Nuclear Reporter Genes
For noninvasive nuclear imaging
Nuclear reporter genes are proteins that trap various radiotracers in the cells in which they are expressed. Most nuclear reporters, including the sodium iodide symporter (NIS), human norepinephrine transporter (hNET), human somatostatin receptor 2 (hSSTR2), and human dopamine receptor D2 (hDRD2), are transporters or receptors that directly mediate uptake of specific radiotracers into the cells. These reporter proteins are endogenously expressed in various human tissues, where they have a diverse range of important functions. Another nuclear reporter, Herpes Simplex Virus Thymidine Kinase (HSVTK), is an enzyme that catalyzes the phosphorylation of intracellular radiolabeled pro-drugs so that they are no longer membrane permeable and are trapped in the cell. For imaging studies, target cells and viruses can be engineered to express high levels of any of the recombinant nuclear reporter proteins.
Because they concentrate radiotracers, nuclear reporters can be used to noninvasively track cells in vivo through nuclear imaging. Imaging with nuclear reporters offers several key advantages: it produces high-resolution 3D images that are fully quantitative, it is translational from small to large animals as well as humans (depending on the reporter), and it can be used for longitudinal imaging studies as species-specific versions exist for some of the reporters.
For more detailed information about our favorite reporter, NIS, check out our Discover NIS page.
Imaging nuclear reporter genes
How to use nuclear reporters for imaging
Reagents: Nuclear reporters trap a variety of different radiotracers. The following table indicates which radiotracers are compatible with each reporter.
Reporter SPECT radiotracers PET radiotracers NIS
Equipment: SPECT or PET machines can be used to detect radiotracer signal and biodistribution of nuclear reporter-expressing cells or viruses. Combining SPECT or PET with computed tomography (CT) or magnetic resonance (MR) imaging gives the most informative results, as images can be co-registered to give anatomical localization of the radiotracer signal.
Additional considerations: Most of the nuclear reporters are endogenously expressed in certain organs or tissues. When selecting a nuclear reporter, the imaging target site should be considered. Additionally, not all radiotracers may effectively reach certain target tissues/organs. See the chart in the “When to use nuclear reporters” tab for more information.
When to use nuclear reporter genes
Nuclear reporter genes are well suited for longitudinal, noninvasive imaging studies in regenerative medicine, gene therapy, oncology, and oncolytic virotherapy, where they can be used to track the biodistribution of cell/virus therapies or the destruction of tumors. Nuclear reporters can be used for small or large animal imaging and most are translatable to the clinic. The following chart gives general guidelines for organs/tissues that are suitable for imaging with the different reporters:
Reporter Endogenously expression Recommended for … Not recommended for … NIS Thyroid, stomach, mammary glands, salivary glands Heart, lungs, liver, kidneys, orthopedics (joints, bone), immune cells Brain, CNS hNET CNS and PNS Brain, CNS, immune cells Liver, kidneys, intestines hSSTR2 Cerebrum, kidney Tracking oncolytic viruses Kidneys, pancreas, pituitary gland HSVTK None Heart, muscle, immune cells Liver, intestines hDRD2 Striatal-Nigral System of the brain Brain and CNS Liver, kidneys, intestinesCan’t figure out which reporter is best for you? Check out our page on Choosing a Reporter for helpful considerations and comparisons.