Maejima Yuko, Horita Shoichiro, Kobayashi Daisuke, Aoki Miho, O'hashi Rie, Imai Ryota, Sakamoto Kazuho, Mori Masatomo, Takasu Katsuya, Ogawa Kazuma, Takenoshita Seiichi, Zhao Songji, Hazama Akihiro, Shimomura Kenju
Department of Pharmacology, Fukushima Medical University School of Medicine, Fukushima, Japan.
Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Peptides. 2017 Sep;95:10-15. doi: 10.1016/j.peptides.2017.07.001. Epub 2017 Jul 8.
The anorexigenic neuropeptide NEFA/nucleobindin 2 (NUCB2)/nesfatin-1-containing neurons are distributed in the brain regions involved in feeding regulation. In spite of the growing knowledge of its physiological functions through extensive studies, its molecular mechanism of reaction, including its receptor, remains unknown. NUCB2/nesfatin-1 is also involved in various peripheral regulations, including glucose homeostasis. In pancreatic beta-cells, NUCB2/nesfatin-1 is reported to enhance glucose-stimulated insulin secretion (GSIS) but its exact mechanism remains unknown. To clarify this mechanism, we measured the effect of nesfatin-1 on the electrical activity of pancreatic beta-cells. Using mouse primary beta cells, we measured changes in the ATP-sensitive K (K) channel current, the voltage-gated K (Kv) channel current, and insulin secretion upon application of nesfatin-1. Nesfatin-1 inhibited the Kv channel, but K channel activity was unaffected. Nesfatin-1 enhanced insulin secretion to a same level as Kv channel blocker tetraethylammonium (TEA). The effect was not further enhanced when nesfatin-1 and TEA were applied simultaneously. The inhibition binding assay with [I]nesfatin-1 in Kv2.1 channels, major contributor of Kv current in beta cell, expressing HEK239 cells indicated the binding of nesfatin-1 on Kv2.1 channel. Because Kv channel inhibition enhances insulin secretion under high glucose conditions, our present data suggest a possible mechanism of nesfatin-1 on enhancing GSIS through regulation of ion channels rather than its unidentified receptor.
厌食性神经肽NEFA/核结合蛋白2（NUCB2）/含nesfatin-1的神经元分布于参与进食调节的脑区。尽管通过广泛研究对其生理功能的了解不断增加，但其反应的分子机制，包括其受体，仍然未知。NUCB2/nesfatin-1还参与包括葡萄糖稳态在内的各种外周调节。在胰腺β细胞中，据报道NUCB2/nesfatin-1可增强葡萄糖刺激的胰岛素分泌（GSIS），但其确切机制仍不清楚。为了阐明这一机制，我们测量了nesfatin-1对胰腺β细胞电活动的影响。使用小鼠原代β细胞，我们测量了应用nesfatin-1后ATP敏感性钾（K）通道电流、电压门控钾（Kv）通道电流和胰岛素分泌的变化。Nesfatin-1抑制Kv通道，但对K通道活性无影响。Nesfatin-1将胰岛素分泌增强到与Kv通道阻滞剂四乙铵（TEA）相同的水平。同时应用nesfatin-1和TEA时，效果未进一步增强。在表达HEK239细胞的Kv2.1通道（β细胞中Kv电流的主要贡献者）中用[I]nesfatin-1进行的抑制结合试验表明nesfatin-1与Kv2.1通道结合。由于在高葡萄糖条件下Kv通道抑制可增强胰岛素分泌，我们目前的数据提示nesfatin-1通过调节离子通道而非其未明确的受体增强GSIS的可能机制。
