Calcium Imaging of GPCR Activation Using Arrays of Reverse Transfected HEK293 Cells in a Microfluidic System
by
Margriet Roelse 1,2,*, Maurice G.L. Henquet 1, Harrie A. Verhoeven 1, Norbert C.A. De Ruijter 3
, Ron Wehrens 1,4, Marco S. Van Lenthe 4, Renger F. Witkamp 5, Robert D. Hall 1,2 and Maarten A. Jongsma 1
Margriet Roelse 1,2,*, Maurice G.L. Henquet 1, Harrie A. Verhoeven 1, Norbert C.A. De Ruijter 3, Ron Wehrens 1,4, Marco S. Van Lenthe 4, Renger F. Witkamp 5, Robert D. Hall 1,2 and Maarten A. Jongsma 1
1
BU Bioscience, Wageningen University and Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
2
Laboratory of Plant Physiology, Wageningen University and Research, 6708 PB Wageningen, The Netherlands
3
Laboratory of Cell Biology, Wageningen University and Research, 6708 PB Wageningen, The Netherlands
4
BU Biometris, Wageningen University and Research, 6708 PB Wageningen, The Netherlands
5
Human Nutrition and Health, Wageningen University and Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
*
Author to whom correspondence should be addressed.
Sensors 2018, 18(2), 602; https://doi.org/10.3390/s18020602
Received: 6 December 2017 / Revised: 6 February 2018 / Accepted: 12 February 2018 / Published: 16 February 2018
(This article belongs to the Special Issue Microfluidic Sensors)
Reverse-transfected cell arrays in microfluidic systems have great potential to perform large-scale parallel screening of G protein-coupled receptor (GPCR) activation. Here, we report the preparation of a novel platform using reverse transfection of HEK293 cells, imaging by stereo-fluorescence microscopy in a flowcell format, real-time monitoring of cytosolic calcium ion fluctuations using the fluorescent protein Cameleon and analysis of GPCR responses to sequential sample exposures. To determine the relationship between DNA concentration and gene expression, we analyzed cell arrays made with variable concentrations of plasmid DNA encoding fluorescent proteins and the Neurokinin 1 (NK1) receptor. We observed pronounced effects on gene expression of both the specific and total DNA concentration. Reverse transfected spots with NK1 plasmid DNA at 1% of total DNA still resulted in detectable NK1 activation when exposed to its ligand. By varying the GPCR DNA concentration in reverse transfection, the sensitivity and robustness of the receptor response for sequential sample exposures was optimized. An injection series is shown for an array containing the NK1 receptor, bitter receptor TAS2R8 and controls. Both receptors were exposed 14 times to alternating samples of two ligands. Specific responses remained reproducible. This platform introduces new opportunities for high throughput screening of GPCR libraries.
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Keywords:
reverse transfection; cell array; GPCR; NK1 receptor; Cameleon YC3.6; microfluidics
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MDPI and ACS Style
Roelse, M.; Henquet, M.G.; Verhoeven, H.A.; De Ruijter, N.C.; Wehrens, R.; Van Lenthe, M.S.; Witkamp, R.F.; Hall, R.D.; Jongsma, M.A. Calcium Imaging of GPCR Activation Using Arrays of Reverse Transfected HEK293 Cells in a Microfluidic System. Sensors 2018, 18, 602.
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Supplementary File 3:
Supplementary File: Calcium Imaging of GPCR Activation Using Arrays of Reverse Transfected HEK293 Cells in a Microfluidic System (DOI: 10.5281/zenodo.1184390)
