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A hybrid approach to measuring electrical activity in genetically specified neurons


The development of genetically encoded fluorescent voltage probes is essential to image electrical activity from neuronal populations. Previous green fluorescent protein (GFP)-based probes have had limited success in recording electrical activity of neurons because of their low sensitivity and poor temporal resolution. Here we describe a hybrid approach that combines a genetically encoded fluorescent probe (membrane-anchored enhanced GFP) with dipicrylamine, a synthetic voltage-sensing molecule that partitions into the plasma membrane. The movement of the synthetic voltage sensor is translated via fluorescence resonance energy transfer (FRET) into a large fluorescence signal (up to 34% change per 100 mV) with a fast response and recovery time (0.5 ms). Using this two-component approach, we were able to optically record action potentials from neuronal cell lines and trains of action potentials from primary cultured neurons. This hybrid approach may form the basis for a new generation of protein-based voltage probes.

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Figure 1: The hVOS system in HEK 293 cells.
Figure 2: Speed and recovery of hVOS.
Figure 3: Toxicity of hVOS system.
Figure 4: Recording of action potentials with hVOS in GT1 cells.
Figure 5: Primary neurons transfected with farnesylated eGFP.
Figure 6: Optical recordings of electrical activity in primary neuronal cultures.
Figure 7: Fluorescence recordings of membrane potential using DPA in conjunction with fluorescently labeled anti-CD8 antibodies.


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We thank W. Hubbell (UCLA) for the gift of DPA and A. Charles (UCLA) for the GT1 cells. Thanks to F. Chow for her assistance with primary neuronal cultures and transfections. We also thank T. Otis and M. Pratap for preparing viruses for slice transfections and for access to their setup. This work was supported by grants from the US National Institutes of Health (GM30376 to F.B., NS30549 to I.M., NS41317 to F.E.S.), the American Heart Association (0225006Y and 0535214N to B.C.) and Deutschen Forschungsgemeinschaft (BL538-1/1 to R.B.).

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Correspondence to Francisco Bezanilla.

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Chanda, B., Blunck, R., Faria, L. et al. A hybrid approach to measuring electrical activity in genetically specified neurons. Nat Neurosci 8, 1619–1626 (2005).

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