title: A macrophage colony-stimulating factor receptor-green fluorescent protein transgene is expressed throughout the mononuclear phagocyte system of the mouse.
abstract: 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.
authors.affiliation: Institute for Molecular Bioscience and ARC Special Research Centre for Functional and Applied Genomics, University of Queensland, Brisbane, Australia.
authors.forename: R Tedjo
authors.initials: RT
authors.lastname: Sasmono
authors.forename: Delvac
authors.initials: D
authors.lastname: Oceandy
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Pollard
authors.forename: Wei
authors.initials: W
authors.lastname: Tong
authors.forename: Paul
authors.initials: P
authors.lastname: Pavli
authors.forename: Brandon J
authors.initials: BJ
authors.lastname: Wainwright
authors.forename: Michael C
authors.initials: MC
authors.lastname: Ostrowski
authors.forename: S Roy
authors.initials: SR
authors.lastname: Himes
authors.forename: David A
authors.initials: DA
authors.lastname: Hume
mesh_terms: 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
chemical_list: D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins; D016186:Receptor, Macrophage Colony-Stimulating Factor