Liss B, Franz O, Sewing S, Bruns R, Neuhoff H, Roeper J
Medical Research Council, Anatomical Neuropharmacology Unit, Department of Pharmacology, Oxford University, Oxford OX1 3TH, UK.
EMBO J. 2001 Oct 15;20(20):5715-24. doi: 10.1093/emboj/20.20.5715.
The activity of dopaminergic (DA) substantia nigra (SN) neurons is essential for voluntary movement control. An intrinsic pacemaker in DA SN neurons generates their tonic spontaneous activity, which triggers dopamine release. We show here, by combining multiplex and quantitative real-time single-cell RT- PCR with slice patch-clamp electrophysiology, that an A-type potassium channel mediated by Kv4.3 and KChip3 subunits has a key role in pacemaker control. The number of active A-type potassium channels is not only tightly associated with the pacemaker frequency of individual DA SN neurons, but is also highly correlated with their number of Kv4.3L (long splice variant) and KChip3.1 (long splice variant) mRNA molecules. Consequently, the variation of Kv4alpha and Kv4beta subunit transcript numbers is sufficient to explain the full spectrum of spontaneous pacemaker frequencies in identified DA SN neurons. This linear coupling between Kv4alpha as well as Kv4beta mRNA abundance, A-type channel density and pacemaker frequency suggests a surprisingly simple molecular mechanism for how DA SN neurons tune their variable firing rates by transcriptional control of ion channel genes.
多巴胺能（DA）黑质（SN）神经元的活动对于自主运动控制至关重要。DA SN神经元中的一种内在起搏器产生其紧张性自发活动，进而触发多巴胺释放。我们在此通过将多重定量实时单细胞逆转录聚合酶链反应（RT-PCR）与脑片膜片钳电生理学相结合，表明由Kv4.3和KChip3亚基介导的A型钾通道在起搏器控制中起关键作用。活跃的A型钾通道数量不仅与单个DA SN神经元的起搏器频率密切相关，还与其Kv4.3L（长剪接变体）和KChip3.1（长剪接变体）mRNA分子数量高度相关。因此，Kv4α和Kv4β亚基转录本数量的变化足以解释已鉴定的DA SN神经元自发起搏器频率的全谱。Kv4α以及Kv4β mRNA丰度、A型通道密度和起搏器频率之间的这种线性耦合表明，DA SN神经元如何通过离子通道基因的转录控制来调节其可变发放率，这是一种惊人的简单分子机制。
