Improved calcium imaging in transgenic mice expressing a troponin C-based biosensor

Area of Science:

• Neuroscience
• Molecular Biology
• Biochemistry

Background:

• Fluorescent Ca(2+) indicator proteins (FCIPs) are crucial for real-time monitoring of intracellular calcium dynamics.
• Existing FCIPs have limitations in sensitivity and specificity for certain cellular applications.
• Understanding neuronal circuit function requires precise tools to measure calcium signaling.

Purpose of the Study:

• To develop and characterize a novel troponin C (TnC)-based fluorescent biosensor for improved calcium ion (Ca(2+)) detection.
• To evaluate the biosensor's performance in terms of Ca(2+) sensitivity and expression patterns in vivo.
• To demonstrate the utility of the biosensor for advanced imaging of neuronal activity in live animals.

Main Methods:

• Generation of transgenic mouse lines expressing a TnC-based Ca(2+) biosensor.
• In vitro characterization of the biosensor's Ca(2+) sensitivity and dynamic range.
• In vivo two-photon Ca(2+) imaging of neuronal activity in distinct neurons and their dendrites.

Main Results:

• The TnC-based biosensor exhibits widespread expression in neurons.
• The biosensor demonstrates enhanced Ca(2+) sensitivity compared to existing indicators, both in vitro and in vivo.
• Successful in vivo two-photon imaging of Ca(2+) signals in individual neurons and their dendritic processes was achieved.

Conclusions:

• A novel and highly sensitive TnC-based FCIP biosensor has been developed.
• This biosensor facilitates advanced in vivo Ca(2+) imaging in neuronal circuits.
• The tool provides new opportunities for structure-function analysis of intact neural networks.