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Wnt signaling in estrogen-induced lactotroph proliferation.
- Source :
-
Journal of cell science [J Cell Sci] 2011 Feb 15; Vol. 124 (Pt 4), pp. 540-7. Date of Electronic Publication: 2011 Jan 18. - Publication Year :
- 2011
-
Abstract
- Prolactinomas are the most common type of functioning pituitary adenoma in humans, but the control of lactotroph proliferation remains unclear. Here, using microarray analysis, we show that estrogen treatment increased expression of Wnt4 mRNA in adult Fischer rat pituitary tissue. Dual immunofluorescence analysis revealed that Wnt4 expression was not confined to lactotrophs, but that it was expressed in all anterior pituitary cell types. Estradiol induced proliferation in the somatolactotroph GH3 cell line, in parallel with Wnt4 mRNA and protein induction. A reporter gene assay for TCF- and LEF-dependent transcription revealed that there was no activation of the canonical Wnt pathway in GH3 cells upon stimulation with Wnt-conditioned culture medium or coexpression of constitutively active mutant β-catenin. Expression of β-catenin in both GH3 cells and normal rat anterior pituitary cells was restricted to the cell membrane and was unaltered by treatment with estradiol, with no nuclear β-catenin being detected under any of the conditions tested. We show for the first time that Wnt4 affects non-canonical signaling in the pituitary by inhibiting Ca(2+) oscillations in GH3 cells, although the downstream effects are as yet unknown. In summary, Wnt4 is expressed in the adult pituitary gland, and its expression is increased by estrogen exposure, suggesting that its involvement in adult tissue plasticity is likely to involve β-catenin-independent signaling pathways.
- Subjects :
- Animals
Calcium metabolism
Cell Line, Tumor
Female
Gene Expression Regulation
Humans
Rats
Rats, Inbred F344
Wnt Proteins genetics
Wnt4 Protein
beta Catenin genetics
beta Catenin metabolism
Cell Proliferation
Estrogens metabolism
Lactotrophs cytology
Lactotrophs metabolism
Signal Transduction
Wnt Proteins metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1477-9137
- Volume :
- 124
- Issue :
- Pt 4
- Database :
- MEDLINE
- Journal :
- Journal of cell science
- Publication Type :
- Academic Journal
- Accession number :
- 21245194
- Full Text :
- https://doi.org/10.1242/jcs.078642