title: Independent and dynamic reallocation of pitx gene expression during vertebrate evolution, with emphasis on fish pituitary development.
abstract: Several transcription regulators play key roles during pituitary morphogenesis. Well known intrinsic signals of the adenohypophysis such as the K(50)paired-like homeodomain proteins regulate commitment, proliferation, differential specification and maintenance of adenohypophyseal cells. We have cloned and successively characterized the mRNA localization of three pitx gene-pairs and three of their splice variants in salmon, pitx1alpha, pitx1beta; pitx2alpha, pitx2beta; pitx3alpha, pitx3beta; pitx1alphash, pitx1betash and pitx2alphaA. The high level of conservation between the pitx paralog-pairs indicates that they likely arose from lineage-specific genome duplication. We also report the isolation of a pitx1 gene in zebrafish. Comparative ISH studies of zebrafish, salmon and mouse pitx genes indicate both conservation and divergence of spatial expression domains in vertebrates. Significant differences were observed between the expressions of pitx orthologs during pituitary development. We suggest that the ancestral pituitary expression at early and late events of morphogenesis is preserved in different species through complementary shuffling of expression between the distinct pitx members of the family. Moreover, ISH analysis of the pitx salmon repertoire shows rapid evolution in this lineage, differences in spatio-temporal expression are observed between gene duplicates.
authors.affiliation: Sars, International Centre for Marine Molecular Biology, University of Bergen, High Technology Centre, Thormoehlensgt 55, N-5008 Bergen, Norway.
authors.forename: Anna R
authors.initials: AR
authors.lastname: Angotzi
authors.forename: Kari Merete
authors.initials: KM
authors.lastname: Ersland
authors.forename: Sutada
authors.initials: S
authors.lastname: Mungpakdee
authors.forename: Sigurd
authors.initials: S
authors.lastname: Stefansson
authors.forename: Daniel
authors.initials: D
authors.lastname: Chourrout
mesh_terms: D000818:Animals; D005075:Biological Evolution; D005399:Fishes / Q000196:embryology / Q000235:genetics*; D020440:Gene Duplication; D015870:Gene Expression; D009024:Morphogenesis; D010802:Phylogeny; D010902:Pituitary Gland / Q000196:embryology* / Q000378:metabolism; D012474:Salmon; D014157:Transcription Factors / Q000235:genetics; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000235:genetics
chemical_list: C530967:Pitx1 protein, zebrafish; D014157:Transcription Factors; D029961:Zebrafish Proteins