A Csf1r-EGFP Transgene Provides a Novel Marker for Monocyte Subsets in Sheep.

Clare Pridans,Mary E Mcculloch,Kristin A Sauter,David A Hume,Gemma M Davis,Bruce Whitelaw,Rachel Young,Anna Raper,Elspeth Milne,Simon Lillico,Lucas Lefevre,Zofia M Lisowski,Yolanda Corripio-Miyar

doi:10.4049/jimmunol.1502336

Clare Pridans, Mary E Mcculloch + Show 11 more

Open Access

https://doi.org/10.4049/jimmunol.1502336

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Abstract

Expression of Csf1r in adults is restricted to cells of the macrophage lineage. Transgenic reporters based upon the Csf1r locus require inclusion of the highly conserved Fms-intronic regulatory element for expression. We have created Csf1r-EGFP transgenic sheep via lentiviral transgenesis of a construct containing elements of the mouse Fms-intronic regulatory element and Csf1r promoter. Committed bone marrow macrophage precursors and blood monocytes express EGFP in these animals. Sheep monocytes were divided into three populations, similar to classical, intermediate, and nonclassical monocytes in humans, based upon CD14 and CD16 expression. All expressed EGFP, with increased levels in the nonclassical subset. Because Csf1r expression coincides with the earliest commitment to the macrophage lineage, Csf1r-EGFP bone marrow provides a tool for studying the earliest events in myelopoiesis using the sheep as a model.

Highlights

Zygotes were injected with lentivirus (Csf1r:EGFP-Fms-intronic regulatory element (FIRE) [12]) and developed to blastocysts in vitro to create germline transgenic Csf1rEGFP sheep
MacGreen (Csf1r-EGFP) mice express the transgene in the same locations as the endogenous gene [4]
MacGreen (Csf1r-EGFP) mice express the transgene in the same locations as the endogenous gene, and expression is dependent on FIRE [4]