Monitoring neural activity and [Ca2+] with genetically encoded Ca2+ indicators

Pologruto, T. A., Yasuda, R., Svoboda, K. (October 2004) Monitoring neural activity and [Ca2+] with genetically encoded Ca2+ indicators. J Neurosci, 24 (43). pp. 9572-9. ISSN 1529-2401 (Electronic)

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DOI: 10.1523/jneurosci.2854-04.2004

Abstract

Genetically encoded Ca2+ indicators (GECIs) based on fluorescent proteins (XFPs) and Ca2+-binding proteins [like calmodulin (CaM)] have great potential for the study of subcellular Ca2+ signaling and for monitoring activity in populations of neurons. However, interpreting GECI fluorescence in terms of neural activity and cytoplasmic-free Ca2+ concentration ([Ca2+]) is complicated by the nonlinear interactions between Ca2+ binding and GECI fluorescence. We have characterized GECIs in pyramidal neurons in cultured hippocampal brain slices, focusing on indicators based on circularly permuted XFPs [GCaMP (Nakai et al., 2001), Camgaroo2 (Griesbeck et al., 2001), and Inverse Pericam (Nagai et al., 2001)]. Measurements of fluorescence changes evoked by trains of action potentials revealed that GECIs have little sensitivity at low action potential frequencies compared with synthetic [Ca2+] indicators with similar affinities for Ca2+. The sensitivity of GECIs improved for high-frequency trains of action potentials, indicating that GECIs are supralinear indicators of neural activity. Simultaneous measurement of GECI fluorescence and [Ca2+] revealed supralinear relationships. We compared GECI fluorescence saturation with CaM Ca2+-dependent structural transitions. Our data suggest that GCaMP and Camgaroo2 report CaM structural transitions in the presence and absence of CaM-binding peptide, respectively.

Item Type: Paper
Uncontrolled Keywords: Action Potentials physiology Animals Calcium metabolism Calmodulin physiology Cytoplasm metabolism Fluorescence Recovery After Photobleaching Luminescent Proteins Microscopy Confocal Microscopy Fluorescence Multiphoton Models Chemical Neurons metabolism physiology Pyramidal Cells metabolism physiology Rats Tissue Culture Techniques Transfection
Subjects: bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types
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Depositing User: CSHL Librarian
Date: 27 October 2004
Date Deposited: 26 Jan 2012 17:57
Last Modified: 26 Jan 2012 17:57
URI: http://repository.cshl.edu/id/eprint/22462

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