title: Gene expression profiling of pituitary melanotrope cells during their physiological activation.
abstract: The pituitary melanotrope cells of the amphibian Xenopus laevis are responsible for the production of the pigment-dispersing peptide α-melanophore-stimulating hormone, which allows the animal to adapt its skin color to its environment. During adaptation to a dark background the melanotrope cells undergo remarkable changes characterized by dramatic increases in cell size and secretory activity. In this study we performed microarray mRNA expression profiling to identify genes important to melanotrope activation and growth. We show a strong increase in the expression of the immediate early gene (IEG) c-Fos and of the brain-derived neurotrophic factor gene (BDNF). Furthermore, we demonstrate the involvement of another IEG in the adaptation process, Nur77, and conclude from in vitro experiments that the expression of both c-Fos and Nur77 are partially regulated by the adenylyl cyclase system and calcium ions. In addition, we found a steady up-regulation of Ras-like product during the adaptation process, possibly evoked by BDNF/TrkB signaling. Finally, the gene encoding the 105-kDa heat shock protein HSPh1 was transiently up-regulated in the course of black-background adaptation and a gene product homologous to ferritin (ferritin-like product) was >100-fold up-regulated in fully black-adapted animals. We suggest that these latter two genes are induced in response to cellular stress and that they may be involved in changing the mode of mRNA translation required to meet the increased demand for de novo protein synthesis. Together, our results show that microarray analysis is a valuable approach to identify the genes responsible for generating coordinated responses in physiologically activated cells.
authors.affiliation: Department of Cellular Animal Physiology, Donders Institute for Brain, Cognition and Behaviour, Centre for Neuroscience, Radboud University Nijmegen, Nijmegen, The Netherlands.
authors.forename: Miyuki
authors.initials: M
authors.lastname: Kuribara
authors.forename: Nick H M
authors.initials: NH
authors.lastname: van Bakel
authors.forename: Dyan
authors.initials: D
authors.lastname: Ramekers
authors.forename: Daan
authors.initials: D
authors.lastname: de Gouw
authors.forename: Roel
authors.initials: R
authors.lastname: Neijts
authors.forename: Eric W
authors.initials: EW
authors.lastname: Roubos
authors.forename: Wim J J M
authors.initials: WJ
authors.lastname: Scheenen
authors.forename: Gerard J M
authors.initials: GJ
authors.lastname: Martens
authors.forename: Bruce G
authors.initials: BG
authors.lastname: Jenks
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D020869:Gene Expression Profiling; D052717:Melanotrophs / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D014982:Xenopus laevis / Q000235:genetics*