title: Transgene-driven protein expression specific to the intermediate pituitary melanotrope cells of Xenopus laevis.
abstract: In the present study, we examined the amphibian Xenopus laevis as a model for stable transgenesis and in particular targeted transgene protein expression to the melanotrope cells in the intermediate pituitary. For this purpose, we have fused a Xenopus proopiomelanocortin (POMC) gene promoter fragment to the gene encoding the reporter green fluorescent protein (GFP). The transgene was integrated into the Xenopus genome as short concatemers at one to six different integration sites and at a total of one to approximately 20 copies. During early development the POMC gene promoter fragment gave rise to GFP expression in the total prosencephalon, whereas during further development expression became more restricted. In free-swimming stage 40 embryos, GFP was found to be primarily expressed in the melanotrope cells of the intermediate pituitary. Immunohistochemical analysis of cryosections of brains/pituitaries from juvenile transgenic frogs revealed the nearly exclusive expression of GFP in the intermediate pituitary. Metabolic labelling of intermediate and anterior pituitaries showed newly synthesized GFP protein to be indeed primarily expressed in the intermediate pituitary cells. Hence, stable Xenopus transgenesis with the POMC gene promoter is a powerful tool to study the physiological role of proteins in a well-defined neuroendocrine system and close to the in vivo situation.
authors.affiliation: Department of Molecular Animal Physiology, Nijmegen Centre for Molecular Life Sciences, University of Nijmegen, Geert Grooteplein Zuid 28, 6525GA, Nijmegen, The Netherlands.
authors.forename: Eric J R
authors.initials: EJ
authors.lastname: Jansen
authors.forename: Tjadine M
authors.initials: TM
authors.lastname: Holling
authors.forename: François
authors.initials: F
authors.lastname: van Herp
authors.forename: Gerard J M
authors.initials: GJ
authors.lastname: Martens
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics; D008856:Microscopy, Fluorescence; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism*; D011333:Pro-Opiomelanocortin / Q000235:genetics*; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000235:genetics; D014982:Xenopus laevis / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development
chemical_list: D018076:DNA, Complementary; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D011333:Pro-Opiomelanocortin