Molecular and Cell Biology Program and Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742, USA.
Endocrinology. 2013 Jan;154(1):308-19. doi: 10.1210/en.2012-1566. Epub 2012 Nov 16.
Glucocorticoids play a role in functional differentiation of pituitary somatotrophs and lactotrophs during embryogenesis. Ras-dva was identified as a gene regulated by anterior neural fold protein-1/homeobox expressed in embryonic stem cells-1, a transcription factor known to be critical in pituitary development, and has an expression profile in the chicken embryonic pituitary gland that is consistent with in vivo regulation by glucocorticoids. The objective of this study was to characterize expression and regulation of ras-dva mRNA in the developing chicken anterior pituitary. Pituitary ras-dva mRNA levels increased during embryogenesis to a maximum on embryonic day (e) 18 and then decreased and remained low or undetectable after hatch. Ras-dva expression was highly enriched in the pituitary gland on e18 relative to other tissues examined. Glucocorticoid treatment of pituitary cells from mid- and late-stage embryos rapidly increased ras-dva mRNA, suggesting it may be a direct transcriptional target of glucocorticoids. A reporter construct driven by 4 kb of the chicken ras-dva 5'-flanking region, containing six putative pituitary-specific transcription factor-1 (Pit-1) binding sites and two potential glucocorticoid receptor (GR) binding sites, was highly activated in embryonic pituitary cells and up-regulated by corticosterone. Mutagenesis of the most proximal Pit-1 site decreased promoter activity in chicken e11 pituitary cells, indicating regulation of ras-dva by Pit-1. However, mutating putative GR binding sites did not substantially reduce induction of ras-dva promoter activity by corticosterone, suggesting additional DNA elements within the 5'-flanking region are responsible for glucocorticoid regulation. We have identified ras-dva as a glucocorticoid-regulated gene that is likely expressed in cells of the Pit-1 lineage within the developing anterior pituitary gland.
糖皮质激素在胚胎发生过程中在垂体生长激素细胞和催乳素细胞的功能分化中发挥作用。 Ras-dva 被鉴定为受前神经褶蛋白-1/胚胎干细胞表达的同源盒-1 转录因子调节的基因,该转录因子已知在垂体发育中至关重要,并且在鸡胚胎垂体中的表达谱与体内糖皮质激素调节一致。本研究的目的是表征发育中的鸡前垂体中 ras-dva mRNA 的表达和调节。垂体 ras-dva mRNA 水平在胚胎发生过程中增加,在胚胎日 (e) 18 达到最大值,然后下降并保持低水平或无法检测。Ras-dva 在 e18 时在垂体中的表达相对于其他检查的组织高度富集。糖皮质激素处理从中期和晚期胚胎的垂体细胞可迅速增加 ras-dva mRNA,表明它可能是糖皮质激素的直接转录靶标。由包含六个潜在的垂体特异性转录因子-1 ( Pit-1 )结合位点和两个潜在的糖皮质激素受体 (GR) 结合位点的鸡 ras-dva 5 '侧翼区 4 kb 驱动的报告基因构建体在胚胎垂体细胞中高度激活,并被皮质酮上调。最近端 Pit-1 位点的突变降低了鸡 e11 垂体细胞中的启动子活性,表明 ras-dva 受 Pit-1 调节。然而,突变潜在的 GR 结合位点并没有显著降低皮质酮对 ras-dva 启动子活性的诱导,表明 5 '侧翼区中的其他 DNA 元件负责糖皮质激素调节。我们已经确定 ras-dva 是一种糖皮质激素调节基因,可能在发育中的前垂体中 Pit-1 谱系的细胞中表达。