Abstract
Progress in our understanding of the molecular cellular basis of immune function depends on our ability to track and image individual immune cells in vivo. To this end, the development of mouse models over-expressing various fluorescent proteins would represent an important experimental tool. In this report, we describe the generation and characterization of pUbi-mRFP-1 transgenic mice, in which the monomeric form of red fluorescent protein is ubiquitously expressed in various lymphoid and non-lymphoid tissues. Our newly generated pUbi-mRFP-1 mice are unique among previously reported mice transgenic for red fluorescent proteins because a single-copy of the mRFP-1 transgene driven by human ubiquitin C promoter has been integrated by homologous recombination into the mouse hypoxanthine-guanine phosphoribosyltransferase (HPRT) locus. We show that the distinct and uniform levels of mRFP-1 expression allow easy identification of transferred hematopoetic cells by FACS analysis or confocal microscopy, even when the transferred population represents a very small proportion in the target organ. Also, even in long-term experiments, we have seen no evidence of rejection of transferred pUbi-mRFP-1 lymphocytes. Due to its far-red spectrum, mRFP-1 is an ideal partner for dual imaging with green fluorescent proteins. We observed a good visual separation between donor lymphocytes derived from either mRFP-1 or eGFP transgenic mice in recipient animals. Our study suggests that the new pUbi-mRFP-1 transgenic mouse strain offers new opportunities for studying cellular interactions and migratory patterns of cells, especially for dual imaging of different cell types. In summary, our results demonstrate that a controlled strategy of transgenesis provides an effective means of ubiquitously expressing fluorescent proteins in vivo.
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Acknowledgements
We are grateful for the McGill Flow Cytometry Facilities for their effort in cell sorting. We would like to thank the meticulous assistance provided by Patrick Bastedo and Dr. Gregory T. Marczinsky, as well as the technical support of the animal care staff at the McGill Animal Center. We acknowledge the financial support of the Canadian Institutes for Health Research (CIHR MOP 67211) and Canadian Foundation for Innovation. E.Y. is a recipient of a fellowship from the CIHR Training Grant in Neuroinflammation. C.A.P is the recipient of the Canada Research Chair in Regulatory Lymphocytes of the Immune System.
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Yurchenko, E., Friedman, H., Hay, V. et al. Ubiquitous expression of mRFP-1 in vivo by site-directed transgenesis. Transgenic Res 16, 29–40 (2007). https://doi.org/10.1007/s11248-006-9030-6
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DOI: https://doi.org/10.1007/s11248-006-9030-6