Cloning and functional expression of GABAB receptors from Drosophila
Cloning and functional expression of GABAB receptors from Drosophila
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DOI：
10.1046/j.1460-9568.2001.01410.x
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发表时间：
2001-02-01
影响因子：
3.4
通讯作者：
Raming, K
中科院分区：
文献类型：
--
作者：
Mezler, M;Müller, T;Raming, K
神经递质GABA（γ-氨基丁酸）在脊椎动物和无脊椎动物的中枢神经系统中作为主要的抑制性神经递质起作用。在脊椎动物中，GABA通过离子型受体（GABA（A）、GABA（C））和代谢型受体（GABA（B）传递信号，离子型受体诱导快速突触抑制反应，代谢型受体在减少突触前递质释放和突触后抑制电位中起重要作用。虽然GABA（A）和GABA（C）受体已从脊椎动物以及无脊椎动物中克隆，但迄今为止仅在脊椎动物物种中鉴定出GABA（B）受体，尽管间接证据表明它们也存在于节肢动物中。本文报道了从黑腹果蝇（Drosophilamelanogaster）中分离的三种GABA（B）受体亚型（D-GABA（B）R1、R2和R3）的克隆。虽然D-GABA（B）R1和R2分别与哺乳动物GABA（B）R1和R2显示出高序列同一性，但受体D-GABA（B）R3似乎是昆虫特异性亚型，迄今为止还没有已知的哺乳动物对应物。所有三种D-GABA（B）R亚型在胚胎中枢神经系统中表达。果蝇胚胎的原位杂交显示，两个D-GABA（B）R（D-GABA（B）R1和R2）在相似的区域表达，表明两个受体共表达，而第三个D-GABA（B）R（D-GABA（B）R3）显示独特的表达模式。与这些结果一致，我们只能在功能上表征D-GABA（B）R1和R2的两个亚型在非洲爪蟾卵母细胞或哺乳动物细胞系中共表达时，而D-GABA（B）R3在任何组合中均无活性。共表达的D-GABA（B）R1/2受体的药理学与哺乳动物GABA（B）Rs不同：例如，哺乳动物GABA（B）Rs的激动剂巴氯芬显示无作用。
The neurotransmitter GABA (gamma -aminobutyric acid) functions as the major inhibitory neurotransmitter in the central nervous system of vertebrates and invertebrates. In vertebrates GABA signals both through ionotropic receptors (GABA(A), GABA(C)), which induce fast synaptic inhibitory responses, and through metabotropic receptors (GABA(B)), which play a fundamental role in the reduction of presynaptic transmitter release and postsynaptic inhibitory potentials. Whilst GABA(A) and GABA(C) receptors have been cloned from vertebrates as well as invertebrates, GABA(B) receptors have only been identified in vertebrate species to date, although indirect evidence suggests their existence in arthropods, too. Here we report the cloning of three putative invertebrate GABA(B) receptor subtypes (D-GABA(B)R1, R2 and R3) isolated from Drosophila melanogaster. Whilst D-GABA(B)R1 and R2 show high sequence identity to mammalian GABA(B)R1 and R2, respectively, the receptor D-GABA(B)R3 seems to be an insect-specific subtype with no known mammalian counterpart so far. All three D-GABA(B)R subtypes are expressed in the embryonic central nervous system. In situ hybridization of Drosophila melanogaster embryos shows that two of the D-GABA(B)Rs (D-GABA(B)R1 and R2) are expressed in similar regions, suggesting a coexpression of the two receptors, whilst the third D-GABA(B)R (D-GABA(B)R3) displays a unique expression pattern. In agreement with these results we have only been able to functionally characterize D-GABA(B)R1 and R2 when the two subtypes are coexpressed either in Xenopus laevis oocytes or mammalian cell lines, whilst D-GABA(B)R3 was inactive in any combination. The pharmacology of the coexpressed D-GABA(B)R1/2 receptor was different from the mammalian GABA(B)Rs: e.g. baclofen, an agonist of mammalian GABA(B)Rs, showed no effect.