Table 1 Popular reporter transgenes
From: The regulation of reporter transgene expression for diverse biological imaging applications
Reporter | Modality | Mechanism | Advantages | Disadvantages | Reviewed |
|---|---|---|---|---|---|
Firefly or Renilla luciferase and variants | Optical: Bioluminescence | Enzymatic | Excellent sensitivity, low cost, high throughput. Large number of variant enzymes and custom-made substrates available | Signal is scattered and absorbed by overlying tissue. Relatively low image resolution, signal is surface-weighted | |
Green fluorescent protein (GFP) and variants | Optical: Fluorescence (whole body) | Photoexcitation followed by high quantum yield emission | Relatively low cost, large number of spectrally-distinguishable variants available | Spectrally-dependent tissue penetration, autofluorescence can affect SNR | |
Optical: Fluorescence (intravital microscopy) | Photoexcitation followed by high quantum yield emission | Large number of spectrally-distinguishable variants available. Up to intracellular spatial resolution, up to millisecond temporal resolution | Sub-millimeter tissue depth and limited field-of-view. Some studies involving tissue-windows limit period of assessment. | ||
Optical: Fluorescence (light sheet) | Photoexcitation followed by high quantum yield emission | Imaging of whole organs or body | Requires optically cleared tissue | ||
Optical: Fluorescence (fusion proteins for chemical sensing and optical readout) | Photoexcitation followed by high quantum yield emission | Quantitative imaging corresponds to changes in signaling/chemicals. In vitro and in vivo application | Poor signal-to-noise ratio can make interpretation difficult. Spatial resolution can be limited. | ||
Sodium iodide symporter (NIS), Herpes simplex virus – tyrosine kinase (HSV-tk) | PET/SPECT | Transporter, or enzymatic | Quantitative, excellent sensitivity, tissue-depth independent | Imaging probes are radioactive, cost can be high | |
Ferritin, Organic anion-transporting polypeptides (OATP) | MRI | Iron sequestration, or transporter | Excellent image resolution, signal independent of tissue-depth | Signal enhancement can be modest relative to other reporters, relatively expensive modality | |
Acoustic reporter genes (ARG) | Ultrasound | Gas-filled vesicle | Excellent image resolution, relatively low cost | Transgene is large and multi-component, limiting some gene delivery options. US not well-suited for whole-body scans | |
Tyrosinase, near-infrared fluorescent proteins (NIR FP) | Photoacoustic | Photon quenching, or photoexcitation followed by low quantum yield emission | Uniquely, both reasonable image resolution and sensitivity | Spatial resolution worsens with tissue penetration depth |
