A macrophage colony-stimulating factor receptor-green fluorescent protein transgene is expressed throughout the mononuclear phagocyte system of the mouse.
The c-fms gene encodes the receptor for macrophage colony-stimulating factor (CSF-1). The gene is expressed selectively in the macrophage and trophoblast cell lineages. Previous studies have indicated that sequences in intron 2 control transcript elongation in tissue-specific and regulated expression of c-fms. In humans, an alternative promoter was implicated in expression of the gene in trophoblasts. We show that in mice, c-fms transcripts in trophoblasts initiate from multiple points within the 2-kilobase (kb) region flanking the first coding exon. A reporter gene construct containing 3.5 kb of 5' flanking sequence and the downstream intron 2 directed expression of enhanced green fluorescent protein (EGFP) to both trophoblasts and macrophages. EGFP was detected in trophoblasts from the earliest stage of implantation examined at embryonic day 7.5. During embryonic development, EGFP highlighted the large numbers of c-fms-positive macrophages, including those that originate from the yolk sac. In adult mice, EGFP location was consistent with known F4/80-positive macrophage populations, including Langerhans cells of the skin, and permitted convenient sorting of isolated tissue macrophages from disaggregated tissue. Expression of EGFP in transgenic mice was dependent on intron 2 as no lines with detectable EGFP expression were obtained where either all of intron 2 or a conserved enhancer element FIRE (the Fms intronic regulatory element) was removed. We have therefore defined the elements required to generate myeloid- and trophoblast-specific transgenes as well as a model system for the study of mononuclear phagocyte development and function.
Sasmono
R Tedjo
RT
Institute for Molecular Bioscience and ARC Special Research Centre for Functional and Applied Genomics, University of Queensland, Brisbane, Australia.
Oceandy
Delvac
D
Pollard
Jeffrey W
JW
Tong
Wei
W
Pavli
Paul
P
Wainwright
Brandon J
BJ
Ostrowski
Michael C
MC
Himes
S Roy
SR
Hume
David A
DA
D000818:Animals; D001483:Base Sequence; D004622:Embryo, Mammalian / Q000166:cytology; D005260:Female; D015870:Gene Expression; D017930:Genes, Reporter / Q000235:genetics; D049452:Green Fluorescent Proteins; D007438:Introns; D008164:Luminescent Proteins / Q000008:administration & dosage / Q000235:genetics* / Q000493:pharmacokinetics; D008198:Lymph Nodes / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D022423:Myeloid Cells / Q000378:metabolism; D010586:Phagocytes / Q000378:metabolism*; D010920:Placenta / Q000166:cytology; D011401:Promoter Regions, Genetic; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000008:administration & dosage / Q000235:genetics*; D014018:Tissue Distribution; D019076:Transgenes / Q000235:genetics*; D014327:Trophoblasts / Q000378:metabolism
D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins; D016186:Receptor, Macrophage Colony-Stimulating Factor