CR-CHUM (Centre de recherche du Centre Hospitalier de l'Université de Montréal), Département d'obstétrique-gynécologie, Hôpital Saint-Luc, 264 René-Lévesque E., Montréal, Québec, Canada H2X 1P1.
Gen Comp Endocrinol. 2010 Jun 1;167(2):215-27. doi: 10.1016/j.ygcen.2010.03.008. Epub 2010 Mar 17.
We have cloned and sequenced a cDNA from the surf clam (Spisula solidissima, a pelecypod mollusc) that encodes an octopamine receptor which we have named Spi-OAR. The sequence of Spi-OAR shares many similarities with two Aplysia and three Drosophila octopamine receptors belonging to a sub-group of beta-adrenergic-like octopamine receptors. Using an expression vector and transient transfections of Spi-OAR into HEK 293 cells, we observed an increase of cAMP upon addition of octopamine and, to a lesser extent, of tyramine, but not after addition of dopamine, serotonin, or histamine. Using a battery of known agonists and antagonists for octopamine receptors, we observed a rather unique pharmacological profile for Spi-OAR through measurements of cAMP. Spi-OAR exhibited some constitutive activity in HEK 293 cells and no Ca(2+) responses could be detected following addition of octopamine to Spi-OAR-transfected cells. RT-PCR analysis revealed ubiquitous expression of Spi-OAR mRNA in all adult tissues, oocytes and early embryos examined. While addition of serotonin to isolated clam oocytes resulted in meiotic activation, similar additions of octopamine had no effect, suggesting that its potential role in clam reproductive physiology differs significantly from that of serotonin. This work identifies Spi-OAR as a novel mollusc octopamine receptor closely related to other invertebrate beta-adrenergic-like octopamine receptors, with possible reproductive and other physiological functions. This initial characterization of Spi-OAR makes possible further investigations and comparisons with more studied and familiar insect or gastropod mollusc octopamine receptors.
我们从菲律宾蛤仔（Spisula solidissima，双壳贝类软体动物）克隆并测序了一个编码章鱼胺受体的 cDNA，我们将其命名为 Spi-OAR。Spi-OAR 的序列与两种 Aplysia 和三种 Drosophila 章鱼胺受体具有许多相似之处，它们属于β-肾上腺素样章鱼胺受体的一个亚群。我们使用表达载体和 Spi-OAR 瞬时转染 HEK 293 细胞，观察到章鱼胺和（在较小程度上）酪胺的加入会增加 cAMP，但多巴胺、血清素或组氨酸的加入则不会。使用一系列已知的章鱼胺受体激动剂和拮抗剂，我们通过 cAMP 的测量观察到 Spi-OAR 相当独特的药理学特征。Spi-OAR 在 HEK 293 细胞中表现出一些固有活性，并且在向 Spi-OAR 转染细胞中添加章鱼胺后，无法检测到 Ca(2+)反应。RT-PCR 分析显示 Spi-OAR mRNA 在所有检查的成年组织、卵母细胞和早期胚胎中均有广泛表达。虽然向分离的蛤仔卵母细胞中添加血清素会导致减数分裂激活，但类似地添加章鱼胺则没有效果，这表明其在蛤仔生殖生理学中的潜在作用与血清素有很大的不同。这项工作鉴定了 Spi-OAR 作为一种新型软体动物章鱼胺受体，与其他无脊椎动物β-肾上腺素样章鱼胺受体密切相关，可能具有生殖和其他生理功能。Spi-OAR 的这一初步特征分析使得进一步的研究和与更具研究和熟悉的昆虫或腹足纲软体动物章鱼胺受体的比较成为可能。
