Liu T I, Gilly W F
Department of Biological Sciences, Stanford University, Pacific Grove, CA 93950, USA.
Recept Channels. 1995;3(4):243-54.
Recent cloning of a putative Na+ channel alpha subunit cDNA, GFLN1, from the squid stellate ganglion has allowed us to study the expression of this ion channel at a cellular level. In situ hybridizations with a probe derived from and specific to 3' untranslated and coding sequence of GFLN1 were used to determine its tissue distribution as well as its subcellular localization. In sections of the stellate ganglion, the probe labeled all of the cells in the giant fiber lobe (GFL) and most cells in the cellular layer of the main ganglion. In these non-GFL portions of the stellate ganglion, labeling was particularly intense in the ventral large cells and weak or absent in the dorsal small cells. In the optic lobe, only a select group of cells, the second-order visual giant neurons, were intensely labeled. These results are consistent with electrophysiological data that show GFL-like Na+ currents in rare large cells dissociated from the optic lobe and in most but not all cells from the non-GFL part of the stellate ganglion. In sections of the subesophageal mass of the central nervous system, strong labeling for GFLN1 mRNA occurred in the fin lobe, posterior chromatophore lobe, central and latero-ventral palliovisceral lobes, and posterior pedal lobe. In all cases, labeling was detected only in the cellular layer of these tissues and never in nerves or neuropil. In situ hybridization with dissociated GFL neurons maintained in primary culture verified that Na+ channel mRNA is confined to the cell body. These results indicate that GFLN1 is expressed predominately in large cells with large or long axons, and that this mRNA is restricted to the cell bodies of these neurons.
最近，从鱿鱼星状神经节中克隆出了一种假定的钠离子通道α亚基cDNA（GFLN1），这使我们能够在细胞水平上研究该离子通道的表达情况。利用源自GFLN1 3'非翻译区和编码序列且对其具有特异性的探针进行原位杂交，以确定其组织分布及其亚细胞定位。在星状神经节切片中，该探针标记了巨纤维叶（GFL）中的所有细胞以及主神经节细胞层中的大多数细胞。在星状神经节的这些非GFL部分，腹侧大细胞中的标记尤为强烈，而背侧小细胞中的标记则较弱或无标记。在视叶中，只有一组特定的细胞，即二级视觉巨神经元，被强烈标记。这些结果与电生理数据一致，电生理数据显示，从视叶分离出的罕见大细胞以及星状神经节非GFL部分的大多数（但不是所有）细胞中存在类似GFL的钠离子电流。在中枢神经系统食管下神经节团块的切片中，GFLN1 mRNA在鳍叶、后色素细胞叶、中央和腹外侧苍白内脏叶以及后足叶中出现强烈标记。在所有情况下，仅在这些组织的细胞层中检测到标记，而在神经或神经纤维网中从未检测到。对原代培养中维持的解离GFL神经元进行原位杂交证实，钠离子通道mRNA局限于细胞体。这些结果表明，GFLN1主要在具有大轴突或长轴突的大细胞中表达，并且这种mRNA局限于这些神经元的细胞体。
