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/endo.137.5.8612546
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发表时间：
1996-05
期刊：
影响因子：
4.8
通讯作者：
B. Boston;R. Cone
中科院分区：
文献类型：
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作者：
B. Boston;R. Cone
多年来人们已经知道脂肪细胞表达高亲和力 ACTH 和 α-促黑素细胞刺激素 (MSH) 结合位点，并且 ACTH、α-MSH 和 β-促脂激素是有效的脂肪分解激素。我们在此表明，脂肪细胞对黑皮质素肽的反应是由于 MC2 (ACTH) 受体以及新发现的 MC5 受体的表达所致。使用 RT-PCR 和 Northern 印迹杂交，在小鼠检查的所有脂肪组织中发现了高水平的 MC2 受体信使 RNA (mRNA)，而在其中的一部分中发现了 MC5 受体 mRNA。两种受体 mRNA 也在 3T3-L1 细胞系中被发现，但仅在细胞被诱导分化为脂肪细胞后才发现。然后使用该细胞系来表征原位 MC2 和 MC5 受体位点的药理学特性。 MC2 受体表现出与肾上腺皮质细胞中 ACTH 受体相似的特性，与腺苷酸环化酶的激活偶联，EC50 约为 1 nM。这些细胞中的 MSH 结合位点可能是 MC5 受体，因为观察到这是在这些细胞中检测到的唯一其他黑皮质素受体 mRNA。 3T3-L1 脂肪细胞中的 MC5 受体响应 α-MSH 刺激而激活腺苷酸环化酶。有趣的是，Nle4，D-Phe7-α-MSH (NDP-MSH) 是一种常用的合成 α-MSH 激动剂，是 3T3-L1 细胞系中表达的 MC5 受体的有效拮抗剂。尽管agouti信号肽是NDP-MSH与MC1和MC4黑皮质素受体结合的有效拮抗剂，但agouti无法阻断3T3-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 receptors 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 EC50 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 alpha-MSH stimulation. Interestingly, Nle4, D-Phe7-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.