Itoh Masayuki, Ishihara Keiko, Nakashima Noriyuki, Takano Makoto
Division of Integrated Autonomic Function, Department of Physiology, Kurume University School of Medicine, 67 Asahimachi, Kurume, Fukuoka, 830-0011, Japan.
Department of Physiology, Faculty of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-ku, Kyoto, 606-8501, Japan.
J Physiol Sci. 2016 May;66(3):241-8. doi: 10.1007/s12576-015-0420-5. Epub 2015 Nov 6.
Expression of hyperpolarization-activated cyclic nucleotide-gated channels (HCN1-4) on distal dendrites of neurons is suggested to modify synaptic integration in the central nervous system. However, the mechanisms of dendritic localization are not fully understood. Recent studies have revealed that S-palmitoylation plays an important role in the enrichment of various molecules at the postsynaptic membrane. Thus, we performed an acyl-biotinyl exchange assay, and found that HCN1, HCN2, and HCN4, but not HCN3, were S-palmitoylated in HEK293 cells. Mutation of multiple intracellular cysteine residues at the N-terminus of HCN2 was required for complete inhibition of S-palmitoylation. However, this mutagenesis had a minimal effect on surface expression of HCN2 proteins or electrophysiological properties of HCN2 current when expressed in HEK293 cells or in Xenopus oocytes. These findings provide insight into the physiological roles of S-palmitoylation of HCN channels in native neurons.
超极化激活的环核苷酸门控通道（HCN1 - 4）在神经元远端树突上的表达被认为可改变中枢神经系统中的突触整合。然而，树突定位的机制尚未完全了解。最近的研究表明，S-棕榈酰化在各种分子富集于突触后膜中起着重要作用。因此，我们进行了酰基生物素交换试验，发现HCN1、HCN2和HCN4在HEK293细胞中发生了S-棕榈酰化，而HCN3没有。完全抑制HCN2的S-棕榈酰化需要对其N端多个细胞内半胱氨酸残基进行突变。然而，当在HEK293细胞或非洲爪蟾卵母细胞中表达时，这种诱变对HCN2蛋白的表面表达或HCN2电流的电生理特性影响极小。这些发现为HCN通道S-棕榈酰化在天然神经元中的生理作用提供了见解。
