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Updated: Jun 16, 2026
Imaging Ca2+ Dynamics in Cone Photoreceptor Axon Terminals of the Mouse Retina
Published on: May 6, 2015
A photoprotein in mouse embryonic stem cells measures Ca2+ mobilization in cells and in animals
Silvia Cainarca1, Simone Fenu, Cinzia Ferri
1Axxam SpA, Milan, Italy. silvia.cainarca.sc@axxam.com
Abstract:
Exogenous expression of pharmacological targets in transformed cell lines has been the traditional platform for high throughput screening of small molecules. However, exogenous expression in these cells is limited by aberrant dosage, or its toxicity, the potential lack of interaction partners, and alterations to physiology due to transformation itself. Instead, primary cells or cells differentiated from precursors are more physiological, but less amenable to exogenous expression of reporter systems. To overcome this challenge, we stably expressed c-Photina, a Ca(2+)-sensitive photoprotein, driven by a ubiquitous promoter in a mouse embryonic stem (mES) cell line. The same embryonic stem cell line was also used to generate a transgenic mouse that expresses c-Photina in most tissues. We show here that these cells and mice provide an efficient source of primary cells, cells differentiated from mES cells, including cardiomyocytes, neurons, astrocytes, macrophages, endothelial cells, pancreatic islet cells, stably and robustly expressing c-Photina, and may be exploited for miniaturized high throughput screening. Moreover, we provide evidence that the transgenic mice may be suitable for ex-vivo bioimaging studies in both cells and tissues.
Insights
Researchers developed a novel method using a calcium-sensitive photoprotein (c-Photina) in mouse stem cells and transgenic mice. This enables efficient high-throughput screening and bioimaging of various primary cell types.
Area of Science:
- Biotechnology
- Molecular Biology
- Cell Biology
Background:
- Traditional high-throughput screening uses transformed cell lines with limitations like aberrant dosage and altered physiology.
- Primary cells offer physiological relevance but are difficult to engineer for reporter systems.
Purpose of the Study:
- To develop a robust system for reporter gene expression in physiological cells for drug discovery.
- To create a platform for miniaturized high-throughput screening and ex-vivo bioimaging.
Main Methods:
- Stable expression of c-Photina, a Ca(2+)-sensitive photoprotein, in mouse embryonic stem (mES) cells using a ubiquitous promoter.
- Generation of transgenic mice from these engineered mES cells to express c-Photina ubiquitously.
- Differentiation of mES cells into various primary cell types (cardiomyocytes, neurons, etc.) for functional assays.
Main Results:
- Successfully generated mES cell lines and transgenic mice stably expressing c-Photina.
- Demonstrated robust c-Photina expression in diverse differentiated cell types including cardiomyocytes, neurons, astrocytes, macrophages, endothelial cells, and pancreatic islet cells.
- Validated the utility of these cells and tissues for miniaturized high-throughput screening and ex-vivo bioimaging.
Conclusions:
- Engineered mES cells and transgenic mice provide a versatile platform for physiological cell-based assays.
- This system overcomes limitations of traditional screening methods, enabling efficient drug discovery and bioimaging applications.
- The c-Photina reporter system offers a promising tool for studying cellular function in a more physiologically relevant context.
