Mouse CSF-1 genomic structure, the TgCS transgene construct, and CSF-1 expression in Csf1^op/Csf1op; TgCS/+ mice. (A) The genomic organization of the mouse CSF-1 gene constructed from the sequences of cDNA encoding full-length mouse CSF-1 (M21952), csCSF-1 (BC025593), and the genomic sequence of mouse chromosome 3 published in National Center for Biotechnology Information GenBank (NT_039239). The positions of 3 major proteolytic cleavage sites (▿), the unique glycosaminoglycan addition site (♦), and the transmembrane domain (TM) are shown in the coding sequence of full-length CSF-1. To construct the TgCS transgene, the exon 2-8 fragment of the cDNA encoding the csCSF-1 possessing a truncated exon 6 was cloned downstream of the 3.13-kb promoter and first intron fragment and an additional hGH polyA signal fragment was added at the 3′ end of the cDNA. The fragment of exon 6 deleted in the TgCS transgene encodes the peptide fragment containing the major proteolytic cleavage sites and the glycosaminoglycan addition site. BlgII and EcoRI were used to linearize TgCS plasmid DNA for microinjection. P1 and P2 were primers for PCR genotyping.³²  (B) Serum CSF-1 concentrations of Csf1op/Csf1op; TgCS/+ mice and their controls measured by RIA. Means ± SD (n ≥ 5 mice). (C) Surface CSF-1 expression on skin fibroblasts derived from the mice of the indicated genotypes was measured by flow cytometry following staining with anti-CSF-1 antibodies. (D) The CSF-1 concentrations in culture supernatants of skin fibroblasts with the indicated genotypes were determined by RIA. Means ± SD of 3 cultures.