Localization of ATP-sensitive K^+ channel in neuron, glial cells, and uriniferous epithelial cells.

atp敏感的K^+通道属于内纠偏K^+通道家族，具有维持膜负电位、控制细胞体积和K^+分泌等重要作用。Kir6.1普遍存在于各种器官，而Kir6.2则存在于胰腺β细胞和其他器官。这些通道亚基与磺酰脲受体（SUR）形成异聚体，后者是该通道的调节亚基。采用原位杂交和免疫组化的方法研究了Kir6.1和Kir6.2在脑组织中的定位。Kir6.1和Kir6.2在大多数神经元群体中广泛表达。在免疫电镜下，Kir6.1定位于线粒体（分子脑研究，74,15 - 25,1999），而Kir6.2定位于内质网和高尔基体。此外，Kir6.1和Kir6.2在胼胝体和小脑白质的胶质细胞中表达。在免疫电镜下，这些胶质细胞是星形胶质细胞和少突胶质细胞。然后，我们在大多数神经元以及胼胝体和小脑白质的胶质细胞中观察到这些通道的调节亚基SURs的mRNA。这些通道分子可能在神经元和神经胶质细胞中起着重要作用。SURs蛋白及其亚细胞定位以及在尿小管上皮细胞中的表达正在研究中。

ATP-sensitive K^+ channel, which belongs to inwardly rectifying K^+ channel family, have important roles such as maintenance of negative membrane potential, control of cellular volume, and K^+ secretion. Kir6.1 is localized ubiquitously in various organ, while Kir6.2 is localized in pancreatic β cells and other organ. These channel subunis form heteromultimer with sulphonylurea receptors (SUR), which are regulatory subunits of this channel.We investigated localization of Kir6.1 and Kir6.2 in brain by in situ hybridization and immunohistochemistry. Kir6.1 and Kir6.2 are widely expressed in most neuronal population. In immunoelectron microscopy Kir6.1 is localized in mitochondria (Molecular Brain Research, 74, 15-25, 1999), while Kir6.2 in endoplasmic reticulum and Golgi apparatus. In addition, Kir6.1 and Kir6.2 are expressed in glial cells in corpus callosum and in cerebellar white matter. In immunoelecton microscopy these glial cells are astrocytes and oligodendrocytes. We then observed mRNA for SURs, regulatory subunits of these channel, in most neurons and in glial cells of corpus callosum and cerebellar white matter. These channel molecules may play fundamental roles in neurons and in glial cells. Protein for SURs and their subcellular localization, as well as expression in uriniferous tubular epithelial cells, are being investigated.