School of Biomedical Sciences and Li Ka Shing Institute of Health Science, The Chinese University of Hong Kong, Hong Kong, China.
Department of General Surgery, The First Affiliated Hospital of Harbin Medical University, Harbin, China.
Pflugers Arch. 2022 Jul;474(7):665-680. doi: 10.1007/s00424-022-02700-z. Epub 2022 May 14.
Mammalian expression systems, particularly the human embryonic kidney (HEK-293) cells, combined with electrophysiological studies, have greatly benefited our understanding of the function, characteristic, and regulation of various ion channels. It was previously assumed that the existence of endogenous ion channels in native HEK-293 cells could be negligible. Still, more and more ion channels are gradually reported in native HEK-293 cells, which should draw our attention. In this regard, we summarize the different ion channels that are endogenously expressed in HEK-293 cells, including voltage-gated Na channels, Ca channels, K channels, Cl channels, nonselective cation channels, TRP channels, acid-sensitive ion channels, and Piezo channels, which may complicate the recording of the heterogeneously expressed ion channels to a certain degree. We noted that the expression patterns and channel profiles varied with different studies, which may be due to the distinct originality of the cells, cell culture conditions, passage numbers, and different recording protocols. Therefore, a better knowledge of endogenous ion channels may help minimize potential problems in characterizing heterologously expressed ion channels. Based on this, it is recommended that HEK-293 cells from unknown sources should be examined before transfection for the characterization of their functional profile, especially when the expression level of exogenous ion channels does not overwhelm the endogenous ion channels largely, or the current amplitude is not significantly higher than the native currents.
哺乳动物表达系统，特别是人胚肾（HEK-293）细胞，结合电生理研究，极大地促进了我们对各种离子通道的功能、特性和调节的理解。以前认为，天然 HEK-293 细胞中内源性离子通道的存在可以忽略不计。然而，越来越多的离子通道逐渐在天然 HEK-293 细胞中被报道，这应该引起我们的注意。在这方面，我们总结了内源性表达在 HEK-293 细胞中的不同离子通道，包括电压门控 Na 通道、Ca 通道、K 通道、Cl 通道、非选择性阳离子通道、TRP 通道、酸敏感离子通道和 Piezo 通道，这些通道可能会在一定程度上使异源表达的离子通道的记录复杂化。我们注意到，不同的研究中表达模式和通道特征有所不同，这可能是由于细胞的原始特性、细胞培养条件、传代数和不同的记录方案不同所致。因此，更好地了解内源性离子通道可能有助于最大限度地减少异源表达的离子通道特征分析中潜在的问题。基于此，建议在转染前检查未知来源的 HEK-293 细胞，以研究其功能特性，特别是当外源离子通道的表达水平不会显著超过内源性离子通道，或者电流幅度不会明显高于本底电流时。
