Abstract
PurposeBioluminescence imaging is a powerful tool for studying gene expression and cell migration in intact living organisms. However, production of bioluminescence by cells transfected to express luciferase can be limited by the rate of plasma membrane transport of its substrate d-luciferin. We sought to identify a plasma membrane transporter for d-luciferin that could be expressed alongside luciferase to increase transmembrane flux of its substrate and thereby increase light output.ProceduresLuciferase-expressing cells were transfected with a lentivirus encoding the rat reno-hepatic organic anion transporter protein, Oatp1, which was identified as a potential transporter for d-luciferin. Light output was compared between cells expressing luciferase and those also expressing Oatp1.ResultsIn two cell lines and in mouse xenografts, co-expression of Oatp1 with luciferase increased light output by several fold, following addition of luciferin.ConclusionsThe increase in light output thus obtained will allow more sensitive detection of luciferase-expressing cells in vivo.Electronic supplementary materialThe online version of this article (doi:10.1007/s11307-014-0741-4) contains supplementary material, which is available to authorized users.
Highlights
Bioluminescence imaging is a versatile and widely available method for imaging gene expression and cell migration [1]
We found recently, when investigating Oatp1 as a potential gene reporter for use with magnetic resonance imaging (MRI) and single-photon emission computed tomography (SPECT) [36], that Oatp1 expression increased bioluminescence from cells expressing luciferase in vivo
Expression of Oatp1, in cells transduced with LV-PGK-SO, and of Timd2, in cells transduced with LV-PGK-ST, was confirmed by observations of fluorescence from the co-expressed mStrawberry and by detection of mStrawberry on western blots
Summary
Bioluminescence imaging is a versatile and widely available method for imaging gene expression and cell migration [1]. Detection of cells expressing firefly luciferase in vivo is limited by scattering and absorption of the emitted light by proteins such as hemoglobin [2]. While this is less of a problem at relatively superficial body locations, it can reduce both the sensitivity and resolution. Light output of luciferase-expressing mammalian cells was increased by reducing the number of membranes that luciferin had to cross to reach the enzyme. This was achieved by removing the peroxisomal targeting sequence found in the native
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