A sensitive soma-localized red fluorescent calcium indicator for in vivo imaging of neuronal populations at single-cell resolution
Year: 2025
Type: article
Abstract: Recent advancements in genetically encoded calcium indicators, particularly those based on green fluorescent proteins, have optimized their performance for monitoring neuronal activities in a variety of model organisms. However, progress in developing red-shifted GECIs, despite their advantages over green indicators, has been slower, resulting in fewer options for end users. In this study, we explored topological inversion and soma-targeting strategies, which are complementary to conventional mutagenesis, to re-engineer a red genetically encoded calcium indicator, FRCaMP, for enhanced in vivo performance. The resulting sensors, FRCaMPi and soma-targeted FRCaMPi (SomaFRCaMPi), exhibit up to 2-fold higher dynamic range and peak ΔF/F0 per single AP compared to widely used jRGECO1a in neurons both in culture and in vivo. Compared to jRGECO1a and FRCaMPi, SomaFRCaMPi reduces erroneous correlation of neuronal activity in the brains of mice and zebrafish by two- to 4-fold due to diminished neuropil contamination without compromising the signal-to-noise ratio. Under wide-field imaging in primary somatosensory and visual cortices in mice with high labeling density (80-90%), SomaFRCaMPi exhibits up to 40% higher SNR and decreased artifactual correlation across neurons. Altogether, SomaFRCaMPi improves the accuracy and scale of neuronal activity imaging at single-neuron resolution in densely labeled brain tissues due to a 2-3-fold enhanced automated neuronal segmentation, 50% higher fraction of responsive cells, up to 2-fold higher SNR compared to jRGECO1a. Our findings highlight the potential of SomaFRCaMPi, comparable to the most sensitive soma-targeted GCaMP, for precise spatial recording of neuronal populations using popular imaging modalities in model organisms such as zebrafish and mice.
Source: PLoS Biology
Authors: Shihao Zhou, Qiyu Zhu, Minho Eom, Shilin Fang, Oksana M. Subach, Chen Ran, Jonnathan Singh Alvarado, Praneel S. Sunkavalli, Yuanping Dong, Yangdong Wang, Jiewen Hu, Hanbin Zhang, Zhiyuan Wang, Xiaoting Sun, Tao Yang, Yu Mu, Young-Gyu Yoon, Zengcai V. Guo, Fedor V. Subach, Kiryl D. Piatkevich
Institutions: Westlake University, Center for Life Sciences, Tsinghua University, Korea Advanced Institute of Science and Technology, Chinese Academy of Sciences, Center for Excellence in Brain Science and Intelligence Technology, State Key Laboratory of Neuroscience, Kurchatov Institute, Scripps Research Institute, Beth Israel Deaconess Medical Center, Harvard University, University of Chinese Academy of Sciences
Language: English
Subfield: Biophysics
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $5,500
Funders: Westlake University, National Natural Science Foundation of China, Beijing Normal University, Tsinghua University, Ministry of Science and Higher Education of the Russian Federation, National Institutes of Health, National Eye Institute, National Institute of Diabetes and Digestive and Kidney Diseases
OpenAlex ID: W4409912500