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Baladi T, Nilsson JR, Gallud A, Celauro E, Gasse C, Levi-Acobas F, Sarac I, Hollenstein MR, Dahlén A, Esbjörner EK, Wilhelmsson LM. Stealth Fluorescence Labeling for Live Microscopy Imaging of mRNA Delivery. J Am Chem Soc 2021; 143:5413-5424. [PMID: 33797236 PMCID: PMC8154517 DOI: 10.1021/jacs.1c00014] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
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Methods for tracking
RNA inside living cells without perturbing
their natural interactions and functions are critical within biology
and, in particular, to facilitate studies of therapeutic RNA delivery.
We present a stealth labeling approach that can efficiently, and with
high fidelity, generate RNA transcripts, through enzymatic incorporation
of the triphosphate of tCO, a fluorescent tricyclic cytosine
analogue. We demonstrate this by incorporation of tCO in
up to 100% of the natural cytosine positions of a 1.2 kb mRNA encoding
for the histone H2B fused to GFP (H2B:GFP). Spectroscopic characterization
of this mRNA shows that the incorporation rate of tCO is
similar to cytosine, which allows for efficient labeling and controlled
tuning of labeling ratios for different applications. Using live cell
confocal microscopy and flow cytometry, we show that the tCO-labeled mRNA is efficiently translated into H2B:GFP inside human
cells. Hence, we not only develop the use of fluorescent base analogue
labeling of nucleic acids in live-cell microscopy but also, importantly,
show that the resulting transcript is translated into the correct
protein. Moreover, the spectral properties of our transcripts and
their translation product allow for their straightforward, simultaneous
visualization in live cells. Finally, we find that chemically transfected
tCO-labeled RNA, unlike a state-of-the-art fluorescently
labeled RNA, gives rise to expression of a similar amount of protein
as its natural counterpart, hence representing a methodology for studying
natural, unperturbed processing of mRNA used in RNA therapeutics and
in vaccines, like the ones developed against SARS-CoV-2.
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Affiliation(s)
- Tom Baladi
- Department of Chemistry and Chemical Engineering, Chemistry and Biochemistry, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.,Medicinal Chemistry, Research and Early Development, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Jesper R Nilsson
- Department of Chemistry and Chemical Engineering, Chemistry and Biochemistry, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
| | - Audrey Gallud
- Department of Biology and Biological Engineering, Chemical Biology, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
| | - Emanuele Celauro
- Department of Biology and Biological Engineering, Chemical Biology, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
| | - Cécile Gasse
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, 91057 Evry, France
| | - Fabienne Levi-Acobas
- Department of Structural Biology and Chemistry, Laboratory for Bioorganic Chemistry of Nucleic Acids, CNRS UMR3523, Institut Pasteur, 28, Rue du Docteur Roux, 75724 Paris CEDEX 15, France
| | - Ivo Sarac
- Department of Structural Biology and Chemistry, Laboratory for Bioorganic Chemistry of Nucleic Acids, CNRS UMR3523, Institut Pasteur, 28, Rue du Docteur Roux, 75724 Paris CEDEX 15, France
| | - Marcel R Hollenstein
- Department of Structural Biology and Chemistry, Laboratory for Bioorganic Chemistry of Nucleic Acids, CNRS UMR3523, Institut Pasteur, 28, Rue du Docteur Roux, 75724 Paris CEDEX 15, France
| | - Anders Dahlén
- Medicinal Chemistry, Research and Early Development, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Elin K Esbjörner
- Department of Biology and Biological Engineering, Chemical Biology, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
| | - L Marcus Wilhelmsson
- Department of Chemistry and Chemical Engineering, Chemistry and Biochemistry, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
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