Luque Raul M, Amargo Geraldine, Ishii Shinya, Lobe Corrinne, Franks Roberta, Kiyokawa Hiro, Kineman Rhonda D
Department of Medicine, University of Illinois, Chicago, Illinois 60612, USA.
Endocrinology. 2007 May;148(5):1946-53. doi: 10.1210/en.2006-1542. Epub 2007 Feb 8.
This report describes the development and validation of the rGHp-Cre transgenic mouse that allows for selective Cre-mediated recombination of loxP-modified alleles in the GH-producing cells of the anterior pituitary. Initial screening of the rGHp-Cre parental line showed Cre mRNA was specifically expressed in the anterior pituitary gland of adult Cre+/- mice and cephalic extracts of e17 Cre+/- fetuses. Heterozygote rGHp-Cre transgenic mice were crossbred with Z/AP reporter mice to generate Cre+/-,Z/AP+/- offspring. In this model system, the GH promoter-driven, Cre-mediated recombination of the Z/AP reporter leads to human placental alkaline phosphatase (hPLAP) expression that serves to mark cells that currently produce GH, in addition to cells that would have differentiated from GH cells but currently do not express the GH gene. Double immunocytochemistry of adult male and female Cre+/-,Z/AP+/- pituitary cells revealed the majority (approximately 99%) of GH-producing cells of the anterior pituitary also expressed hPLAP, whereas ACTH-, TSH-, and LH-producing cells were negative for hPLAP, confirming previous reports that corticotropes, thyrotropes, and gonadotropes develop independently of the somatotrope lineage. A small subset (approximately 10%) of the prolactin-producing cells was positive for hPLAP, consistent with previous reports showing lactotropes can arise from somatotropes during pituitary development. However, the fact that 90% of prolactin-producing cells were negative for hPLAP suggests that the majority of lactotropes in the adult mouse pituitary gland develop independently of the somatotrope lineage. In addition to developmental studies, the rGHp-Cre transgenic mouse will provide a versatile tool to study the role of a variety of genes in somatotrope function and neoplastic transformation.
本报告描述了rGHp-Cre转基因小鼠的构建及验证，该小鼠可在前脑垂体产生生长激素（GH）的细胞中实现loxP修饰等位基因的选择性Cre介导重组。对rGHp-Cre亲本品系的初步筛选显示，Cre mRNA在成年Cre+/-小鼠的前脑垂体以及E17 Cre+/-胎儿的头部提取物中特异性表达。将杂合子rGHp-Cre转基因小鼠与Z/AP报告基因小鼠杂交，以产生Cre+/-,Z/AP+/-后代。在该模型系统中，GH启动子驱动的Z/AP报告基因的Cre介导重组导致人胎盘碱性磷酸酶（hPLAP）表达，除了那些本应从GH细胞分化而来但目前不表达GH基因的细胞外，hPLAP表达还可标记当前产生GH的细胞。对成年雄性和雌性Cre+/-,Z/AP+/-垂体细胞进行双重免疫细胞化学分析发现，前脑垂体中产生GH的细胞大部分（约99%）也表达hPLAP，而产生促肾上腺皮质激素（ACTH）、促甲状腺激素（TSH）和促黄体生成素（LH）的细胞hPLAP呈阴性，这证实了之前的报道，即促肾上腺皮质激素细胞、促甲状腺激素细胞和促性腺激素细胞独立于生长激素细胞谱系发育。一小部分（约10%）产生催乳素的细胞hPLAP呈阳性，这与之前的报道一致，即在垂体发育过程中催乳素细胞可由生长激素细胞产生。然而，90%产生催乳素的细胞hPLAP呈阴性这一事实表明，成年小鼠垂体中的大多数催乳素细胞独立于生长激素细胞谱系发育。除了发育研究外，rGHp-Cre转基因小鼠将为研究多种基因在生长激素细胞功能和肿瘤转化中的作用提供一个多功能工具。
