Generation of transgenic mice with the optimized opt_sgp130Fc cDNA. (A) cDNA-optimization and intron localization positively influence sgp130Fc protein accumulation in transiently transfected HepG2-cells. The constructs differ in (1) position of the intron (upstream/downstream of the transgene) and (2) optimization status (wild-type [WT]/optimized cDNA). 1. pTZ-PEPCK-sgp130Fc-βglob.intron, 2. pTZ-PEPCK-βglob.intron-sgp130Fc, 3. pTZ-PEPCK-opt_sgp130Fc-βglob.intron, 4. pTZ-PEPCK-βglob.intron-opt_sgp130Fc. sgp130Fc was precipitated from cell supernatant with Protein A sepharose and detected by immunoblotting. (B) opt_sgp130Fc construct injected into fertilized mouse eggs (pTZ-PEPCK-βglob.intron-opt_sgp130Fc). (C) sgp130Fc from serum of founder animals was precipitated from cell supernatant with Protein A sepharose and detected by immunoblotting. * indicates an unspecific band. A vertical line has been inserted to indicate where a gel lane was cut. This gel came from one experiment; irrelevant lanes have been cut out. (D) Expression of sgp130Fc protein in opt_sgp130Fc transgenic mice. Serum was prepared from 8- to 10-week-old WT mice, heterozygous (+/−) and homozygous (+/+) transgenic mice of the lines opt2 and opt3 and sgp130Fc protein levels were determined by ELISA. Data represent mean values plus or minus SD (n) mice per group.