Genetically encoded calcium indicator with NTnC-like design and enhanced fluorescence contrast and kinetics
| Autor: | Doronin, D. A, Barykina, N. V, Subach, O. M, Sotskov, V. P, Plusnin, V. V, Ivleva, O. A, Isaakova, E. A, Varizhuk, A. M, Pozmogova, G. E, Malyshev, A. Y, Smirnov, I. V, Anokhin, K. V, Enikolopov, G. N, Subach, F. V, Doronin, D. A., Barykina, N. V., Subach, O. M., Sotskov, V. P., Plusnin, V. V., Ivleva, O. A., Isaakova, E. A., Varizhuk, A. M., Pozmogova, G. E., Malyshev, A. Y., Smirnov, I. V., Piatkevich, K. D., Anokhin, K. V., Enikolopov, G. N., Subach, F. V., Piatkevich, Kiryl |
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| Přispěvatelé: | Massachusetts Institute of Technology. Media Laboratory, Piatkevich, Kiryl |
| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
0301 basic medicine
Male Patch-Clamp Techniques Calmodulin lcsh:Biotechnology Kinetics Calcium imaging chemistry.chemical_element Calcium Genetically encoded calcium indicator Hippocampus Time-Lapse Imaging Fluorescence spectroscopy Fluorescence Cell Line Troponin C 03 medical and health sciences 0302 clinical medicine lcsh:TP248.13-248.65 Animals Humans Fluorometry Patch clamp Neurons biology Hydrogen-Ion Concentration Recombinant Proteins Molecular Imaging Mice Inbred C57BL 030104 developmental biology chemistry Microscopy Fluorescence biology.protein Biophysics Protein engineering 030217 neurology & neurosurgery Biotechnology Research Article |
| Zdroj: | BioMed Central BMC Biotechnology, Vol 18, Iss 1, Pp 1-15 (2018) BMC Biotechnology |
| Popis: | Background The recently developed genetically encoded calcium indicator (GECI), called NTnC, has a novel design with reduced size due to utilization of the troponin C (TnC) as a Ca2+-binding moiety inserted into the mNeonGreen fluorescent protein. NTnC binds two times less Ca2+ ions while maintaining a higher fluorescence brightness at the basal level of Ca2+ in neurons as compared with the calmodulin-based GECIs, such as GCaMPs. In spite of NTnC’s high brightness, pH-stability, and high sensitivity to single action potentials, it has a limited fluorescence contrast (F-Ca2+/F+Ca2+) and slow Ca2+ dissociation kinetics. Results Herein, we developed a new NTnC-like GECI with enhanced fluorescence contrast and kinetics by replacing the mNeonGreen fluorescent subunit of the NTnC indicator with EYFP. Similar to NTnC, the developed indicator, named iYTnC2, has an inverted fluorescence response to Ca2+ (i.e. becoming dimmer with an increase of Ca2+ concentration). In the presence of Mg2+ ions, iYTnC2 demonstrated a 2.8-fold improved fluorescence contrast in vitro as compared with NTnC. The iYTnC2 indicator has lower brightness and pH-stability, but similar photostability as compared with NTnC in vitro. Stopped-flow fluorimetry studies revealed that iYTnC2 has 5-fold faster Ca2+ dissociation kinetics than NTnC. When compared with GCaMP6f GECI, iYTnC2 has up to 5.6-fold faster Ca2+ association kinetics and 1.7-fold slower dissociation kinetics. During calcium transients in cultured mammalian cells, iYTnC2 demonstrated a 2.7-fold higher fluorescence contrast as compared with that for the NTnC. iYTnC2 demonstrated a 4-fold larger response to Ca2+ transients in neuronal cultures than responses of NTnC. iYTnC2 response in neurons was additionally characterized using whole-cell patch clamp. Finally, we demonstrated that iYTnC2 can visualize neuronal activity in vivo in the hippocampus of freely moving mice using a nVista miniscope. Conclusions We demonstrate that expanding the family of NTnC-like calcium indicators is a promising strategy for the development of the next generation of GECIs with smaller molecule size and lower Ca2+ ions buffering capacity as compared with commonly used GECIs. Electronic supplementary material The online version of this article (10.1186/s12896-018-0417-2) contains supplementary material, which is available to authorized users. |
| Databáze: | OpenAIRE |
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