Optimized ratiometric calcium sensors for functional in vivo imaging of neurons and T lymphocytes.
Thomas ThestrupJulia LitzlbauerIngo BartholomäusMarsilius MuesLuigi RussoHod DanaYuri KovalchukYajie LiangGeorgios KalamakisYvonne LaukatStefan BeckerGregor WitteAnselm GeigerTaylor AllenLawrence C RomeTsai-Wen ChenDouglas S KimOlga GaraschukChristian GriesingerOliver GriesbeckPublished in: Nature methods (2014)
The quality of genetically encoded calcium indicators (GECIs) has improved dramatically in recent years, but high-performing ratiometric indicators are still rare. Here we describe a series of fluorescence resonance energy transfer (FRET)-based calcium biosensors with a reduced number of calcium binding sites per sensor. These 'Twitch' sensors are based on the C-terminal domain of Opsanus troponin C. Their FRET responses were optimized by a large-scale functional screen in bacterial colonies, refined by a secondary screen in rat hippocampal neuron cultures. We tested the in vivo performance of the most sensitive variants in the brain and lymph nodes of mice. The sensitivity of the Twitch sensors matched that of synthetic calcium dyes and allowed visualization of tonic action potential firing in neurons and high resolution functional tracking of T lymphocytes. Given their ratiometric readout, their brightness, large dynamic range and linear response properties, Twitch sensors represent versatile tools for neuroscience and immunology.
Keyphrases
- energy transfer
- quantum dots
- high resolution
- fluorescent probe
- living cells
- low cost
- lymph node
- single molecule
- sensitive detection
- white matter
- metabolic syndrome
- oxidative stress
- spinal cord injury
- copy number
- hydrogen peroxide
- dna methylation
- quality improvement
- mass spectrometry
- brain injury
- insulin resistance
- risk assessment
- photodynamic therapy
- genome wide
- high speed
- subarachnoid hemorrhage
- neural network