：
Cone, RD
中科院分区：
文献类型：
--
作者：
Boston, BA;Cone, RD
多年来，人们已经知道脂肪细胞表达高亲和力的ACTH和α-黑素细胞刺激激素（MSH）结合位点，并且ACTH、α-MSH和β-促脂素是有效的脂解激素。我们在这里表明，脂肪细胞对黑皮质素肽的反应是由MC 2（ACTH）受体和新发现的MC 5受体的表达引起的。使用RT-PCR和北方印迹杂交，高水平的MC 2受体信使RNA（mRNA）被发现在所有的小鼠脂肪组织检查，而MC 5受体mRNA被发现在这些子集。这两种受体mRNA也在3 T3-L1细胞系中发现，但仅在细胞被诱导分化为脂肪细胞之后。然后使用该细胞系原位表征MC 2和MC 5受体位点的药理学性质。MC 2受体表现出与肾上腺皮质细胞中的ACTH受体相似的特性，与腺苷酸环化酶的激活偶联，EC（50）约为1 nM。在这些细胞中表征的MSH结合位点可能是MC 5受体，基于这是在这些细胞中检测到的唯一其它黑皮质素受体mRNA的观察。3 T3-L1脂肪细胞中的MC 5受体响应于cr-MSH刺激而激活腺苷酸环化酶。有趣的是，Nle（4），D-Phe（7）-α-MSH（NDP-MSH），一种常用的合成α-MSH激动剂，是3 T3-L1细胞系中表达的MC 5受体的有效拮抗剂。尽管agglutinin信号肽是NDP-MSH与MC 1和MC 4黑皮质素受体结合的有效拮抗剂，但agglutinin不能阻断3 T3-L1脂肪细胞中的NDP-MSH结合。
It has been known for many years that adipocytes express high affinity-ACTH and alpha-melanocyte stimulating hormone (MSH) binding sites, and that ACTH, alpha-MSH, and beta-lipotropin are potent lipolytic hormones. We show here that the adipocyte response to the melanocortin peptides results from the expression of both the MC2 (ACTH) receptor as well as the newly discovered MC5 receptor. Using RT-PCR and Northern blot hybridization, high levels of MC2 receptor messenger RNA (mRNA) were found in all adipose tissues examined in the mouse, whereas MC5 receptor mRNA was found in a subset of these. Both receptor mRNAs were also found in the 3T3-L1 cell line but only after the cells had been induced to differentiate into adipocytes. This cell line was then used to characterize the pharmacological properties of the MC2 and MC5 receptor sites in situ. The MC2 receptor exhibits properties similar to the ACTH receptor characterized in adrenocortical cells, coupling to activation of adenylyl cyclase with an EC(50) of approximately 1 nM. An MSH binding site characterized in these cells is presumably the MC5 receptor, based on the observation that this is the only other melanocortin receptor mRNA detected in these cells. The MC5 receptor in the 3T3-L1 adipocyte activated adenylyl cyclase in response to cr-MSH stimulation. Interestingly, Nle(4), D-Phe(7)-alpha-MSH (NDP-MSH), a commonly used synthetic alpha-MSH agonist, was a potent antagonist of the MC5 receptor expressed in the 3T3-L1 cell line. Although the agouti signaling peptide is a potent antagonist of NDP-MSH binding to the MC1 and MC4 melanocortin receptors, agouti was unable to block NDP-MSH binding in the 3T3-L1 adipocyte.