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See detailThe HMG-Box Transcription Factor Sox4b Is Required for Pituitary Expression of gata2a and Specification of Thyrotrope and Gonadotrope Cells in Zebrafish.
Quiroz O'Donova, Yobhana ULg; Lopez, Mauricio; Mavropoulos, A et al

in Molecular Endocrinology (2012), 26(6), 1014-1027

The pituitary is a complex gland comprising different cell types each secreting specific hormones. The extensive network of signaling molecules and transcription factors required for determination and ... [more ▼]

The pituitary is a complex gland comprising different cell types each secreting specific hormones. The extensive network of signaling molecules and transcription factors required for determination and terminal differentiation of specific cell types is still not fully understood. The SRY-like HMG-box (SOX) transcription factor Sox4 plays important roles in many developmental processes and has two homologs in zebrafish, Sox4a and Sox4b. We show that the sox4b gene is expressed in the pituitary anlagen starting at 24 h after fertilization (hpf) and later in the entire head region including the pituitary. At 48 hpf, sox4b mRNA colocalizes with that for TSH (tshbeta), glycoprotein subunit alpha (gsualpha), and the Zn finger transcription factor Gata2a. Loss of Sox4b function, using morpholino knockdown or expression of a dominant-negative Sox4 mutant, leads to a drastic decrease in tshbeta and gsualpha expression and reduced levels of gh, whereas other anterior pituitary gland markers including prl, slbeta, pomc, and lim3 are not affected. Sox4b is also required for expression of gata2a in the pituitary. Knockdown of gata2a leads to decreased tshbeta and gsualpha expression at 48 hpf, similar to sox4b morphants. Injection of gata2a mRNA into sox4b morphants rescued tshbeta and gsualpha expression in thyrotrope cells. Finally, sox4b or gata2a knockdown causes a significant decrease of gonadotropin expression (lhbeta and fshbeta) at 4 d after fertilization. In summary, our results indicate that Sox4b is expressed in zebrafish during pituitary development and plays a crucial role in the differentiation of thyrotrope and gonadotrope cells through induction of gata2a expression in the developing pituitary. [less ▲]

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See detailIdentification of novel prolactin releasing peptide receptors of Cyprinus carpio and Salmo salar expressed in the pituitary gland
Romero, A. P.; Montefusco, R.; Lopez, Mauricio et al

in Journal of Experimental Zoology. Part A, Comparative Experimental Biology (2006, February 01), 305A(2), 171

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See detailExpression of the somatolactin beta gene during zebrafish embryonic development
Lopez, Mauricio; Nica, G.; Motte, Patrick ULg et al

in Gene Expression Patterns (2006), 6(2), 156-161

Somatolactin (Sl) is a pituitary hormone closely related to prolactin (Prl) and growth hormone that was until now only found in various fish species. We isolated the cDNA coding for zebrafish Sl beta and ... [more ▼]

Somatolactin (Sl) is a pituitary hormone closely related to prolactin (Prl) and growth hormone that was until now only found in various fish species. We isolated the cDNA coding for zebrafish Sl beta and we identified the gene encoding this hormone. We also obtained a 1 kb genomic fragment corresponding to the sl beta upstream promoter region. Furthermore, the sl beta expression pattern was examined during zebrafish embryogenesis using whole-mount in situ hybridization. Sl beta mRNA is first detected in a single cell at the anterior border of the neural plate starting at 23 h post fertilization (hpf). Sl beta-expressing cells also express the transcription factor pit1 and are located close to prl-expressing cells. Using combined fluorescent in situ hybridization, we show that sl beta- and prl-expressing cells are clearly distinct at 29 hpf. Starting at 30 hpf, the number of sl beta positive cells increases and their location becomes more clearly distinct from lactotrope cells, in a more posterior position. At later stages (48 hpf), sl beta expression was observed posterior to growth hormone expression, again in a distinct cell type. We show that zebrafish mutants aal, as well as mutants in the pit1 gene, are deficient in sl beta expression. In conclusion, sl beta expression defines a new, additional cell type in zebrafish pituitary that depends on pit1 and aal for its differentiation. (C) 2005 Elsevier B.V. All rights reserved. [less ▲]

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