title: 'Green mice' display limitations in enhanced green fluorescent protein expression in retina and optic nerve cells.
abstract: Characterization of retinal cells, cell transplants and gene therapies may be helped by pre-labeled retinal cells, such as those transfected with vectors for green fluorescent protein expression. The aim of this study was to analyze retinal cells and optic nerve components from transgenic green mice (GM) with the 'enhanced' green fluorescent protein (EGFP) gene under the control of the CAG promoter (a chicken β-actin promoter and a cytomegalovirus enhancer). The structural analysis and electroretinography recordings showed a normal, healthy retina. Surprisingly, EGFP expression was not ubiquitously located in the retina and optic nerve. Epithelial cells, photoreceptors and bipolar cells presented high green fluorescence levels. In contrast, horizontal cells, specific amacrine cells and ganglion cells exhibited a null EGFP expression level. The synaptic terminals of rod bipolar cells displayed a high green fluorescence level when animals were kept in the dark. Immature retinas exhibited different EGFP expression patterns to those noted in adults. Axons and glial cells in the optic nerve revealed a specific regional EGFP expression pattern, which correlated with the presence of myelin. These results suggest that EGFP expression might be related to the activity of both the CAG promoter and β-actin in mature retinal neurons and oligodendrocytes. Moreover, EGFP expression might be regulated by light in both immature and adult animals. Since GM are used in numerous retina bioassays, it is essential to know the differential EGFP expression in order to select cells of interest for each study.
authors.affiliation: School of Medicine and Institute for Research in Neurological Disabilities (IDINE). University of Castilla-La Mancha, Albacete, Spain. elena.caminos@uclm.es.
authors.forename: Elena
authors.initials: E
authors.lastname: Caminos
authors.affiliation: School of Medicine and Regional Center for Biomedical Research (CRIB). University of Castilla-La Mancha, Albacete, Spain.
authors.forename: Cecilia F
authors.initials: CF
authors.lastname: Vaquero
authors.affiliation: Experimental Research Unit, University General Hospital of Albacete, Spain.
authors.forename: Dolores C
authors.initials: DC
authors.lastname: García-Olmo
mesh_terms: D000199:Actins / Q000235:genetics; D000818:Animals; D005455:Fluorescent Antibody Technique; D018014:Gene Transfer Techniques; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D018613:Microscopy, Confocal; D009900:Optic Nerve; D011401:Promoter Regions, Genetic / Q000235:genetics; D012160:Retina; D014162:Transfection
chemical_list: D000199:Actins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins