title: Activated phenotype of the pituitary stem/progenitor cell compartment during the early-postnatal maturation phase of the gland.
abstract: The rodent pituitary gland undergoes prominent maturation during the first weeks after birth, including a well-known increase in hormone-producing cells. In the past, it has frequently been postulated that stem cells are involved in this early-postnatal growth phase. This hypothesis can now be explored, as pituitary stem/progenitor cells were recently identified. Here, we analyzed in detail the mouse pituitary stem/progenitor cell compartment during the first postnatal week and compared its phenotype with that at the end of the first pituitary growth wave and at adult age. Stem/progenitor cells, as assessed by both side population phenotype and Sox2 expression, are most abundant at birth and gradually decline toward adulthood. The neonatal stem/progenitor cell compartment is clearly more active in terms of proliferation, stemness gene expression, and stem cell-related functional activity including sphere formation and multipotent differentiation capacity. In situ examination of pituitary sections reveals peculiar topographical arrangements of Sox2+ cells, again more pronounced at the neonatal age. Sox2+ cells are particularly prominent at the wedge junction of the anterior and intermediate lobe, and clusters of Sox2+ cells appear to sprout from this and other cleft-lining, marginal zone regions. Colocalization of Sox2 and hormones is generally not observed, thus suggesting mutually exclusive expression. Together, the neonatal pituitary stem/progenitor cell compartment displays an activated phenotype, thus supporting its involvement in the early-postnatal maturation process of the gland.
authors.affiliation: Laboratory of Tissue Plasticity, Department of Molecular Cell Biology, University of Leuven (K.U. Leuven), Leuven, Belgium.
authors.forename: Lies
authors.initials: L
authors.lastname: Gremeaux
authors.forename: Qiuli
authors.initials: Q
authors.lastname: Fu
authors.forename: Jianghai
authors.initials: J
authors.lastname: Chen
authors.forename: Hugo
authors.initials: H
authors.lastname: Vankelecom
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002454:Cell Differentiation / Q000235:genetics; D002467:Cell Nucleus / Q000378:metabolism; D049109:Cell Proliferation; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D008297:Male; D051379:Mice; D018613:Microscopy, Confocal; D010641:Phenotype; D010903:Pituitary Gland, Anterior / Q000166:cytology* / Q000196:embryology / Q000254:growth & development; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055748:SOXB1 Transcription Factors / Q000235:genetics / Q000378:metabolism; D055153:Stem Cell Niche / Q000235:genetics*; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism*; D013997:Time Factors
chemical_list: D055748:SOXB1 Transcription Factors; C527783:Sox2 protein, mouse