Lan Zi-Jian, Xu Xueping, Chung Arthur C-K, Cooney Austin J
Birth Defects Center, University of Louisville Health Sciences Center, Louisville, Kentucky, USA.
Biol Reprod. 2009 May;80(5):905-12. doi: 10.1095/biolreprod.107.067322. Epub 2009 Jan 21.
Nuclear receptor subfamily 6, group A, member 1 (NR6A1) is an orphan member of the nuclear receptor superfamily and is required for normal mouse embryonic development. In adult mice, NR6A1 is predominantly expressed in spermatogenic cells and growing oocytes of the gonads and has a role in female reproduction by modulating the transcription of the oocyte-specific genes bone morphogenetic protein 15 (Bmp15) and growth differentiation factor 9 (Gdf9). In our goal to further understand the functional role of NR6A1 during postnatal development, we generated a Nr6a1:beta-galactosidase (LacZ) knockin reporter (Nr6a1(LacZ/+)) mouse line in which the Nr6a1:LacZ fusion gene was expressed and then characterized Nr6a1 expression in these reporter mice by performing LacZ staining. Our RT-PCR analyses showed that Nr6a1 was expressed in a variety of somatic tissues (e.g., oviduct and lung) other than gonads of normal adult mice. In adult Nr6a1(LacZ/+) mice, robust LacZ staining was observed in the gametes of gonads. Strong positive LacZ staining was also observed in the sperm of the epididymis, epithelial cells of the oviduct, and bronchioles within the lung. In adult Nr6a1(LacZ/+) mice, positive LacZ staining was observed in other somatic tissues, including hippocampus, cerebral cortex, cerebellum, and thalamus of brain; pars intermedia and pars anterior of pituitary; parathyroid; and islet of pancreas. NR6A1 expression in sperm within the epididymis, epithelial cells in the oviduct, and bronchioles of the lung was further confirmed by immunohistochemical studies. Nr6a1 is expressed not only in the germ cells of mouse gonads but also in a variety of somatic tissues, including epididymis, oviduct, brain, and pituitary. The extra-germ cell expression of NR6A1 makes it a less attractive contraceptive.
核受体亚家族6，A组成员1（NR6A1）是核受体超家族的一个孤儿成员，是正常小鼠胚胎发育所必需的。在成年小鼠中，NR6A1主要在性腺的生精细胞和生长中的卵母细胞中表达，并通过调节卵母细胞特异性基因骨形态发生蛋白15（Bmp15）和生长分化因子9（Gdf9）的转录在雌性生殖中发挥作用。为了进一步了解NR6A1在出生后发育过程中的功能作用，我们构建了一个Nr6a1:β-半乳糖苷酶（LacZ）敲入报告基因（Nr6a1(LacZ/+)）小鼠品系，其中Nr6a1:LacZ融合基因得以表达，然后通过进行LacZ染色来表征这些报告基因小鼠中的Nr6a1表达情况。我们的逆转录聚合酶链反应（RT-PCR）分析表明，Nr6a1在正常成年小鼠性腺以外的多种体细胞组织（如输卵管和肺）中表达。在成年Nr6a1(LacZ/+)小鼠中，在性腺的配子中观察到强烈的LacZ染色。在附睾精子、输卵管上皮细胞和肺内细支气管中也观察到强阳性LacZ染色。在成年Nr6a1(LacZ/+)小鼠中，在其他体细胞组织中观察到阳性LacZ染色，包括脑的海马体、大脑皮层、小脑和丘脑；垂体的中间部和前部；甲状旁腺；以及胰腺胰岛。免疫组织化学研究进一步证实了NR6A1在附睾精子、输卵管上皮细胞和肺细支气管中的表达。Nr6a1不仅在小鼠性腺的生殖细胞中表达，还在包括附睾、输卵管、脑和垂体在内的多种体细胞组织中表达。NR6A1在生殖细胞外的表达使其成为一种不太理想的避孕药。
