Devignot V, Prado de Carvalho L, Bregestovski P, Goblet C
Laboratoire de Biologie Cellulaire et Moléculaire du Neurone, Institut National de la Santé et de la Recherche Médicale U261, Département des Biotechnologies, Institut Pasteur, 25 rue du Dr Roux, F-75724 Paris, France.
Neuroscience. 2003;122(2):449-57. doi: 10.1016/s0306-4522(03)00171-4.
Alpha subunits of the inhibitory glycine receptor (GlyR) display genetic heterogeneity in mammals and zebrafish. This diversity is increased in mammals by the alternative splicing mechanism. We report here in zebrafish, the characterization of a new alphaZ1 subunit likely arising from alphaZ1 gene by an alternative splice process (alphaZ1L). This novel cDNA possesses 45 supplementary nucleotides at the putative exon2/exon3 boundary. The corresponding protein contains 15 additional amino acids in the NH2-terminal domain. Heterologous expression of homomeric GlyRalphaZ1L in human embryonic kidney-293 cells generates glycine-gated strychnine-sensitive chloride channels with no obvious discrepancy with pharmacological properties of GlyRalphaZ1. Moreover, zinc modulation of glycine-induced currents is identical in alphaZ1 and alphaZ1L glycine receptors. During ontogenesis, simultaneous alphaZ1 and alphaZ1L mRNA synthesis have been observed. Embryonic and adult alphaZ1 and alphaZ1L mRNA expressions are restricted to the CNS. Embryonic alphaZ1L mRNA anatomical pattern of expression is, however, highly restrained and strictly limited to the rostral part of the brain revealing a highly regionalized function of alphaZ1L in the CNS. This report contributes to the characterization of the diversity of glycine receptor isoforms in zebrafish and emphasizes the common mechanism used among vertebrates for creating GlyR variety and specificity.
抑制性甘氨酸受体（GlyR）的α亚基在哺乳动物和斑马鱼中表现出遗传异质性。在哺乳动物中，这种多样性通过可变剪接机制进一步增加。我们在此报告斑马鱼中一种新的αZ1亚基的特征，它可能是由αZ1基因通过可变剪接过程产生的（αZ1L）。这个新的cDNA在假定的外显子2/外显子3边界处有45个额外的核苷酸。相应的蛋白质在NH2末端结构域含有15个额外的氨基酸。在人胚肾-293细胞中同源表达同聚体GlyRαZ1L会产生甘氨酸门控的对士的宁敏感的氯离子通道，其药理学特性与GlyRαZ1没有明显差异。此外，锌对甘氨酸诱导电流的调节在αZ1和αZ1L甘氨酸受体中是相同的。在个体发育过程中，已观察到αZ1和αZ1L mRNA同时合成。胚胎和成年期的αZ1和αZ1L mRNA表达仅限于中枢神经系统。然而，胚胎期αZ1L mRNA的解剖学表达模式受到高度限制，严格局限于脑的前部，揭示了αZ1L在中枢神经系统中具有高度区域化的功能。本报告有助于对斑马鱼中甘氨酸受体亚型多样性的表征，并强调了脊椎动物中用于产生GlyR多样性和特异性的共同机制。
