Tg(CLCNKB-EGFP)5-4Suc

An 11-kb human genomic DNA fragment that includes the promoter and first intron of the chloride channel Kb (CLCNKB) gene, extending from the 3' end of the CLCNKA gene to immediately upstream of the translation start site of CLCNKB, is joined to the 5' end of the enhanced green fluorescent protein (EGFP) cDNA, which is followed by the SV40 polyadenylation signal. EGFP fluorescence is observed in the kidney, localized to the thick, ascending limb of Henley's loop, the distal tubules, the connecting tubules and the intercalated cells - but not the aquaporin-2-expressing principal cells - of the collecting duct. Fluorescence is also seen in the inner ear, specifically in marginal cells of the striata vascularis and in dark cells of the vestibular labyrinth. Immunoblot analysis of multiple tissues with antibody versus EGFP also revealed very weak expression in heart and somewhat greater expression in brain, where fluorescence analysis localized it to the medullary reticular formation; per the authors, the last is the only site where expression of the transgene differs from that previously demonstrated for the endogenous mouse Clcnkb. (J:110245)