The expression of endogenous voltage‐gated potassium channels in HEK293 cells is affected by culture conditions

• Published in: Physiological reports 2018-04, Vol.6 (8), p.e13663-n/a
• Main Authors: Ponce, Arturo, Castillo, Aida, Hinojosa, Lorena, Martinez‐Rendon, Jacqueline, Cereijido, Marcelino
• Format: Article
• Language: English
• Subjects: 4AP; Cell culture; Cell Culture Techniques; Cell density; Cellular Physiology; Culture Media; Cycloheximide; HEK293; HEK293 Cells; Humans; Ion Channel Gating - physiology; Ion channels; Ion currents; Membrane Physiology; mRNA; Original Research; Patch-Clamp Techniques; Physiology; Potassium; Potassium channels; Potassium channels (voltage-gated); Potassium Channels, Voltage-Gated - genetics; Potassium Channels, Voltage-Gated - metabolism; Potassium currents; Protein biosynthesis; Regulatory Pathways; TEA; Transcription; Trypsin
• ISSN: 2051-817X
• DOI: 10.14814/phy2.13663

HEK293 cells are widely used as a host for expression of heterologous proteins; yet, little care has been taken to characterize their endogenous membrane components, including ion channels. In this work, we aimed to describe the biophysical and pharmacological properties of endogenous, voltage‐dependent potassium currents (IKv). We also examined how its expression depends on culture conditions. We used the electrophysiological technique of whole‐cell patch clamp to record ion currents from HEK293 cells. We found that HEK cells express endogenous, voltage‐dependent potassium currents. We also found that diverse culture conditions, such as the passage number, the cell density, the type of serum that complements the culture media and the substratum, affect the magnitude and shape of IKv, resulting from the relative contribution of fast, slow, and noninactivating component currents. Incubation of cells in mature monolayers with trypsin–EDTA, notoriously reduces the magnitude and modifies the shape of voltage‐dependent potassium endogenous currents; nonetheless HEK cells recover IKv′s magnitude and shape within 6 h after replating, with a process that requires synthesis of new mRNA and protein subunits, as evidenced by the fact that actinomycin D and cycloheximide, inhibitors of synthesis of mRNA and protein, respectively, impair the recovery of IKv after trypsinization. In addition to be useful as a model expression system, HEK293 may be useful to understand how cells regulate the density of ion channels on the membrane. We show in this work that HEK293 cells, a line frequently used as a model system for expression of heterologous ion channels, express endogenous voltage‐dependent potassium currents and that its expression depend on the culture conditions used. We also show that trypsinization reduces its magnitude and shape; however, cells recover its former condition in a process dependent of synthesis of new components.