title: Prion protein mRNA expression in Xenopus laevis: no induction during melanotrope cell activation.
abstract: In mammals, the prion protein (PrP) is expressed in most tissues, but predominantly in neuronal tissues. Here, we investigated the temporal and spatial mRNA expression of PrP in the non-mammalian South African claw-toed frog Xenopus laevis. PrP transcripts were maternally expressed and detected throughout embryonic development, most strongly from neurulation onwards and including the tadpole stage. Microinjection of PrP mRNA into fertilized Xenopus eggs did not affect early embryonic development. In adult frogs, PrP mRNA expression was observed in all tissues examined, with high expression in brain, pituitary and testis. In Xenopus, the intermediate pituitary melanotrope cells are involved in background adaptation of the animal and produce high levels of the prohormone proopiomelanocortin (POMC) when the melanotrope cells are active (i.e. when the animal is black-adapted). Remarkably and in contrast to most secretory pathway components, PrP was not upregulated in the melanotropes of black-adapted animals, arguing against a direct role of this protein in POMC biosynthesis.
authors.affiliation: Department of Molecular Animal Physiology, Nijmegen Center for Molecular Life Sciences (NCMLS) and Institute for Neuroscience, Radboud University Nijmegen, Geert Grooteplein Zuid 28, 6525 GA Nijmegen, The Netherlands.
authors.forename: Jos W G
authors.initials: JW
authors.lastname: van Rosmalen
authors.forename: Jurriaan M
authors.initials: JM
authors.lastname: Born
authors.forename: Gerard J M
authors.initials: GJ
authors.lastname: Martens
mesh_terms: D000818:Animals; D004625:Embryo, Nonmammalian / Q000502:physiology*; D047108:Embryonic Development; D005260:Female; D018507:Gene Expression Regulation, Developmental; D010902:Pituitary Gland / Q000196:embryology; D011328:Prions / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics*
chemical_list: D011328:Prions; D012333:RNA, Messenger